HEP Phenomenology·hep-ph

Tue·Jun 23, 2026Tuesday·June 23, 2026

72 papers—46 primary·26 cross-listed

01
Leggett-Garg Inequality Violation in Muon $g - 2$ Experiments
Brian Batell🇺🇸 · Morgan Cassidy🇺🇸 · Kun Cheng🇺🇸
We present the first study of Leggett-Garg inequality violation in polarized muon spin precession. We formulate a procedure to reconstruct temporal correlators of the longitudinal muon polarization from measured time-dependent muon decay spectra and apply it to publicly available Fermilab Muon $g - 2$ data corresponding to approximately $10$ billion muon decays. Using a simplified model of the detector acceptance and efficiency, the Leggett-Garg inequality is found to be violated with a single-bin significance of $5.5 σ$ , while combining neighboring bins further increases the significance. While our analysis is limited by systematic uncertainties associated with the detector modeling, a dedicated experimental analysis could reduce these uncertainties toward the statistical level, $O (1 0^{- 3})$ , potentially enabling one of the most precise measurements of temporal quantum correlations.
hep-ph2 citations
02
Minimal Proton-Mass Dark Matter
Majed Khalaf🇮🇱 · Eric Kuflik🇮🇱 · Alessandro Lenoci🇮🇱 · Hitoshi Murayama🇺🇸 · Edoardo Vitagliano🇮🇹
We present a minimal dark matter scenario: a single complex scalar carrying baryon and lepton number, with no new exact stabilizing symmetry. Its leading interaction is a dimension-7 semileptonic portal that, below confinement, generates a low-energy Yukawa coupling with the proton and electron. Requiring absolute stability of both the proton and dark matter forces the dark matter mass into a narrow window around the proton mass, which may be anthropically selected. Despite its minimal field content, the model can be probed by many observables: proton burning in stars, hydrogen decay, brown dwarfs and neutron star heating, and nucleon decay-like signatures in direct detection. UV-dominated freeze-in produces the observed relic abundance. This framework provides a unique testable example of dark matter arising from a minimal extension of the Standard Model.
hep-phastro-ph.COastro-ph.HEastro-ph.SR0 citations
03
Phenomenology of heavy-flavour jet angularities at hadron colliders
Andrea Ghira🇩🇪 · Lorenzo Mai🇮🇹 · Simone Marzani🇮🇹 · Daniel Reichelt🇨🇭 · Steffen Schumann🇩🇪 · Leon Stöcker🇩🇪
We compute resummed and matched predictions for jet angularities in hadronic Z+jet events, where the jet is initiated by a b-quark. The analysis is performed both with and without grooming the candidate jets using the SoftDrop algorithm. Mass effects are consistently included at both fixed-order and resummed levels. Our theoretical predictions also incorporate non-perturbative corrections from the underlying event and hadronization, implemented through parton-to-hadron transfer matrices extracted from dedicated Monte Carlo simulations with Sherpa. Finally, we compare results for b-jets with the ones from light-flavour jets, in order to quantify the impact of finite-mass effects.
hep-phhep-ex0 citations
04
Warm fermionic dark matter from freeze-in at stronger coupling
Duarte Feiteira🇫🇮 · Vinícius Oliveira🇵🇹
We study warm fermionic dark matter (DM) in the framework of freeze-in at stronger coupling, in the minimal Higgs portal scenario. The reheating temperature is taken to be low, so that DM production from the Standard Model thermal bath is Boltzmann-suppressed and the DM stays out of equilibrium even for a sizeable coupling. This opens the possibility of observable signatures, in particular invisible Higgs decays. We compute the DM relic abundance including both the pre- and post-reheating contributions. We find that the fermionic DM production reaction is strongly velocity suppressed, requiring larger reheating temperatures than those obtained for scalar DM in order to reproduce the correct relic abundance. The resulting DM momentum distribution is strongly non-thermal and its shape is not captured by the common $α β γ$ -parametrization. We find that the Lyman- $α$ constraint excludes DM masses below about $100 - 180 keV$ , depending on the reheating history.
hep-phastro-ph.CO0 citations
05
Centauric 1-Jettiness in DIS and Universal Power Corrections
Andrew Dotson🇺🇸 · June-Haak Ee🇺🇸 · Christopher Lee🇺🇸 · Yiannis Makris🇮🇹 · John Terry🇺🇸
We introduce the \emph{Centauric 1-jettiness}, $τ_{1}^{C}$ , a generalized event shape for Deep Inelastic Scattering (DIS) with adjustable beam and jet reference vectors and thus beam and jet regions. We demonstrate that a specific choice of weights allows this observable to exactly reproduce the geometric boundaries of the Centauro jet algorithm in the Breit frame. Within the framework of Soft-Collinear Effective Theory (SCET), we derive a factorized cross section in the small- $τ_{1}^{C}$ region in terms of known perturbative ingredients. This allows the resummation of large logarithms to N $^{3}$ LL accuracy, which we then match to fixed-order NLO QCD ( $O (α_{s}^{2})$ ) predictions from \texttt{NLOJet++}. We establish that the soft measurement reduces to a rescaled hemisphere measurement, placing Centauric 1-jettiness in the same universality class, for the leading non-perturbative corrections, as DIS thrust and jet mass. As a consequence, the leading non-perturbative shift depends on the same universal first-moment-shift parameter $Ω_{1}$ and scales exactly as $1/ R$ with the jet radius, thanks to the boost invariance of the Centauro algorithm along the photon axis in the Breit frame, a scaling that we test using \textsc{Pythia} simulations. These results open new strategies for determining the strong coupling from DIS event shapes, with $R$ providing a handle to break the degeneracy between $α_{s}$ and the universal non-perturbative shift parameter $Ω_{1}$ .
hep-ph4 citations
06
Counting axions with IAXO
Benjamín Grinstein🇺🇸 · Carlos Miró🇮🇹 · Pablo Quílez Lasanta🇺🇸
The existence of multiple axion species is a generic prediction of a number of extensions of the Standard Model. If more than one axion couples to photons, their combined signal in helioscope experiments may mimic that of a single axion with different parameters. This raises a fundamental question: if a next-generation helioscope such as IAXO detected a signal, would we be able to disentangle whether it originated from one or multiple axions? To answer this question, we first recast current CAST bounds and derive IAXO/IAXO+ projections in the two-axion parameter space, identifying the regions where a signal could be observed. Then, we analyze the spectral signatures of axion flavor oscillations in both the quasi-degenerate and hierarchical mass regimes, and point out where IAXO can discriminate a two-axion signal from the single-axion hypothesis given the expected energy resolutions of the detector. Finally, we show that these results extend to a broad class of $N$ -axion systems.
hep-phhep-ex1 citation
07
When CPT Violation Hides in Plain Sight: How CP Measurements Are Compromised and How to Fix Them
Miaochen Jin🇺🇸 · Gabriela Barenboim🇪🇸 · Carlos A. Argüelles🇺🇸 · Pablo Fernández-Menéndez🇪🇸 · Ivan Martinez-Soler🇬🇧
The extraction of the leptonic charge-parity (CP)-violating phase $δ_{CP}$ from long-baseline neutrino oscillation experiments rests on the assumption of charge-parity-time (CPT) conservation. We show that CPT violation, parametrized as an asymmetry $δ Δ m_{31}^{2} \equiv Δ m ˉ_{31}^{2} - Δ m_{31}^{2}$ between neutrino and antineutrino mass splittings, induces an effective, energy-dependent phase shift $ϕ_{eff} (E)$ that is functionally degenerate with $δ_{CP}$ in the appearance asymmetry $⟨ Δ P ⟩$ . This has a profound implication for long-baseline experiments, where the tension between T2K and NO $ν$ A CPT-conserving best-fit $δ_{CP}$ values can be significantly alleviated by a CPT-violating truth; and a CPT-conserving fit can miss the true CP phase entirely for $∣ δ Δ m_{31}^{2} ∣ ≳ 0.3 \times 1 0^{- 3} eV^{2}$ for DUNE. We then demonstrate that atmospheric neutrino telescopes provide the natural tool to resolve this degeneracy: using existing data from IceCube-DeepCore (7.74 yr) and KM3NeT/ORCA-6 (433 kt-yr), we derive a world-leading constraint on CPT-violation at $∣ δ Δ m_{31}^{2} ∣ \leq 0.57 \times 1 0^{- 3} eV^{2}$ at 90% CL. With the IceCube Upgrade and full ORCA detector, we can reach a $1 σ$ constraint at $1 0^{- 4} eV^{2}$ within a decade, providing the independent CPT constraint needed to ensure that DUNE's $δ_{CP}$ measurement is unambiguous.
hep-phhep-ex0 citations
08
Event-Level QCD Inference Framework for Quark-Gluon Imaging
Patrick Barry🇺🇸 · Pi-Yueh Chuang🇺🇸 · Ian Cloët🇺🇸 · Emil Constantinescu🇺🇸 · Arkaprabha Ganguli🇺🇸 · Chao Peng🇺🇸
We introduce and demonstrate an event-level analysis framework for quark-gluon imaging. For a first application we use it for the inference of parton distribution functions from synthetic deep inelastic scattering data. This framework removes the need for unfolding of detector effects and the binning of events, and therefore eliminates two key sources of information loss. We contrast this event-level framework with the traditional histogram approach by performing a closure test for parton distribution functions from event data obtained from a known ground truth. In this study we assume a perfect detector, which makes unfolding straightforward. The elimination of binning in the event-level framework is demonstrated to have important benefits over the traditional histogram approach, and performs better in the closure test, particularly for a smaller number of events. For example, defining a mean-squared error distance metric, we find that the event-level framework performs around $35%$ better than the traditional approach for a moderate number of events. The benefits of an event-level framework should increase for inference associated with 3D quark-gluon imaging, because these differential cross sections are of higher dimension and the comparative number of measured events is significantly reduced.
hep-phhep-exnucl-th0 citations
09
Gluon GTMD at strong coupling: fixed-spin saddle factorization and Reggeization
Kiminad A. Mamo🇺🇸 · Ismail Zahed🇺🇸
Generalized transverse-momentum-dependent parton distributions (GTMDs) are the most complete two-parton correlation functions in QCD, encoding the joint spatial and momentum structure of hadrons. Through appropriate projections and limits they yield generalized parton distributions (GPDs), transverse-momentum-dependent distributions (TMDs), parton distribution functions (PDFs), and phase-space (Wigner) distributions. We construct conformal moments of unpolarized gluon GTMDs at strong coupling using gauge/string duality. For fixed even conformal spin $j$ , we distinguish the local boundary limit at $b_{T} = 0$ from the finite-separation regime $b_{T} > 0$ , where the planar semiclassical amplitude is governed by a minimal worldsheet. There the GTMD moment factorizes into a universal staple-worldsheet soft factor and a stripped spin- $j$ Witten amplitude carrying target dependence. The cusp of the renormalized minimal area generates the rapidity-logarithmic Collins-Soper structure. We derive universal ultraviolet and infrared endpoint reductions. As $b_{T} \to 0^{+}$ , the finite-separation sector matches onto the local conformal moment through a universal overlap kernel. At large $b_{T}$ , after cusp/perimeter subtraction, it factorizes into target projections and infrared transfer kernels. The ultraviolet endpoint is universal within the leading saddle, whereas the infrared tail depends on the holographic completion: soft-wall, gap-matched hard-wall, and repulsive-wall backgrounds generate algebraic, exponential, and Gaussian falloffs, respectively. Analytic continuation in $j$ yields the low- $x$ Regge regime governed by the holographic Pomeron spectral curve. The framework describes hadron tomography, transverse structure, rapidity evolution, and Reggeization for GTMD moments and provides a unified starting point for holographic studies of observables relevant to the Electron-Ion Collider.
