HEP Phenomenology·hep-ph

Fri·Jul 10, 2026Friday·July 10, 2026

37 papers—27 primary·10 cross-listed

01
Axion-Induced Casimir Interaction Between Graphene Plates
Ahmad Alachkar🇫🇷 · Philippe Brax🇫🇷 · Pierre Brun🇫🇷
Axion dark matter may induce observable electromagnetic effects in resonant cavity systems and potentially lead to modifications of the Casimir interaction. In this context, graphene represents an attractive platform owing to its tunable electromagnetic properties, and the fact that its electromagnetic response can be modelled microscopically from first principles within quantum field theory. The electromagnetic response induced by axion dark matter is investigated in a planar cavity consisting of parallel graphene interfaces in the presence of a homogeneous external magnetic field, incorporating finite temperature, chemical potential and dissipation through the graphene conductivity. Closed analytical expressions are obtained for the induced electric field and the resulting pressure. The pressure exhibits resonant enhancement at a series of plate separations satisfying $d_{n} = (2 π n - ϕ (r)) / m_{a}$ , where $m_{a}$ is the axion mass and the phase $ϕ (r)$ is determined by the reflection coefficient $r$ , which depends on the graphene conductivity evaluated at $ω = m_{a}$ . The resonant structure is strongly influenced by the graphene chemical potential and damping parameter. In particular, increased doping, for example via a gate voltage, sharpens the resonances and amplifies the axion-induced signal. By comparing the resonantly enhanced signal with the conventional Casimir background, the parametric regimes in which the effect could become experimentally relevant are identified, with the strongest sensitivity obtained for highly doped low-dissipation graphene configurations operated near resonance. These results demonstrate that graphene-based Casimir-type configurations may provide a sensitive framework for probing axion-induced electromagnetic phenomena and highlight the interplay between axion electrodynamics, cavity resonances, and material properties in low-dimensional systems.
hep-phcond-mat.mes-hallhep-th0 citations
02
Factorization of elastic, single, and double diffractive $pp$ scattering
Philipp B. Aretz🇺🇸 · Kyle Lee🇺🇸 · Stella T. Schindler🇺🇸 · Iain W. Stewart🇺🇸
We use effective field theory techniques to factorize elastic, single, and double diffractive forward $pp$ scattering in the Regge limit $∣ t ∣ ≪ s$ , where $t$ is the squared momentum transfer. These processes involve a large rapidity gap and comprise about half the total $pp$ cross section. We explain why the diffractive PDFs appearing in $e p$ diffraction do not appear as universal hadronic functions for $pp$ diffraction. For $∣ t ∣ \sim Λ_{QCD}^{2}$ , we show that the hadronic functions in $e p$ and $pp$ diffraction differ, and hence are non-universal. In general, we prove that rapidity anomalous dimensions are universal between diffractive $e p$ and $pp$ processes, and that color-singlet (Pomeron) evolution equations can be determined at the amplitude level.
hep-phnucl-th2 citations
03
PDF effects in high-mass Drell-Yan SMEFT analyses across flavour space
David Marzocca🇮🇹 · Manuel Morales-Alvarado🇮🇹
High-mass Drell-Yan dilepton production provides one of the most sensitive probes of semileptonic four-fermion operators in the Standard Model Effective Field Theory (SMEFT), thanks to the energy growth of the corresponding contributions. At the same time, these measurements also constrain parton distribution functions (PDFs) in the large- $x$ region, where PDF uncertainties can mimic or obscure smooth new-physics effects. In this work we study how the impact of PDF profiling on SMEFT constraints depends on the quark-flavour structure of the effective operators, by performing a joint fit of SMEFT Wilson coefficients and PDF nuisance parameters. We find that PDF profiling induces a strongly flavour-dependent degradation of the SMEFT sensitivity, both with current data and in HL-LHC projections. The largest broadenings occur for operators involving first-generation quarks, whose effects are correlated with the high- $x$ valence-quark luminosities that dominate the high-mass spectrum. Operators involving heavier quark flavours are less affected, although with non-negligible operator-dependent variations. As a byproduct of our analysis, we obtain an estimate on the changes induced in the PDF sector by profiling SMEFT effects. We also show that angular information provides an important handle to reduce degeneracies among SMEFT directions and between SMEFT effects and allowed PDF deformations. These results demonstrate that the relevance of PDF uncertainties in high-energy SMEFT fits is not uniform across flavour space, and must be assessed in a flavour-dependent way.
hep-ph0 citations
04
Dissecting Parton Showers with Multi-Point Energy Correlators
Mark Gonzalez🇺🇸 · Philip Harris🇺🇸 · Kyle Lee🇺🇸 · Ian Moult🇺🇸 · Simon Rothman🇺🇸
The last several years have seen tremendous progress in the ability to both compute and measure multi-point correlations in energy flux. The highly differential nature of energy correlators makes them ideal probes of multi-collinear factorization and azimuthal structure within jets. In this paper, we explore the phenomenology of four-point correlators in jet substructure. We identify experimentally realizable projections that probe different factorization channels onto splitting tensors and splitting functions. We perform a detailed phenomenological study using both Herwig and Pythia. By comparing parton shower results with analytic calculations in kinematic limits, we are able to disentangle intrinsic spin correlations from kinematic azimuthal correlations. In experimentally accessible kinematic regions, we find the spin correlations are subdominant, strongly motivating a complete calculation of the four-point correlator in QCD to provide a test of the parton shower results. We also present parameterizations and analysis algorithms that can be used experimentally. Our work sets the stage for the experimental measurement of these observables at the LHC, and their use as probes of the next generation of parton showers.
