HEP Phenomenology·hep-ph

Fri·Jun 19, 2026Friday·June 19, 2026

52 papers—32 primary·20 cross-listed

01
The next-to-leading order of the differential cross-section of the subprocess of Compton scattering of quark-gluon of prompt photon production in proton-proton collisions at NICA energies
Mohsun Rasim Alizada🇦🇿 · Azar Inshalla Ahmadov🇦🇿
In the presented article, the next-to-the-leading-order calculation of the differential cross-section of the Compton scattering subprocess $q g \to q γ$ for prompt photon production in proton-proton collisions at NICA energies has been carried out, both without and taking into account the longitudinal polarization of colliding protons. It is shown that the contribution of the next-to-leading order to the differential cross-section is significant at high energies of colliding protons and constitutes around $15%$ of the leading-order calculation. The influence of the polarization of colliding protons on the next-to-leading-order calculation is more significant than on the leading-order calculation.
hep-phInt.J.Mod.Phys.A(2026)·0 citations
02
Emergent Gauge Symmetries in Particle Physics and Cosmology
Steven D. Bass🇵🇱
Where do gauge symmetries come from? These lectures develop the idea that the Standard Model might be emergent, with its gauge symmetries dissolving in some phase transition deep in the ultraviolet. The (meta-)stability of the Higgs vacuum may be pointing to some new critical phenomena at very high energy scales, with the Higgs connecting physics at LHC laboratory energies to that in the deep ultraviolet. In the emergence scenario, the dark energy scale comes out similar to the size of light Majorana neutrino masses. These two quantities appear at the same order in a low energy expansion in inverse powers of the scale of emergence, about $1 0^{16}$ GeV. Dark matter candidates include axions and phonon like excitations of degrees of freedom above the scale of emergence. Possible tests of these ideas involve neutrinos as well as gravitational-waves-related signals from the early Universe, which are sensitive to physics at very high energy scales.
hep-phastro-ph.COActa Phys.Polon.B(2026)·0 citations
03
LeWRON: Agentic Analysis of Electroweak Phase Transitions
Isaac R. Wang🇺🇸
The electroweak phase transition (EWPT) is a central topic in particle physics and cosmology, connecting collider phenomenology, baryogenesis, and gravitational-wave observatories. Its analysis requires a technically demanding, convention-sensitive, and model-dependent pipeline, from constructing the finite-temperature effective potential to tracking thermal histories, computing bubble nucleation rates, and predicting gravitational-wave spectra. We present LeWRON (Learning ElectroWeak phase tRansitiON), an agentic framework that orchestrates this pipeline starting from an input Lagrangian. LeWRON combines audited toolbox construction with an Explorer module that uses the generated model-specific code for further analysis, including scans and plots. Intermediate analytic outputs are checked by auditor agents and stored as structured artifacts, enabling reproducible human inspection and downstream use through both a command-line interface and a public Python API. The framework supports a reproduction mode, which infers conventions from the literature and reproduces published results, and a discovery mode, which guides users through structured checkpoints for new models. We demonstrate LeWRON across representative beyond-the-Standard-Model scenarios and release the code on GitHub.
hep-ph8 citations
04
Partial-wave unitarity and long-range interactions
Ryan Plestid🇨🇭 · Pablo Quílez Lasanta🇺🇸
Theories with massless particles contain $t$ -channel (forward scattering) singularities that cause standard fixed order expressions for partial-wave amplitudes to be ill-defined. This presents an obstruction to systematically improvable partial-wave unitarity bounds. In this work, we study the construction of partial-wave amplitudes in a modified perturbation theory that incorporates long-range interactions focusing on the role of off-shell Coulomb modes. We find that there exists a universal description of the forward scattering region that renders the amplitudes renormalization scale independent. The resulting partial-wave amplitudes become well defined single-scale objects without spurious dependence on the infrared regulator, and we present a practical method for their computation order-by-order in perturbation theory.
hep-phhep-th0 citations
05
From Rags to Jeans: Axion Miniclusters from Early matter domination
Ariel Angulo🇨🇳 · Paola Arias🇨🇱 · Nicolás Bernal🇦🇪 · Javier Redondo🇪🇸
In an early matter-dominated era, density and temperature inhomogeneities of the radiation bath grow more efficiently than in the standard radiation-dominated history. If the axion mass depends on temperature, these inhomogeneities induce spatial fluctuations of the axion mass, providing a new source term for axion density perturbations. We show that this mechanism is most efficient when the reheating temperature lies just below the mass-saturation scale $T_{Λ}$ , and can drive axion overdensities to order unity by matter--radiation equality. For the QCD axion saturating the observed dark matter abundance, the nonlinear spectrum at equality exhibits two characteristic regions: one associated with the gravitational enhancement already present in moduli-driven cosmologies, and another produced by the temperature dependence of the axion mass. We estimate the resulting minicluster masses and discuss the possible formation of axion miniclusters and axion-star substructure.
hep-phastro-ph.CO1 citation
06
Spin Identification of Dark Sector Mediators through Angular Distributions
D. Aristizabal Sierra🇨🇱 · S. Fuenzalida Garrido🇨🇱 · F. Kling🇩🇪 · T. Mäkelä🇺🇸 · N. Viaux🇨🇱
A variety of experiments are operating or planned to search for displaced decays of light long-lived dark sector particles. In case such a state is discovered, the next step is determining its quantum numbers. We identify an angular observable, reconstructible solely from the decay products' four-momenta, that exhibits an anisotropic distribution for vector bosons from light meson decays and an isotropic distribution for scalars. We demonstrate that searches at DUNE, SHiP and FASER2 will be able to identify the mediator spin in sizable regions of yet unconstrained parameter space.
hep-phhep-ex0 citations
07
Real and Virtual Propagation in Neutrino Oscillations
Kenji Nishiwaki🇮🇳 · Kin-ya Oda🇯🇵 · Juntaro Wada🇯🇵
We revisit flavor oscillations in vacuum in terms of the propagation time of intermediate states. In the limit of a long propagation time (or distance), degenerate intermediate states exhibit oscillatory behavior, as described by the Jacob--Sachs (or Grimus--Stockinger) theorem within wave-packet quantum field theory. By explicitly evaluating the relevant integrals using the saddle-point method, we derive an extended expression for the flavor-changing amplitude that remains valid even for shorter propagation times. We show that oscillations occur only when the propagation time exceeds a threshold set by the energy uncertainty of the external wave packets and by the decay width of the propagating particle. For shorter propagation, the intermediate particle behaves as a purely virtual state, in the sense that it cannot propagate over a macroscopic distance. Although a direct experimental test of the transition from virtual to real propagation is challenging, since it typically occurs at microscopic scales, our result implies that the Jacob--Sachs theorem holds to higher accuracy than previously expected, even at short propagation times. Our formalism applies not only to neutrinos but also to other propagating particles, and future improvements in energy resolution may make this threshold observable.
hep-phhep-exhep-th0 citations
08
Freeze-in at all couplings
Andreas Goudelis🇫🇷 · Andre Lessa🇧🇷 · Lucas Magno Dantas Ramos🇧🇷 · Thomas Reggio🇫🇷
We perform a comprehensive analysis of a charged parent freeze-in dark matter model, focusing on scenarios where the Universe reheats to a temperature comparable to or lower than the mass scales of the theory. In such configurations, dark matter production is Boltzmann-suppressed, allowing for stronger couplings between dark matter and the Standard Model thermal bath while still reproducing the observed relic abundance. We emphasize the non-trivial interplay between the reheating temperature, the mediator and dark matter masses and the coupling strength. We show that tracking the number density evolution of both dark matter and the mediator is essential to obtain reliable predictions, including unexpected behaviors such as the mediator non-equilibration due to fast decays. Lastly, we explore the phenomenological implications of this scenario, updating constraints from LHC searches and lepton flavour-violating decays and highlighting the complementarity of these searches in probing the cosmologically viable parameter space.