hep-phhep-thnucl-th0 citations
10
Neutrino Dipole Moments and Radiative Signatures from Partial Compositeness
Benoît Assi🇺🇸 · Pedro A.N. Machado🇺🇸
We investigate composite neutrino models where heavy neutrinos emerge as bound states from a near-conformal strongly coupled sector. Standard Model neutrinos mix with these composite singlets via an inverse seesaw mechanism, where the anomalous scaling dimensions of the composite-sector operators naturally suppress light neutrino masses to sub-eV scales. Matching the conformal dynamics onto low-energy theory yields enhanced electromagnetic transition dipole operators with couplings $d_{μ N} \sim 1 0^{- 6}$ - $1 0^{- 8} GeV^{- 1}$ , parametrically larger than the loop-level predictions of minimal Dirac or Majorana models. We carry out a dedicated event-level simulation of the production-and-decay chain $ν X \to U X \to ν γ X$ and compute the resulting event rates at MiniBooNE and MINERvA within the model, accounting for the composite production cross section and decay kinematics in detail. We further present predictions for the photon energy, angular, and multiplicity distributions. For the benchmark scenarios accessible at these experiments the radiative signal is predominantly single-photon; the composite structure additionally permits fragmentation of the up-scattered state into multiple heavy neutrinos, each decaying as $N \to ν γ$ , with multi-photon final states emerging for lighter compositeness scales or higher beam energies as a qualitatively new probe of the composite dynamics.
hep-phhep-ex0 citations
11
Pion structure from its light-front wave function
Khépani Raya🇪🇸 · Zhen-Ni Xu🇪🇸 · Zhao-Qian Yao🇪🇸 · José Rodríguez-Quintero🇪🇸
Understanding the structural properties of the pion is essential for elucidating the mechanisms of mass generation within the Standard Model and their role in the emergence and properties of the hadronic matter. Light-front wave functions encode extensive information about the internal structure of these systems and provide the link to measurable quantities such as generalized parton distributions and transverse-momentum-dependent distributions. Guided by recent progress in continuum Schwinger methods, we derive well-founded and practical representations of these quantities, enabling the exploration of several facets of the pion structure, including distribution amplitudes and distribution functions, elastic and gravitational form factors, and the associated momentum and spatial distributions. The results presented here are consistent with expectations and can be tested at modern experimental facilities, including the new generation of electron-ion colliders.
hep-phnucl-th2 citations
12
Spin correlations and quantum entanglement in $γ γ \to t t ˉ$ at polarized photon colliders with NLO QCD corrections
Jun Jiang🇨🇳 · Zong-Guo Si🇨🇳 · Han Zhang🇨🇳 · Xin-Yi Zhang🇨🇳
We study spin correlations and quantum entanglement in the process $γ γ \to t t ˉ$ with the photons coming from Compton backscattered laser beam. We present predictions for the cross sections and spin observables including next-to-leading order (NLO) QCD corrections under various beam-polarization configurations. The NLO QCD corrections significantly enhance the total cross section while having only a minor impact on spin observables. Using the spin density matrix of the $t t ˉ$ system, we further investigate quantum entanglement and Bell nonlocality. We find that the entanglement is the strongest near the $t t ˉ$ invariant-mass threshold, while both entanglement and Bell nonlocality are highly sensitive to the initial beam polarization. Our results provide a theoretical basis for future studies of quantum correlations in top-quark pair production at photon colliders.
hep-ph2 citations
13
Large Language Model-Assisted Framework for BSM Model Building
Shaikh Saad🇸🇮
Recent advances in artificial intelligence (AI), particularly large language models (LLMs), have created new opportunities for natural-language interaction with scientific software, but reliable theoretical model building still requires deterministic symbolic calculations. We present \texttt{bsm_agent}, an open-source symbolic framework for beyond the Standard Model (BSM) model building that combines a deterministic physics backend with an LLM chat interface. Starting from the SM field content and a user-specified set of additional scalars and/or fermions, the package constructs renormalizable Lagrangian, performs gauge-anomaly checks, expands operators into component fields, and derives electroweak symmetry breaking stationary conditions and tree-level mass matrices. The key novelty of the framework is that all of these tasks are performed automatically once the user specifies the quantum numbers of the new fields through a natural-language interface, eliminating the need for manual model construction. The symbolic calculations are performed entirely by the Python backend to ensure the correctness and reproducibility of the physics results; the LLM is used only as an orchestration layer that interprets natural-language requests, manages confirmation steps for ambiguous inputs, triggers backend tools, and formats report-ready summaries. The package supports three provider classes: local Ollama inference, remote self-hosted model servers accessed through the implemented remote provider interface, and commercial hosted APIs via OpenAI and Anthropic. This separation between conversational control and deterministic computation preserves reproducibility while making interactive BSM model construction substantially more convenient.
hep-ph4 citations
14
Theoretical consistency and phenomenology of supercooled cosmological phase transitions
Maciej Kierkla🇵🇱
This dissertation investigates a supercooled phase transition (PT) in the early Universe. Using high-temperature dimensional reduction (DR), we compute the NLO thermal bubble nucleation rate. By explicitly evaluating fluctuation determinants, we provide a state-of-the-art description of thermal bubble nucleation. As a case study, we consider the SU(2)cSM, an extension of the conformal Standard Model with an additional SU(2) $_{X}$ gauge sector and scalar field that acquires a vev through radiative symmetry breaking. This symmetry breaking proceeds via a supercooled first-order phase transition. The first part of the thesis introduces the theoretical framework, including effective actions, RG improvements, finite-temperature quantum field theory, effective field theory techniques, and thermal bubble nucleation. The second part applies these methods to the SU(2)cSM. We establish a consistent power-counting scheme, construct the leading-order effective potential, analyse symmetry breaking and parameter space, derive an RG-improved potential, and incorporate thermal corrections. We then apply high-temperature DR to a classically scale-invariant model for the first time, derive the corresponding three-dimensional EFT, and compute the NLO nucleation rate. A detailed numerical evaluation of fluctuation determinants enables a comparison of different approximation schemes and their limitations. Finally, we present the phenomenological implications. We determine phase transition parameters, perform parameter scans, and predict the resulting gravitational wave signals. We find that the supercooled phase transition in the SU(2)cSM produces a strong signal detectable by LISA throughout the parameter space considered, making the model experimentally testable. We also demonstrate that higher-order corrections can significantly affect both phase transition dynamics and gravitational wave predictions.
hep-phastro-ph.COhep-th1 citation
15
Accessing the HQET B-Meson Shape Function from a LaMET Quasi-Shape Function
Ao-Sheng Xiong🇨🇳 · Jun Ding🇨🇳 · Ji Xu🇨🇳 · Jun Zeng🇨🇳 · Shuai Zhao🇨🇳
The shape function and the light-cone distribution amplitude of heavy meson jointly characterize the nonperturbative structure of the heavy meson on the light-cone, with the former being essential for theoretical predictions of inclusive decays and the latter for exclusive decays. While first-principles lattice QCD results for the heavy meson LCDA have become available in recent years, lattice results for the shape function remain absent. In this work, we establish a two-step factorization scheme -- known as the HQLaMET framework -- for computing the $B$ -meson shape function on the lattice, which fully disentangles the effects of the disparate scales $P_{B}^{z}$ , $m_{b}$ , and $Λ_{QCD}$ . For illustration, starting from a phenomenological model for the shape function in HQET, we provide a graphical presentation of the entire procedure of this framework. The results of the current work lay the foundation for nonperturbative lattice QCD determinations of the shape function in the near future.
hep-ph2 citations
16
Heavy-quark pair-production in DIS at NLO QCD matched to a parton shower
Santiago Castro🇭🇺 · Clara Del Pio🇺🇸 · Adam Kardos🇭🇺 · Sven-Olaf Moch🇩🇪 · Aris Spourdalakis🇭🇺
We present theoretical predictions for heavy-quark pair-production in deep-inelastic scattering (DIS) at next-to-leading order (NLO) in quantum chromodynamics (QCD), matched to a parton shower in the POWHEG framework. We revisit the NLO heavy-quark pair-production cross section and implement a consistent matching to parton-shower evolution, with careful treatment of heavy-quark mass effects and the avoidance of double counting between fixed-order and parton-shower radiation. In addition, we compare the virtual NLO corrections available in the literature to one-loop amplitudes obtained through massification in the small-mass limit. This provides an independent validation of the virtual contributions. The study is presently restricted to the gluon-initiated channel, which dominates the kinematic region of interest at the HERA collider and remains important for the future Electron-Ion Collider.
hep-ph0 citations
17
Probing Light Dark Fermions in $B \to D^{(*)} ℓ X_{inv}$ via Rate Distributions
Lipika Kolay🇮🇳 · Soumitra Nandi🇮🇳 · Shantanu Sahoo🇮🇳 · Ria Sain🇨🇳
Experimental analyses of the semileptonic decays $B \to D^{(*)} ℓ ν ˉ$ typically rely on the assumption that the missing energy originates from a massless neutrino, as predicted by the Standard Model. However, this assumption may not hold in scenarios where the invisible final-state particle is instead massive, such as a sterile neutrino or a dark-sector fermion. In this work, we explore how the presence of a massive dark sector fermion modifies the kinematic and angular distributions of these decays. Our analysis is carried out within the framework of a general weak effective theory, and we also discuss effective and simplified models in which these interactions may arise. In addition, we study the implications of these effects for the extraction of the CKM matrix element $∣ V_{c b} ∣$ . Overall, our results show that relaxing the standard assumption of a massless neutrino can lead to observable effects and provide a framework for systematically investigating their impact on semileptonic $B$ - decay distributions.
hep-ph1 citation
18
Globally Charged Vacuum Decay
Giulio Barni🇪🇸 · Jose R. Espinosa🇪🇸
Vacuum decay at zero temperature is generically described by a real $O (4)$ -symmetric Coleman bounce. When the scalar field driving the decay carries a conserved global charge, this picture changes qualitatively: the path integral must be projected onto a definite charge sector, the Euclidean field obeys twisted boundary conditions, and the saddle is complex. For the simplest case of a $U (1)$ global symmetry, we first reformulate this problem in a two-field real Euclidean description with a real saddle. We then solve the resulting two-dimensional partial differential equation problem describing the decay of a homogeneous charged medium to a deeper vacuum via bubble nucleation. At finite charge the bounce departs from $O (4)$ symmetry, the barrier between vacua is lowered, and the decay rate increases. Continuing the solution to real time, we find that charge rearrangement around the expanding wall costs phase-gradient energy and drives the bubble to a subluminal terminal velocity even in vacuum. We also clarify how the fixed-charge construction interfaces with finite-temperature and finite-chemical-potential descriptions.
