Fri·Dec 13, 2024Friday·December 13, 2024

1. 01*

   Status and Perspectives on Axion Searches

   Maurizio Giannotti🇪🇸

   The search for axions and axion-like particles (ALPs) remains a major endeavor in modern physics investigation. Axions play essential roles in the quest to understand dark matter, the strong CP problem, and various astrophysical phenomena. This paper provides a very brief overview of the current status of experimental efforts, highlighting significant advancements, ongoing projects, and future opportunities. Particular attention is given to cavity haloscopes, helioscopes, and laboratory-based light-shining-through-wall experiments, as well as astrophysical probes. Some future perspectives are also discussed.

   hep-phastro-ph.HEastro-ph.SRhep-exPoS(2025)·13 citations
2. 02*

   Non-local material vacuum and Cherenkov radiation in non-linear massive $3$D-Electrodynamics

   Patricio Gaete🇨🇱 · J. A. Helayël-Neto🇧🇷

   We examine the effects of electromagnetic field non-linearities in $3$ space-time dimensions. We focus on how these non-linearities influence permittivity and susceptibility. This, in turn, leads to changes in the refractive index through the use of the dispersion relation in the context of massless and massive non-linear electrodynamics. We also verify that, by inspecting the model addressed in the frequency/wave vector space, we identify the characteristics of a non-local material in the behavior of the vacuum, which exhibits a spatially-dispersive profile. Furthermore, it is important to highlight that the cause of this phenomenon is the de Broglie-Proca mass term. We subsequently investigate the electromagnetic radiation emitted by a moving charged particle interacting with a medium for massless and massive non-linear electrodynamics. Our findings indicate that the radiation is driven by the medium through which the particle travels, similar to what is observed in the Cherenkov effect.

   hep-phEur.Phys.J.Plus(2026)·0 citations
3. 03*

   High Quality QCD Axion via Electric-Magnetic Duality

   Shota Nakagawa🇨🇳 · Yuichiro Nakai🇨🇳 · Junxuan Xu🇨🇳 · Yufei Zhang🇨🇳

   We propose a novel paradigm for the QCD axion with high-quality Peccei-Quinn (PQ) symmetry on the basis of electric-magnetic duality in the conformal window of a supersymmetric gauge theory. PQ breaking fields, that contain the QCD axion, emerge in the magnetic theory and possess a large anomalous dimension, which leads to not only generation of an intermediate scale of spontaneous PQ breaking but also significant suppression of explicit PQ symmetry breaking operators. The high PQ quality and the absence of a Landau pole in the color gauge coupling are achieved. The parameter space to realize the correct abundance of the axion dark matter (DM) predicts explicit PQ violation which may be probed by future measurements of the neutron electric dipole moment. In the other viable parameter space, the lightest supersymmetric particle can become a DM candidate. Since the model naturally accommodates a mechanism to suppress the axion isocurvature fluctuation, it provides a complete solution to the strong CP problem as well as the identity of DM.

   hep-phastro-ph.COhep-thJHEP(2025)·9 citations
4. 04*

   The curtain lowers on directly detectable higgsino dark matter

   Stephen P. Martin🇺🇸

   A higgsino could be some or all of the dark matter, with a mass bounded from above by about 1.1 TeV assuming a thermal freezeout density, and from below by collider searches. Direct detection experiments imply purity constraints on a dark matter higgsino, limiting the mixing with the electroweak gauginos. Using the new strong limits available as of the end of 2024 from the LUX-ZEPLIN experiment, I quantify the resulting lower bounds on gaugino masses and upper bounds on higgsino mass splittings, assuming that the scalar superpartners and Higgs bosons of minimal supersymmetry are in the decoupling limit. Similar bounds are projected for the critical future scenario that direct detection experiments reach the neutrino fog that hampers discovery prospects.

