Wed·Oct 8, 2025Wednesday·October 8, 2025

1. 01*

   Primordial Black Holes at the Junction

   James B. Dent🇺🇸 · Bhaskar Dutta🇺🇸 · Mudit Rai🇺🇸

   Primordial black holes (PBHs) formed during first-order phase transitions provide a powerful link between the early-universe microphysics and observable signatures today, including dark matter and gravitational waves. In this work we develop a unified description of PBH formation based on the Israel junction conditions, which capture collapse dynamics without relying on conventional overdensity or pressure-balance arguments. As a first application, we show that exotic objects such as Fermi-balls can collapse into PBHs even when most of the vacuum energy is trapped in solitonic cores, leading to a different gravitational-wave signal relative to vacuum-only scenarios. As a second application, we study multiple phase transitions in a hidden sector, which generate correlated gravitational-wave spectra and PBH abundances across transitions. Our framework, while analytically controlled, is broadly applicable to hidden-sector models with general vacuum, radiation, and matter contributions. We present the resulting predictions for PBH mass spectra, dark matter fractions, and gravitational-wave signals, highlighting parameter regions that remain open in current searches and motivating future probes.

   hep-phgr-qcJHEP(2026)·5 citations
2. 02*

   Unitary perturbation theory on the light cone using adiabatic switching

   Stéphane Munier🇫🇷

   Light-cone perturbation theory is a powerful tool for calculating high-energy scattering amplitudes, particularly for quantum particles such as electrons, photons, or protons scattering off heavy nuclei, a process analogous to potential scattering. Central to these computations are the light-cone wave functions of incoming and outgoing particles, representing the projection of dressed initial and final states onto partonic Fock states. The dressed states are obtained by applying an evolution operator in the Dirac picture to bare partonic states, which may be interpreted physically as a time evolution from preparation to interaction. In standard approaches, a non-unitary operator is used, and proper normalization is imposed a posteriori. Here, we systematically develop perturbation theory from a perturbatively unitary evolution operator, using adiabatic switching to regularize the infinite-time limits. This provides a theoretically coherent framework for organizing calculations, reproducing known results entirely diagrammatically without enforcing unitarity by hand. We illustrate the method with a simple quantum mechanical model, enabling calculations to arbitrary perturbative orders, and then evaluate wave functions in field theories quantized on the light cone, focusing on a massive scalar theory with cubic interaction at one-loop accuracy.

   hep-phEPJC(2026)·2 citations
3. 03*

   Feebly Interacting Particles: FIPs at LHCb

   J. Alimena · J. Boyd · G. Cacciapaglia · A. Casais Vidal · X. Cid Vidal · S. Collaviti · A. De Oyanguren Campos · G. Dalla Valle Garcia · G. Elor · G. Ferretti · D. Gorbunov · E. Goudzovski and 27 other authors

   With the establishment and maturation of the experimental programs searching for new physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astrophysics community for exploring the physics of light and feebly-interacting particles as a paradigm complementary to a New Physics sector at the TeV scale and beyond. FIPs@LHCb continues the successful series of the FIPs workshops, FIPs 2020 and FIPs 2022. The main focus of the workshop was to explore the LHCb potential to search for FIPs thanks to the new software trigger deployed during the recent upgrade. Equally important goals of the workshop were to update the available parameter space in the commonly used FIPs benchmarks by including recent results from the high energy physics community and to discuss recent theory progress necessary for a more accurate definition of observables related to FIP benchmarks. This document presents the summary of the talks presented at the workshops and the outcome of subsequent discussions.

   hep-ph19 citations
4. 04*

   The influence of invisible light particles on ${\Lambda }_b\to \Lambda E_{\mathrm{miss}}$

   Quan-Yi Hu🇨🇳 · Zhi-Bin Duan🇨🇳

   In this work, we study the contribution of invisible light particles to ${\Lambda }_b\to \Lambda E_{\mathrm{miss}}$, particularly the three-body decays ${\Lambda }_b\to \Lambda \varphi \bar{\varphi }$ and ${\Lambda }_b\to \Lambda \psi \bar{\psi }$. The differential branching ratio of ${\Lambda }_b\to \Lambda E_{\mathrm{miss}}$ and the $q^2$-dependent longitudinal polarization asymmetry of $\Lambda$ in scenarios explaining the Belle II excess are presented. In the chiral basis, we investigate the correlations between $\mathcal{B}(B\to K{E}_{\mathrm{miss}})$ and $\mathcal{B}({\Lambda }_b\to \Lambda E_{\mathrm{miss}})$, as well as between $\mathcal{B}(B\to K{E}_{\mathrm{miss}})$ and $P_L^{\Lambda }$, in eight distinct new physics scenarios. We find that the $P_L^{\Lambda }$ can be used to distinguish the chirality of the hadronic current part in the effective operators, which is similar to the cases in the two-body decays ${\Lambda }_b\to \Lambda \varphi$ and ${\Lambda }_b\to \Lambda V$.