hep-phastro-ph.COhep-th3 citations
19
Domain Structures and Static Potentials in $G_2$ Gauge Theory
Seyed Mohsen Hosseini Nejad🇮🇷
We investigate the domain structures of the $G_2$ vacuum and the associated static potentials within the domain model, considering both zero and non-zero aggregate flux vacuum domains. Potentials associated with domains of zero aggregate flux exhibit favorable Casimir scaling and convexity properties at intermediate distances, and their long-range behavior matches the expected ordering of constant potential values according to representation. In contrast, potentials derived from domains with nonzero aggregate flux deviate from the key features of the confining force, as the absence of a minimal center-flux magnitude renders such configurations physically improbable. Furthermore, the potential ratios for $SU(3)$ and $SU(2)$ subgroups are found to be consistent with Casimir ratios of $G_2$ at intermediate regimes, suggesting a possible role for these subgroups in the confinement mechanism of the $G_2$ gauge group.
hep-ph0 citations
20
Analytic results for heavy-quark contributions to charged-current DIS at NNLO
Fabrizio Caola🇬🇧 · Giulio Gambuti🇨🇭 · Martin Link🇬🇧
We present analytic results for the next-to-next-to-leading-order QCD corrections to heavy-quark production in charged-current deep-inelastic scattering, retaining the exact dependence on the charm quark mass. We compute the complete partonic coefficient functions for the structure functions $F_{2}$ , $F_{L}$ , and $F_{3}$ in the quark and gluon channels, including contributions with up to three heavy quarks in the final state. Working within the reverse-unitarity framework, we use integration-by-parts and canonical differential-equations techniques to express all contributions with at most two final-state heavy quarks in terms of manifestly real Goncharov polylogarithms which allow for a robust and efficient numerical evaluation. The three-heavy-quark contribution involves elliptic structures for which we give a general representation in terms of Chen iterated integrals, as well as expressions in terms of rapidly convergent expansions that are valid in the perturbative $Q ≳ 5 GeV$ region and also allow for a flexible and fast numerical evaluation. We validate our results against known exact results at lower orders, massless NNLO coefficient functions, and existing leading-power expansions in the asymptotic limit where the virtuality $Q$ is much larger than the charm mass.
hep-phhep-ex4 citations
21
Generalized parton distributions of a deuteron in an AdS/QCD hard-wall model
Minaya Allahverdiyeva🇦🇿 · Shahin Mamedov🇦🇿
We investigate the gravitational form factors (GFFs) and the generalized parton distributions (GPDs) of the deuteron within the framework of the hard-wall AdS/QCD model. The momentum dependence of the GFFs obtained here is in good agreement with the results of the soft-wall AdS/QCD model. The value of the gravitational mean square radius in this model agrees with the experimental data. GFFs provide a holographic description of the. Deuteron GPDs are obtained from GFFs via sum rules and have shapes of plots similar to those for GPDs extracted from the electromagnetic form factors (EFFs) calculated in the framework of the soft-wall AdS/QCD model.
hep-ph0 citations
22
The shear viscosity of quark-gluon matter calculated with parton transport and comparisons with the Chapman-Enskog results
Mason Alexander Ross🇺🇸 · Zi-Wei Lin🇺🇸
We numerically calculate the shear viscosity of quark-gluon matter via the Green-Kubo relation with an improved ZPC model. We include all $2 \leftrightarrow 2$ parton cross sections at finite temperature, which are based on perturbative QCD and screened with thermal masses, and consider massless quark-gluon systems with Boltzmann statistics in chemical equilibrium. We then compare the Green-Kubo results with the analytical results from the leading-order Chapman-Enskog method for the same parton cross sections over the temperature range $150 - 600$ MeV. We also examine the simpler case of isotropic and constant parton cross sections. Overall, we find that the two methods agree rather well. Specifically, the Green-Kubo results are greater than the Chapman-Enskog results by an average of $\sim 9%$ for isotropic and constant cross sections and by an average of $\sim 3%$ for finite-temperature pQCD cross sections, where the difference between the two methods is presumably due to higher-order corrections to the leading-order Chapman-Enskog results.
hep-phnucl-th1 citation
23
The feasibility of single $Λ$ production via $ℓ^{-}$ $+$ $p$ $\to$ $Λ$ $+$ $ν_{ℓ}$ at $e^{+} e^{-}$ colliders
Yueling Yang🇨🇳 · Peisheng Tian🇨🇳 · Shuangshi Fang🇨🇳 · Bingbing Yang🇨🇳 · Junfeng Sun🇨🇳
We present a comprehensive investigation of single $Λ$ hyperon production via the lepton-nucleon deep inelastic scattering (LNDIS) process, $ℓ^{-}$ $+$ $p$ $\to$ $ν_{ℓ}$ $+$ $Λ$ , in the experimental environment of electron-positron colliders. Our approach utilizes incident leptons originating from the decays of resonances ( $J / ψ$ , $ψ (2 S)$ , $Υ (1 S)$ , $Υ (2 S)$ , and $Z^{0}$ ) produced in $e^{+} e^{-}$ collisions, which then scatter off stationary protons in the surrounding detector materials. The differential and total cross sections are calculated using baryonic transition form factors parameterized with the $z$ -expansion scheme within both the quantum chromodynamics (QCD) sum rule and lattice QCD frameworks. Our results indicate that the cross section increases with center-of-mass energy and is highly sensitive to the choice of form factors, resulting in significant theoretical uncertainties. This study highlights the experimental challenges in observing the LNDIS process at $e^{+} e^{-}$ colliders and underscores the need for improved determination of baryonic form factors. It serves as a valuable reference for future experimental searches and suggests that an anomalous observation of single $Λ$ hyperon production at $e^{+} e^{-}$ colliders could indicate new physics.
hep-phhep-exEPJC(2026)·0 citations
24
Monte Carlo Event Generators for Future Lepton Colliders
Alan Price🇵🇱
Monte Carlo event generators are essential tools in collider physics, providing the link between theoretical predictions and experimental measurements through fully exclusive event simulation. Future collider programmes, particularly high-precision lepton colliders will place significantly increased demands on their accuracy and scope. This contribution reviews key challenges in MC generator development, including electroweak corrections, initial-state radiation, beam dynamics, perturbative QCD, and non-perturbative modelling. The discussion is not exhaustive and reflects a selective choice of topics.
hep-phhep-exEur.Phys.J.Plus(2026)·0 citations
25
Rare Exclusive Decays of the Z-boson into S-wave Quarkonia within the Bethe-Salpeter Formalism
Asif Ali🇨🇳 · Yi-Jie Li🇨🇳 · Guang-Zhi Xu🇨🇳 · Kui-Yong Liu🇨🇳
This paper investigates the rare decays of the Z boson into S-wave quarkonia within the Bethe-Salpeter formalism. Both the production of double S-wave quarkonia and radiative decays into single S-wave quarkonium are analyzed. For double quarkonia production, i.e., $Z \to V V$ and $Z \to V P$ (where $V$ and $P$ represent vector and pseudoscalar quarkonia, respectively), we consider the leading order contribution from both QCD as well as electromagnetic transition via virtual photon (QED) amplitudes. The heavy quark limit is adopted to simplify calculations. Additionally, we have introduced another possible leading order channel for Z-boson decays to double S-wave quarkonia, where the Z boson decays into bottomonium plus charmonium via QED amplitude. Such processes may include $Z \to J / ψ + Υ (1 S)$ , $Z \to η_{b} + J / ψ$ and $Z \to η_{c} + Υ (1 S)$ . Moreover, we have also studied radiative Z boson decays to S-wave quarkonium, namely $Z \to X (Q Q ˉ) γ$ , where $X (Q Q ˉ) = J / ψ$ , $Υ$ , $η_{c}$ , and $η_{b}$ . Interestingly, for double charmonium and radiative charmonium production, our results are larger than the NRQCD finding, while for the bottomonium case, our findings are comparatively smaller. This shows that charmonium is a relativistic particle, while bottomonium is a non-relativistic particle.
hep-ph0 citations
26
Pseudo-scalar dark matter from a broken gauged symmetry
Junho Kang🇰🇷 · Sarif Khan🇮🇳 · Jongkuk Kim🇰🇷 · Hyun Min Lee🇰🇷
We propose a novel model for pseudo-scalar dark matter (PSDM) by extending the Standard Model (SM) with a dark gauged $U (1)_{X}$ symmetry, but without dark charged fermions. We impose a $Z_{2}$ symmetry to ensure the stability of pseudo-scalar dark matter and regard the $U (1)_{X}$ symmetry as being broken dominantly by a large VEV of the singlet scalar field. The would-be Goldstone associated with the $U (1)_{X}$ gauge boson is almost orthogonal to the direction of PSDM. As a result, we show that PSDM appears as a stable pseudo-Nambu-Goldstone boson receiving the mass from the $U (1)_{X}$ invariant mixing potential and the corresponding cross section for direct detection gets suppressed even for the weak-scale mass of PSDM. We also show that the correct relic density can be explained by the PSDM annihilations into the SM particles or into a pair of light Higgs-like scalars, being compatible with the bounds from Higgs invisible decay, Higgs data and indirect detection.
hep-phJHEP(2026)·0 citations
27
Probing Anomalous $t q ˉ Z$ Interactions at Muon Colliders
Liangliang Shang🇨🇳 · Lu Zhang🇨🇳 · Bingfang Yang🇨🇳 · Stefano Moretti🇬🇧
In the framework of effective field theory, we study the anomalous $t q ˉ Z$ interaction through the process $μ^{+} μ^{-} \to t q ˉ Z$ at future muon colliders with $s = 3, 10, 14 TeV$ . Based on the top quark decay modes involving $W$ and $Z$ bosons, we first divide the signal into six cases. Then, in order to obtain the limits on the corresponding branching ratios, we perform a detector simulation for both signals and Standard Model backgrounds. To enhance the signal significance, we exploit the polarization of the muon beams and employ the fat jet method to reconstruct signals in hadronic final states. For $s = 14 TeV$ with $20 ab^{- 1}$ , we find that the upper limit on the branching ratio for $t \to q Z$ can reach the order of $O (1 0^{- 8})$ , which exceeds the limits provided by the CMS and ATLAS collaborations by 2 to 3 orders of magnitude. Our study thus demonstrates that TeV-scale muon colliders can provide an efficient and complementary platform for probing rare top quark interactions.
hep-ph0 citations
28
Analytical calculation of the spectrum of nonlinear Compton scattering beyond local approximations
M. P. Malakhov🇷🇺 · Th. Benahmed🇨🇿 · E. G. Gelfer🇨🇿 · A. M. Fedotov🇷🇺 · O. Klimo🇨🇿 · S. Weber🇨🇿 · S. G. Rykovanov🇷🇺
We derive compact analytical formulae for the spectrum of nonlinear Compton scattering in a finite plane-wave pulse with a smooth temporal envelope. The strong-field QED probability is reduced to finite-pulse phase integrals, which are evaluated asymptotically for multicycle pulses with a broad class of smooth envelopes. We use the uniform approximation to remove the caustic divergences that appear at the nonlinear edges of broadened harmonics. Away from the caustics, it reduces to the standard saddle-point result. The behavior near the linear edge is further improved by an envelope-corrected saddle-point approximation. The approach retains the harmonic substructure in the spectral-angular region carrying the dominant part of the emitted radiation. The locally monochromatic approximation is recovered by averaging the finite-pulse interference. Within their asymptotic domain of applicability, the resulting formulae agree with direct numerical calculations and can be used to evaluate spectra from an electron beam.