hep-phhep-ex2 citations
05
Flavor Hierarchies the Right Way
Pavel Fileviez Perez🇺🇸 · Clara Murgui🇨🇭
We propose a framework for fermion mass generation based on a universal seesaw. The Standard Model is extended by an Abelian gauge symmetry acting on right-handed fermions, together with vector-like fermions and scalar fields. The ordinary Yukawa couplings are forbidden, except for the top-quark coupling to the Higgs, which is allowed at the renormalizable level and remains unsuppressed. The charged-fermion hierarchies then arise from mixing with the vector-like sector, and light neutrino masses emerge from a neutral sector Majorana seesaw. CP is exact in the ultraviolet and broken spontaneously by scalar vacuum expectation values. The resulting CP-violating phase is transmitted to the quark sector and generates the CKM phase, while a Nelson-Barr structure, realized through the universal seesaw block form, keeps the physical QCD vacuum angle zero at tree level. Consistency with EDM bounds beyond tree level requires moderately suppressed Yukawa couplings between SM doublets to the vector-like sector. If the leading higher-dimensional operators are unsuppressed, the same requirement can favor a low breaking scale for the new Abelian symmetry. In this regime the vector-like fermions can lie at the TeV scale, with suppressed mixing with the electroweak sector. This framework provides a simple setting in which the hierarchies of charged-fermion masses, neutrino masses, and CP-violating parameters can be accounted for within a common extension of the Standard Model.
hep-ph0 citations
06
Azimuthal momentum isotropization in the Quark-Gluon Plasma thermalization
Sergio Barrera Cabodevila🇪🇸 · Xiaojian Du🇨🇳 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸
Azimuthal anisotropies coming from the initial state of a heavy-ion collision have been historically disregarded in the study of thermalization because they are expected to be rapidly washed out due to final-state interactions. However, they may be important when one attempts to describe azimuthal correlations observed in the collisions of small systems. In this work, we study how these initial anisotropies relax in the context of the Boltzmann Equation in Diffusion Approximation (BEDA). We find a clear hierarchy in the relaxation time of the anisotropies in terms of each harmonic coefficient. We also explore the evolution of the $p_{T}$ -dependent harmonic coefficients in time, finding a shift in the initial peak towards higher momenta that mimics the experimental data when we perform a phenomenologically motivated simulation.
hep-phhep-exnucl-th0 citations
07
Impact of QED Radiation on SMEFT Constraints in Deep Inelastic Scattering
Sonny Mantry🇺🇸 · Jian-Wei Qiu🇺🇸 · Jia-Yue Zhang🇺🇸
Deep-inelastic scattering (DIS) provides a powerful probe of physics beyond the Standard Model through precision measurements interpreted within the Standard Model Effective Field Theory (SMEFT). We study the impact of collision-induced QED radiation on SMEFT constraints using the joint QCD+QED factorization framework based on lepton distribution and fragmentation functions. QED radiation can substantially modify DIS cross sections and, in some kinematic regions, significantly alter the effective momentum transfer relevant for factorization. We find that while cross sections receive order-one corrections, longitudinal electron spin asymmetries are affected only at the few-percent level, making them significantly more robust observables for SMEFT studies. Benchmark projections for SoLID and the Electron-Ion Collider are provided to demonstrate the impact of QED radiation for future precision DIS analyses and the extraction of SMEFT constraints.
hep-phhep-exnucl-ex0 citations
08
Neutrino Masses and Dark Matter Stability in 3HDMs with Minimal Non-Abelian Discrete Symmetries
Cesar Bonilla🇨🇱 · Andres Layana-Ramirez🇨🇱
We present minimal three-Higgs-doublet models (3HDMs) based on global non-Abelian discrete symmetries that simultaneously explain neutrino masses and dark matter stability. A residual $Z_{2}$ parity from the spontaneous breaking of the new symmetry stabilizes the dark matter candidate, which runs in the loop generating neutrino masses at one loop alongside a tree-level type-I seesaw contribution. We identify $S_{3}$ and $D_{4}$ as the smallest non-Abelian groups realizing this framework and determine the minimal models in both cases that are consistent with current neutrino oscillation data. The resulting models conserve CP in both the Yukawa and scalar sectors.
hep-ph1 citation
09
Lepton mixing from the $Δ (96)$ Modular Littlest Seesaw
Hai-Zhi Hao🇨🇳 · Li-Na Yan🇨🇳 · Xiang-Gan Liu🇺🇸 · Cai-Chang Li🇨🇳
We perform the first comprehensive and model independent study of Modular Littlest Seesaw models based on the finite modular group $Δ (96)$ . We construct the vector-valued modular forms (VVMFs) for all irreducible representations of modular $Δ (96)$ , classify the inequivalent symmetry-preserving fixed points, and derive the corresponding alignments of the low-weight and next-to-lowest-weight triplet VVMFs. These results allow an exhaustive scan over the residual symmetries in the charged lepton, atmospheric neutrino, and solar neutrino sectors. We identify 35 phenomenologically viable and inequivalent breaking patterns, including 21 with normal ordering and 14 with inverted ordering. The resulting Dirac neutrino mass matrices go beyond the conventional CSD $(n)$ structure, yielding new fixed PMNS columns and novel correlations among the lepton mixing parameters beyond the TM $_{1}$ paradigm. The viable models are highly predictive, giving narrow ranges for neutrino masses, mixing parameters and CP phases, and can be stringently tested by upcoming experiments such as JUNO, DUNE and T2HK.
hep-ph0 citations
10
QCD for electroweak precision measurements: Foundations
George Sterman🇺🇸
The couplings of the strong to electroweak sectors of the Standard Model enable the exploration of each using our growing knowledge of the other. In this review, we will follow the sweep of history. Starting with QED as a precision theory, deep inelastic scattering served as a gateway to the strong interactions, followed by leptonic annihilation and quark-antiquark annihilation in hadron-hadron scattering. In turn, the resulting understanding of QCD helped establish the Standard Model. The same techniques form the basis for many precision electroweak measurements at high energy and searches for signs of new physics.