   hep-phPRD(2025)·20 citations
5. 05*

   Unveiling the Mechanisms of Electron Energy Spectrum Evolution

   Xu-Lin Dong🇨🇳 · Shu-Wei Ma · Yi-Qing Guo🇨🇳 · Shu-Wang Cui🇨🇳

   The electron spectrum exhibits a complex structure and has controversially proposed origins. This work reproduce the evolution of the electron spectrum based on a spatially dependent propagation (SDP) model. The key point is that our SPD model features two diffusion regions leading to two diffusion timescales, competing with the cooling timescale. This results in a three-segment power-law electron spectrum: (1) The spectrum below tens of GeV is primarily influenced by cooling effects from distant sources. (2) The spectrum dominated by diffusion effects from nearby sources from tens of GeV to TeV. (3) The spectrum above TeV, which is predominantly governed by cooling effects from nearby sources. This evolution is unique to the SDP model, and we offer a comprehensive and clear depiction of electron evolution under a single propagation scenario for the first time.

   hep-phastro-ph.HE2 citations
6. 06*

   Fast Flavor Pendulum: Instability Condition

   Damiano F. G. Fiorillo🇩🇪 · Manuel Goimil-García🇩🇰 · Georg G. Raffelt🇩🇪

   Even in the absence of neutrino masses, a neutrino gas can exhibit a homogeneous flavor instability that leads to a periodic motion known as the fast flavor pendulum. A well-known necessary condition is a crossing of the angular flavor lepton distribution. In an earlier work, some of us showed that homogeneous flavor instabilities also obey a Nyquist criterion, inspired by plasma physics. This condition, while more restrictive than the angular crossing, is only sufficient if the unstable branch of the dispersion relation is bounded by critical points that both lie under the light cone (points with subluminal phase velocity). While the lepton-number angle distribution, assumed to be axially symmetric, easily allows one to determine the real-valued branch of the dispersion relation and to recognize if instead superluminal critical points exist, this graphical method does not translate into a simple instability condition. We discuss the homogeneous mode in the more general context of the dispersion relation for modes with arbitrary wave number and stress that it plays no special role on this continuum, except for its regular but fragile long-term behavior, owed to its many symmetries.

   hep-phastro-ph.HEPRD(2025)·17 citations
7. 07*

   NNLL Transverse Momentum Dependent evolution in the Parton Branching method

   Aleksandra Lelek🇧🇪

   In the preparation period for precision measurements in the newly planned collider experiments, the understanding of the 3D structure of hadron is becoming increasingly urgent. This triggers the activities to include elements of Transverse Momentum Dependent (TMD) factorization physics in Monte Carlo (MC) event generators. The method designed especially to address this need is the TMD Parton Branching (PB) method. The equivalence of the PB Sudakov form factor, both perturbative and non-perturbative, to the one of Collins-Soper-Sterman (CSS) is demonstrated and the recent development to increase the low-qt resummation precision of the PB Sudakov up to next-to-next-to-leading logarithmic order by using effective soft-gluon coupling is discussed. The Collins-Soper (CS) kernel is extracted from PB Drell-Yan (DY) predictions obtained with different modelling of radiation.

   hep-phhep-th5 citations
8. 08*

   Exploring the chiral magnetic effect in isobar collisions through Chiral Anomaly Transport

   Zilin Yuan🇨🇳 · Anping Huang🇨🇳 · Guannan Xie🇨🇳 · Wen-Hao Zhou🇨🇳 · Guo-Liang Ma🇨🇳 · Mei Huang🇨🇳

   We investigate the signal of the chiral magnetic effect (CME) in Au+Au collisions and isobar collisions of ${}_{44}^{96}\text{Ru}+{}_{44}^{96}\mathrm{Ru}$ and ${}_{40}^{96}\text{Zr}+{}_{40}^{96}\mathrm{Zr}$ in the newly developed chiral anomaly transport (CAT) module based on the state-of-the-art model a multiphase transport (AMPT). Our numerical simulation results for the ratio charge correlation $\Delta \gamma$ in Ru+Ru and Zr+Zr collisions are close to the latest experimental data. The simulation shows that the CME signal is larger in Ru+Ru collisions than that in Zr+Zr collisions, while the background is smaller, and the upper limit of the CME signal is $15\%$ in the isobar collisions.