   hep-phPRD(2025)·4 citations
5. 05*

   Space-time geometry of small and large collision systems at LHC energies

   Thomas A. Trainor🇺🇸

   Identified-hadron (PID) spectra from 2.76 TeV Pb-Pb and $p$-$p$ collisions are analyzed via a two-component (soft + hard) model (TCM) of hadron production in high-energy nuclear collisions. The Pb-Pb TCM is adopted with minor changes from a recent analysis of PID hadron spectra from 5 TeV $p$-Pb collisions. The object of study is evidence for jet suppression in small and large collision systems as indicating quark-gluon plasma (QGP) formation there. Conventional methods have included Pb-Pb centrality determination via classical Glauber model and evidence for high-$p_t$ suppression sought via spectrum ratio $R_{\text{AA}}$. In the present study alternative geometry determination via ensemble-mean ${\bar{p}}_t$ data reveals that the number of participant nucleons in central Pb-Pb collisions is about 1/3 of the Glauber estimate. Based on certain features of Pb-Pb spectra the validity of the factorization assumption is also questioned. The entire jet contribution is therefore treated without factorization in ratio to a $p$-$p$ spectrum model as reference. The new results indicate that exclusivity and time dilation (experienced by participant partons) play an essential role in jet production not incorporated in Glauber model or hard-component factorization. The combination determines an effective number of N-N collisions per participant nucleon given specific Pb-Pb centrality. The effect on parton fragment (jet) distributions on $p_t$ is similar to projectile-proton fragment distributions on pseudorapidity from fixed-target $p$-A experiments where low-$\eta$ densities scale with A while high-$\eta$ densities are consistent with $p$-$p$ collisions. $p$-Pb and Pb-Pb spectra similarly analyzed reflect the same physics given different geometries. Jet suppression related to QGP formation is not evident.

   hep-ph4 citations
6. 06*

   Higher-spin light-flavor baryonic spectroscopy in AdS/QCD at finite temperature

   R. da Rocha🇧🇷 · P. H. O. Silva🇧🇷

   Light-flavor baryon resonances in the $J^P=3/2^{+}$, $J^P=5/2^{+}$, and $J^P=5/2^{-}$ families are investigated in a soft-wall AdS/QCD model at finite temperature, including the zero temperature limit. Regge-like trajectories relating the configurational entropy underlying these resonances to both the radial quantum number and the baryon mass spectra are constructed, allowing for the extrapolation of the higher-spin light-flavor baryonic mass spectra to higher values of the radial quantum number. The configurational entropy is shown to increase drastically with temperature, in the range beyond T ~ 38 MeV. The mass spectra of baryon families are analyzed, supporting a phase transition nearly above the Hagedorn

   hep-phhep-thPLB(2025)·1 citation
7. 07*

   Comment on "Unruh effect for neutrinos interacting with accelerated matter"

   R. R. S. Oliveira🇧🇷

   In the present comment, we show that the fundamental equation worked by Dvornikov in his paper, which is the Dirac equation for a massive neutrino interacting with linearly accelerated matter, is incorrect. In particular, Dvornikov incorrectly wrote/defined the effective external current in a curved space-time. In other words, Dvornikov wrote/defined such an effective current in a flat space-time, which is a mistake. Consequently, the second-order differential equation (generated through the quadratic Dirac equation) in your paper is incorrect, where such an equation is given by the Whittaker equation. So, since the solutions of such a differential equation (whose solutions are the Whittaker functions) are the basis for its results, it implies that such results are also incorrect. In this way, starting from the true/correct Dirac equation with an effective external current in a curved space-time, we obtain in detail the second-order differential equation (also a Whittaker equation) and its solutions for a neutrino interacting with linearly accelerated matter.

   hep-ph0 citations
8. 08*

   Dissociative associated $J/\psi$ and dimuon production in Ap ultraperipheral collisions via double parton scattering