hep-ph0 citations
11
Serendipitous supersymmetric solution to the strong CP problem
Howard Baer🇺🇸 · Vernon Barger🇺🇸 · Dibyashree Sengupta🇮🇹
The Minimal Supersymmetric Standard Model (MSSM) has several problems: 1. its $μ$ term must be forbidden, then regenerated at the weak scale, 2. it allows for $R$ -parity violating superpotential terms which lead to rapid proton decay, 3. it allows for dimension-5 proton decay operators. The usual imposition of $R$ - or matter parity $P_{M}$ solves only the second of these, whereas anomaly-free discrete $Z_{n}^{R}$ symmetries (consistent with grand unification) address all of them. Once the $μ$ -term is forbidden by the imposition of a discrete $Z_{n}^{R}$ symmetry (which can emerge as a discrete remnant of string compactifications to 4-dimensions), the MSSM develops an accidental global $U (1)_{P Q}$ symmetry (thus providing a plausible origin for the global $U (1)_{P Q}$ needed for solving the strong CP problem). By coupling the Higgs fields to PQ-charged gauge singlet fields $X, Y$ (in the Kim-Nilles mechanism), and imposing SUSY breaking, one regenerates $μ$ at the weak scale whilst breaking the discrete $Z_{n}^{R}$ and the $U (1)_{P Q}$ . The broken global $U (1)_{P Q}$ develops a pseudo-Goldstone boson, the DFSZ axion, thus (perhaps inadvertently) solving the strong CP problem. In this setting, SUSY develops a dark matter candidate, the SUSY DFSZ axion, and possibly, though not necessarily, a WIMP dark matter candidate as well, depending on the order of the induced $R$ -parity violating operators.
hep-ph1 citation
12
Multipolar Dark Matter Freeze-out in an Early Matter-Dominated Universe
Debajit Bose🇮🇳 · Prolay Chanda🇮🇳 · Suvam Maharana🇮🇳 · Poulami Mondal🇮🇳
The relic abundance of thermal dark matter depends not only on its particle interactions but also on the expansion history of the early Universe. We study the freeze-out of fermionic dark matter interacting with the Standard Model through higher-dimensional electromagnetic operators in an early matter-dominated cosmology. In particular, we consider magnetic dipole, electric dipole, anapole, and charge-radius interactions, and compute the couplings required to reproduce the observed dark matter relic abundance in the presence of entropy injection from the decay of a long-lived heavy field. The resulting parameter space is compared with that obtained in the standard radiation-dominated freeze-out scenario and confront it with current constraints from direct-detection experiments and solar neutrino observations. We find that the entropy dilution associated with an early matter-dominated epoch significantly reduces the interaction strength required to obtain the observed relic abundance, thereby rendering viable regions of parameter space that are excluded in the conventional cosmological history. Our results demonstrate that the cosmological history prior to Big Bang nucleosynthesis can have an important impact on the phenomenology and experimental viability of electromagnetic multipole dark matter.
hep-phastro-ph.CO1 citation
13
Experimental access to the gluonic origin of the proton mass
Zein-Eddine Meziani🇺🇸 · Ismail Zahed🇺🇸
Most of the proton mass originates not from the Higgs mechanism but from the quantum structure of the QCD vacuum. The dominant contribution arises from the gluonic trace anomaly associated with the breaking of conformal symmetry in quantum chromodynamics. We show that this anomaly contribution is experimentally accessible through scalar gravitational form factors. The key observable is the scalar gluonic trace form factor of the proton, which can be reconstructed from three measurable quantities: the quark scalar gravitational form factor accessible in deeply virtual Compton scattering, the gluon scalar gravitational form factor measurable in near-threshold heavy quarkonium production, and the nucleon sigma-term form factor. We also show that the scalar gluonic form factor extracted from the trace anomaly is quantitatively consistent with lattice QCD and the instanton liquid model over hadronic distance scales. These results provide a direct experimental path to probing the gluonic origin of visible mass.
hep-phnucl-ex0 citations
14
Study of exotic hadron states in the $D D^{*}$ system via the complex momentum representation and Green's function method
Di Wu🇨🇳 · Mao Song🇨🇳 · Jian-You Guo🇨🇳 · Gang Li🇨🇳 · Xuan Luo🇨🇳 · Peng Wang🇨🇳
In this paper, we propose a novel approach to investigate exotic hadronic states. For the $D D^{*}$ system, we employ the projection operator method to derive the momentum-space interaction potential. Subsequently, the complex momentum representation (CMR) method is adopted to realize a unified description of bound states, resonant states, and the continuum. By combining the Green's function and the CMR, the scattering phase shifts and cross sections are determined. This integrated approach provides a comprehensive framework for analyzing the scattering dynamics of the $D D^{*}$ system. In the hadronic molecular state framework, the $X (3872)$ , $T_{cc}^{+}$ , and $Z_{c} (3900)$ states can be consistently explained as bound states, while the $G (3900)$ can be interpreted as a $P$ -wave resonant state. The decomposition of the scattering phase shifts and cross sections facilitates understanding the roles of resonant and continuum spectrum.