   hep-phnucl-thPRC(2025)·7 citations
9. 09*

   Exclusive diffractive dijets at HERA and EIC using GTMDs

   Antoni Szczurek🇵🇱 · Barbara Linek🇵🇱

   We calculate differential distributions for diffractive production of dijets in $ep\to e^{{}^{\prime }}pjetjet$ reaction using off diagonal unintegrated gluon distributions, often called GTMDs for brevity. Different models are used. We focus on the contribution to exclusive $q\bar{q}$ dijets. The results of our calculations are compared with the H1 and ZEUS data. Except of one GTMD, our results are below the HERA data points. This is in contrast with recent results where the normalization was adjusted to some selected distributions and no agreement with other observables was checked. We conclude that the calculated cross sections are only a small part of the measured ones which probably contain also processes with pomeron remnant, reggeon exchange, etc. We present also azimuthal correlations between the sum and the difference of dijet transverse momenta. The cuts on transverse momenta of jets generate azimuthal correlations (in this angle) which can be easily misinterpreted as due to so-called elliptic GTMD.

   hep-phActa Phys.Polon.Supp.(2025)·0 citations
10. 10*

    Exploring the lifetime frontier with a beam-dump experiment at CiADS

    Liangwen Chen🇨🇳 · Mingxuan Du🇨🇳 · Zhiyu Sun🇨🇳 · Zeren Simon Wang🇹🇼 · Fang Xie🇨🇳 · Ju-Jun Xie🇨🇳 · Lei Yang🇨🇳 · Pei Yu🇨🇳 · Yu Zhang🇨🇳

    We propose a beam-dump experiment (BDE) at the upcoming facility of China initiative Accelerator Driven System (CiADS), called CiADS-BDE, in order to search for long-lived particles (LLPs) predicted in various beyond-the-Standard-Model (BSM) theories. The experiment is to be located in the forward direction of the incoming low-energy proton beam at CiADS, leveraging the strong forward boost of the produced particles at the beam dump in general. The space between the dump and the detector is largely available, allowing for installation of shielding and veto materials and hence low levels of background events. We elaborate on the detector setup, and choose dark photon as a benchmark model for sensitivity study. We restrict ourselves to the signature of an electron-positron pair and perform detailed background estimates. We find that with 5 years' operation, unique, currently unexcluded parts of the parameter space for $\mathcal{O}(100)$~MeV dark-photon masses and $\mathcal{O}(10^{-9}\text{–}10^{-8})$ kinetic mixing can be probed at the CiADS-BDE. Furthermore, considering that there is no need to set up a proton beam specifically for this experiment and that the detector system requires minimal instrumentation, the experiment is supposed to be relatively cost-effective. Therefore, we intend this work to promote studies on the sensitivity reach of the proposed experiment to additional LLP scenarios, and in the end, the realization of the experiment. Incidentally, we study the sensitivity of the same BDE setups at the High Intensity Heavy-ion Accelerator Facility (HIAF), presently in operation near the CiADS program site, and conclude that HIAF-BDE could probe new parameter regions, too.

    hep-phhep-ex2 citations
11. 11*

    High-energy Coulomb scattering of spatially extended particles

    M. L. Nekrasov🇷🇺

    We analyze pure Coulomb high-energy elastic scattering of charged particles (hadrons or nuclei), discarding their strong interactions. We distinguish three scattering modes, determined by the magnitude of the momentum transfer, in which particles behave as point-like, structureless extended, and structured composite objects. The results are compared in the potential and QFT approaches of the eikonal model. In the case of proton Coulomb scattering at the LHC the difference between these two approaches is significant. This indicates the unsuitability of the potential approach. However, in the case of Coulomb scattering of heavy nuclei, the leading one is the optical approximation, which formally reproduces the prescription of the potential approach.