hep-phphysics.app-phphysics.plasm-ph2 citations
29
Taming Symbolic IBP Reduction with Intermediate Bases
Qian Song🇧🇪
Despite many years of development in integration-by-parts reduction, reconstructing all reduction coefficients, which are rational polynomials of kinematic variables and the space-time dimension, remains a non-trivial problem. The main difficulty comes from the large number of unknowns in a general ansatz, which can lead to a linear system that is too large to solve. In this paper, we present an algorithm for reconstructing reduction coefficients through a sequence of intermediate bases. The resulting analytic reduction coefficients are products of a few analytic matrices, whose non-zero entries are simple rational polynomials. We demonstrate the efficiency of this algorithm with two cutting edge examples: a three-point massive box-triangle and a four-point massive pentagon-triangle. Reconstructing all reduction coefficients for the box-triangle (pentagon-triangle) requires 3289 (13013) numerical samplings, significantly fewer than the number of unknowns in the general ansatz, 1407406 (21638331).
hep-ph0 citations
30
Study on the Cabibbo-favored $B_{d, s}$ $\to$ $D_{d, s}^{(*) +} S^{-}$ weak decays in QCD factorization
Lili Chen🇨🇳 · Chenyang Jing🇨🇳 · Kaiyuan Gao🇨🇳 · Shuai Xu🇨🇳 · Mengfei Zhao🇨🇳
Motivated by recent experimental progress and theoretical developments, we investigate the Cabibbo-favored $b \to c$ governed $B_{d, s}$ $\to$ $D_{d, s}^{(*) +} S^{-}$ ~( $S$ $=$ $K_{0}^{*} (1430)$ , $a_{0} (1450)$ ) weak decays by considering the next-to-leading (NLO) contributions within QCDF framework. With the updated values of $B_{(s)} \to D_{(s)}^{(*)}$ transition form factors obtained from a covariant light-front quark model, branching ratios are estimated in two scenarios for scalar mesons. It is found that the branching ratios for $B^{0} \to D^{+} a_{0}^{-}$ and $B_{s}^{0} \to D_{s}^{+} a_{0}^{-}$ decays can reach up to the order of $O (1 0^{- 4})$ in scenario-2 by assuming that the scalar mesons are lowest-lying p-wave states, which deserve high-priority experimental searches and may be observed in the ongoing LHCb and SuperKEKB experiments.
hep-ph0 citations
31
Dynamics of ( $Z_{N}$ ) Domain Walls in SU(N) Gauge Theories
Sayanjit Banerjee🇮🇳 · Sanatan Digal🇮🇳 · Sumit Shaw🇮🇳
We study collisions of domain walls in $S U (N)$ gauge theories using the Polyakov-loop effective potential models. We find that string junctions play a crucial role in the dynamics of $Z_{N}$ domain walls. In $S U (3)$ gauge theory, the merger of two non-planar $Z_{3}$ domain walls into a single wall proceeds via the creation of a vortex--antivortex pair in $2 + 1$ dimensions. In $S U (4)$ gauge theory, low-energy collisions of $Z_{4}$ walls result in the formation of a single domain wall without the creation of vortices. At higher collision energies, two $Z_{4}$ domain walls can either bounce back or scatter into another pair of domain walls through the formation of vortices. The creation of vortex--antivortex pairs generalises to the creation of string loops in $3 + 1$ dimensions for both gauge theories. These results demonstrate a direct dynamical role for topological strings in the evolution of center-domain-wall networks and reveal a new aspect of defect dynamics in non-Abelian gauge theories.
hep-phhep-th0 citations
32
Quantum Simulation of Generalized Parton Distributions in the Schwinger Model
Tianyin Li🇯🇵 · Hongxi Xing🇨🇳
We present a quantum algorithm for simulating Generalized Parton Distributions (GPDs) in the Schwinger model. Unlike the staggered fermions widely utilized in current quantum simulations, we employ Wilson fermions for lattice discretization. This choice is critical for the quantum computation of GPDs due to their strict preservation of charge conjugation symmetry. We construct a comprehensive algorithmic framework that includes the preparation of hadronic states with non-zero momentum and the measurement of light-cone correlation functions incorporating Wilson lines. We provide a complexity analysis, demonstrating that the resources required for our algorithm scale polynomially with both the number of qubits and the desired precision $ε$ . Finally, we benchmark our approach using exact diagonalization, extracting mass spectra and GPDs (also parton distribution functions) that are consistent with theoretical expectations and fundamental physical constraints.
hep-phhep-latnucl-th0 citations
33
Radiative Lifting of $Z_{3}$ Domain-Wall Degeneracy in a Type-III Seesaw Model: Implications for Leptogenesis and Gravitational Waves
Priya🇮🇳 · Labh Singh🇮🇳 · B. C. Chauhan🇮🇳 · Surender Verma🇮🇳
In this work, we study a $Z_{3}$ -symmetric extension of the Standard Model with three hyperchargeless $S U (2)_{L}$ fermion triplets responsible for neutrino mass generation $via$ the Type-III seesaw mechanism together with a complex scalar singlet $χ$ whose vacuum expectation value spontaneously breaks the $Z_{3}$ symmetry. Radiative corrections induced by the Yukawa interactions between the $S U (2)_{L}$ fermion triplets and the complex scalar singlet $χ$ generate a Coleman-Weinberg vacuum bias that lifts the degeneracy among the $Z_{3}$ vacua, leading to the annihilation of unstable domain-walls. Consequently, the degeneracy among the $Z_{3}$ vacua is lifted radiatively through the Coleman-Weinberg effective potential, generating a dynamical bias term that triggers the annihilation of unstable domain walls. We perform a numerical analysis consistent with current neutrino oscillation data and identify viable regions of parameter space accommodating the observed neutrino masses and leptonic mixing parameters. The observed baryon asymmetry of the Universe is generated through thermal leptogenesis $via$ the out-of-equilibrium decay of the lightest fermion triplet for masses around $O (1 0^{9}) GeV$ , consistent with the Type-III seesaw framework. Depending on the choice of model parameters, the predicted gravitational-wave spectrum can fall within the sensitivity reach of future space-based and ground-based gravitational-wave detectors. Our framework therefore establishes a correlation between neutrino mass generation, leptogenesis, radiative domain-wall instability, and gravitational-wave phenomenology.
hep-phhep-th1 citation
34
Remarks on atmospheric effect of D-foam in light of muon puzzle
Chengyi Li🇨🇳
In our recent paper~[1], we used a stringy model for quantum space-time foam to suggest that the so-induced subluminal Lorentz violation~(LV) for photons would not lead to experimentally unacceptable changes in the developments of particle showers initiated by cosmic $γ$ -rays in the Earth's atmosphere, in contrast to other approaches to LV. The result indicated, nonetheless, at the same time that the foam can mildly modify the electromagnetic cascades under certain conditions, by suppressing pair creation on nuclei by primary photons. In this addendum, we consider how this modification affects the detection of extensive air shower~(EAS) initiated by an ultrahigh-energy cosmic-ray particle~(viz., a primary hadron), like proton with $E \sim 1 0^{19} eV$ , given that secondary photon subshowers following $π^{0}$ decays could be similarly influenced. We argue that fewer electrons would reach the detector and hence the energy of the primary particle may be underestimated due to foam effects, enhancing in such a way the muon content in EASs. This opens up the possibility of interpreting the alleged ``excess'' of muons, as reported by Auger and Telescope Array collaborations recently and many other experiments on high-energy cosmic rays, with a quantum-gravitational effect. Future observations are anticipated to confirm whether this anomaly really exists.
hep-phastro-ph.HEgr-qcPLB(2026)·0 citations
35
A novel approach for studying two-particle momentum correlation function in relativistic nuclear collisions
Zhi-Lei She🇨🇳 · Wen-Chao Zhang🇨🇳 · An-Ke Lei🇨🇳 · Dai-Mei Zhou🇨🇳 · Hua Zheng🇨🇳 · Li-Lin Zhu🇨🇳 · Qiang Wang🇨🇳 · Yu-Liang Yan🇨🇳 · Zhong-Qi Wang🇨🇳 · Ben-Hao Sa🇨🇳
Two particle momentum correlation functions provide a nontrivial tool for probing the strong interaction and/or extracting particle emission source information in relativistic nuclear collisions. Although transport models can describe the microscopic phase-space evolution of the collision system, calculating correlation functions within the framework of transport models remains challenging. In this paper, we employ the mixed-event technique to calculate two particle momentum correlation function as $C (k^{*}) = N ξ (k^{*}) \frac{N _{same} ( k ^{*} )}{N _{mixed} ( k ^{*} )}$ based on the parton and hadron cascade model PACIAE simulated final hadronic state (FHS) with introducing a modification factor $ξ (k^{*})$ to improve the treatment of final-state interactions and quantum statistics effects in the PACIAE model. The simulated results show good agreement with the ALICE data for $K p$ , $pp$ , $p Λ$ , and $ΛΛ$ momentum correlation functions in $pp$ collisions at $s = 7$ TeV. On the other hand, the particle emission source radius of the correlated pairs are also evaluated based on the simulated FHS self-consistently. Since the PACIAE model employs hadron-hadron cross sections derived from the additive quark model, the calculation of two-particle momentum correlation functions does not require prior assumptions about the interaction between the two correlated particles. This successful ``PACIAE + modification factor" approach may shed light on the future study of momentum correlation functions for dimesons, dibaryons, and even diexotic hadrons.
hep-phnucl-th0 citations
36
Twisting Small- $x$ Gluon Tomography with Orbital Angular Momentum
Wei Kou🇨🇳 · Xurong Chen🇨🇳
We propose an orbital-angular-momentum-resolved extension of small- $x$ gluon tomography in hard diffractive dijet deep inelastic scattering. In the standard plane-wave setup, the elliptic correlation between the dijet relative momentum and the target recoil probes the elliptic component of the small- $x$ gluon Wigner distribution through a fixed transverse readout. We show that replacing the plane-wave lepton current by a twisted wave-packet current promotes this readout into a tunable OAM--Bessel projection kernel. The exchanged virtual photon is not treated as an asymptotic vortex particle; the OAM dependence enters through the transverse structure of the lepton electromagnetic current. The resulting observable is a family of $M$ -resolved elliptic correlations $A_{2}^{(M)} (q_{T}, R_{γ})$ , where $q_{T}$ denotes the transverse Bessel scale of the projection kernel, not the transverse momentum of the exchanged photon. We derive the normalized linear response and show that it contains a subtraction from the deformation of the total diffractive rate. Consequently, the elliptic response can vanish while the diffractive rate remains finite. This finite-rate null is a normalized projection zero of the response to the target elliptic gluon component, not a disappearance of diffraction. It is not available as a tunable mode zero in the standard single plane-wave readout, and provides an external projection basis in which the response to the same small- $x$ elliptic geometry can be probed with either sign or tuned to zero.