hep-ph2 citations
09
Sensitivity of the photon-induced processes to the proton radius
Nikhil Krishna🇵🇱 · Mariola Klusek-Gawenda🇵🇱 · Rafal Staszewski🇵🇱
We study the exclusive production of dileptons in proton--proton collisions as a probe of the proton radius. Using a dipole form factor model, we compare the conventional choice of $Λ^{2} = 0.71$ ~GeV $^{2}$ with PDG test scenarios corresponding to $r_{p} = 0.8751$ ~fm and $r_{p} = 0.84087$ ~fm. The sensitivity is greatest at large dilepton invariant masses and forward/backward rapidity. Fitting to the current ATLAS and CMS data within the adopted model gives $Λ^{2} = 0.465 \pm 0.056 GeV^{2}$ , corresponding to an effective radius $r_{p} = 1.002 \pm 0.038 fm$ , which indicates non-trivial sensitivity on the proton radius scale, but is not yet a definitive solution to the proton radius puzzle.
hep-ph1 citation
10
$U (1)_{B - L}$ Dark Matter Constrains Smooth (SUSY) Hybrid Inflation
Karim M. Selim🇪🇬 · A.Y. Ellithi🇪🇬 · M.Abolmahassen🇪🇬
We propose a unified framework that connects inflationary dynamics with dark matter production within a supersymmetric $U (1)_{B - L}$ extension of the Standard Model. The setup is based on smooth hybrid inflation embedded in supergravity, with a non-minimal Kahler potential ensuring control of higher-order corrections. The model involves three scalar fields: the inflaton $σ$ , an auxiliary field $ζ$ responsible for ending inflation, and a singlet mediator $η$ that links the inflationary and dark sectors. Dark matter is realized as an inert scalar stabilized by a $Z_{2}$ symmetry and produced non-thermally via reheating dynamics. We show that reproducing the observed dark matter relic abundance imposes strong constraints on the inflationary sector, significantly reducing the allowed parameter space. As a result, the scalar spectral index is tightly constrained to $n_{s} ≃ 0.972 - 0.974$ , consistent with current observational bounds. While the inflaton-dark matter coupling has a negligible effect on the background evolution, it induces observable modifications in the tensor-to-scalar ratio and the spectrum of primordial gravitational waves. This establishes a direct link between dark matter physics and inflationary observables.
hep-ph0 citations
11
Charged Lepton Flavor Violation at Neutrino Telescopes
Writasree Maitra🇺🇸 · Carlos A. Argüelles🇺🇸 · P. S. Bhupal Dev🇺🇸 · Ivan Martinez-Soler🇬🇧 · Manibrata Sen🇮🇳
Any observation of charged lepton flavor violation (CLFV) would be a clear signal of beyond-the-Standard-Model physics. Here, we propose a novel CLFV search using neutrino telescopes with their large cosmic-ray muon samples. Specifically, we use a recent IceCube cosmic-ray muon dataset and propose a new search for muon-to-tau conversion inside the IceCube detector. We illustrate our idea with CLFV interactions described by model-independent Effective Field Theory (EFT) operators and present the IceCube sensitivity on the relevant EFT scale. We also consider a specific realization of the EFT operator in terms of an axial-vector $Z^{'}$ interaction and show sensitivities in the $Z^{'}$ mass-coupling plane. We compare our sensitivities with those from low-energy CLFV searches, as well as from current and future collider experiments. We also show projections from next-generation neutrino telescopes, such as IceCube-Gen2 and HUNT, and demonstrate how neutrino telescopes can provide a powerful complementary probe of CLFV.
hep-phastro-ph.HEhep-ex0 citations
12
Constraining ADD black holes at the LHC with $s = 14$ TeV
Ashfaque Ahmad🇮🇳 · Sudhir Kumar Gupta🇮🇳 · Abbas Ali🇮🇳
We explore microscopic black holes at the Large Hadron Collider (LHC) in the context of the ADD model for the centre-of-mass energy $s = 14 TeV$ at an integrated luminosity of $349.4 fb^{- 1}$ and provide constraints on the black hole mass, $M_{B}$ by taking into account the effects of loss during the formation process of black holes through the parameter $ζ$ . Our analysis reveals that for $ζ = 0$ , black holes with $M_{B} \leq 11.83 TeV$ are disfavored in the case of three extra dimensions ( $D$ ), for the reduced Planck scale ( $Λ_{D}$ ) of about a TeV. The corresponding values for $Λ_{D} = 9 TeV$ turned out to be about $10.33 TeV$ . A significant reduction in the aforementioned limits is observed while the loss gets higher, e.g. for $ζ = 0.35$ , $M_{B}$ reduces to $7.65 (6.82) TeV$ at $Λ_{D} = 1 (9) TeV$ . These limits change to $12.03 (10.88) TeV$ and $7.80 (7.03) TeV$ respectively for $ζ = 0 (0.35)$ for $Λ_{D} = 1 (9) TeV$ at 95\% C.L. in case $D$ is raised to seven.
hep-phhep-th0 citations
13
Extraction of charmonium branching fractions from $J / ψ \to γ η_{c}$ radiative decays
Magnus C. Schaaf🇩🇪 · Antonio Vairo🇩🇪
We assess the tension between theoretical predictions and the values quoted by the Particle Data Group (PDG) for the partial decay width and branching fraction associated with the radiative charmonium decay $J / ψ \to γ η_{c}$ . A profile scan over the most recent PDG data depending on the branching fraction $B (J / ψ \to γ η_{c})$ suggests that the correlation between measured branching fractions is compatible with lattice QCD determinations of the partial decay widths $Γ (J / ψ \to γ η_{c})$ and $Γ (η_{c} \to γ γ)$ . We propose a theoretically grounded photon line shape for the radiative decay spectrum and a prescription for the extraction of (product) branching fractions involving the magnetic dipole (M1) transition $J / ψ \to γ η_{c}$ . This approach obviates the need to modify the photon energy spectrum line shape using empirical damping functions, as done in the most recent experimental extractions of $B (J / ψ \to γ η_{c})$ from the photon line shape, thereby eliminating an inherent ambiguity in the determination of the derived observables.
hep-phhep-exhep-lat0 citations
14
New Avenues of Heavy Neutral Lepton at Muon Collider
Fa-Xin Yang🇨🇳 · Feng-Lan Shao🇨🇳 · Zhi-Long Han🇨🇳 · Honglei Li🇨🇳
With initial state radiation, the multi-TeV muon collider can be regarded as an electroweak boson collider. The dominant production mode of the certain process becomes the vector boson fusion channel, because the corresponding cross section typically increases logarithmically at high energies. This also holds true for new physics beyond the standard model. Within the $U (1)$ gauged extension of seesaw models, the heavy neutral lepton has additional interactions with the new gauge boson $Z^{'}$ and heavy Higgs $H$ . In this paper, we investigate the production of heavy neutral lepton $N$ via the new vector boson fusion processes $Z^{'} Z^{'} \to H \to N N$ with and $Z^{'} Z^{'} \to N N$ without heavy Higgs at the multi-TeV muon collider. Different from the canonical vector boson fusion processes $W W / Z Z \to H \to N N$ , the new process $Z^{'} Z^{'} \to H \to N N$ is not suppressed by the small mixing angle $α$ between the Higgs bosons. Meanwhile, the pair production process $Z^{'} Z^{'} \to N N$ is also viable even for heavy Higgs $m_{H} > s$ . Therefore, these new avenues provide alternative pathways to probe the intrinsic feature of the heavy neutral lepton. We then perform a detailed analysis of the lepton number violation signals via the new vector boson fusion with heavy Higgs $μ^{+} μ^{-} \to μ^{+} μ^{-} H \to μ^{+} μ^{-} N N$ and without heavy Higgs $μ^{+} μ^{-} \to μ^{+} μ^{-} N N$ , followed by $N \to μ^{\pm} j j$ , where the two jets from $W$ boson decay are treated as one fat-jet $J$ .