    hep-phhep-thnucl-thNPA(2025)·1 citation
12. 12*

    Two photon exchange corrections at large momentum transfer revised

    Nikolay Kivel🇩🇪

    Motivated by experimental data at large momentum transfer we update the analysis of the two-photon exchange effect in the electron-nucleon scattering using the effective field theory formalism. Our approach is suitable for describing the hard region, where the hadronic model calculations are not accurate enough. We improve the estimates of various long-range matrix elements and discuss the obtained numerical effects for the unpolarised elastic cross section. Assuming a linear behaviour of the reduced cross section with respect to the photon polarisation, we show that the obtained description allows us to resolve the form factor discrepancy for $Q^2=2.5-3.5$GeV${}^2$. However, the effect obtained is quite small for higher values of $Q^2$. It is possible that nonlinear effects may be important in understanding the discrepancy in this region. Estimates of the elastic electron-neutron cross section in the region are also performed. The obtained TPE effects are sufficiently large and must be taken into account.

    hep-phActa Phys.Polon.B(2025)·1 citation
13. 13*

    Complete NLO corrections to $t\bar{t}\gamma$ and $t\bar{t}\gamma \gamma$

    Daniel Stremmer🇩🇪

    In this contribution we discuss recent progress in associated top-quark pair production with one or two isolated photons, $pp\to t\bar{t}\gamma (\gamma )$. The focus is the simultaneous inclusion of higher-order effects and photon radiation in the production of the top-quark pair and in the decay processes. This allows us to quantify the importance of photon radiation in decay processes and the size of the so-called complete NLO corrections in realistic final states.

    hep-phhep-exSciPost Phys.Proc.(2026)·0 citations
14. 14*

    A harmonic oscillator in nonadditive statistics and a novel transverse momentum spectrum in high-energy collisions

    Trambak Bhattacharyya🇵🇱 · Maciej Rybczyński🇵🇱 · Grzegorz Wilk🇵🇱 · Zbigniew Włodarczyk🇵🇱

    It is widely observed that particles produced in high-energy collisions follow a power-law distribution. One such power-law distribution used extensively in the phenomenological studies owes its origin to nonadditive statistics proposed by C. Tsallis. In this article, we derive a novel nonadditive generalization of the conventional Bose-Einstein distribution using a single-mode harmonic oscillator. The approach taken in this paper eliminates the need of a regularization procedure proposed in previous works. We observe that the spectra of the bosonic particles like the pions and kaons produced in high-energy collisions are well-described by the nonadditive bosonic distribution derived in this paper.

    hep-phhep-exnucl-thPLB(2025)·2 citations
15. 15*

    Stability of the Higgs Potential in the Standard Model and Beyond

    Tom Steudtner🇩🇪

    The question of stability of the Higgs potential in the Standard Model is revisited employing advanced theoretical precision and recent experimental results. We show that the top mass and strong coupling constants are key observables in order to reach or refute absolute stability. We highlight new physics scenarios that lead to a decisive stabilisation of the Higgs sector. These proceedings summarise findings first reported in~[1,2].

    hep-phSciPost Phys.Proc.(2026)·0 citations
16. 16*

    Non-singular solutions to the Boltzmann equation with a fluid Ansatz

    Gláuber C. Dorsch🇧🇷 · Thomas Konstandin🇩🇪 · Enrico Perboni🇩🇪 · Daniel A. Pinto🇧🇷

    Cosmological phase transitions can give rise to intriguing phenomena, such as baryogenesis or a stochastic gravitational wave background, due to nucleation and percolation of vacuum bubbles in the primordial plasma. A key parameter for predicting these relics is the bubble wall velocity, whose computation relies on solving the Boltzmann equations of the various species along the bubble profile. Recently it has been shown that an unphysical singularity emerges if one assumes these local quantities to be described as small fluctuations over a constant equilibrium background. In this work we solve this issue by including the spatial dependence of the background into the fluid Ansatz. This leads to a modification of the Boltzmann equation, and all terms that would give rise to a singularity now vanish. We recalculate the different contributions to the counter-pressure of the plasma on the expanding wall, and discuss their relative importance. The Standard Model with a low cutoff is chosen as benchmark model and the results are shown for different values of the cutoff scale $\Lambda$. In this setup, deflagration solutions are found for almost all the values of $\Lambda$ considered, while detonations are found only for some restricted corner of the parameter space.

    hep-phJCAP(2025)·18 citations
17. 17*

    Multi-dimensional investigation of the pion pair-source in heavy-ion collisions with EPOS