   Bruna O. Stahlhöfer🇧🇷 · Edgar Huayra🇧🇷 · Emmanuel G. de Oliveira🇧🇷

   We study the dissociative associated production of a $J/\psi$ meson and a dimuon via double parton scattering (DPS) in nucleus--proton ultraperipheral collisions. This new channel, characterized by a rapidity gap, is sensitive to the photon and gluon distributions of the proton. We derive a DPS pocket formula for this process, together with a corresponding expression for the effective cross section. Furthermore, we demonstrate the kinematic dependence of the effective cross section and present predictions for the differential DPS cross section at LHC and FCC energies.

   hep-phPRD(2026)·1 citation
9. 09*

   Study of the two-body nonleptonic $B_c(2S)$ weak decays with the QCD factorization approach

   Na Wang🇨🇳 · Yueling Yang🇨🇳 · Junfeng Sun🇨🇳

   Inspired by the promising prospect of the $B_c(2S)$ meson at the coming HL-LHC experiments, the nonleptonic $B_c(2S)$ meson weak decays induced by both the $b$ and $c$ decays are investigated with the QCD factorization approach. It is found that branching ratios for the color- and CKM-favored $B_c(2S)$ $\to$ $B_s\rho$, $B_s\pi$ decays can reach up to $\mathcal{O}(10^{-9})$, which might be measurable. The $B_c(2S)$ decays into the final states containing one charmonium are highly suppressed by the CKM factors, and have significantly small branching ratios, $\mathcal{O}(10^{-12})$ and less, which might be outside the future measurement capability. This paper provides a ready reference for the future experimental study on the hadronic $B_c(2S)$ weak decays.

   hep-phPRD(2025)·1 citation
10. 10*

    Probing a long-lived pseudoscalar in type-I 2HDM with displaced vertices and jets at the LHC

    Lei Wang🇨🇳 · Zeren Simon Wang🇨🇳 · Haotian Xu🇨🇳

    In the type-I two-Higgs-doublet model, the pseudoscalar $A$ can act as a long-lived particle (LLP) for sufficiently large values of $\tan \beta$. At the LHC, the $A$ particles are predominantly produced in pairs through $pp\to W^{\ast }/Z^{\ast }\to H^{\pm }/HA$, with subsequent decays $H^{\pm }/H\to W^{\pm }/ZA$. For the mass range of our interest, $10\text{GeV}\lesssim m_A\lesssim 100\text{GeV}$, the pseudoscalar $A$ typically decays into a pair of bottom quarks after traveling a macroscopic distance from its production point, giving rise to displaced-vertex (DV) signatures inside the inner detector. We perform Monte Carlo simulations of signal events with DVs plus jets, and assess the discovery prospects of $A$ as an LLP at the ATLAS and CMS experiments. Our findings show that a substantial portion of the parameter space with $m_A>10$ GeV has already been excluded by LHC Run-2 data, while the high-luminosity LHC will be able to probe broader regions.

    hep-phhep-exJHEP(2026)·1 citation
11. 11*

    Tensor-current contributions to B Anomalies

    Qiaoyi Wen🇨🇳 · Fanrong Xu🇨🇳

    Tensor-current operators, potentially generated by scalar leptoquarks in grand unified theories (GUTs), are among the plausible new physics (NP) candidates suggested by the anomalies observed in $B$-meson decays. As experimental data continue to accumulate, exploring this possibility remains timely and well motivated. In this work, we present a systematic analysis of representative tensor-current Wilson coefficients ($C_T,C_{T5}$) in $b\to s{\ell }^{+}{\ell }^{-}$ transitions. By incorporating contributions from the high-$q^2$ region, our framework fully exploits the available experimental data across the entire $q^2$ range. Within this setup, five distinct lepton-flavor-universal (LFU) scenarios are proposed and tested through global fits. Our results show that it is difficult to resolve the tension between experimental measurements and theoretical predictions using only $C_T$ and $C_{T5}$. Meanwhile, the significance of $\Delta C_9$ remains essentially unchanged, even in the presence of tensor contributions. In one representative scenario (S-III), we obtain $[C_9,C_{10},C_T,C_{T5}]\simeq [-1.05,0.22,0.02,0.01]$, with a reduced chi-squared statistic ${\tilde{\chi }}^2\equiv {\chi }_{\min }^2/d.o.f.=708.7/486=1.46$. Furthermore, we derive a stringent 95$\%$ C.L. constraint on tensor operators, $$F(x,y){|}_{x=\Delta C_T,y=\Delta C_{T5}}^{\text{S-I}}=x^2+0.063xy+0.989y^2+0.034x+0.043y\le 0.003,$$ which provides one of the strongest bounds to date on $C_T$ and $C_{T5}$.