hep-phhep-ex1 citation
15
$Ξ_{cc}^{++} - Ξ_{cc}^{+}$ Transitions as a Two-Charm-Selective Portal to Ultra-Low- $Q$ Charged Currents
Yong Du🇨🇳
The recent LHCb observation of $Ξ_{cc}^{+}$ opens the ultra-low- $Q$ transition $Ξ_{cc}^{++} \to Ξ_{cc}^{+}$ as an experimentally motivated null test of charged-current new physics. Our two- and three-body analyses show sensitivity to effective baryon-level couplings of $O (1 0^{- 6} - 1 0^{- 7})$ for MeV-scale recoil momenta. We establish a practical no-go result for a universal light charged scalar $ϕ^{+}$ : with a first-generation $ϕ^{+} u ˉ d$ coupling, existing electroweak-precision and beta-decay constraints are parametrically stronger than the projected LHCb sensitivity. We then identify a two-charm-selective charged-current portal whose leading operator has a nonzero matrix element in doubly charmed baryons but vanishes at leading order in pions, nucleons, nuclei, and singly charmed mesons. In this class of models, $Ξ_{cc}^{++} \to Ξ_{cc}^{+}$ transitions can provide the leading direct probe of the portal interaction.
hep-phhep-ex0 citations
16
NLO QCD and EW corrections to semileptonic vector-boson scattering at the LHC
Ansgar Denner🇩🇪 · Robert Franken🇩🇪 · Daniele Lombardi🇮🇹 · Santiago Lopez Portillo Chavez🇩🇪
Vector-boson scattering with semileptonic final states has recently been measured at the LHC, and future experiments are expected to further increase the precision of its measurement, calling for adequate theoretical predictions. In this work, we present a calculation of the NLO QCD and electroweak corrections to the process $p p \to ℓ^{+} ν_{ℓ} + 4 j$ in two different fiducial regions relevant for vector-boson scattering. In a fully off-shell calculation, we provide results for the leading electroweak contribution of $O (α^{6})$ and the corresponding corrections of $O (α^{7})$ and $O (α_{s} α^{6})$ for fiducial cross sections and a selection of differential distributions.
hep-phhep-ex0 citations
17
Two Flavon Froggatt-Nielsen Models with Genetic Algorithms
Miguel Crispim Romão🇬🇧 · Stephen F. King🇬🇧
We present the first systematic and comprehensive scan of two-flavon Froggatt-Nielsen (FN) models, employing artificial intelligence techniques to explore the high-dimensional, mixed discrete-continuous parameter space. Extending the standard single-flavon FN framework to a two-flavon setup in which separate flavon fields couple independently to the up- and down-type sectors, we demonstrate that the relative phase between their vacuum expectation values (vevs) provides a natural and generic source of CP violation absent in single-flavon models. To explore this enlarged model space, we cast the search for phenomenologically viable models as a multi-objective optimisation problem, formulating each experimental constraint as a separate objective, and employ the Non-dominated Sorting Genetic Algorithm III to simultaneously fit all 18 FN charges, 45 Wilson coefficients, and flavon parameters to both the quark and lepton sectors. Our approach requires no separate training phase and identifies phenomenologically viable models orders of magnitude faster than prior reinforcement learning methods. Imposing experimental constraints on CKM and PMNS mixing angles and CP phases, charged fermion masses, and neutrino squared-mass differences, we discover over $100000$ unique viable models with a remarkably low duplication rate, indicating that the space of valid two-flavon FN realisations has not been exhausted. Both Normal and Inverted neutrino mass squared orderings are realised, with the relative hierarchy between the flavon vevs producing qualitatively distinct predictions for the effective neutrinoless double beta decay mass $m_{ee}$ . We further demonstrate the existence of minimal FN realisations with maximal flavon exponent as small as three, and of models reproducing charged fermion masses to within $6%$ without any dedicated continuous parameter optimisation.
hep-phphysics.comp-ph0 citations
18
Non-standard decays of vector-like top partners in a $2$ -Higgs doublet model at the HL-LHC
Tanumoy Mandal🇮🇳 · Stefano Moretti🇬🇧 · Rachit Sharma🇮🇳
Extensions of the Standard Model featuring both an enlarged scalar sector and vector-like fermions arise naturally in a wide class of well-motivated theoretical frameworks. In such scenarios, vector-like Quarks (VLQs) can exhibit non-standard decay modes involving additional Higgs states, giving rise to distinctive collider signatures that remain largely unexplored by existing experimental searches. We investigate the prospects of probing this possibility at the high-luminosity Large Hadron Collider (HL-LHC) through the decay of vector-like top partner ( $T$ ) to charged Higgs ( $H^{\pm}$ ) followed by the decay, $H^{\pm} \to τ ν$ , producing a final state containing two tau leptons, two $b$ -jets, and missing transverse energy. A model-independent collider analysis is performed using global kinematic observables constructed from visible objects and the missing transverse momentum vector to suppress the dominant backgrounds. Polarization-sensitive observables built from the hadronic $τ$ decay products are also examined as complementary probes of the spin- $0$ origin of the $τ$ leptons. The expected discovery sensitivity is evaluated using the Asimov significance for an integrated luminosity of $3$ ab $^{- 1}$ at $s = 14$ TeV. Our results demonstrate that the $2 τ + 2 b +$ missing $E_{T}$ channel provides a promising and largely orthogonal avenue to search for non-standard VLQ decays in extended Higgs sectors, with discovery-level sensitivity achievable for VLQ masses up to approximately $1.9$ TeV.
hep-phhep-ex0 citations
19
Toward Precision Fragmentation of $Ω_{3 Q}$ Baryons: The OMG3Q1.1 Framework
Francesco Giovanni Celiberto🇪🇸
Recent experimental advances in the baryon sector, including the observation of doubly charmed states, have renewed interest in the production mechanisms of increasingly heavy hadronic systems, calling for precision and uncertainty-controlled descriptions. We present the OMG3Q1.1 framework for the fragmentation of same-flavor all-heavy $Ω_{3 Q}$ baryons in high-energy hadronic collisions. The construction combines diquark-inspired inputs for constituent-heavy-quark and gluon channels with threshold-aware DGLAP evolution within the HF-NRevo scheme. A replica-based strategy consistently quantifies perturbative missing-higher-order effects (F-MHOUs) and nonperturbative wave-function uncertainties (F-NPWFs), yielding the first uncertainty-resolved fragmentation-function set for the $Ω_{3 Q}$ sector. The resulting LHAPDF6 grids are employed to investigate semi-inclusive $Ω_{3 Q}$ plus jet production at the HL-LHC and future FCC within the (sym)JETHAD environment. The OMG3Q1.1 framework establishes a precision-oriented baseline for rare triply heavy baryons and provides a foundation for future studies of the heavy-flavor baryon landscape.
hep-phhep-exnucl-exnucl-th4 citations
20
The Simplest Dirac Scoto-Seesaw Realization
Sin Kyu Kang🇰🇷 · Ranjeet Kumar🇮🇳 · Hemant Kumar Prajapati🇮🇳
We present a simple Dirac scoto-seesaw framework based on the anomaly-free $U (1)_{B - L}$ charge assignment $(- 4, - 4, 5)$ for $ν_{R}$ . This chiral charge assignment naturally accounts for the observed neutrino mass-squared differences, with $Δ m_{atm}^{2}$ generated at tree level and $Δ m_{sol}^{2}$ arising radiatively. After the spontaneous breaking of gauged $U (1)_{B - L}$ , a residual $Z_{6}$ symmetry stabilizes the dark matter candidate. We investigate two minimal realizations of the framework, finding that both normal and inverted orderings are viable in one case, whereas only normal ordering survives in the other, with distinctive features for neutrino observables. Moreover, the chiral nature of the $U (1)_{B - L}$ charges suppresses the dilepton branching fraction of $Z^{'}$ , resulting in weaker ATLAS mass bounds than in the conventional vector $B - L$ scenario, thereby easing constraints on the dark sector. We explore the dark matter phenomenology of the singlet scalar and fermionic dark matter candidates. While singlet scalar DM is often severely constrained, the presence of the $Z^{'}$ portal together with annihilation and co-annihilation channels substantially broadens the allowed parameter space. Thus, the framework offers a predictive scenario for neutrino and dark matter phenomenology that can be probed in future experiments.