hep-phPRD(2026)·0 citations
15
$Z^{'}$ Portal Dark Matter with Observable $Δ N_{eff}$
Ang Liu🇨🇳 · Zhi-Long Han🇨🇳 · Fei Huang🇨🇳
In the conventional $Z^{'}$ portal dark matter scenario, the prediction of detectable dark matter $χ$ typically relies on the collider sensitivities of $Z^{'}$ and direct detection, where the Majorana type right-handed neutrinos are usually assumed. However, if the right-handed neutrinos $ν_{R}$ are Dirac type, they will contribute to the additional effective number of relativistic species $Δ N_{eff}$ , which brings different detectable predictions for $Z^{'}$ portal dark matter. In light of the great improvement of $Δ N_{eff}$ for the upcoming experiments, we investigate the $Z^{'}$ portal dark matter with Dirac type $ν_{R}$ . Under the $U (1)_{B - L}$ symmetry, this model includes $ν_{R}$ with $U (1)_{B - L}$ charge $Q_{ν_{R}} = - 1$ and $χ$ with arbitrary $Q_{χ}$ beyond the SM. Based on the relation in the production of $χ$ and $ν_{R}$ , both the WIMP and FIMP dark matter through the $Z^{'}$ portal scenario are considered. We perform a comprehensive exploration of the viable parameter space under the constraints from $Δ N_{eff}$ induced by thermal and non-thermal $ν_{R}$ , perturbative limit, dark matter direct and indirect detection, and collider searches of $Z^{'}$ .
hep-ph1 citation
16
Overview of Applications of Quantum Computing in QCD
Germán Rodrigo🇪🇸
Quantum computing has emerged as a promising framework for addressing computationally demanding problems in collider physics. In recent years, a growing number of quantum algorithms have been proposed for applications ranging from event generation and parton shower simulation to the evaluation of scattering amplitudes, loop and phase-space integration, and optimization problems relevant to experimental analysis. We provide a concise overview of the main ideas behind these developments, with emphasis on the potential advantages of quantum approaches in comparison with classical methods, as well as on the current limitations imposed by noisy intermediate-scale quantum hardware.
hep-phhep-exhep-thquant-ph0 citations
17
Transformer-based machine learning using low-level calorimeter signals for collimated photon identification at collider experiments
Gabriel Matos🇺🇸 · Lauren Larson🇺🇸 · Abhilasha Dave🇺🇸 · Maria Bressan🇺🇸 · Azal Amer🇺🇸 · Cindy Liu🇨🇳 · Nikiforos Nikiforou🇨🇭 · Jonathan Long🇺🇸 · Timothy Andeen🇺🇸 · John Parsons🇺🇸 · Julia Gonski🇺🇸
Electromagnetic calorimeters provide essential information for reconstructing and selecting both Standard Model (SM) and potential beyond the SM physics events at high-energy particle colliders. The fine-grained segmentation of modern calorimeters captures rich information about the internal structure of particle showers, much of which is discarded by conventional high-level reconstruction methods. In this work, we leverage calorimeter cell-level information to classify highly collimated diphoton signatures, arising from the decay of light axion-like particles, from isolated single-photon showers. We systematically compare a range of machine learning architectures, spanning high-level, shower shape variable-based approaches and direct cell-level methods. Cell-level machine learning shows significantly superior classification ability, with a Transformer in particular representing the best performance among six different architectures studied, and an MLP Mixer representing a resource-constrained alternative for potential real-time, trigger-level applications. Beyond classification, the Transformer model developed enables direct invariant mass regression from calorimeter cells, improving the characterization of light resonances and providing an additional handle in reducing the $π^{0}$ and $η$ fake photon backgrounds. These results demonstrate that cell-level machine learning methods can extend calorimeter-based particle identification and performance well beyond the capabilities of current conventional techniques.
hep-phhep-ex0 citations
18
Probing Quadratically Coupled Ultralight Dark Matter with the Laser Interferometer Space Antenna
Xucheng Gan🇩🇪 · Hyungjin Kim🇫🇷 · Anna-Malin Lemke🇩🇪 · Andrea Mitridate🇩🇪
Ultralight dark matter can interact with Standard Model particles via gravitational and non-gravitational interactions. Through such interactions, it can leave distinctive signals in gravitational-wave experiments. In this work, we investigate signals induced by ultralight dark matter quadratically coupled to the Standard Model in the future space-borne gravitational-wave detector, the Laser Interferometer Space Antenna (LISA). Due to the quadratic nature of the coupling, dark matter signals appear at two distinct frequencies: the frequency corresponding to twice the dark matter mass, and frequencies below the typical dark matter kinetic energy. We analyze both contributions and show that LISA can surpass current constraints from terrestrial and astrophysical probes in certain mass ranges. We also find that dark matter signals in LISA are free from screening effects which significantly limit the sensitivity of terrestrial experiments.
hep-phastro-ph.CO1 citation
19
Precision three-Dimensional Atmospheric Neutrino Flux Calculation Based on Honda Flux Model
Jie Cheng🇨🇳 · Yu-Feng Li🇨🇳 · Liang-Jian Wen🇨🇳
We present a comprehensive three-dimensional atmospheric neutrino flux calculation based on the well-recognized simulation framework develeped by Honda and his collaborators, incorporating for the first time the muon propagation inside the Earth and its subsequent decay or nuclear capture. Other updates of essential input models include: the AMS02-based primary cosmic ray model, IGRF2020 geomagnetic field, and muon-recalibrated hadronic interaction model. The calculation covers seven detector sites across diverse geomagnetic environments, spanning 10~MeV to $1 0^{4}$ ~GeV. Significant site-dependent differences appear at $E_{ν} < 10$ ~GeV, with $ν_{μ}$ flux at IceCube approximately twice that at JUNO below 1~GeV. Compared to HKKMS15, deviations of 2\%--10\% are attributed to the updated input models. Below 100~MeV, we present precise flux results, revealing that muon propagation contributes a globally significant component to the low-energy neutrino flux at all sites, with an approximately site-independent absolute increment. The hadronic uncertainty is re-estimated across the energy range using the updated hadronic interaction model, with significant reduction of the systematic error compared to previous calculations. These results provide essential inputs for neutrino oscillation and rare-event search experiments including JUNO, Super-Kamiokande/Hyper-Kamiokande, DUNE, KM3NeT/ORCA, and IceCube, as well as direct dark matter detection experiments facing the neutrino fog.