    hep-phEPJC(2026)·0 citations
12. 12*

    Electromagnetic probes as signatures for a first-order QCD phase transition

    Mohamad Lukman Aidid Mohd Yusoff🇲🇾 · Norhasliza Yusof🇲🇾 · Hasan Abu Kassim🇲🇾 · Jan Steinheimer🇩🇪 · Marcus Bleicher🇩🇪 · Apiwit Kittiratpattana🇹🇭 · Ayut Limphirat🇹🇭 · Christoph Herold🇹🇭

    We investigate dimuon production in the context of a first-order phase transition in QCD matter using a chiral fluid dynamics model. This approach incorporates non-equilibrium effects such as entropy production and reheating, which emerge during the dynamical evolution through a first-order phase transition. By comparing equilibrium and non-equilibrium scenarios across a range of beam energies ($\sqrt{s_{NN}}=2.2-6.2$~GeV), we analyze the resulting invariant mass spectra. Our results reveal a substantial enhancement of dilepton yields in the non-equilibrium scenario, particularly pronounced at lower beam energies, where reheating leads to a prolonged lifetime of the fireball and increased emission. The enhancement persists even after normalizing to pion multiplicities, indicating sensitivity beyond effects of entropy production.

    hep-phPRC(2026)·1 citation
13. 13*

    NLP threshold corrections to W+jet production

    Sourav Pal🇮🇳 · Satyajit Seth🇮🇳

    We perform a detailed computation of the helicity-dependent next-to-leading power leading logarithms in W+jet production, originating from next-to-soft gluon radiation and soft (anti-)quark emissions. These contributions are systematically captured via helicity-sensitive spinor shifts and soft quark operators. The resulting expressions exhibit full agreement with a recently proposed universal structure of NLP corrections for processes involving the production of an arbitrary massive colourless final state in association with a jet.

    hep-phJHEP(2026)·1 citation
14. 14*

    Self-Interacting Sub-GeV Dark Matter with Strong MeV Gamma-ray

    Yu Watanabe🇺🇸

    Sub-GeV dark matter (DM) with $s$-channel resonant self-scattering provides a promising framework for addressing small-scale structure problems. However, models that also account for the observed relic abundance through the same resonance are strongly constrained by current $\gamma$-ray observations, since the associated signals are significantly enhanced. To overcome this limitation, we propose a framework in which the relic abundance and self-scattering are governed independently by two distinct mediators. As a concrete realization, we present a singlet scalar DM model in which self-scattering is mediated by a vector boson associated with a gauged baryon number, while the relic density is determined by forbidden annihilation into dark Higgs bosons that generate the gauge boson mass. By imposing cosmological, experimental, and theoretical constraints, We identify viable parameter regions that reproduce the observed relic density, alleviate small-scale problems, and remain consistent with current bounds. Notably, the model predicts multiple distinctive MeV $\gamma$-ray signals, a significant fraction of which will be testable with next-generation MeV $\gamma$-ray telescopes, including the Compton Spectrometer and Imager (COSI).

    hep-phJHEP(2026)·2 citations
15. 15*

    How large are hadronic contributions to $h\to \gamma \gamma$?

    Ulrich Haisch🇩🇪

    The decay of the Higgs boson into two photons, $h\to \gamma \gamma$, is a loop-induced process within the Standard Model, predominantly mediated by loops of $W$ bosons and top quarks. While these leading contributions are well understood, the role of hadronic effects, which arise from non-perturbative QCD dynamics, has received less attention, with recent studies reporting puzzling and contradictory results. In this work, we present a systematic evaluation of the hadronic contributions to the $h\to \gamma \gamma$ decay width using dispersion relations. Our analysis shows that these contributions are exceedingly small, as expected, altering the decay width by about $0.004\%$ under conservative assumptions. Therefore, hadronic effects can be safely neglected even in the context of future high-precision Higgs measurements at current and next-generation colliders. As an aside, we also estimate the possible size of hadronic contributions to Higgs production in gluon-gluon fusion.

    hep-phhep-exJHEP(2025)·1 citation
16. 16*

    Gravitational Wave Signatures of Warm Dark Matter in Gauge Extensions of the Standard Model

    Lucia A. Popa (Institute of Space Sciences (ISS/INFLPR subsidiary), Atomiştilor 409, Magurele-Ilfov, Ro-077125, Romania)🇷🇴