hep-phhep-th1 citation
37
Diffuse Supernova Neutrinos with Secret Neutrino Interactions
Praveen Bharadwaj🇮🇳 · Utpal Chattopadhyay🇮🇳 · Dilip Kumar Ghosh🇮🇳 · Arnab Sarker🇮🇳
The Diffuse Supernova Neutrino Background (DSNB), an isotropic flux arising from the cumulative neutrino emission of all stellar core-collapse events throughout cosmic history, is expected to be detected by next-generation neutrino observatories. As DSNB neutrinos propagate over cosmological distances through the cosmic neutrino background (C $ν$ B), they may undergo non-standard neutrino self-interactions ( $ν$ SI), leaving distinct spectral imprints on the observed flux. In this work, we investigate the impact of scalar ( $ϕ$ )-mediated $ν$ SI on the DSNB within a full three-flavor framework that retains the complete PMNS structure. We consider four representative flavor-diagonal coupling structures--universal, $e$ -, $μ$ -, and $τ$ -specific. The resonant scattering $ν_{i} ν_{k} \to ϕ \to ν_{j} ν_{l}$ off the lightest, relativistic C $ν$ B state produces broad spectral depletion whose pattern depends on the coupling structure and the neutrino mass ordering, generating distinctive signatures across the six flavor fluxes. We compute the resulting event spectra at JUNO, Hyper-Kamiokande with gadolinium loading, and DUNE, and derive projected $3 σ$ sensitivities in the $(m_{ϕ}, g)$ parameter plane. We find that these experiments can probe couplings as low as $g \sim 1 0^{- 8}$ for $m_{ϕ} \sim 100$ -- $300$ eV, surpassing existing bounds by up to a few orders of magnitude in the sub-100 eV mass range. Moreover, unlike the flavor-blind cosmological and supernova bounds, the DSNB sensitivity is flavor-discriminating, offering a unique opportunity to identify the underlying flavor structure of $ν$ SI in the event of a detection.
hep-phastro-ph.HE2 citations
38
Signatures of gravity-mediated dark matter interaction in theories with large extra dimensions
A. Clarke🇺🇸 · V. V. Flambaum🇦🇺 · M. Pospelov🇺🇸 · I. B. Samsonov🇦🇺
Dark matter particles that couple to the Standard Model only through gravity are usually regarded as inaccessible to laboratory detection. This expectation can change in theories with $n$ extra spatial dimensions, where gravity is enhanced at short distances and the potential scales as $1/ r^{1 + n}$ . We reconsider the gravity-mediated dark matter (DM) interactions in Arkani-Hamed-Dimopoulos-Dvali (ADD) models with $n$ large extra dimensions. The cumulative exchange of the gravitational Kaluza-Klein (KK) modes leads to the effective strength of interactions with the Standard Model nucleons that scales as $m_{p} m_{χ} M_{*}^{- 4}$ , where $m_{χ}$ is the mass of DM and $M_{*}$ is the fundamental $4 + n$ dimensional mass scale. We confront this interaction with sensitivity achieved in the large Xe-based underground direct detection experiments and derive bounds on the ${m_{χ}, M_{*}}$ parameter space that stretches all the way to $M_{*} \sim$ few TeV. We also address the indirect detection of scalar $χ$ that can resonantly annihilate via the on-shell KK modes into the SM particles $W^{\pm}, Z, h$ . The annihilation cross section for the process scales as $⟨ σ v ⟩ \sim m_{χ}^{n} M_{*}^{- n - 2}$ , and stringent limits on the same parameter space can be derived from observations of high-energy galactic $γ$ rays.
hep-phastro-ph.GAastro-ph.HE1 citation
39
Pair Production of Singlet Vector-Like B Quarks in Boosted bZ Final States at a Muon Collider
Eda Alici🇹🇷
We investigate the pair production of singlet vector-like bottom quarks at a future $10 TeV$ muon collider in the boosted $Z b$ final-state topology. The signal process is considered as $μ^{+} μ^{-} \to B B ˉ \to (Z b) (Z b ˉ)$ , with one $Z$ boson decaying leptonically and the other hadronically, leading to a final state with an opposite-sign same-flavour dilepton pair, multiple jets, and two $b$ -tagged jets. Signal and Standard Model background events are generated at leading order with MadGraph5\_\allowbreak aMC@NLO and subsequently interfaced with \textsc{Pythia}~8 for parton showering and hadronization. Detector effects are simulated with \textsc{Delphes} using a muon-collider detector configuration. A cut-based analysis exploiting boosted kinematics, including hard leading- $b$ -jet transverse momentum, small dilepton angular separation, and large hadronic activity, is performed to suppress the dominant $Z Z j j$ , $Z Z b b ˉ$ , and $t t ˉ$ backgrounds. Statistical sensitivities are evaluated with the Asimov approximation, including both zero and $10%$ background systematic uncertainty scenarios. For the singlet benchmark $BR (B \to b Z) = 0.25$ and an integrated luminosity of $10 ab^{- 1}$ , a $5 σ$ discovery reach up to $M_{B} ≃ 4.3 TeV$ is obtained, reduced slightly to $M_{B} ≃ 4.2 TeV$ when systematic effects are included. These results demonstrate that a $10 TeV$ muon collider provides a powerful and clean environment for probing vector-like $B$ quarks well beyond present LHC limits.
hep-ph0 citations
40
Hadronisation of in-medium $c c ˉ$ pairs to the exotic $X (3872)$
Henrique Legoinha🇨🇳 · Bernardo Picão🇵🇹 · Pedro Bicudo🇵🇹
The separation of $c c ˉ$ pairs in the quark-gluon plasma and the characteristic size of the final state quarkonia should lead to the observed hadron ratios in nuclear collisions. Such dependence manifests itself through the Fermi Golden rule, where hadron ratios are sensitive to the inner product between vacuum and in-medium wave functions. A novel hard probe is the exotic $X (3872)$ , which is expected to have a molecular and a compact component. We bridge more than a decade of LHC experimental results on hard probes, namely regarding the $J /Ψ$ , $Ψ (2 S)$ and $X (3872)$ hadrons, to the degree of separation and dissociation of in-medium hidden-charm systems.
hep-phhep-ex0 citations
41
Angular Analysis of $B \to D^{*} ℓ ν ˉ_{ℓ}$ from Lattice and Experiment: $∣ V_{c b} ∣$ and New Physics Constraints
Marzia Bordone🇩🇪 · Ollie Heald🇬🇧 · Andreas Jüttner🇨🇭
We present a combined angular analysis within and beyond the Standard Model (SM) of experimental measurements for the $B \to D^{*} ℓ ν ˉ_{ℓ}$ angular coefficients provided by the Belle collaboration, together with lattice-calculated hadronic form-factor data from the HPQCD, JLQCD, and FNAL/MILC collaborations. We focus on determining the CKM matrix element $∣ V_{c b} ∣$ and constraining a set of Wilson coefficients associated with new physics (NP) mediated by scalar and tensor currents. SM predictions for the angular coefficients are obtained using form-factor parameterisations based on the Boyd-Grinstein-Lebed (BGL) ansatz, with unitarity constraints imposed as Bayesian priors. Experimental and theoretical data are analysed jointly by considering the cases $ℓ = e, μ$ separately and comparing with the massless approximation. For the latter, we determine $∣ V_{c b} ∣ = 0.03997 (71)$ , with no resolution of the exclusive-inclusive puzzle. Using the full expressions for the angular coefficients in the presence of scalar, vector, and tensor currents, the corresponding Wilson coefficients are constrained through a joint Bayesian fit to lattice and experimental data. By including the renormalisation group evolution of the Wilson coefficients in the SM effective field theory (SMEFT), these constraints translate into bounds on the effective scale of potential heavy NP at the TeV scale. We find, at the $68%$ confidence level, that NP mediated by a scalar leptoquark and a vector leptoquark/colourless scalar boson are excluded at the effective scales 1.0 and 2.5 TeV, respectively.
hep-phhep-exhep-lat1 citation
42
Charting Dark Matter down to the neutrino floor/fog in the 2HD+a scenario
Giorgio Arcadi🇮🇹 · Abdelhak Djouadi🇪🇸 · Stefano Profumo🇺🇸
Next-generation direct detection experiments will probe dark matter (DM) scattering cross-sections deep into the neutrino fog, the regime where coherent neutrino scattering becomes an irreducible background. We investigate whether thermally produced weakly interacting massive particles (WIMPs) can naturally populate this regime while satisfying relic density and indirect detection constraints. Adopting as a case study the 2HD+a model, we have performed comprehensive parameter scans over the Type-I and Type-II Yukawa configurations. We have included the limit of strongly suppressed singlet--doublet {\it A-a} mixing sin $θ \to 0$ and we show that annihilation into {\it ha} and $Ha$ final states sustains the correct relic density while loop-induced direct detection cross-sections naturally land inside the neutrino fog; in the same limit the light pseudoscalar boson becomes long-lived, featuring displaced-vertex signatures when produced at colliders. Finally, in the case of zero mixing, we have considered a new possibility for DM phenomenology as the $a$ state becomes cosmologically stable and, consequently, an additional DM component. We map all the viable parameter space against current LZ and FERMI-LAT bounds and projected XLZD and CTA sensitivities. We find that the single component setup lies naturally below the neutrino floor for DM masses above 100 GeV while, on the contrary, most of the parameter space of the two component DM scenario is strongly disfavored already considering present limit. The parameter space of both single and two component DM scenario can be nevertheless broadened by considering specific relations among the model parameters to suppress the coupling between the 125 GeV bosons and two $a$ states. Our results represent in any case a motivation to fully exploit future tonne-scale detectors.
hep-ph0 citations
43
Irrelevance of Anomalous Breaking of Axial U(1) Symmetry and the U(1) Problem
Nodoka Yamanaka🇯🇵
The eta and eta' mesons are conventionally known to receive contribution from the anomalous breaking of axial U(1) symmetry, and they are considered to not be the Nambu-Goldstone (NG) bosons of the spontaneous chiral SU(3)_L x SU(3)_R symmetry breaking of QCD. However, it has recently been shown that this axial U(1) anomaly is not actually physical. In this contribution, we first review this statement and then propose a mechanism in which eta and eta' mesons are indeed NG bosons while being consistent with the axial U(1) problem.
hep-phhep-exnucl-th0 citations
44
Quantification of the Flavor Diagonal Hadronic CP Violation
Nodoka Yamanaka🇯🇵
The flavor diagonal CP violation of elementary particle physics contributes to the atomic, nuclear, and nucleon electric dipole moments (EDMs), T-violating neutron optics, and to the angular correlations of beta decay. In this contribution, we review the basics and the importance of CP violation in the search for new physics beyond the standard model, the recent progress in the quantification of the hadron level CP violation contributing to the aforementioned observables, and finally the current attempt to solve the strong CP problem without additional interactions and fields.
hep-phhep-exhep-thnucl-ex+10 citations
45
Next-to-next-to-leading-order QCD corrections to $^{3} S_{1}^{(8)}$ gluon fragmentation function for quarkonium
Feng Feng🇨🇳 · Yu Jia🇨🇳 · Wen-Long Sang🇨🇳
We present the first computation of the next-to-next-to-leading-order (NNLO) QCD corrections to the $^{3} S_{1}^{(8)}$ gluon fragmentation function for quarkonium within the nonrelativistic QCD (NRQCD) factorization framework, accurate to the lowest order in the velocity expansion. The calculation is performed with high numerical precision and encompasses both polarized and unpolarized cases. We find that the NNLO corrections are positive and substantial across most of the $z$ region. Furthermore, the logarithmic singularities near the endpoint $z \to 1$ are fully reconstructed, providing essential inputs for future threshold resummation beyond leading-logarithmic accuracy. Combined with threshold-resummed formulas in the large- $z$ region, our results yield phenomenologically viable inputs for the $^{3} S_{1}^{(8)}$ gluon fragmentation function. This enables a more reliable description of large- $p_{T}$ $J / ψ$ ( $ψ^{'}$ ) and $χ_{c J}$ production and polarization at hadron colliders, representing a crucial step toward a definitive test of the color-octet mechanism.
hep-ph1 citation
46
Observables and conformal properties of dark matter admixed isentropic neutron stars
Arijit Das🇮🇳 · Prashanth Jaikumar🇺🇸 · Adarsh Karekkat🇮🇳 · Tanumoy Mandal🇮🇳
We construct an equation of state for isentropic dark-matter-admixed neutron stars (DMANS) with a hot core and relatively cold crust incorporating self-consistent temperature and DM density profiles for GeV-scale fermionic DM. We show that the enhancement of central stellar density due to DM accumulation, previously reported for cold neutron stars, remains robust. Substantial observable effects of DM accumulation arise only for sufficiently massive stellar configurations. Similar to earlier studies of cold NS, the speed of sound profile is shown to exhibit non-monotonic behavior for sufficiently large DM density in the core. We identify a competition between thermal effects due to nonzero values of entropy per baryon and softening effects of the dark sector which drive macroscopic properties and conformality indicators in opposite directions. This competition determines the onset of conformality near the stellar core and indicates that conformality signatures attributed to quark-matter in cold NS could be mimicked by DM admixture in isentropic stars.
hep-phastro-ph.HE1 citation
47
A charming ICECUBE discover?