hep-phastro-ph.HEhep-ex0 citations
20
Revisiting One-Zero and Two-Zero Neutrino Mass Textures in Light of Recent Oscillation and Cosmological Data
Haruto Kitagawa🇯🇵 · Coh Miyao🇯🇵 · Satsuki Nishimura🇯🇵 · Hajime Otsuka🇯🇵
We revisit one-zero and two-zero textures of the neutrino mass matrix under current experimental and cosmological constraints. We identify the phenomenologically viable texture structures using the latest results on neutrino oscillation parameters, the cosmological bound on the sum of neutrino masses, the kinematic bound on the effective electron-neutrino mass, and limits from neutrinoless double-beta decay. For two-zero textures, several structures are still allowed if only the CMB bound on the neutrino mass sum is imposed. Among them, the $B$ -series textures show a characteristic prediction for the Dirac CP phase, with $δ_{CP}$ lying around $π /2$ and $3 π /2$ , and are within the reach of future neutrinoless double-beta decay searches. When the stronger CMB+BAO constraint is included, however, only the $A$ -series textures remain viable. Therefore, we also analyze one-zero textures by using machine learning techniques, particularly flow matching. It turns out that some of the texture structures are already excluded by current data, while the allowed ones give distinct predictions for $\sum_{i} m_{i}$ , $m_{ν_{e}}^{eff}$ , $⟨ m_{ee} ⟩$ , and $δ_{CP}$ . We further discuss how the one-zero texture structures can arise from non-invertible selection rules.
hep-phcs.LG2 citations
21
Electron-Ion Collision Environment: Distribution of Quark Spin and Orbital Angular Momentum
Sujit Jana🇮🇳 · Ashutosh Dwibedi🇮🇳 · Vikash Kumar Ojha🇮🇳 · Sabyasachi Ghosh🇮🇳
The future Electron-Ion Collider (EIC) will enable measurements of the same partonic distributions inside both the proton and the nucleus through electron-proton (eP) and electron-ion (eA) collisions. This capability motivates the present theoretical study of the distributions of quark spin and orbital angular momentum within the proton and the nucleus. To map the eP and eA collision environments, we employ the Nambu--Jona-Lasinio (NJL) model at finite nuclear density to determine the constituent quark masses at zero nuclear density and near the nuclear saturation density. Using these quark mass inputs, we calculate the generalized transverse momentum-dependent parton distributions (GTMDs) associated with quark orbital angular momentum (OAM), spin, and spin-orbit correlations within the light-front dressed quark model. Furthermore, inspired by the nuclear suppression factor widely used in heavy-ion collision experiments, we introduce a set of GTMD ratios between eP and eA collisions. Any deviation of these ratios from unity provides an indirect measure of many-body nuclear density effects arising from non-perturbative quantum chromodynamics (QCD).
hep-ph0 citations
22
AMFlow 2.0: significant algorithmic and software improvements for Feynman integral evaluation
Rui-Jun Huang🇨🇳 · Xiao Liu🇨🇳 · Yan-Qing Ma🇨🇳
We present significant improvements to the AMFlow package for the numerical computation of dimensionally regularized Feynman integrals. Several new features are introduced to reduce computational cost, including an alternative recursion mode, a high-performance differential equation solver, support for state-of-the-art integration-by-parts reducers and other useful improvements. We benchmark the new version on a three-loop five-point topology and find that both the symbolic and numerical performance are significantly improved.
hep-phhep-th3 citations
23
Leptogenesis and Low Reheating Temperatures
Marcos A. G. Garcia🇲🇽 · Stephen E. Henrich🇺🇸 · Wenqi Ke🇺🇸 · Keith A. Olive🇺🇸
We study leptogenesis during non-instantaneous reheating in the canonical type-I seesaw framework, with the dominant source of right-handed neutrino (RHN) production being non-thermal from inflaton decays ( $ϕ \to N N$ ). While matter-like reheating ( $w_{ϕ} = 0$ ) fails to be compatible with standard leptogenesis for very low reheating temperatures, the situation is strikingly different for generalized Starobinsky potentials approximated by $V (ϕ) \propto ϕ^{k}$ with $k \geq 4$ about the minimum. In the latter cases, the observed baryon asymmetry can readily be obtained for arbitrarily low reheating temperatures above the BBN bound of $\sim 4$ MeV. We study radiation-like reheating ( $w_{ϕ} = 1/3$ , $k = 4$ ) in detail, showing that the evolving effective mass of the inflaton condensate leads to kinematic shutoff of the $ϕ \to N N$ channel, which qualitatively changes the leptogenesis dynamics. We include a detailed treatment of the effects of fragmentation of the inflaton condensate. The final baryon asymmetry depends primarily on only two parameters: the inflaton-RHN coupling, $y_{ϕN N}$ , and the CP-violating parameter $∣ ϵ ∣$ . Interestingly, the final asymmetry is largely insensitive to the RHN mass, the reheating temperature, and the RHN decay rate. While we focus on fermionic reheating, we show that the general features of these results also hold for bosonic reheating to scalars.