hep-ph1 citation
21
Addressing uncertainties of model predictions for extensive air showers initiated by high energy cosmic rays
Sergey Ostapchenko🇩🇪 · Tanguy Pierog🇩🇪 · Günter Sigl🇩🇪
A new Monte Carlo generator of hadronic collisions, QGSb, is applied for studying model uncertainties regarding calculations of the development of extensive air showers (EAS) initiated by interactions of high energy cosmic rays in the atmosphere. More specifically, we investigate possibilities to modify the model predictions for two EAS characteristics mostly used in experimental studies of cosmic ray composition: air shower maximum depth and the muon number at ground level. For all the considered modifications of the model, we discuss in some detail the underlying physics mechanisms and investigate the impact of the changes, regarding a comparison of the model results to relevant accelerator data.
hep-ph0 citations
22
Three-particle di-light-cone distribution amplitudes of the $B$ -meson in heavy-quark effective theory
Riccardo Bartocci🇩🇪 · Philipp Böer🇨🇭 · Thorsten Feldmann🇩🇪 · Max Ferré🇩🇪 · Nico Gubernari🇩🇪 · Daniel Vladimirov🇩🇪
We present a systematic study of the three-particle di-light-cone distribution amplitudes (DLCDAs) of the $B$ -meson. They are defined through $B$ -meson--to--vacuum matrix elements of trilocal HQET operators, in which the light antiquark and the gluon field-strength tensor are located on two back-to-back light rays. In this sense, the DLCDAs generalise the conventional $B$ -meson light-cone distribution amplitudes to configurations where soft fields couple to collinear degrees of freedom in two distinct directions. As such, they parametrise the non-perturbative dynamics associated with non-factorisable soft-gluon contributions in rare and non-leptonic exclusive $B$ -meson decays. We derive the complete Lorentz decomposition of the matrix elements of generic trilocal operators, identify eight independent DLCDAs, and organise them in a basis of definite twist. Using local operator identities and equations-of-motion constraints, we obtain tree-level relations for their normalisation integrals and first moments in terms of a minimal set of hadronic parameters. These relations allow us to construct simple momentum-space models for all independent DLCDAs. For the leading-twist distribution, we further incorporate the perturbative radiative tail at order $α_{s}$ and discuss its impact on the resulting parametrisation.
hep-ph2 citations
23
Dyonic lattices, $θ$ -angles and axions in the Standard Model
Rodrigo Alonso🇬🇧 · Francesca Chadha-Day🇬🇧 · Despoina Dimakou🇬🇧 · Yunji Ha🇬🇧 · Valentin V. Khoze🇬🇧
We investigate the implications of the Witten effect in the Standard Model with a general global gauge group structure and determine the values of the three $θ$ -parameters that lead to distinct families of allowed spectra of dyons. We construct and classify the corresponding dyonic charge lattices consistent with the Standard Model gauge structure. This approach enables us to re-derive the known global-group--dependent periodicities of the $θ$ angles and to determine all CP-invariant points in $θ$ -space. The electromagnetic subgroup $U (1)_{em}$ is shown to arise \emph{prior} to electroweak symmetry breaking by factoring out the effect of the anomalous $B + L$ transformations, which reduces the physical $θ$ -parameter space from a three-torus to a two-torus. Our phenomenological conclusions include an observation that a discovery of a $U (1)_{em}$ monopole carrying non-zero electric charge would determine the last remaining unknown parameter of the Standard Model. Lastly we study how $θ$ -space shapes axion physics with emphasis on the axion-photon coupling and show that a single axion is insufficient to render the Standard Model vacuum fully CP invariant.
hep-ph0 citations
24
Theory Calculations for LDMX and LOHENGRIN beyond Coherent Bethe-Heitler Scattering
Martin Schürmann🇩🇪 · Herbert K. Dreiner🇩🇪 · Rhorry Gauld🇩🇪
The Light Dark Matter eXperiment (LDMX), DarkSHINE, and LOHENGRIN are proposed new experiments. They aim to search for missing momentum signals sourced by the direct production of dark photons with masses in the MeV-GeV range in bremsstrahlung processes, in which an electron beam of a few GeV scatters off a fixed target. So far, the signal characteristics, i.e. the behavior of the recoiling electron, have mostly been studied in coherent Bethe-Heitler electron-nucleus scattering with a dark photon that couples only to the Standard Model charged leptons. In this work, we present the calculations of the differential cross sections of all contributing real emission processes up to third order in the electromagnetic fine structure constant and fourth order in the kinetic mixing parameter associated with the dark photon. We consider a dark photon coupling to both the beam electron and the hadronic target and we take into account the scattering off both the target nucleus and its nuclear constituents. Besides real emission processes, we also discuss virtual dark photon contributions and their relevance for the signal prediction. After discussing the different phase space regions and constraints emerging from the experimental setups, we show numerical results of the cross sections and differential distributions, including the signal and dominant background. Within our framework, we find that the LOHENGRIN experiment will require an extension of its HCAL to effectively veto background processes originating from diffractive scattering. Apart from that, the contributions beyond coherent Bethe-Heitler scattering, in the presence of realistic experimental selections, have only a limited effect on the predicted signal and background in the relevant dark photon mass range.
hep-phhep-ex1 citation
25
Renormalization of axial anomaly in SU(N) $\times$ U(1)
Tanmoy Pati🇮🇳 · Narayan Rana🇮🇳
Defining $γ_{5}$ within dimensional regularization remains a fundamental challenge. Larin's prescription addresses this by introducing additional renormalization constants to restore standard and chiral Ward identities. While these constants are known up to four loops in pure quantum chromodynamics, current precision Standard Model phenomenology requires extending these corrections to mixed gauge sectors. In this article, we propose a novel technique utilizing form factors and the universality of infrared divergences to compute these constants. Applying this framework, we present the new three-loop results for the renormalization constants, as well as the pure-singlet contributions to the quark axial-vector form factor, for a mixed $S U (N) \times U (1)$ gauge group.
hep-phhep-th0 citations
26
Revisiting the role of saturation in diffractive vector meson production
Heikki Mäntysaari🇫🇮 · Hendrik Roch🇫🇮 · Björn Schenke🇺🇸 · Chun Shen🇺🇸 · Wenbin Zhao🇨🇳
We perform a global Bayesian analysis of coherent and incoherent diffractive $J / ψ$ photoproduction in $γ + p$ and $γ + Pb$ collisions using a Color Glass Condensate (CGC)-based framework and ultraperipheral collision data from the Large Hadron Collider (LHC), corrected for the expected effect of electromagnetic dissociation (EMD). Using Gaussian-process emulators of the underlying CGC calculations, we infer model parameters from a combined set of HERA and LHC measurements. We find that the $γ + Pb$ data with EMD correction substantially reduce the previously observed tension between proton and nuclear datasets, enabling a consistent simultaneous description of diffractive $J / ψ$ production in $γ + p$ and $γ + Pb$ collisions within the CGC framework.