    Emese Árpási🇭🇺 · Márton I. Nagy🇭🇺

    The purpose of femtoscopy is to unveil the space-time characteristics of heavy-ion collisions as mirrored in the correlation function of identical particles. We aim to augment such research by investigating the source function of particle creation based on a modern event generator, the EPOS package. It simulates high energy nuclear collisions and is proven to reliably reproduce the characteristics of real collisions. The source function has been almost always assumed to be Gaussian, but lately it is experimentally found that Lévy-stable distributions provide a much more acceptable description. This paper focuses on the source shape that is reconstructed in a femtoscopic measurement, in particular, the event-by-event geometry as well as the deviation from spherical symmetry of the source in the EPOS simulation. Such an investigation tests some scenarios of the appearance of non-Gaussian source functions. We find that in such a realistic simulation, non-Gaussian sources indeed appear, even in a three-dimensional setting and without event averaging. However, our reconstructed Lévy exponent (responsible for the long-range behavior of the source) is systematically larger than that observed in experiment; a discrepancy that might hint at further significance of this exponent.

    hep-phInt.J.Mod.Phys.A(2025)·1 citation
18. 18*

    Revisiting Universal Extra-Dimension Model with Gravity Mediated Decays

    Kirtiman Ghosh🇮🇳 · Katri Huitu🇫🇮 · Rameswar Sahu🇮🇳

    We explore the collider phenomenology of the fat-brane realization of the Minimal Universal Extra Dimension (mUED) model, where Standard Model (SM) fields propagate in a small extra dimension while gravity accesses additional large extra dimensions. This configuration allows for gravity-mediated decay (GMD) of Kaluza-Klein (KK) particles, resulting in unique final states with hard photons, jets, massive SM bosons, and large missing transverse energy due to invisible KK gravitons. We derive updated constraints on the model's parameter space by recasting ATLAS mono-photon, di-photon, and multi-jet search results using 139 inverse femtobern of integrated luminosity data. Recognizing that current LHC search strategies are tailored for supersymmetric scenarios and may not fully capture the distinct signatures, we propose optimized strategies using machine learning algorithms to tag boosted SM bosons and enhance signal discrimination against SM backgrounds. These methods improve sensitivity to fat-brane mUED signatures and offer promising prospects for probing this model in future LHC runs.

    hep-phJHEP(2025)·0 citations
19. 19*

    Effective Lagrangians and thermal resonances under extreme conditions

    Andrea Vioque Rodríguez🇪🇸 · Angel Gómez Nicola🇪🇸 · Jacobo Ruiz de Elvira🇪🇸

    We analyze various problems related to the physics of hadrons under extreme conditions of temperature and chemical potentials. On the one hand, we show that the thermal resonances $f_0(500)$ and $K_0^{\ast }(700)$, generated in the framework of Unitarized Chiral Perturbation Theory $\pi \pi$ and $K\pi$ scattering at finite temperature, play an essential role concerning chiral and $U(1{)}_A$ restoration. On the other hand, a low-energy effective Lagrangian has been constructed within ChPT at non-zero chemical potential, which we discuss here for an axial chemical potential.

    hep-phPoS(2025)·0 citations
20. 20*

    Non-$D\bar{D}$ Decays into Light Meson Pairs of the $D$-Wave Charmonium ${\psi }_3(3842)$

    Zi-Yue Bai🇨🇳 · Bao-Jun Lai🇨🇳 · Qin-Song Zou · Xiang Liu🇨🇳

    As a $D$-wave partner of $\psi (3770)$ identified by the LHCb Collaboration, ${\psi }_3(3842)$ lies between the $D\bar{D}$ and $D\overline{D^{\ast }}$ thresholds. Its non-$D\bar{D}$ decay channels have attracted considerable interest. In this study, we investigate these allowed non-$D\bar{D}$ decays of ${\psi }_3(3842)$ into $PP$, $PV$, and $VV$ final states using the hadronic loop mechanism, where $P$ and $V$ represent light pseudoscalar and vector mesons, respectively. Our results suggest that these non-$D\bar{D}$ decays of ${\psi }_3(3842)$ can be significant, with contributions primarily driven by hadronic loops. Notably, the $\rho \pi$ channel stands out as the main non-$D\bar{D}$ decay mode, while non-$D\bar{D}$ decay channels involving strange mesons are also sizable. These predictions could be tested in future experiments such as those at LHCb and BESIII.