hep-phastro-ph.CO2 citations
24
Analysis of Nuclear Fragmentation Functions for Pions with $A$ and $ν$ Dependence
Mengyang Li🇨🇳 · Zijian Ye🇨🇳 · Jun Gao🇨🇳 · Xiaomin Shen🇨🇳 · Hongxi Xing🇨🇳 · Yuxiang Zhao🇨🇳
We present a QCD analysis of pion nuclear fragmentation functions (nFFs), which encode nuclear modifications to hadronization in high-energy nuclear collisions. Within this framework, vacuum fragmentation functions and their nuclear modifications are extracted simultaneously. The nuclear effects are parameterized as functions of the mass number $A$ , the energy of the fragmenting parton in the target rest frame $ν$ , and the hadron energy fraction $z$ , allowing their dependence on these variables to be quantified. Our analysis includes semi-inclusive deep-inelastic scattering data on nuclear targets, with kinematic cuts chosen to ensure the applicability of perturbative QCD and collinear factorization. The resulting fit provides a good description of most datasets, with the nFFs well constrained in the energy fraction range $z \in [0.2, 0.7]$ . Additionally, with our new nFFs, we present next-to-leading order predictions in $pp$ and $p A$ collisions, which show reasonable agreement with ALICE data within the current experimental uncertainties.
hep-ph0 citations
25
Heavy quark coalescence probability in the presence of a potential
Taesoo Song🇩🇪 · Jiaxing Zhao🇩🇪
In this study, we explore the role of the heavy quark potential in heavy quark coalescence, whose probability is expected to be unity at low momentum. To this end, we develop a phenomenological heavy quark potential based on the constituent quark model that reproduces the vacuum masses of pseudoscalar and vector heavy mesons. Using this potential, we demonstrate its enhancement effect on the coalescence probability. We also investigate how medium-induced modifications of the heavy quark potential in the quark gluon plasma affect the coalescence process. Our results indicate that the coalescence probability remains close to unity as long as the modification of the potential is sufficiently moderate.
hep-phnucl-th0 citations
26
Optimal-Transport-Based Cell Resampling for Negative and Pathological Event Weights
Regan Doherty🇺🇸 · Lauren Hay🇺🇸 · Rishabh Jain🇮🇳 · Matt LeBlanc🇺🇸 · Julia Marrinan🇺🇸 · Camille Mauceri🇺🇸 · Jennifer Roloff🇺🇸
Negative and pathologically large Monte Carlo event weights strain the computing budgets of experiments at the Large Hadron Collider. Cell resampling algorithms locally redistribute event weights among nearby events in a metric space. We study the performance of metrics defined in terms of Optimal Transport, namely the Energy Mover's Distance and a spectral variant, in the context of such algorithms. As these metrics are insensitive to the addition of soft and collinear radiation, they may be applied directly to particles at any stage of event generation. When applied to samples simulated at next-to-leading-order in quantum chromodynamics, this approach reduces the observed bias relative to other cell resampling techniques presented in the literature. We also study the Cross-Section Mover's Distance as an unbinned, broadly-applicable figure of merit for quantifying the bias introduced by any full-phase-space reweighting.
hep-phphysics.comp-phphysics.data-an0 citations
27
Internal pseudospin, lepton-number superselection, and neutrino--antineutrino coherence in massive neutral-fermion one-particle states
Ricardo Romero🇨🇱
At fixed three-momentum, massive Dirac neutrino one-particle states span a 4D space of particle--antiparticle identity and helicity. We show that helicity flip, charge conjugation, and their product close an internal $S U (2)$ pseudospin subalgebra within $S U (4)$ , distinct from the Wigner little group. Its helicity generator is the lepton-number-weighted spin rotation $U_{1} = 2 L J_{2}$ . The lepton-number $L$ and helicity $H_{h}$ grade the 16 generators $τ_{μ} \otimes σ_{ν}$ , organizing the $Δ L = 2$ sector. Helicity-preserving directions $τ_{1, 2} \otimes σ_{0, 3}$ carry the pseudo-Dirac mixing $κ_{pD} = Δ m^{2} /4 E$ (active--sterile), while helicity-flipping directions $τ_{1, 2} \otimes σ_{1, 2}$ carry the neutrinoless double-beta decay mass factor (active--active). Furthermore, charge conjugation matches the $U_{2}$ generator. The Majorana condition is thus a projection onto the $U_{2} = + 1$ eigenspace, where only the Wigner algebra survives. This framework algebraically classifies Majorana masses and pseudo-Dirac splittings without assuming neutrinos are Majorana particles.
hep-phhep-th0 citations
28
First Search for Kaluza-Klein Gravitons and Radion Using Planck Data
Alexander P. Cassem🇺🇸 · Soubhik Kumar🇺🇸
Heavy moduli and Kaluza-Klein (KK) gravitons from extra dimensions may evade terrestrial probes but can be produced during inflation, generating primordial non-Gaussianity (NG) through unavoidable couplings to density perturbations. In a warped five-dimensional (5D) model, we compute the full radion- and KK-graviton-mediated bispectra and perform the first search for these signals using Planck 2018 temperature and polarization data. We find no significant evidence for NG, with the maximum significance being $1.8 σ$ for $m_{KK} \approx 1.6 H$ . We also identify a 5D setup which naturally generates NG with $f_{NL} \sim 1 - 50$ , within the reach of future surveys.
↳ astro-ph.COhep-phhep-th4 citations
29
Alleviating the Hubble Tension with Smooth Sign-Switching Dark Energy: Full CMB Constraints with DESI and PantheonPlus
Mariam Bouhmadi-López🇪🇸 · Hsu-Wen Chiang🇨🇳 · Beñat Ibarra-Uriondo🇪🇸
Sign-switching dark energy has recently been proposed as a minimal modification of the late-time expansion history aimed at alleviating tensions within the standard cosmological model. In this work, we investigate ECDM, a smooth realisation of this scenario, with the dark energy density gradually transitioning from a negative to a positive value. We develop a consistent formulation of the perturbation equations that remains well behaved even when the dark energy equation-of-state parameter diverges during the transition. We confront the model with a comprehensive set of cosmological observations, including cosmic microwave background measurements from Planck 2018, ACT DR6 and SPT-3G, baryon acoustic oscillation measurements from DESI DR2, Type Ia supernova distances from Pantheon+, and local Hubble constant measurement of SH0ES. The inclusion of perturbations allows us to assess the impact of the model on structure growth and CMB anisotropies, providing a more thorough test of sign-switching dark energy. Our results show that this class of models is fully compatible with current precision cosmological observations while alleviating the Hubble tension and providing a compelling modification of the late-time dynamics of the Universe.