hep-phnucl-thPRD(2026)·3 citations
27
Phase Transitions and Gravitational Wave Production at the End of Thermal Inflation
Hyukjung Kim🇰🇷 · İlayda Kuzu🇹🇷 · Kerem Özsoy🇹🇷 · Zeynep Kahraman🇹🇷 · Wan-Il Park🇰🇷 · Heeseung Zoe🇹🇷
We investigate the first-order phase transition that terminates thermal inflation and evaluate the associated stochastic gravitational-wave signals. The transition is first characterized through semi-analytic calculations of the bounce action, which are compared with numerical results obtained using CosmoTransitions. We then study its real-time evolution in a three-dimensional Langevin lattice simulation that incorporates Hubble expansion and the corresponding temperature evolution throughout the transition. The lattice dynamics are consistent with the bounce-action estimates: the transition proceeds through localized bubble nucleation and subsequent bubble growth, rather than through a phase-mixing instability. Using the resulting transition parameters, we estimate the gravitational-wave spectra generated by bubble collisions and acoustic motions in the plasma. The predicted stochastic background lies within the projected sensitivity ranges of future gravitational-wave observatories, including BBO and DECIGO.
hep-phastro-ph.COgr-qc0 citations
28
New Gauge Forces, Neutron Stars and Schwinger Neutrino Production
Yuxin Liu🇨🇳 · Zhen Liu🇺🇸 · Andrey Shkerin🇨🇦 · Jing Shu🇨🇳 · Yue Zhao🇨🇳
We investigate neutrino effects of new long-range forces arising from gauging $B - L$ , $L_{e} - L_{μ / τ}$ or $L_{μ} - L_{τ}$ symmetries of the Standard Model. The leptonic potential generated by astronomical bodies, such as the Earth, the Sun or a neutron star, results in the Schwinger pair production of neutrinos charged under the new gauge symmetry. The oppositely charged particles accumulate in the potential well forming a degenerate Fermi gas, while equally charged particles fly away forming a steady flux of neutrinos. We find that, for the $B - L$ and $L_{e} - L_{μ / τ}$ forces, these effects are too weak to be observable. For the $L_{μ} - L_{τ}$ force these effects are significant in neutron stars if the gauge coupling is $g ≳ 1 0^{- 18}$ . The muonic force changes the element abundances of a neutron star in equilibrium and suppresses its $L_{μ} - L_{τ}$ charge. This invalidates the constraint on $g$ from neutron star mergers, at $g ≳ 1 0^{- 17}$ . Furthermore, for such values of $g$ , the neutrino flux produced by the Schwinger effect could potentially be detected from a single young neutron star at a distance of $≃ 100$ pc, with the typical neutrino energy $E_{ν} \sim 100$ MeV. A dedicated search for such a signal will reassert the bound $g ≲ 1 0^{- 18}$ .
hep-phastro-ph.COastro-ph.HE0 citations
29
The X17 Anomaly: Experimental Evidence and Theoretical Interpretations
Raoul Serao🇮🇹 · Aniello Quaranta🇮🇹 · Antonio Capolupo🇮🇹
This review summarizes the experimental evidence for the hypothetical X17 particle, examines the theoretical frameworks in which it can be accommodated, and discusses its potential implications for the Standard Model and couplings to known particles. Future experimental prospects are also highlighted.
hep-ph2 citations
30
String Axiverse Enhancement of Superradiant Dark Matter Production
Diogo S. Gorgulho🇳🇱 · Jacob A. Litterer🇵🇹 · João G. Rosa🇵🇹
We study the effects of string axion emission on dark matter production by light primordial black holes (PBHs), through both evaporation and superradiance. We show, in particular, that the Hawking emission of $O (100 - 1 0^{5})$ light axion species predicted in realistic string theory constructions can significantly enhance the efficiency of superradiance, given the associated increase in the PBH spin. The string axiverse thus significantly expands the parametric regions (dark matter mass and PBH mass and spin) for which a sizeable fraction of dark matter may presently be in the form of "micro-boson stars": the self-gravitating remnants of superradiant dark matter clouds. Conversely, for too large a number of axion species PBHs evaporate too quickly for superradiant clouds to attain their maximum mass. Finally, assuming that all dark matter is produced by PBHs (through both superradiance and Hawking emission), we show that the axions emitted during PBH evaporation give an immeasurably small contribution to the relativistic degrees of freedom at recombination.
hep-phastro-ph.COgr-qc0 citations
31
The $B^{+} \to K^{+} ν ν ˉ$ decay as a QCD axion search: comparing reinterpretation approaches
Merna Abumusabh🇫🇷 · Giulio Dujany🇫🇷 · Diego Guadagnoli🇫🇷 · Méril Reboud🇫🇷 · Claudio Toni🇫🇷
Two recent independent analyses of Belle II $B^{+} \to K^{+} ν ν ˉ$ data yield limits on $B (B^{+} \to K^{+} a)$ -- the two-body mode to a light invisible particle such as the QCD axion -- differing by a factor of roughly four; we trace this to the choice of kinematic variable space. The central figure of merit is the resolution in the reconstructed di-neutrino invariant mass $q_{rec}^{2}$ : fine-grained binning resolves the narrow axion signal, while coarse binning dilutes it into a background-dominated range. A BDT axis trained on $B^{+} \to K^{+} ν ν ˉ$ adds little discriminating power for $B^{+} \to K^{+} a$ , as this axis is largely uncorrelated with $q^{2}$ . These expectations are confirmed by a set of numerical tests. The subleading shape systematics omitted from our $q_{rec}^{2}$ -based approach {\em lower}, not raise, the $B^{+} \to K^{+} a$ limit: by better accommodating the $B^{+} \to K^{+} ν ν ˉ$ shape, they leave less room for the axion signal, making our $q_{rec}^{2}$ -based bound conservative, if anything. A dedicated reanalysis confirms that the kinematic-axes choice alone accounts for the factor-of-four sensitivity difference, and that the $B^{+} \to K^{+} a$ bound varies sizeably within the $q_{rec}^{2} \times η (BDT_{2})$ space, depending on the SM-likeness of $B^{+} \to K^{+} ν ν ˉ$ , thus losing the dual-probe feature of our $q_{rec}^{2}$ -based approach. These results point to a broader consideration: likelihoods dominated by BDT variables are of limited use for reinterpretations when the signal shape differs appreciably from the BDT's training signal. We therefore advocate that experimental collaborations publish likelihood projections in physical variable spaces alongside BDT-based likelihoods, to maximise the reinterpretability of their measurements.
hep-phhep-ex0 citations
32
Rotating magnetized pion gas of finite transverse size: condensation constraints and transport properties
Ankit Kumar🇮🇳 · Diwakar Gaur🇮🇳 · Vinod Chandra🇮🇳
This work investigates the electric, thermal, and thermoelectric responses of a rotating pion gas of finite transverse radius in the presence of a background magnetic field, with the rotation axis aligned with the magnetic field. We explicitly calculate the parameter limits for $π^{+}$ condensation and restrict our working regime safely outside these boundaries, ensuring well-behaved transport coefficients. Notably, the system exhibits a condensation asymmetry, with $π^{-}$ remaining uncondensed at the parameters that induce $π^{+}$ condensation. Using the Boltzmann Transport Equation under the Relaxation Time Approximation, we calculate the longitudinal electrical conductivity, thermal conductivity, and the Seebeck coefficient. Our results reveal a competing interplay between the magnetic field and rotation, highlighting the substantial impact of rotation on the medium's transport properties: while the magnetic field suppresses the transport coefficients in a static medium, rotation, acting as an effective chemical potential, introduces an energy shift that favors their increase. Beyond an angular velocity, this rotational enhancement overpowers the magnetic suppression, leading to an increase in the transport coefficients with increasing magnetic field. Finally, we analyze the relative significance of charge and heat transport through the Lorenz number, providing further insight into the transport characteristics of the rotating magnetized pion medium.
hep-phnucl-th1 citation
33
SS433 PeV neutron jet feeding the far TeV gamma beam
Daniele Fargion🇮🇹 · Pier Giorgio De Sanctis Lucentini🇷🇺 · Sara Turriziani · Danila Sopin · Maxim Yu. Khlopov🇫🇷
The SS433 is a well-known binary system with an internal black hole, which is stripping mass from an orbiting companion of ten solar masses, at a hundred of light-seconds away. The black hole and its accretion disk fuel a thin precessing jet, whose spirals are well-observed. Surprisingly, disconnected gamma-ray tails have recently been discovered by H.E.S.S., HAWC and LHAASO, hundreds of light-years away and with energies of tens of TeV. We suggest that tens PeV neutron burst jets were ejected from the SS433 system over the past century. These beams of ultra high-energy PeVatron neutrons, by their in-flight beta decay and Inverse Compton scattering, could be the source of the enigmatic, distant and disconnected tens of TeV gamma-ray beams. These ultra-relativistic PeV neutron jets could have been formed during one of the system's rare and intense tidal eruptions, when tens of PeV protons collide CV October 2025 with thermal ultraviolet photons, creating delta resonances. Their decay into secondary neutron beams of tens of PeV is well consistent with observations. Alternative models appear uncompetitive.