D. Fargion🇮🇹 · P.G. De Sanctis Lucentini🇷🇺 · M.Yu. Khlopov🇷🇺 · P. Oliva🇮🇹 · F. La Monaca🇮🇹 · P. Paggi🇮🇹
Last two years high energy neutrino data are studied. The two recent tau neutrino double bang candidate are discussed within their detectability, noise and expected rate. The neutrino flavor distribution mainly favoring equal electron and muon presence, is reminded. The angular distribution of highest muon neutrino tracks is analyzed. Their horizontal strong anisotropy and their remarkable up-down asymmetry, with the absence of clustering, is noticed. The main persistent missing of astrophysical X,gamma sources (as GRB and AGN flaring source) and all the above signatures led us to suggest a dominance of prompt charmed (atmospheric) events able to pollute, to smear and to hide any minor astronomical presence.
↳ astro-ph.HEastro-ph.IMhep-phPoS(2019)·2 citations
48
UHECR Clustering: Lightest Nuclei from Local Sheet Galaxies
Daniele Fargion🇮🇹 · Pier Giorgio De Sanctis Lucentini🇷🇺 · Maxim Yu. Khlopov🇫🇷
The ultra-high-energy cosmic ray (UHECR) puzzle is reviewed under the hints of a few basic results: clustering, anisotropy, asymmetry, bending, and composition changes with energies. We show how the lightest UHECR nuclei from the nearest AGN or Star-Burst sources, located inside a few Mpc Local Sheets, may explain, at best, the observed clustering of Hot Spots at tens EeV energy. Among the possible local extragalactic candidate sources, we derived the main contribution of very few galactic sources. These are located in the Local Sheet plane within a distance of a few Mpc, ejecting UHECR at a few tens of EeV energy. UHECR also shine at lower energies of several EeV, partially feeding the Auger dipole by LMC and possibly a few nearer galactic sources. For the very recent highest energy UHECR event, if a nucleon, it may be explained by a model based on the scattering of UHE ZeV neutrinos on low-mass relic neutrinos. Such scatterings are capable of correlating, via Z boson resonance, the most distant cosmic sources above the GZK bound with such an enigmatic UHECR event. Otherwise, these extreme events, if made by the heaviest composition, could originate from the largest bending trajectory of heaviest nuclei or from nearby sources, even galactic ones. In summary, the present lightest to heavy nuclei model UHECR from the Local Sheet could successfully correlate UHECR clustering with the nearest galaxies and AGN. Heavy UHECR may shine by being widely deflected from the Local Sheet or from past galactic, GRB, or SGR explosive ejection.
↳ astro-ph.HEastro-ph.COastro-ph.GAhep-ph+1Universe(2024)·8 citations
49
Selective enhancement of quantum decay channels
Pritam Nanda🇮🇳 · Kinjalk Lochan🇮🇳
In the decay of quantum particles under field theoretic consideration, the decay rate is typically a convolution of the density of modes the primary field is allowed to decay into and the allowed probability density for the field to decay into such modes. In free space, though many such processes show high amplitude of such transitions towards the infrared sector, the depletion of allowed mode density in that regime arrests the efficacy of such decays at low energies. Therefore in free space, in order to enhance the decay rate, one needs the transition probability density to be rich enough towards the high energy sector where mode density support is also high enough to make the rate sufficiently large. In this work we argue that in the controlled boundary condition environment e.g. in a cavity, the mode functions of product field receive significant support towards their infrared sector, boosting the probability (and hence rates) of low energy processes. The cavity geometry offers sweet spots in terms of resonant geometry around which the interaction of a primary field with product fields receives dramatic enhancement, significantly enlarging its decay rates. Therefore, a judicious selection of cavity geometry serves as a potential substitute to studying interesting processes at high energy. The results have direct relevance for the study of QED processes and implications for the study of exotic new physics are also discussed.
↳ gr-qchep-phhep-th0 citations
50
Neural Wavefunctions in Quantum Field Theory I: Asymptotic Freedom
Paulo F. Bedaque🇺🇸 · Hersh Kumar🇺🇸 · Suryansh Rajawat🇺🇸 · Gregory Ridgway🇺🇸
We present a variational approach to quantum field theory based on wavefunctions parameterized by neural networks. While variational methods have a celebrated history across many fields, their application to quantum field theory has been limited by well-known challenges. We show that neural-network wavefunctions, combined with modern machine-learning techniques, enable competitive variational calculations in nontrivial field theories. As a demonstration, we reproduce the essential features of the two-dimensional nonlinear $σ$ -model: asymptotic freedom, dynamical mass generation and the model's step-scaling function.
↳ hep-lathep-phhep-thnucl-th+10 citations
51
Relativistic effects in extreme-mass-ratio inspirals within scalar clouds: Eccentric and inclined orbits
Qi-Xuan Xu🇵🇹 · Richard Brito🇵🇹 · Riccardo Della Monica🇵🇹 · Rodrigo Vicente🇳🇱 · Chen Yuan🇵🇹
We study extreme-mass-ratio inspirals (EMRIs) evolving in a scalar cloud environment that may form through superradiant instabilities, using a fully relativistic perturbative framework that allows for eccentric and inclined orbits. EMRIs, consisting of a stellar-mass compact object inspiraling into a supermassive black hole, are key sources for space-based gravitational-wave detectors such as LISA. Previous relativistic studies of EMRIs in scalar clouds have been restricted to circular, equatorial motion. Here, instead, we focus on a Schwarzschild black hole background to incorporate eccentricity and orbital inclination. By computing the scalar energy and angular momentum scattered off to spatial infinity and absorbed at the event horizon, we show that orbital eccentricity can induce a dense spectrum of resonances near the last stable orbit, associated with strong relativistic apsidal precession. We further find that orbital inclination can significantly modify the orbital energy and angular momentum losses. In particular, we identify a critical inclination angle below which, at sufficiently small orbital radii, there is a net transfer of energy from the scalar cloud to the orbit. Moreover, for sufficiently large eccentricities, resonances associated with relativistic apsidal precession persist across the full range of inclinations, although their structure changes significantly between prograde and retrograde orbits. These results provide a foundation for future studies of EMRIs in scalar cloud environments on fully generic orbits around spinning black holes.
↳ gr-qcastro-ph.HEhep-ph7 citations
52
Are Cosmological Data Excluding Sterile Neutrinos or Only the Fully Thermalized Limit?
Artur Ladeira🇧🇷 · Rafael C. Nunes🇧🇷 · Eleonora Di Valentino🇬🇧 · Stefano Gariazzo🇪🇸
We present a cosmological reassessment of light sterile-neutrino scenarios, examining whether current observations exclude sterile neutrinos as a class or primarily constrain the fully thermalized case. We consider three distinct realizations: (i) a fully thermalized sterile species (FTS), (ii) a different-temperature sterile-neutrino thermal relic (DTS) relative to the active neutrino background and (iii) a Dodelson--Widrow-like (DW) sterile neutrino with reduced phase-space normalization. Constraints are derived within both $Λ$ CDM and the CPL dynamical dark-energy framework using combinations of Planck-CMB data, DESI DR2 BAO measurements, and the PantheonPlus and Union3 Type Ia supernova samples. For baseline data combinations without a local $H_{0}$ prior, the FTS scenario is strongly disfavored in both cosmological models. Adding the local $H_{0}^{DN}$ prior allows $Λ$ CDM+FTS to accommodate the high local $H_{0}$ value and become statistically competitive with standard $Λ$ CDM once SNIa data are included, although the sterile-neutrino mass remains consistent with zero. By contrast, partially populated sterile-neutrino scenarios remain viable: the DW realization is broadly compatible with current observations, while the DTS scenario yields the least cosmological pressure among the cases considered. Overall, cosmological data mainly require a strongly suppressed effective sterile abundance, leading to tight constraints on \textbf{ $m_{s}^{eff}$ } while allowing substantially weaker bounds on the physical sterile mass. We conclude that current observations do not generically exclude sterile neutrinos, but rather place strong pressure on fully thermalized or highly populated scenarios, highlighting the importance of production history and phase-space distribution when interpreting cosmological constraints.
↳ astro-ph.COhep-phhep-thPRD(2026)·0 citations
53
Asymptotically safe quantum gravity and its phenomenology -- a review
Astrid Eichhorn🇩🇪
Asymptotically safe quantum gravity is an approach to quantum gravity. It is based on the premise that quantum field theory can describe the quantum nature of gravity in our universe. At its core lies quantum scale symmetry. This review provides an introduction to the key ideas of the approach and surveys the current status of the field. Over the last years, the field has taken large strides towards an increasingly realistic setting: First, compelling evidence for quantum scale symmetry exists in four-dimensional, Euclidean, pure gravity, establishing the Reuter fixed point robustly. Second, matter fields, including the Standard Model as well as beyond-Standard-Model-candidates, have been studied in depth, with increasingly conclusive evidence for quantum scale symmetry. Most recently, the final gap to a realistic description of quantum gravity is being closed, because Lorentzian spacetime signature can now be accounted for. As a consequence of quantum scale symmetry in the ultraviolet, the approach is highly predictive at all scales. This review discusses the physics of asymptotic safety across all scales. Predictive power for particle physics, black holes and cosmology provides a clear pathway to confronting quantum gravity with current and near-future observations. The review closes by discussing the connection to other approaches to quantum gravity. It advocates the perspective that such connections between approaches may lead us to an understanding of universal physical features of quantum gravity.
↳ hep-thgr-qchep-ph5 citations
54
Cosmology as Representation: Informational Invariance and the Limits of Scientific Realism
Stefano Profumo🇺🇸
Modern cosmology is often taken to provide an increasingly accurate description of the universe's underlying ontology through progressively refined mathematical models. I challenge this interpretation by arguing that the empirical success of cosmology underdetermines not only ontology but also the mathematical and conceptual frameworks used to represent observational data. I propose instead that the objective content of cosmology is best identified with cross-representational informational invariants-features of observational structure that persist across empirically adequate descriptions. These invariants can be characterized in information-theoretic terms, including correlation structure, statistical distinguishability, and limits on accessible information, and formalized using tools such as the Fisher-Rao metric on model space. On this view, cosmological models are best understood as efficient encodings of observational structure rather than uniquely privileged descriptions of fundamental reality. Scientific progress, accordingly, consists not in convergence toward a fixed ontology, but in the progressive refinement of the informational structure accessible to observation.