↳ astro-ph.COgr-qchep-phhep-th4 citations
30
Deuterium-Proton Fusion in an Effective Field Theory Constructed from On-Shell Amplitudes
Tim M.P. Tait🇺🇸
Big Bang nucleosynthesis (BBN) predicts the primordial deuterium abundance to a precision now limited by the nuclear reactions that burn deuterium. For the simplest of them, proton-deuteron radiative capture, d + p -> \gamma + 3He [d(p,\gamma)3He], the precise LUNA data sit below the ab initio benchmark, and BBN reaction networks split on which to adopt. We develop an effective field theory (EFT) expanding in the finite size of the nuclei, building the amplitude with modern on-shell methods that enumerate every tree-level structure consistent with symmetries without the need for an explicit Lagrangian. A global Bayesian fit to the capture data and nuclear-theory priors returns S(0) = 0.209 +/- 0.008 eV b and traces the offset from the ab initio benchmark to a single natural-sized next-to-leading contact term (t_E1 ~ -0.15, the fractional shift of the electric-dipole amplitude) -- equivalently a ~15% lower effective 3He asymptotic normalization. We estimate the leading EFT truncation errors and identify an elastic d-p observable that would separate them. Our results suggest that amplitude methods enable systematic and complete tree-level construction and matching of EFTs for low-energy nuclear reactions.
↳ nucl-thastro-ph.COhep-phhep-th1 citation
31
The Status of Single Scalar Field Dark Energy
Carlos García-García🇬🇧 · Pedro G. Ferreira🇬🇧 · William J. Wolf🇬🇧
We present an assessment of the current observational status of single scalar field models of dark energy. Motivated by recent cosmological measurements -- including baryon acoustic oscillations, Type Ia supernovae, and CMB data -- we examine whether a dynamical scalar field offers a viable explanation for the accelerated expansion of the Universe. Working within an effective field theory (EFT) framework, we argue that cosmological observations are fundamentally limited and can at most constrain a small number of parameters that govern scalar field dynamics. We show that quintessence remains only marginally distinguishable from a cosmological constant, $Λ$ , and that more general EFT extensions exhibit modest statistical preference, though such evidence is sensitive to data set selection and prior assumptions. These extended models generically predict fifth forces and modifications to the growth of structure, raising challenges from astrophysical constraints. We compare their predictions with current growth rate measurements, Integrated Sachs-Wolfe (ISW) effect and Solar System constraints. We emphasize that viable screening mechanisms remain theoretically non-trivial and observationally testable. On the other hand, we find that current ISW and growth data remain largely in agreement. Looking ahead to Stage IV surveys we forecast improvements in constraints on the dark energy behaviour; although there will be some tightening of bounds, we argue that the problem of underdetermination will persist. We conclude that while single scalar field dark energy remains a natural and flexible framework, its ultimate viability will hinge on improved low-redshift growth measurements and a clearer understanding of gravitational screening.
↳ astro-ph.COgr-qchep-phhep-th11 citations
32
Static regular black holes in Horndeski theories: analytic no-go and nonanalytic obstructions
Antonio De Felice🇯🇵 · Shinji Tsujikawa🇯🇵
Regular black holes in Horndeski theories must have stable horizons and regular centers. We study static, spherically symmetric, asymptotically flat configurations with a time-independent scalar. The horizon branch on which the scalar kinetic term $X$ remains nonzero is generically obstructed by divergent propagation speeds or ghost/gradient instabilities, aside from special degeneracies. On the regular branch, where $X$ vanishes at the horizon, analyticity at the relevant $X = 0$ endpoints reduces the leading scalar equation to finite sets of Taylor coefficients. For nondegenerate shift-symmetric theories this gives a nonperturbative current no-hair theorem: the scalar is constant and the metric is Schwarzschild, hence centrally singular for nonzero ADM mass. For non-shift-symmetric positive-power couplings, the corresponding exclusion applies to the perturbative branch continuously connected to Schwarzschild. We also classify marginal nonanalytic departures: covariant regularity fixes the scalar-Gauss-Bonnet chain as the unique marginal nonanalytic completion. Hairy black holes in this completion evade the analytic current step but remain centrally singular.
↳ gr-qchep-phhep-th1 citation
33
Signal-to-Noise Ratio Contours for LISA
Kai Schmitz🇩🇪 · Joseph D. Romano🇺🇸
The Laser Interferometer Space Antenna (LISA) will search for a stochastic gravitational-wave (GW) background at millihertz frequencies, from both astrophysical and cosmological sources, and thereby open a new chapter in GW astronomy. In the literature, LISA's sensitivity to prospective GW background (GWB) signals is often quantified in terms of an expected signal-to-noise ratio (SNR) assuming perfect knowledge of the detector noise. The commonly employed expression for the SNR is, however, valid only in the limit of a weak GWB signal, which renders a large number of SNR values reported in the literature inaccurate. In this paper, we address this issue by deriving for the first time an expression for the expected optimal SNR of a LISA auto-correlation measurement that is valid at arbitrary signal strength. Based on our generalized expression, we conclude that LISA data worth an observing time of T_obs across the frequency band from f_min to f_max will never yield an SNR in excess of SNR_max = sqrt(T_obs(f_max-f_min)), which evaluates to SNR_max <~ 10^4 for typical mission parameters. We illustrate our findings in terms of generalized power-law-integrated (PLI) sensitivity curves at different SNR levels, i.e., LISA SNR contour lines in plots of the GW energy-density power spectrum. In contrast to earlier work on PLI sensitivity curves, we notably find that the LISA SNR contours are bounded from above, approximately by the LISA strain noise curve multiplied by a factor of Euler's number e. For GWB signals not much weaker than this range, the expected SNR for a LISA auto-correlation measurement needs to be evaluated based on our new expression. Our numerical results for the LISA SNR contours are available on Zenodo [https://doi.org/10.5281/zenodo.21275527].