↳ astro-ph.HEastro-ph.GAastro-ph.IMhep-phPoS(2025)·0 citations
34
Paucity of downward UHE neutrino tracks in IceCube versus unexpected huge KM3-230213A event: solving the puzzles?
D. Fargion🇮🇹
Recently the ARCA array detector published the down-ward-horizontal event: the KM3-230213A. It appeared as the most energetic neutrino ever observed: about 200 PeV (2 10^17 eV) up to EeV (10^18 eV) energy. This huge value, is puzzling. It is not statistically consistent with several upper bound derived by two greater and longer life detectors: by IceCube and in particular by AUGER array. Asymmetry in recent IceCube neutrino alert tracks upward and downward at same horizontal angles as ARCA one, suggest that they are mostly polluted atmospheric muon bundles. This paucity also disfavor the skimming neutrino interpretation by ARCA. We suggest that the array floating and bending in the deep sea may lead, sometime, to a misleading geometry that is pointing to a wrong arrival angle direction: a much less horizontal muon (neutrino) track respect to a much real one, more inclined and vertical, due to atmospheric muon bundle or charmed single event. Contrary to present argument, if such a rare event would be soon rediscovered in data or re-observed, it would open the road to a new guaranteed Tau neutrino Astronomy. At EeV energy such upward tau air-showers should shine AUGER telescopes or blaze future satellite in Space. A previous model in astrophysics considered energetic neutrino E>>100 EeV, neutrino scattering, onto cosmic, relic, light mass ones. Their ultra-relativistic Z boson resonance formation and its decay in flight would produce hadron UHECR relics around tens-hundred EeV energy. Explaining how sources located at far distances, above the usual GZK hundred Mpc, cut off ones, may shine and cluster in AUGER or TA data.
↳ astro-ph.HEastro-ph.COastro-ph.GAhep-ex+1PoS(2025)·1 citation
35
PeV neutrons as origin of separated SS433 TeV signals
D. Fargion🇮🇹 · P.G. De Sanctis Lucentini🇷🇺 · S. Turriziani · M.Y. Khlopov🇫🇷 · D. Sopin
The SS433, a well-known binary system with an internal black hole, have shown since half a century, an inner (a few year light distances) twin precessing jets spirals. These beams are made by tidal forces while stripping mass from large stellar companion feeding an inner BH accretion disk and an orthogonal accelerating twin jet. From it, the radio, X gamma jet emission. A couple of years ago H.E.S.S telescope as well as HAWC and LHAASO array detectors, discovered also the surprising signature of an unexpected far twin separated gamma beam at tens TeV energy. At a hundred light years distances from its central source. We suggest that it is the legacy of a past rare eruption, a century ago, of tens PeV (10^16 eV) relativistic twin neutron beams. Their beta decay in flight at far distances, into proton, neutrino and in particular into tens TeV electrons, could feed the observed TeV gamma traces. They are originated by the same secondary tens TeV electrons emitting hard gamma, by Inverse Compton Scattering onto interstellar infrared photons.
↳ astro-ph.HEastro-ph.GAhep-phhep-thPoS(2025)·0 citations
36
Calling the Brane Next Door: The Kaluza-Klein Tower as a Gravitational Information Channel
Karim Benakli🇫🇷
Could two worlds localised on neighbouring branes communicate through gravity alone? We investigate this question in a minimal higher-dimensional framework in which Standard Model fields are confined to our brane while gravity propagates through the bulk. From the brane-to-brane graviton propagator we derive the retarded transfer kernel of the inter-brane link and identify the transition from evanescent to propagating Kaluza-Klein modes. The central idea is to give the Kaluza-Klein tower a new role: not only as a spectrum of massive gravitational states, but as a set of communication carriers. Below the first KK threshold the channel is effectively four-dimensional and is mediated only by the massless graviton. Above threshold, massive KK modes open as additional propagating subchannels, and information may be encoded in their occupation pattern, relative phases, and arrival-time structure as well as in ordinary signal variables. The compactification determines the KK masses, wavefunctions, brane overlap factors, and propagation phases, which together define a multi-input multi-output (MIMO) channel matrix. In the resolved-mode limit, the tower yields approximate parallel subchannels, to which standard information-theoretic notions such as capacity bounds, water-filling, effective rank, and sparse occupancy codes apply. The production and detection of such signals are highly model-dependent and not assumed to be feasible with known technology. Nevertheless, the channel structure is well defined: a neighbouring brane-world could be separated from us by a microscopic distance in the compact space while remaining hidden because the only shared interaction is gravity. The first observable signature may not be a deliberate message, but the spectral and modal structure of the Kaluza-Klein tower itself, revealing partial information about the geometry of a nearby hidden world.
↳ hep-thcs.ITgr-qchep-ph+11 citation
37
The ESSnuSB Experiment
Monojit Ghosh🇭🇷
In this proceedings, we will describe the physics program of the ESSnuSBplus, phase-I of the ESSnuSB project. ESSnuSB is a future long-baseline neutrino oscillation experiment in Europe which aims to measure $δ_{CP}$ at the second oscillation maximum with with unprecedented precision. Apart from studying the beam based physics, the large far detector is also capable of studying various other physics cases involving solar, atmopsheric and supernova neutrinos. Under the ESSnuSBplus project, there will be a low energy monitored beam and a low energy nuSTORM facility for the measurement of cross-section.
↳ hep-exhep-ph0 citations
38
Bootstrapping Pion Form Factors at Large $N$
Jan Albert🇺🇸 · Dilara Kosva · Leonardo Rastelli🇺🇸
We initiate a bootstrap study of pion form factors in large $N$ QCD. We consider the mixed system of the vector-current two-point function, the pion vector form factor, and the pion scattering amplitude in the chiral limit. At large $N$ these observables are meromorphic, with spectral data constrained by unitarity, crossing symmetry, and Regge boundedness. We obtain bounds of two kinds. The first are rigorous and universal: from analyticity, unitarity and the asymptotic Brodsky-Farrar scaling, we constrain low-energy form-factor coefficients. The second are more phenomenological, of the Shifman-Vainshtein-Zakharov type: feeding in the perturbative ultraviolet behavior at a finite scale lets us bound the pion decay constant, convert a large $N$ lattice measurement into a lower bound on the scale at which asymptotic freedom sets in, and constrain the pion charge radius. Combining these inputs, the space of allowed chiral Lagrangians shrinks toward the region where large $N$ QCD is expected to sit. Our results illustrate how local gauge-invariant probes provide a canonical bridge between the hadronic bootstrap and the microscopic QCD Lagrangian.