    We study the left-right symmetric extension of the Standard Model (LRSM), featuring a TeV-scale right-handed (RH) gauge boson $W_R$ and three RH neutrinos. This setup naturally realises the type-II seesaw mechanism for active neutrino masses. We identify the conditions that yield sufficient entropy dilution to reconcile the keV sterile neutrino dark matter energy density with observations while inducing an early matter domination (EMD) phase. These constrain the lightest active neutrino mass to 8.59 x 10^{-10} eV < m_{\nu_1} < 5.06 x 10^{-9} eV$. The resulting frequency-dependent suppression of the stochastic gravitational wave (GW) background is set by the mass and lifetime of the heavier RH neutrinos. Computing the signal-to-noise ratio (SNR) for future detectors, we find that a blue-tilted primordial tensor spectrum can boost the GW signal to detectable levels (SNR > 10) in experiments such as LISA, BBO, and DECIGO.

    hep-phUniverse(2025)·0 citations
17. 17*

    nCTEQ global analysis of nuclear PDFs

    M. Klasen🇩🇪

    We review the series of specific nCTEQ analyses of nuclear parton distribution functions (PDFs) published since 2020 and present preliminary results of a new global analysis. Building on a modern proton baseline without nuclear data and extending the kinematic range, it combines and updates the previous separate analyses that focused on Jefferson Lab neutral-current deep-inelastic scattering (DIS), neutrino DIS and dimuon production, and the currently available CERN LHC data, in particular on W/Z-boson, single inclusive hadron, and heavy-quark production.

    hep-phhep-exnucl-exPoS(2025)·3 citations
18. 18*

    Flavor-Changing Non-Global Logarithms

    Andrew J. Larkoski🇺🇸

    Non-global logarithms are low energy correlations between the substructure of a jet and the event in which it is immersed. We study the leading non-global logarithms that arise from soft quark--anti-quark emission and calculate their coefficient as a series in the jet radius, $R$, in arbitrary processes. We calculate the exact coefficient through quadratic order in $R$, and show that this truncation is within $5\%$ of the complete result for radii up to $R=1$. These quark flavor-dependent non-global logarithms are also responsible for the infrared unsafety of a naïve definition of jet flavor that is simply the net sum of quark flavors in the jet of interest. We propose a small modification of this naïve jet flavor that we call subtractive jet flavor in which the problematic soft logarithms are explicitly subtracted. We further demonstrate how our analytic results can be interfaced with automated numerical fixed-order codes to extract subtractive jet flavor cross sections.

    hep-phhep-exPRD(2026)·4 citations
19. 19*

    Primordial Quark Stars Made of Long-lived False Vacuum

    Jingdong Shao🇨🇳 · Mei Huang🇨🇳

    A false vacuum could be a profound ingredient of fundamental physics, yet its direct detection in laboratories is hindered when the lifetime is exponentially long. Conventional static phase diagrams often discard metastable false vacuum, we show that, however, in a dynamical treatment of a first-order QCD phase transition at large quark chemical potential that strongly suppresses tunneling, cosmologically long-lived, and thus indispensable false vacuum naturally arises, and makes nontrivial contribution to constituting primordial quark objects. We identify two distinct branches of such primordial quark objects: quark star crusted with false vacuum, and nugget specifically referring to quark star in global false vacuum, which may account for a population of small compact stars. Some long-lived primordial objects may have survived until the late Universe, and hopefully sow the seeds of high red-shift galaxies. Its false vacuum decay can power ultra-energetic long $\gamma$-ray bursts and kHz gravitational waves within multi-messenger facilities, rendering itself an astrophysical and thus testable phenomenon.

    hep-ph1 citation
20. 20*

    Limits on the axion-photon coupling from Chandrayaan-2 observations

    Tanmoy Kumar🇮🇳 · N. P. S. Mithun🇮🇳 · Subhendra Mohanty🇮🇳 · Sourov Roy🇮🇳 · B. S. Bharath Saiguhan🇮🇳 · Santosh Vadawale🇮🇳

    Axions and axion-like particles (ALPs) have gained immense attention in searches for beyond Standard Model (BSM) physics. Experiments searching for axions leverage their predicted couplings to Standard Model (SM) particles to look for observable signals. Though weak, these couplings allow axions to be produced abundantly in the interiors of stars such as the Sun. Once created, axions can escape the Sun and while passing through the solar atmosphere, oscillate into photons in the magnetic field producing x-rays. For the first time, we used data from the observation of soft x-rays from the quiet Sun during the 2019-20 solar minimum by the solar x-ray monitor (XSM), onboard India's Chandrayaan-2 lunar exploration mission, to constrain the coupling of axions to photons ($g_{a\gamma \gamma }$). Using the latest models of the solar atmosphere to calculate the magnetic field and plasma frequency, we constrain $g_{a\gamma \gamma }\lesssim (0.50-2.26)\times 10^{-10}$ GeV${}^{-1}$ at $95\%$ confidence level for axion masses $m_a\lesssim 5\times 10^{-4}$eV.