    hep-phhep-exEPJC(2025)·3 citations
21. 21*

    Counting and building operators in theories with hidden symmetries and application to HEFT

    Rodrigo Alonso🇬🇧 · Shakeel Ur Rahaman🇬🇧

    Identifying a full basis of operators to a given order is key to the generality of Effective Field Theory (EFT) and is by now a problem of known solution in terms of the Hilbert series. The present work is concerned with hidden symmetry in general and Higgs EFT in particular and {\it(i)} connects the counting formula presented in [1] in the CCWZ formulation with the linear frame and makes this connection explicit in HEFT {\it (ii)} outlines the differences in perturbation theory in each frame {\it (iii)} presents a new counting formula with measure in the full $SU(3)\times SU(2)\times U(1)$ group for HEFT and {\it (iv)} provides a Mathematica code that produces the number of operators at the user-specified order in HEFT.

    hep-phhep-thJHEP(2025)·5 citations
22. 22*

    Majorana neutrino dipole moments and masses at a muon collider

    Michele Frigerio🇫🇷 · Natascia Vignaroli🇮🇹

    A future multi-TeV muon collider would provide an important probe for Majorana neutrinos. A muon collider with a collision energy of $\sim$30 TeV would be sensitive to ${\nu }_e-{\nu }_{\mu }$ transition dipole moments of the order of $\sim 10^{-12}{\mu }_B$ and would be thus competitive with the latest astrophysical observation and laboratory experiments. Contrary to the latter, the muon collider would have the unique advantage of a direct and clean identification of lepton number and flavour violation. This would establish the Majorana nature of the neutrino and would provide crucial complementary information on the neutrino properties in the event of a (near) future observation at low-energy experiments. Additionally, a muon collider would improve by orders of magnitude the direct bounds on the Majorana neutrino mass matrix entries $m_{e\mu }$ and $m_{\mu \mu }$.

    hep-phPoS(2025)·1 citation
23. 23*

    Gravitational ABJ Anomaly, Stochastic Matter Production, and Leptogenesis

    Azadeh Maleknejad🇬🇧

    Partially chiral stochastic gravitational wave backgrounds can arise from various processes in the early Universe. The gravitational ABJ anomaly links the chirality of the gravitational field to the chiral fermions, resulting in the stochastic generation of fermionic matter in the radiation era. We show that this mechanism can account for the entire dark matter relic density and discuss its potential as a leptogenesis scenario to explain the observed matter-antimatter asymmetry in the Universe. Remarkably, this letter reveals that even if gravitational waves become unpolarized later, their temporary chirality during their generation process leaves a lasting imprint on the fermionic matter, preserved as a quantum remnant.

    hep-phgr-qchep-thEPJC(2026)·7 citations
24. 24*

    Loss function to optimise signal significance in particle physics

    Jai Bardhan🇮🇳 · Cyrin Neeraj🇮🇳 · Subhadip Mitra🇮🇳 · Tanumoy Mandal🇮🇳

    We construct a surrogate loss to directly optimise the significance metric used in particle physics. We evaluate our loss function for a simple event classification task using a linear model and show that it produces decision boundaries that change according to the cross sections of the processes involved. We find that the models trained with the new loss have higher signal efficiency for similar values of estimated signal significance compared to ones trained with a cross-entropy loss, showing promise to improve sensitivity of particle physics searches at colliders.

    hep-phcs.LGhep-ex0 citations
25. 25*

    Higgs boson production in association with massive bottom quarks at NNLO+PS

    Christian Biello🇩🇪 · Javier Mazzitelli🇨🇭 · Aparna Sankar🇩🇪 · Marius Wiesemann🇩🇪 · Giulia Zanderighi🇩🇪