↳ physics.hist-phastro-ph.COhep-phhep-th1 citation
55
Quantum Gravity Cutoff from Axions: A Type IIB Landscape Study
Matthew Reece🇺🇸 · Tom Rudelius🇬🇧 · Christopher Tudball🇬🇧
Extra-dimensional axions have coupling strength related to fundamental, ultraviolet physics. It has been proposed that the properties of such axions imply a bound on the quantum gravity cutoff: $Λ_{QG} ≲ 2 π S f$ , where $f$ is the axion decay constant and $S$ is the instanton action. In the context of weakly-coupled string theory, we identify $Λ_{QG}$ with the string scale $M_{s}$ . In this paper, we carry out a quantitative study of this bound on the string scale in the context of Calabi-Yau compactifications of Type IIB string theory, considering both $C_{2}$ and $C_{4}$ axions. We show, both analytically and numerically, that the bound holds even near boundaries of the Kähler moduli space, including those where the co-scaling relationship for axion strings fails. This evidence bolsters previous arguments, based on naturalness and on unitarity, that the bound is a general feature of extra-dimensional axions in quantum gravity.
↳ hep-thhep-ph3 citations
56
Towards LLM-Powered Automation of a Dark Matter Constraint Repository
Lanqing Yuan🇺🇸 · Karthik Ramanathan
Dark matter constraint repositories are critical community infrastructure, giving experimentalists and theorists a shared landscape of existing bounds. Yet the most widely-used repositories are maintained by individual volunteers, creating a sustainability risk as the pace of new results accelerates. We present a large language model (LLM) pipeline that monitors arXiv, extracts limit curves from papers, integrates them as code, and opens pull requests (PRs) for human review. On a 346-paper benchmark whose ground truth is the upstream-curated repository itself, the pipeline classifies the coupling type correctly for 90.5% of papers and reaches a median coupling residual of 0.33 dex (a factor of two for 48% of curves), with 76% mean mass-range coverage. This is driven by treating each extraction as a noisy sample reconciled through consensus voting, a physics convention canonicalization layer built with the agentic physics assistant Get Physics Done (GPD), and a scoring methodology that separates genuine extraction error from non-comparability. The remaining difficulty is concentrated in rare coupling types with idiosyncratic conventions (macro-averaged residual 1.1 dex). The pipeline is deployed and has generated limit proposals; none have merged. Governance of AI-generated scientific data is itself an unsolved problem.
↳ hep-exastro-ph.IMhep-ph0 citations
57
What Do Lorentz-Equivariant Jet Taggers Learn?
Jay Agarwal · Siddharth Khare · Dhruv Kumar
We study what Lorentz-equivariant jet taggers learn internally, using equivariance tests, linear probes and grade ablations across five models including L-GATr, L-GATr-slim and LLoCa-T. Linear probes show that equivariant models suppress frame-dependent pseudorapidity to zero while encoding jet mass and N-subjettiness strongly. Grade ablations on L-GATr reveal that bivector channels are negligible for top-quark tagging while vector-like channels are dominant but seed variable, consistent with the network exploiting multiple representational pathways. These results characterize which physical features and algebraic grade structures carry discriminative information in equivariant taggers and may inform future development of such models.
↳ cs.LGhep-exhep-phphysics.data-an1 citation
58
Dark Energy in the DESI Era: A Brief Review of Evidence, Beyond- $Λ$ CDM Interpretations, and Tensions
Tian-Nuo Li🇨🇳 · Guo-Hong Du🇨🇳 · Hao Wang🇨🇳 · Yun-He Li🇺🇸 · Jing-Fei Zhang🇨🇳 · Xin Zhang🇨🇳
Recent baryon acoustic oscillation measurements from DESI provide important new clues for reassessing whether the standard $Λ$ CDM model offers a sufficient description of the late-time expansion history of the Universe. When combined with cosmic microwave background and type Ia supernova data, these measurements show an apparent departure from the $Λ$ CDM model, commonly described as dynamical dark energy (DDE) with equation of state crossing the phantom divide (i.e., quintom behavior). This review examines the current status of the DESI-motivated indications for DDE and their possible implications for physics beyond $Λ$ CDM. We discuss how the strength of the preference for DDE depends on the adopted parametrization and dataset combination, and how residual systematics or internal tensions among datasets may affect its interpretation. At the background level, several mechanisms beyond $Λ$ CDM can produce similar expansion histories. We therefore further discuss how the same effective departure from $w = - 1$ may arise from physically distinct scenarios, including interacting dark energy, non-minimally coupled gravity, and non-standard dark matter. Meanwhile, these different new-physics interpretations may have different implications for current cosmological tensions, especially those involving $H_{0}$ , $S_{8}$ , and $\sum m_{ν}$ . In conclusion, the question posed by DESI is not merely whether dark energy evolves with time, but rather how, within the framework of precision cosmology, to disentangle new physics scenarios from systematic errors.
↳ astro-ph.COastro-ph.GAgr-qchep-ph+1Res.Astron.Astrophys.(2026)·28 citations
59
Quantum Memory in Scalar-Induced Gravitational Waves
Waqas Ahmed🇨🇳
Scalar-induced gravitational waves are usually treated as a classical stochastic background sourced by phase-random curvature perturbations. We show that this description can miss residual quantum information. Starting from a decohered two-mode Gaussian scalar state, we derive explicit transfer relations between the scalar anomalous coherence and the covariance matrix of induced tensor modes. For a localized scalar power spectrum, the ordinary tensor power is sourced by scalar power contractions, whereas the opposite-mode tensor coherence is sourced by scalar anomalous-coherence contractions. This coherence can generate nonzero tensor discord and a connected tensor-power covariance even after scalar entanglement has vanished. We identify the connected covariance and phase-sensitive strain correlations as probes of primordial quantum coherence in secondary gravitational-wave backgrounds, and discuss their possible relevance for future space-based interferometers and pulsar timing arrays.
↳ gr-qchep-phhep-thquant-ph1 citation
60
Entanglement, Discord, and Residual Coherence in Scalar-Induced Gravitational Waves
Waqas Ahmed🇨🇳
Scalar-induced gravitational waves are usually modeled as a classical stochastic background sourced by primordial curvature perturbations. We investigate whether residual quantum-information properties of the scalar sector can survive decoherence and leave imprints in the induced tensor background. Using the covariance-matrix formalism, we describe primordial curvature perturbations as decohered two-mode squeezed Gaussian states and identify the anomalous scalar coherence that may remain after scalar entanglement has vanished. We then derive the leading scalar-to-tensor transfer relations for opposite-momentum induced tensor modes. The ordinary tensor power is sourced by scalar power contractions, whereas the opposite-mode tensor coherence is sourced by anomalous scalar-coherence contractions. This tensor coherence controls the induced Gaussian discord and generates connected and phase-sensitive observables, including a connected power covariance $κ (k) \propto ∣ γ_{k} ∣^{2} / α_{k}^{2}$ . Thus the robust signature is not a universal shift of the gravitational-wave spectrum, but a correlated tensor background with nontrivial covariance and phase structure. We discuss phenomenological templates and provide an illustrative Fisher estimate for future gravitational-wave observations. Our results suggest that scalar-induced gravitational waves may offer a new probe of primordial quantum correlations beyond entanglement.
↳ gr-qchep-phhep-thquant-ph1 citation
61
Phantom-Divide Crossing in Exponentially Coupled Quintessence and the Role of Neutrino-Mass Freedom
Jincheng Wang🇨🇳 · Hongwei Yu🇨🇳 · Puxun Wu🇨🇳
We investigate a quintessence dark-energy model with an exponential potential and an exponential coupling to cold dark matter (CDM), hereafter referred to as the CQ-EXP model, using Planck CMB, DESI BAO, and DES-Dovekie supernova observations. We also examine how variations in the neutrino mass sector affect the constraints. When the neutrino mass sum is fixed at $\sum m_{ν} = 0.06$ eV, the data favor a coupling between quintessence and CDM, with the coupling parameter $β$ deviating from zero at more than $3 σ$ . In particular, the observations favor the $β < 0$ branch, where the energy transfer between the two dark sectors changes sign and the effective equation of state (EoS) of dark energy crosses the phantom divide, $w = - 1$ . When the effective neutrino mass parameter $\sum m_{ν, eff}$ is treated as a free parameter, the data show a preference for negative values of $\sum m_{ν, eff}$ . This additional freedom weakens the preference for the coupling between quintessence and CDM and leads to nearly identical values of $χ_{min}^{2}$ for the CQ-EXP models with $β > 0$ and $β < 0$ , corresponding respectively to models without and with phantom-divide crossing in the effective EoS. Both values are slightly larger than that obtained in the $w_{0} w_{a}$ CDM model, indicating that the CQ-EXP model cannot be statistically distinguished from the $w_{0} w_{a}$ CDM model with the data considered here. Therefore, when $\sum m_{ν}$ is fixed, current observations favor the CQ-EXP model with phantom-divide crossing. In contrast, when negative values of $\sum m_{ν, eff}$ are allowed, a CQ-EXP dark energy without crossing $w = - 1$ can also provide an effective explanation of the latest observations.
↳ astro-ph.COgr-qchep-ph4 citations
62
Metamorphosis of fractional instantons on a twisted $T^{4}$ with a double-trace deformation: a numerical study
Benjamin Dobozy🇨🇦 · Erich Poppitz🇨🇦
We use numerical minimization of the lattice action of trace-deformed Yang-Mills theory on $T^{4}$ with twisted boundary conditions to find the classical minimum action configurations of fractional topological charge. We vary the twists and ratios of torus periods to interpolate between different $R^{4 - k} \times T^{k}$ geometries. This allows us to see how the corresponding minimum action saddle point configurations -- monopole-instantons ( $k = 1$ ), center vortices ( $k = 2$ ), and fractional instantons ( $k = 3, 4$ ) -- morph into each other. We also study how the transition between them depends on the presence of a deformation potential. In particular, we argue that the recent analytic picture of chains of monopole-instantons collimating their flux into center-vortex sheets, while technically relying on the deformation potential, also holds in pure Yang-Mills theory, for tori whose shape causes the abelianization due to the deformation to align with the one due to the twists. Our results also indicate that with nonzero deformation potential, some transitions between different minimal-action fractional charge configurations may be discontinuous and involve level crossing.
↳ hep-thhep-lathep-ph1 citation
63
Dark Matter as an Inflationary Relic in Warm Inflation
Swagat S. Mishra🇰🇷 · Umang Kumar🇮🇳 · Suratna Das🇮🇳 · Varun Sahni🇮🇳
Warm inflation is usually expected to completely deplete the inflaton condensate by dissipating its energy into radiation. We show that this expectation fails in a simple and observationally viable regime. In a strongly dissipative warm inflationary scenario, the dissipative ratio, $Q = Υ/ (3 H)$ , can fall rapidly after the end of inflation as the system approaches radiation domination, thereby suppressing further energy transfer to the thermal bath. This leads to a residual inflaton condensate, which subsequently evolves as an effectively non-dissipative scalar field. For potentials with a stable quadratic minimum, this remnant inflaton manifests as a cold dark matter component. We establish this mechanism for the minimal renormalizable potential, with a dissipative coefficient $Υ \propto T^{3}$ . In this case, current cosmological data allow strong dissipation while leaving the inflaton mass weakly constrained by inflationary observables. The observed dark matter abundance then fixes its mass to be $m \approx 0.02 MeV$ , while larger masses overclose the Universe. The transition to matter-like scaling occurs well before BBN, avoiding a long-lived inflaton dark radiation component. Relic inflaton dark matter therefore turns the post-inflationary dynamics of warm inflation into a new late time constraint on its parameter space.