    hep-phastro-ph.HEastro-ph.SRPRD(2026)·1 citation
21. 21*

    Helicity correlation of dihadron in current and target fragmentation regions of unpolarized SIDIS

    Xue-Qi Xi🇨🇳 · Kai-Bao Chen🇨🇳 · Xuan-Bo Tong🇫🇮 · Shu-Yi Wei🇨🇳 · Jing Wu🇨🇳

    We study the helicity correlation of two $\Lambda$ hyperons produced in unpolarized semi-inclusive deep inelastic scatterings (SIDIS), with one hyperon detected in the current fragmentation region and the other in the target fragmentation region. This observable provides direct access to the spin-dependent fragmentation function $G_{1Lq}$ and the spin-dependent fracture function $l_{1q}^L$ even in unpolarized lepton nucleon collisions. Utilizing the perturbative matching of the fracture function, we present numerical predictions for the helicity correlation, revealing significant variations with flavor and kinematic regions. This observable offers a unique way to investigate the spin-dependent hadronization mechanism across both the current and target fragmentation regions. It also provides new insights into the spin transfer effects in SIDIS processes.

    hep-phEPJC(2025)·5 citations
22. 22*

    A possibility of describing a sequential gauge symmetry as a part of a tetrahedron rotational symmetry and its implications

    Jae Jun Kim🇺🇸

    We present a method in which the dimension-five and -six terms in a sequential gauge can coexist with that in a non-sequential gauge under a tetrahedron rotational symmetry. We start with the contents in the model proposed in a sequential gauge, meeting the conditions for the contents to be described in the rotational symmetry. Given that the breaking of the symmetry takes place in the dimension-five and -six terms via the flavor-specific Higgs scalars, we address how introducing the non-sequential contents can be realized. In doing so, we illustrate that the terms in the sequential gauge could be understood as the higher-order terms, the correction terms, and that in the non-sequential gauge as the leading order term. Our result could be understood as an illustration of introducing the sequential gauge as a reason for the mixing as having non-zero left-handed rotational matrix in the quark and the lepton sectors, how the mixing in the charged lepton sector can be small compared to that of the neutral sector, and how the sequential and the non-sequential gauge terms can coexist without introducing super-symmetry.

    hep-ph0 citations
23. 23*

    Energy-Energy Flow Networks

    Arianna Garcia Caffaro🇺🇸 · Ian Moult🇺🇸 · Chase Shimmin🇺🇸

    Jet substructure provides one of the most exciting new approaches for searching for physics in and beyond the Standard Model at the Large Hadron Collider. Modern jet substructure searches are often performed with Neural Network (NN) taggers which study the jets' radiation distributions in great detail, far beyond what is theoretically described by parton shower generators. While this represents a great opportunity, as NNs look deeper into the structure of jets they become increasingly sensitive both to perturbative and non-perturbative theoretical uncertainties. It is therefore important to be able to control which aspects of both regimes the networks focus on, and to develop techniques for quantifying these uncertainties. In this paper we take two steps in this direction: First, we introduce EnFNs, a generalization of the Energy Flow Networks (EFNs) which directly probes higher point correlations in jets, as motivated by recent advances in the study of energy correlators. Second, we introduce a number of techniques to quantify and visualize their robustness to non-perturbative corrections. We highlight the importance of such considerations in a toy study incorporating systematics into a search, and maximizing for the network's discovery significance, as opposed to absolute tagging performance. We hope this study continues the interest in understanding the role QCD systematics play in Machine Learning applications and opens the door to a better interplay between theory and experiment in HEP.

    hep-phhep-exnucl-ex3 citations
24. 24*

    Witten Effect in $3$-Form Description of $\theta$-vacua

    Maximilian Bachmaier🇩🇪 · Gia Dvali🇩🇪 · Juan Sebastián Valbuena-Bermúdez🇪🇸

    The $\theta$-vacua of a gauge theory admit an equivalent formulation as vacua of a massless Chern-Simons $3$-form, which originate from the topological susceptibility of the vacuum. This formulation provides a framework in which the physical manifestations of the $\theta$-angle, which are quantum in origin, can be captured at the level of effective classical equations of motion. Within this framework, we derive the Witten effect, demonstrating that in the background of a massless $3$-form, the magnetic monopole indeed acquires an electric charge proportional to $\theta$. This result, in particular, provides evidence that instantons, even when constrained by the Higgs effect, maintain a non-zero topological susceptibility of the vacuum. In addition to the Witten effect, we numerically demonstrate that a magnetic monopole exhibits polarizability when placed in a constant background electric field.