↳ hep-thhep-lathep-ph2 citations
39
Cooling, conduction, compact objects: Gravothermal evolution of dissipative self-interacting dark matter halos
Ludwig D. Schmidt🇩🇪 · Moritz S. Fischer🇩🇪 · Mathias Garny🇩🇪
Many proposed self-interacting dark matter (SIDM) models give rise to radiative processes that can dissipate energy. Understanding their impact on astrophysical objects through simulations and comparing the results with observations may thus constrain SIDM models. In this work, we systematically investigate how dissipation alters the gravothermal evolution of isolated SIDM halos by independently varying dissipation and heat conduction and identify potential observational signatures. To this end, we present the first extension of the $N$ -body formalism for frequent small-angle self-interactions (fSIDM) to include effective dissipation. We compare all results for isolated halos with a dissipative gravothermal fluid model to assess its validity and limitations. We find that dissipation qualitatively changes the gravothermal evolution of SIDM halos beyond simply accelerating collapse. Sufficiently strong central cooling can invert the usual role of heat conduction: the formation of an isothermal core is suppressed such that conduction remains directed inward throughout the evolution. Outer halo regions beyond the scale radius can cool efficiently rather than being heated by conduction, resulting in a larger region of mass infall and a less pronounced indentation between the core and the outer halo in the final density profile. These effects depend strongly on the cooling rate but are comparatively insensitive to the angular dependence of the self-interaction cross section. We further show that weakly dissipative self-interactions can explain the properties of the recently observed strong lens perturber in JVAS~B1938+666 with significantly shorter evolution times or, equivalently, smaller cross sections compared to the elastic case. Our results open a new route to connecting halo structure and recently reported compact objects to dark-sector microphysics.
↳ astro-ph.COastro-ph.GAhep-ph2 citations
40
Moduli Stabilisation for ADD and the Dark Dimension Scenario
Andreas P. Braun🇬🇧 · Michele Cicoli🇮🇹 · Riccardo Milioli🇮🇹 · Roberto Valandro🇮🇹
We provide a moduli stabilisation mechanism for realising anisotropic string compactifications with one or two large extra dimensions, corresponding to the ADD and Dark Dimension scenarios. This is achieved within the type IIB Large Volume Scenario, where an exponentially large Calabi-Yau volume in string units can naturally generate a parametrically low Kaluza-Klein scale. Anisotropy is realised by considering a Calabi-Yau threefold which is a K3 fibration over a $P^{1}$ base. The volume of the 4D K3 fibre is stabilised at relatively small values by perturbative corrections to the effective action, in particular string loops and higher-derivative effects, leaving an exponentially large volume of the 2D $P^{1}$ base. We argue that complex structure moduli stabilisation can dynamically deform the $P^{1}$ base, corresponding to a Tyurin degeneration limit where the internal geometry effectively develops a single large 1D cycle. Within a unified description, the ADD case is instead recovered as a symmetric alternative limit. The potential can feature either a dS vacuum or a quintessence runaway, although in both cases some degree of tuning is required to match the observed cosmological constant scale. We also present an explicit Calabi-Yau orientifold example with consistent brane setup, tadpole cancellation and moduli stabilisation. We analyse the resulting moduli spectrum and associated phenomenological constraints, including supersymmetry breaking, cosmological moduli overproduction and fifth force bounds.
↳ hep-thastro-ph.COhep-ph1 citation
41
Eppur non si trovano Vol. 3: Phoebe -- a Mirage of a Primordial Black Hole
Andrzej Udalski🇵🇱 · Przemek Mróz🇵🇱
Recent preprints by Key et al. reported the discovery of a short-lived brightening of a star (nicknamed "Phoebe") located in the Large Magellanic Cloud that was interpreted as a short-timescale gravitational microlensing event produced by a lunar-mass primordial black hole (PBH) in the Milky Way dark matter halo. Here, we present an independent re-analysis of the publicly available DECam observations of this object, incorporating additional data from 2020 and 2021. The object underwent at least three distinct, low-amplitude brightenings (one of which was misinterpreted as a short-timescale microlensing event) in addition to long-term variations of its mean magnitude. These characteristics indicate that Phoebe is an ordinary variable star rather than a microlensing event. This finding resolves the apparent tension with the results from earlier microlensing experiments that rule out the hypothesis that a substantial fraction of dark matter is composed of lunar- and planetary-mass PBHs.
↳ astro-ph.GAastro-ph.COastro-ph.HEastro-ph.SR+21 citation
42
Reheating as a variational probe of cosmological observables
Jinn-Ouk Gong🇰🇷
We formulate reheating as a constrained variational problem in the space of equation-of-state histories, rather than attempting to describe it through microscopic models. We introduce a regularized functional framework that identifies reheating histories which extremize a given cosmological observable under minimal physical assumptions. As illustrative applications, we consider prompt gravitational waves, induced gravitational waves, and primordial black holes. We find that different observables select qualitatively different regions of reheating-history space. These examples demonstrate that cosmological observables define distinct extremal directions in reheating-history space and can therefore be used to systematically explore the space of post-inflationary expansion histories.
↳ astro-ph.COgr-qchep-phhep-th+10 citations
43
Vistas: A Visualization Interface for Particle Collision Simulations
Benoit Assi🇺🇸 · Christan Bierlich🇸🇪 · Rikab Gambhir🇺🇸 · Philip Ilten🇺🇸 · Tony Menzo🇺🇸 · Stephen Mrenna🇺🇸 · Manuel Szewc🇦🇷 · Michael K. Wilkinson🇺🇸 · Ahmed Youssef🇺🇸 · Jure Zupan🇺🇸
We introduce Vistas, a tool for visualizing high-energy particle physics collisions simulated by the Pythia Monte-Carlo event generator. Vistas utilizes the browser-based event display framework Phoenix to show distinct computational stages of a high-energy collision event simulation: the hard process, parton shower, hadronization, and particle decays. Particles produced from each of these stages are represented as lines in an interactive three-dimensional graph structure, where each line is along the direction of its particle's three-momentum vector. The event can be rotated, translated and zoomed, and details for each particle can be accessed by selecting the relevant particle line. Additionally, particle lines from all stages of the simulation can be toggled on and off and can be filtered by particle-level kinematic selection requirements. This interactive environment provides an intuitive interpretation of Pythia simulation output, including detailed features such as color flow, beam remnants, and multiple parton interactions, making it a useful tool in physics education settings, from outreach activities to graduate particle-physics courses.
↳ physics.ed-phhep-ph0 citations
44
Graviton Floor
Himeka Matsuo🇯🇵 · Asuka Ito🇯🇵 · Kazunori Kohri🇯🇵 · Teruaki Suyama🇯🇵 · Ryutaro Tomomatsu🇯🇵
It has been observed that the Universe is permeated by the cosmic photon background, ranging from radio waves to gamma rays. We investigate the conversion of the photon background into gravitons in the presence of background magnetic fields in the Milky Way Galaxy and in blazar jets. We find that the resulting graviton background is dominated by the contribution generated in blazar jets. Importantly, this graviton background constitutes a graviton floor for high-frequency gravitational wave detectors searching for new physics, analogous to the neutrino floor.
↳ gr-qcastro-ph.COhep-ph2 citations
45
Scalar diquark mass and quark--diquark potential from lattice QCD using the potential method with a static quark
Kai-Wen Kelvin-Lee🇯🇵 · Noriyoshi Ishii🇯🇵
We study the scalar diquark mass and the quark--diquark potential by applying a HAL QCD-inspired potential method to a baryonic system composed of a scalar diquark and a static quark. The diquark mass is determined self-consistently by requiring that the p-wave baryonic spectrum obtained from two-point correlators be reproduced within the potential framework. Numerical calculations are performed using $2 + 1$ flavor QCD gauge configurations generated by the PACS-CS Collaboration on a $L^{3} \times T = 3 2^{3} \times 64$ lattice with $a^{- 1} \approx 2.176$ GeV and the pion mass, $m_{π} \approx 702$ MeV. From the analysis, we obtain a scalar diquark mass which is close to the na\"ıve constituent quark estimate $(2/3) m_{N}$ , together with a quark--diquark potential of the Cornell type (Coulomb + linear). The string tension extracted from the quark--diquark potential agrees within approximately 5% with that obtained from the static quark--antiquark potential (Wilson Loop).