↳ gr-qcastro-ph.IMhep-ph1 citation
34
Gram--Wishart--Stiefel formulation of the $N = 2$ , large-- $d$ gauge theory in 1D
Badis Ydri🇩🇿
We develop in this paper the Gram/Wishart/Stiefel formulation of the $N=2$, large--$d$ planar endpoint theory of the BFSS/BMN matrix quantum mechanics on the lattice, obtained in our previous work. In this formulation, the endpoint degrees of freedom are reorganized into rank--two Wishart eigenvalues and relative Stiefel angular variables. This allows the holonomy invariants $A$, $B$, and $R^2=A^2+B^2$ to be analyzed directly in terms of radial and angular Gram data. A central point is the large-$R$ aligned asymptotics of the holonomy potential. Its universal linear contribution $-A$ is absorbed into the Gaussian sector, producing the shifted mass parameter $(\alpha_\Lambda)_{\rm eff}=\alpha_\Lambda-1/2$. In the Gram/Wishart/Stiefel variables, the exact $O(2)$ angular integral encodes this shifted sector in a rank--two Bessel kernel. The pure $-A$ theory, which is exactly solvable in Cartesian variables, then fixes the leading Bessel/HCIZ structure: its exponential part selects the aligned configuration, while its prefactor removes the spurious doubled Wishart entropy. We then apply this structure to the transverse $B$-type expansion and its non-polynomial toy completion. Finite polynomial truncations lead to an apparent large--$d$ perturbativity bound incompatible with the continuum limit, but this bound is shown to be an artifact of truncation. After summing the local transverse completion and balancing the compensating $+A$ term, the Wishart saddle is recovered with the physical shifted mass. The resulting continuum behavior reproduces the universal $-2d$ contribution of the $D_\Lambda$-channel, while the genuinely anisotropic $\beta_\Lambda$-channel lies outside the scope of a pure transverse $B$-type description.
↳ hep-thgr-qchep-lathep-ph+21 citation
35
A symmetry-based resolution of pseudo-gauge ambiguities in local equilibrium
Carlos Hoyos🇪🇸
The total angular momentum current can be decomposed into orbital and spin contributions in different ways, known as pseudo-gauges. This freedom leads to ambiguities in the definition of local-equilibrium density operators, which in turn affect estimates of spin polarization in heavy-ion collisions. In this work, the pseudo-gauge ambiguity, together with other ambiguities associated with improvements of conserved currents, is reformulated in terms of spurious symmetries corresponding to conserved currents with vanishing total charge. A prescription for the unambiguous definition of a local-equilibrium density operator is introduced using the currents associated with genuine symmetries. The resulting density operator is invariant under transformations that add improvement terms to local currents, including the energy-momentum tensor.
↳ nucl-thhep-phhep-th0 citations
36
The statistics of curvature-profile dispersion in primordial black hole formation
Albert Escrivà🇯🇵
In the standard curvature-perturbation scenario, PBHs form from the collapse of superhorizon curvature fluctuations after horizon re-entry. The predicted abundance is exponentially sensitive to the collapse threshold and hence to the shape of the primordial curvature profile. In this work we develop a finite-action framework to describe curvature-profile dispersion around representative peak profiles. Using a multipolar Fourier-Bessel decomposition, we separate the local peak variables of the Gaussian field from residual radial and angular deformations, normalized by their Gaussian action. We apply the formalism to spherical numerical-collapse examples in order to isolate the effect of radial shape dispersion. For finite-width spectra, and in the presence of logarithmic local non-Gaussianity, we compute the collapse threshold as a function of a coherent shape variable and combine the result with peak statistics. We find that the dominant contribution to the PBH abundance is not necessarily the conditional-mean reference profile, nor simply the profile with the lowest threshold. Instead, it is selected by a competition between the Gaussian cost of realizing a coherent deformation and the exponential gain associated with lowering the collapse threshold. Broad spectra and negative non-Gaussianity can make rare shape deformations dominate the abundance. In the examples studied here, the dominant branches can correspond to several-sigma coherent shape fluctuations while enhancing the integrated abundance by orders of magnitude. Equivalently, including shape dispersion can reduce the power-spectrum amplitude required to obtain a fixed PBH abundance. Our results show that residual profile dispersion is a genuine statistical ingredient in PBH formation and can be quantitatively important for accurate abundance estimates.
↳ astro-ph.COgr-qchep-phhep-th4 citations
37
Decoupling Limit of Quiver Theories and the Angular Spectra of Extreme C-metrics
Peng Yang🇨🇳 · Kilar Zhang🇨🇳
We investigate the angular eigenvalue problem of the extreme charged C-metric. In the extreme limit ( $Q \to M$ ), the governing differential equation degenerates from a Fuchsian equation with five regular singular points into a Confluent Extended Heun Equation. To evaluate the angular spectrum analytically, we formulate a decoupling limit within the dual four-dimensional $N = 2$ , $SU (2) \times SU (2)$ linear quiver gauge theory. Within this framework, we derive the parameter dictionary and renormalized Matone relations, which absorb the macroscopic residue shifts induced by the singularity fusion. Based on the regular boundary conditions of the angular equation, we utilize the instanton counting method to establish an algebraic quantization condition, yielding angular eigenvalues consistent with numerical results.
↳ hep-thastro-ph.HEgr-qchep-ph+21 citation

Affiliations

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