    ↳ hep-thhep-phPRD(2026)·2 citations
25. 25*

    New GPU developments in the Madgraph CUDACPP plugin: kernel splitting, helicity streams, cuBLAS color sums

    Andrea Valassi🇨🇭

    The first production release of the CUDACPP plugin for the Madgraph5_aMC@NLO generator, which speeds up matrix element (ME) calculations for leading-order (LO) processes using a data parallel approach on vector CPUs and GPUs, was delivered in October 2024. This was described in previous publications by the team behind that effort. In this paper, I describe my work on some additional developments and optimizations of CUDACPP, mainly but not exclusively for GPUs. The new approach, which represents a major restructuring of the CUDACPP computational engine, primarily consists in splitting the ME calculation, previously performed using a single large GPU kernel, into many smaller kernels. A first batch of changes, involving the move to separate "helicity streams" and the optional offloading of QCD color sums to BLAS, was recently merged into a new CUDACPP release, in collaboration with my colleagues. Since then, I have completed a second batch of changes, involving the possibility to split the calculation into groups of Feynman diagrams in separate source code files. This new feature makes it possible to compute QCD matrix elements for physics processes with a larger number of final state gluons: in particular, I present the first performance results from CUDACPP for the $2\to 6$ process $gg\to t\bar{t}gggg$ on CPUs and GPUs and the $2\to 7$ process $gg\to t\bar{t}ggggg$ on CPUs, which involve over 15k and 230k Feynman diagrams, respectively. I also take this opportunity to describe in detail some previously undocumented features of the CUDACPP software, both in the GPU and vector CPU implementations.

    ↳ physics.comp-phhep-exhep-ph3 citations
26. 26*

    Beyond ${\rho }^{2/3}$ Scaling: Microscopic Origins and Multimessengers of High-Density Nuclear Symmetry Energy

    Bao-An Li🇺🇸

    Nuclear symmetry energy $E_{\mathrm{sym}}(\rho )$ encoding the cost to make nuclear matter more neutron rich has been the most uncertain component of the EOS of dense neutron-rich nucleonic matter. It affects significantly the radii, tidal deformations, cooling rates and frequencies of various oscillation modes of isolated neutron stars as well as the strain amplitude and frequencies of gravitational waves from their mergers, besides its many effects on structures of nuclei as well as the dynamics and observables of their collisions. Siemens (1970s) observed that $E_{\mathrm{sym}}(\rho )$ scales as $(\rho /{\rho }_0{)}^{2/3}$ near the saturation density ${\rho }_0$ of nuclear matter, since both the kinetic part and the potential contribution (quadratic in momentum) exhibit this dependence. The scaling holds if: (1) the nucleon isoscalar potential is quadratic in momentum, and (2) the isovector interaction is weakly density dependent. After examining many empirical evidences and understanding theoretical findings in the literature we conclude that: (1) Siemens' ${\rho }^{2/3}$ scaling is robust and serves as a valuable benchmark for both nuclear theories and experiments up to $2{\rho }_0$ but breaks down at higher densities, (2) Experimental and theoretical findings about $E_{\mathrm{sym}}(\rho )$ up to $2{\rho }_0$ are broadly consistent, but uncertainties remain large for its curvature $K_{\mathrm{sym}}$ and higher-order parameters, (3) Above $2{\rho }_0$, uncertainties grow due to poorly constrained spin-isospin dependent tensor and three-body forces as well as the resulting nucleon short-range correlations. Looking forward, combining multimessengers from both observations of neutron stars and terrestrial heavy-ion reaction experiments is the most promising path to finally constraining precisely the high-density $E_{\mathrm{sym}}(\rho )$ and the EOS of supradense neutron-rich matter.