↳ hep-lathep-phnucl-th1 citation
46
Metastable and critical-bubble branches of Coleman--Weinberg monopoles
Sumit Shaw🇮🇳
We revisit the Coleman--Weinberg monopole problem introduced by Kiselev, where radiative symmetry breaking makes the broken vacuum metastable. We construct the associated static monopole--critical-bubble configuration in the full coupled radial Higgs--gauge system and show that it is a saddle of the static energy functional. The metastable monopole and monopole--critical-bubble branches are characterized by their profiles, energies, and radial Hessian spectra. The monopole--bubble solution carries a negative radial mode, while the metastable monopole remains locally stable until its lowest radial Hessian eigenvalue approaches zero. The resulting branch structure gives a direct static picture of how Coleman--Weinberg monopoles lose metastability, with critical rescaled scalar mass parameter $\mu_c=0.064352(1)$.
↳ hep-thhep-ph0 citations
47
Evolving Dark Energy Is Vacuum Energy After All
Dong Ha Lee🇬🇧 · Carsten van de Bruck🇬🇧 · Eleonora Di Valentino🇬🇧 · Ludovic Van Waerbeke🇨🇦 · Ariel Zhitnitsky🇨🇦
We investigate a physically motivated model of dynamical dark energy arising from the non-perturbative topological structure of the Quantum Chromodynamics (QCD) vacuum. The model introduces no new fundamental field or propagating degree of freedom: the dark energy (DE) density emerges as a global vacuum response to an expanding spacetime. We develop the first comprehensive cosmological implementation of this QCD-DE scenario and confront it with current observations, including Planck, ACT and SPT-3G cosmic microwave background data, DESI DR2 baryon acoustic oscillation measurements, and Type Ia supernova samples from Pantheon+ and DES-Dovekie. We compare the model with $Λ CDM$ and $w_{0} w_{a} CDM$ cosmologies. The model provides an excellent fit to the data and reproduces the late-time DE evolution preferred by DESI. The model naturally predicts effective phantom crossing behaviour at intermediate redshifts ( $z \sim 0.67$ ) while avoiding the instabilities associated with phantom scalar fields. Using goodness-of-fit statistics and Bayesian model-selection tools, including Akaike and Deviance Information Criteria and Bayesian evidence estimated from Markov-Chain Monte Carlo chains, we find that the QCD-induced model is consistently favoured over $Λ CDM$ for the full combination of early and late-time datasets. Unlike the conventional descriptions of dynamical DE, support for QCD-DE in Bayesian evidence remains more consistent across datasets, suggesting that a physically motivated departure from a cosmological constant may provide a more economical description of the expansion history preferred by current observations.
↳ astro-ph.COhep-phhep-th6 citations
48
Hybrid stars with hyperons: structure based on QCD sum rule coupling constants
F. Moradi Jangal🇮🇷 · H. R. Moshfegh🇮🇷 · K. Azizi🇮🇷
We present a comprehensive study of hybrid stars composed of hadrons, leptons, and quarks within a relativistic mean-field framework. Using coupling constants derived from QCD sum rules (QCDSR), we first determine the bulk properties of nuclear matter and evaluate the single-particle potentials of nucleons and hyperons to constrain the hadronic sector. The equation of state (EOS) under beta equilibrium is then constructed employing the $σ - ω - ρ$ model for the hadronic phase, while the quark phase is described using both the MIT bag model and the Nambu-Jona-Lasinio (NJL) model. The hadron-quark phase transition is analyzed through both Gibbs and Maxwell constructions. Based on resulting EOSs, we obtain the mass-radius relations of hybrid stars, investigate particle fractions and their radial distributions, and calculate the tidal Love number ( $K_{2}$ ) and the dimensionless tidal deformability ( $Λ$ ). Our results provide quantitative predictions relevant for comparison with current multimessenger astrophysical observations.
↳ nucl-thastro-ph.HEastro-ph.SRhep-ph0 citations
49
Trace anomaly and interior curvature of neutron stars in energy-momentum squared gravity
Ratikanta Swain🇮🇳 · Sayantan Ghosh🇮🇳 · Bharat Kumar🇮🇳
In energy-momentum squared gravity (EMSG), the spacetime inside a neutron star is sourced by effective thermodynamic variables that need not coincide with the physical fluid pressure and energy density. It is therefore an open question whether the trace anomaly of dense matter -- the QCD measure of how strongly conformal symmetry is broken -- still organizes interior profiles and curvature in the same way it does in general relativity (GR). We adopt a clear matter-geometry separation: the trace anomaly is computed from the fluid sector alone, while spacetime curvature scalars are built from the variables that actually source the modified Tolman-Oppenheimer-Volkoff equations. For five relativistic mean-field equations of state, the radial trace-anomaly profiles increase monotonically from core to surface in all accepted EMSG models, as in GR, but split systematically with the EMSG coupling strength; the splitting grows with stellar compactness. Despite this deformation, curvature invariants still fall onto organized bands when plotted against the trace anomaly, extending the GR thermodynamic-geometric correspondence. The Ricci contraction shows the tightest organization, whereas the Ricci scalar remains the most equation-of-state sensitive. EMSG effects are modest for observationally accessible stars but largest in stiff, ultracompact configurations, indicating that the trace anomaly remains a useful thermodynamic label for interior geometry even when gravity couples nonlinearly to matter.
↳ nucl-thgr-qchep-ph1 citation
50
Statistical Properties of Training & Generalization
Itay Lavie · Noam Levi🇮🇱 · Yonatan Kahn🇨🇦
Deep learning has managed to evade numerous intuitions from classical statistics to achieve unprecedented performance on a number of real-world tasks. In this article, we investigate the key features and surprises of deep learning from a physics-informed perspective, taking care to point out and justify where possible the many choices inherent in constructing a deep learning model. In particular, we review the phenomenon of neural scaling laws and discuss their interplay with the constraints and inductive biases which may be present when applying machine learning to problems in physics.
↳ stat.MLcs.LGhep-phphysics.data-an2 citations
51
On the nature of the GRBs-SGRs blazing jet
Daniele Fargion🇮🇹
Gamma Ray Burst and Soft Gamma Repeaters are neither standard candle nor isotropic explosions. Our model explain them as strong blazing of a light-house, spinning and precessing gamma jet. Such jets at maximal output (as GRBs in Supernova like sources at cosmic edges) or at late lower power stages (SGRs in nearer planetary nebulae in galactic halo) may blaze the observer by extreme beaming $(Ω < 1 0^{- 8})$ and apparent huge luminosity. \keywords{GRB, Jet, Inverse Compton, SGR}
↳ astro-phastro-ph.COastro-ph.HEgr-qc+1Astron.Astrophys.Suppl.Ser.(1999)·34 citations
52
Gamma Ray Burst and Soft Gamma Repeaters. Spinning, Precessing Gamma Jets
Daniele Fargion🇮🇹
Gamma Ray Bursts as recent GRB990123 and GRB990510 are observed to occur in cosmic volumes with a corresponding output reaching, for isotropic explosions, energies as large as two solar masses annihilation. These energies are underestimated because of the neglected role of comparable ejected neutrinos bursts. These extreme power cannot be explained with any standard spherically symmetric Fireball model. A too heavy black hole or Star would be unable to coexist with the shortest millisecond time structure of Gamma ray Burst. Beaming of the gamma radiation may overcome the energy puzzle. However any mild explosive beam $(Ω > 1 0^{- 2})$ should not solve the jet containment at those disruptive energies. Only extreme beaming $(Ω < 1 0^{- 8})$ , by a slow decaying, but long-lived precessing jet, it may coexist with characteristic Supernova energies, apparent GRBs output, statistics as well as their connection with older and nearer SGRs relics.
↳ astro-phastro-ph.COastro-ph.HEhep-phConference 26th ICRC,OG2.3.14,p.32-35,Edi…·3 citations

Affiliations

first authorsco-authorsvia INSPIRE