↳ astro-ph.COgr-qchep-phhep-th1 citation
64
Proton's isovector PDF with updated analysis of large-momentum lattice data
Xiangdong Ji🇺🇸 · Yushan Su🇺🇸
The proton's unpolarized $u (x) - d (x)$ parton distribution function (PDF) has been studied by a number of lattice QCD groups through large momentum expansion. However, due to lattice artifacts (excited state contaminations, unphysical pion masses, and discretization effects) and less-advanced theoretical analysis (renormalizations, large-distance extrapolations, and large-log resummations), the resulting PDFs cannot be compared strictly with experimental data. By using the state-of-the-art theoretical tools and mitigating the lattice artifacts empirically, we reanalyze the available datasets in the literature and find that the new PDF in the physical limits is consistent with global fittings within $\sim 1 σ$ . This provides compelling evidence that large momentum expansion is capable of accurately predicting the $x$ -dependence of the PDFs when ideal lattice data become available.
↳ hep-lathep-phnucl-th0 citations
65
Multistage dynamical modeling of heavy-ion collisions
Lipei Du🇺🇸
Relativistic heavy-ion collisions create deconfined QCD matter whose properties must be inferred from final-state observables through dynamical modeling. This contribution discusses recent progress and open issues in multistage simulations, with emphasis on the connection between bulk evolution, conserved charges, strangeness, and heavy flavor. At RHIC Beam Energy Scan energies, the breaking of longitudinal boost invariance makes charge stopping and rapidity-dependent observables essential for constraining the finite-density medium. Strange hadrons are sensitive to the local chemical environment and conserved-charge correlations, while heavy flavor probes microscopic transport and hadronization. Combining these observables within multi-sector inference frameworks provides a path toward more robust constraints on the equation of state and transport properties of QCD matter.
↳ nucl-thhep-phnucl-ex1 citation
66
Eight loop form factors, amplitudes and patterns in planar $N = 4$ super-Yang-Mills theory
Lance J. Dixon🇺🇸 · Zhenjie Li🇺🇸
The simplest nontrivial amplitude in planar $N = 4$ super-Yang-Mills theory is six-gluon scattering in the maximally-helicity-violating configuration. It has been computed to 8 loops with the help of antipodal duality, which relates it to the three-point form factor of a protected operator, the chiral stress tensor super-multiplet, represented also as $tr ϕ^{2}$ . In this talk, we describe the computation to 8 loops of another three-point form factor, for the operator $tr ϕ^{3}$ . This form factor lives in the same restricted space of polylogarithms as the $tr ϕ^{2}$ form factor. We also report on all-order patterns for sequences of coefficients in the symbols of these polylogarithmic results, for the leading discontinuity of the $tr ϕ^{3}$ form factor.
↳ hep-thhep-ph0 citations
67
Event-by-event fluctuations of elliptic flow in ultrarelativistic O+O collisions
Renata Krupczak🇩🇪 · Nicolas Borghini🇩🇪 · Hendrik Roch🇫🇮
We study O+O collisions at $s_{NN} = 5.36$ TeV within a fully three-dimensional $McDipper$ + $MUSIC$ model, which allows us to describe the experimentally measured dependence of charged hadron multiplicity on centrality and pseudorapidity. We show that the initial elliptical eccentricity is mainly driven by the fluctuations of the energy deposition and thereby varies considerably event-by-event within a fixed centrality class. This also holds for elliptic flow $v_{2}$ , whose origin in O+O thus differs from that in collisions of heavy nuclei. Using a decomposition of initial states in an average event and uncorrelated modes, we find that despite the large size of fluctuations we can reproduce the joint probability distribution of eccentricity and elliptic flow with a reasonable accuracy with only a small set of fluctuation modes.
↳ nucl-thhep-ph0 citations
68
Ferromagnetic broadband sensing of axionlike dark matter
Chenhao Peng🇨🇳 · Dmitry Budker🇩🇪 · Yuanning Gao🇨🇳 · Xinran Li🇨🇳 · Jia Liu🇨🇳 · Wei Ji🇨🇳 · Jing Shu🇨🇳 · Zhenxing Tang🇨🇳 · Liheng Wang🇨🇳
Levitated particles have demonstrated ultrahigh sensitivity to magnetic fields and accelerations owing to their extremely low dissipation. Such systems have strong potential for fundamental physics research, particularly for the detection of axions and axionlike particles, well-motivated dark matter candidates spanning a broad mass range. In this context, both high sensitivity and large bandwidth are essential. Here, we demonstrate a levitated magnet magnetometer based on an engineered double-resonance mode, achieving an effective linewidth at its optimal sensitivity that is approximately three orders of magnitude broader than those of previous approaches. Together with a hard-magnet array that enhances the axion-induced signal and soft-ferromagnetic shielding that suppresses environmental magnetic noise, this system constitutes a hybrid ferromagnetic platform for axionlike dark matter searches. We search for axionlike dark matter through its photon coupling $g_{aγ}$ over the $40$ - $3000 Hz$ frequency range and establish new direct limits in this frequency band. The best sensitivity is achieved near the upper resonance around $276 Hz$ , where the magnetometer reaches a magnetic-field resolution of $0.7 fT$ , corresponding to a limit of $g_{aγ} \sim 1 0^{- 7} GeV^{- 1}$ . At this frequency, this result improves upon previous direct limits by more than four orders of magnitude. The demonstrated high-bandwidth levitated sensor may also enable a broad range of applications, including biological sensing and precision measurements.
↳ hep-exhep-ph2 citations
69
RAD@home discovery of a bow-and-arrow radio galaxy tracing a ~560 kpc bow-shock structure in a multi-halo environment
Ananda Hota · Pratik Dabhade · Shubhrangshu Ghosh · Pranim Limbo · C. Konar · Sagar Sethi · Souvik Manik · Aditya Sahasranshu · Sabyasachi Pal · Mitali Damle · Sravani Vaddi · Arundhati Purohit
We report the RAD@home citizen science discovery of a unique bow-and-arrow-shaped radio galaxy (BAARG; RAD J104501.6+352852, z = 0.159) identified in LoTSS DR2. The source exhibits striking asymmetry: on the western side, a narrow jet feeds a sector-shaped emission region at ~115 kpc, extending backward to form a ~560 kpc arc-like structure; on the eastern side, the jet develops an S-shaped distortion extending to ~250 kpc, followed by a faint, offset tail reaching ~600 kpc. Our analysis shows that the host resides in a dynamically complex, multi-halo environment with nearby cluster-scale systems at similar redshifts. The observed morphology is consistent with interaction between the radio plasma and the surrounding medium, influenced by large-scale environmental gradients and bulk motions. The western structure is consistent with compression of radio plasma near a bow-shock-like feature, possibly linked to supersonic motion of the infalling host galaxy and its circumgalactic medium. This possibly represents one of the first instances in which morphology and environment together suggest signatures of infall- or shock-related processes; surveys such as LoTSS DR3 may reveal similar systems, offering new insights into the interplay between radio galaxies and their large-scale environments.
↳ astro-ph.GAhep-phMNRAS(2026)·0 citations
70
Bounds on nonlinear electrodynamics via resummed relative entropy
Pietro Conzinu🇮🇹 · Daiki Ueda🇮🇱
We investigate nonlinear electrodynamic effective field theories (EFTs) through the relative entropy evaluated in suitable background electromagnetic fields. In this setup, the relative entropy encodes information about the infinite tower of higher-dimensional operators and provides a systematic probe of nonlinear EFT effects. We study these features in fermionic QED, scalar QED, and Dirac-Born-Infeld theory using perturbative analyses, resummation techniques such as Borel--Laplace resummation, and non-perturbative approaches including the Schwinger proper-time method. In the weak-coupling regime, we show that the non-negativity of the perturbative relative entropy imposes sign constraints on finite truncations of higher-dimensional operators, generalizing familiar positivity bounds on leading EFT coefficients. We further show that violations of non-negativity in the strong-coupling regime admit qualitatively different interpretations depending on the framework: perturbatively analyzed violations diagnose the breakdown of the truncated EFT expansion, whereas violations in resummed or genuinely non-perturbative relative entropy signal physical instabilities of the system, such as the Schwinger effect. Extending the analysis to broader classes of UV completions, including theories with factorial or power-law growth of EFT coefficients, we derive general constraints on nonlinear electrodynamic EFT effects from the non-negativity of the resummed relative entropy. Our results suggest that relative entropy provides a unified diagnostic of perturbative consistency and non-perturbative stability in nonlinear EFTs.
↳ hep-thhep-ph1 citation
71
Scattered wave functions and worldline instantons for particle production in curved spacetime
Philip Semrén🇸🇪 · Greger Torgrimsson🇸🇪
We study the production of spin- $1/2$ particle-antiparticle pairs in curved spacetimes with nontrivial dependence on more than one coordinate. To this end, we develop two complementary approaches. First, we extend the scattered-wave-function (SWF) method, originally introduced for pair production in electromagnetic backgrounds, to curved spacetime backgrounds. Second, we complete the development of an open-worldline-instanton method by deriving the pre-exponential factor of the pair-production probability. We apply both methods to several two-dimensional metrics and find good agreement between the resulting probabilities. While the SWF approach provides numerically exact results and is particularly efficient for the examples considered here, the instanton approach offers favorable scaling to higher-dimensional backgrounds and more extreme parameter regimes. These methods provide new tools for studying pair production in multidimensional gravitational backgrounds beyond the reach of many existing approaches.
↳ gr-qchep-phPRD(2026)·0 citations
72
DSWIM:Efficient and Stable Deterministic Computation of Warm Inflation Perturbations
Umang Kumar🇮🇳
Warm inflation perturbations are sourced by both thermal and quantum fluctuations and are commonly computed through stochastic realizations of the perturbation equations, as implemented in the publicly available code SWIM. Deterministic formulations based on correlation matrix evolution provide a computationally efficient alternative, but can become numerically ill-conditioned when the perturbation variables evolve over widely different scales. In this work, we extend SWIM by introducing a deterministic module, DSWIM, based on correlation matrix evolution. We introduce a physically motivated scaling matrix transformation derived from the effective Hubble scaling of the perturbation variables. The transformed system preserves the primordial curvature power spectrum exactly while substantially improving the numerical conditioning of the deterministic evolution equations. Using representative warm inflation models, we show that the scaled framework suppresses numerical artifacts, improves the robustness of the deterministic evolution, and yields substantial computational speedups while preserving accuracy. We further show that correlated thermal noise contributions arise naturally through the diffusion matrix structure, resolving previously observed discrepancies between stochastic and deterministic implementations. Our results establish DSWIM as a numerically robust and computationally efficient framework for computing warm inflation scalar perturbations.
↳ astro-ph.COgr-qchep-phhep-th0 citations

Affiliations

first authorsco-authorsvia INSPIRE