    ↳ nucl-thastro-ph.HEhep-phhep-th+1Eur. Phys. J. Spec. Top. (2026)·10 citations
27. 27*

    Demagnifying gravitational lenses as probes of dark matter structures and nonminimal couplings to gravity

    Hong-Yi Zhang🇨🇳

    Magnification of total image fluxes is typically considered a defining feature of gravitational microlensing. In contrast, I will show that nonminimal couplings to gravity can generate regions of negative gravitational potential curvature, giving rise to the distinctive possibility of demagnification. Such events, appearing as flux troughs in microlensing light curves, provide a direct probe of dark matter structures and, crucially, offer a means to disentangle nonminimal couplings to gravity from other astrophysical and cosmological models.

    ↳ gr-qcastro-ph.COhep-phApJL(2026)·3 citations
28. 28*

    Radiative-Corrected Higgs Inflation in Light of the Latest ACT Observations

    Jureeporn Yuennan🇹🇭 · Farruh Atamurotov🇺🇿 · Phongpichit Channuie🇹🇭

    Recent measurements from the Atacama Cosmology Telescope (ACT), particularly when combined with DESI baryon acoustic oscillation data, have reported a scalar spectral index $n_s$ slightly higher than that inferred by {\it Planck}~2018, suggesting a mild tension with the predictions of standard inflationary attractor models. In this work, we revisit the quantum-corrected Higgs inflation scenario within the framework of a non-minimally coupled scalar field theory. Starting from the one-loop effective action, we incorporate radiative corrections through the anomalous scaling parameter ${\mathbf{A}}_{\mathbf{I}}$ and derive analytic expressions for the inflationary observables $n_s$ and $r$ in the Einstein frame. Our analysis demonstrates that quantum corrections naturally shift $n_s$ toward higher values while keeping the tensor-to-scalar ratio $r$ suppressed. For $\mathcal{N}=60$, the model predicts $n_s\simeq 0.9743$ and $r\simeq 5.4\times 10^{-3}$, in excellent agreement with the latest ACT+DESI (P-ACT-LB) data and fully consistent with the \textit{Planck}~2018 limit $r<0.036$. The derived constraint $4.36\times 10^{-10}<\lambda /{\xi }^2<10.77\times 10^{-10}$ confirms the robustness of the quantum-corrected Higgs framework and indicates that near-future CMB polarization experiments such as CORE, AliCPT, LiteBIRD, and CMB-S4 will be able to probe the predicted parameter space with high precision.

    ↳ astro-ph.COgr-qchep-phPLB(2025)·10 citations
29. 29*

    Stochastic Gravitational Waves from Modulated Reheating

    Michele Benaco🇫🇮 · Dimitrios Karamitros🇬🇧 · Sami Nurmi🇫🇮 · Kimmo Tuominen🇫🇮

    We investigate scalar-induced stochastic gravitational waves from adiabatic curvature perturbations sourced by a spectator field via the modulated reheating mechanism. We consider a spectator scalar with Higgs-like couplings and inflaton decay via shift symmetric dimension-five operators. The spectator is assumed to be in the Sitter vacuum and it sources blue-tilted, strongly non-Gaussian curvature perturbations which can dominate the spectrum on small scales $k\gg {\mathrm{Mpc}}^{-1}$. We find that the setup could generate a gravitational wave signal testable by surveys like BBO and DECIGO but only for large coupling values not expected in low-energy particle physics setups that can be perturbatively extrapolated up to the inflationary scale.

    ↳ astro-ph.COgr-qchep-phJCAP(2026)·1 citation
30. 30*

    New ultralight scalar particles and the mass-radius relation of white dwarfs -- the important role of Sirius B

    Kai Bartnick🇩🇪 · Detlev Koester🇩🇪 · Rolf-Peter Kudritzki🇺🇸 · Konstantin Springmann🇮🇱 · Stefan Stelzl🇨🇭 · Andreas Weiler🇩🇪

    We present the equation of state for two classes of new ultralight particles, a scalar field coupling to electrons and a light ${\mathbb{Z}}_{\mathcal{N}}$ QCD axion field coupling to nucleons. Both are potential candidates for dark matter. Using the scalar modified equations of state, we calculate models for white dwarf stars and compare their radii and masses with observed mass-radius data. The comparison results in stringent constraints on the masses of the particles and the coupling parameters. For a wide range of particle masses and coupling parameters, constraints from the white dwarf equation of state surpass existing limits, outperforming also dedicated laboratory searches. The remarkable accuracy of modern white-dwarf mass-radius relation data, exemplified by Sirius B, now allows stringent tests of dense-matter physics and constraints on new particle scenarios.

    ↳ astro-ph.HEastro-ph.SRhep-phMNRAS(2025)·11 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.