    We study the production of a Higgs boson in association with a bottom-quark pair ($b\bar{b}H$) at hadron colliders. Our calculation is performed in the four-flavour scheme with massive bottom quarks. This work presents the first computation of next-to-next-to-leading-order (NNLO) QCD corrections to this process, and we combine them with all-order radiative corrections from a parton shower simulation (NNLO+PS). The calculation is exact, except for the two-loop amplitude, which is evaluated in the small quark mass expansion, which is an excellent approximation for bottom quarks at LHC energies. For the NNLO+PS matching, we employ the MiNNLO${}_{\mathrm{PS}}$ method for heavy-quark plus colour-singlet production within the POWHEG framework. We present an extensive phenomenological analysis both at the inclusive level and considering bottom jets using flavour-tagging algorithms. By comparing four-flavour and five-flavour scheme predictions at NNLO+PS, we find that the NNLO corrections in the four-flavour scheme resolve the long-standing tension between the two schemes. Finally, we show that our NNLO+PS predictions also have important implications on modelling the $b\bar{b}H$ background in Higgs-pair measurements.

    hep-phhep-exJHEP(2025)·23 citations
26. 26*

    Interpolating amplitudes

    Víctor Bresó🇩🇪 · Gudrun Heinrich🇩🇪 · Vitaly Magerya🇨🇭 · Anton Olsson🇩🇪

    The calculation of scattering amplitudes at higher orders in perturbation theory has reached a high degree of maturity. However, their usage to produce physical predictions within Monte Carlo programs is often precluded by the slow evaluation of two- and higher-loop virtual amplitudes, particularly those calculated numerically. As a remedy, interpolation frameworks have been successfully used for amplitudes depending on up to two kinematic invariants. For amplitude interpolation with more variables, such as the five dimensions of a 2 -> 3 phase space, efficient and reliable solutions are sparse. This work aims to pave the way for using amplitude interpolation in higher-dimensional phase spaces by reviewing state-of-the-art interpolation methods, and assessing their performance on a selection of 2 -> 3 scattering amplitudes. Specifically, we investigate interpolation methods based on polynomials, splines, spatially adaptive sparse grids, and neural networks (multilayer perceptron and Lorentz-Equivariant Geometric Algebra Transformer), all under the constraint of limited obtainable data. Our additional aim is to motivate further studies of the interpolation of scattering amplitudes among both physicists and mathematicians.

    hep-phSciPost Phys.(2025)·24 citations
27. 27*

    Limits on dark matter, ultralight scalars, and cosmic neutrinos with gyroscope spin and precision clocks

    Sara Rufrano Aliberti🇮🇹 · Gaetano Lambiase🇮🇹 · Tanmay Kumar Poddar🇮🇹

    Dark matter (DM) within the solar system induces deviations in the geodetic drift of gyroscope spin due to its gravitational interaction. Assuming a constant DM density as a minimal scenario, we constrain DM overdensity within the Gravity Probe B (GP-B) orbit and project limits for Earth's and Neptune's orbits around the Sun. The presence of electrons in gravitating sources and test objects introduces a scalar-mediated Yukawa potential, which can be probed using terrestrial and space--based precision clocks. We derive projected DM overdensity $(\eta )$ limits from Sagnac time measurements using onboard satellite clocks, highlighting their dependence on the source mass and orbital radius. The strongest limit, $\eta \lesssim 4.45\times 10^3$, is achieved at Neptune's orbit ($\sim 30\mathrm{AU}$), exceeding existing constraints. Correspondingly, the cosmic neutrino overdensity is bounded as $\xi \lesssim 5.34\times 10^{10}$, surpassing results from KATRIN and cosmic ray studies. The best limit on electrophilic scalar coupling is $g\lesssim 7.09\times 10^{-24}$ for scalar mass $m_{\phi }\lesssim 1.32\times 10^{-18}\mathrm{eV}$ competitive with existing fifth-force bounds. These precision measurements offer a robust framework for testing gravity at solar system scales and probing DM in scenarios inaccessible to direct detection experiments.

    hep-phastro-ph.COgr-qcJCAP(2025)·11 citations
28. 28*

    Next-to-leading order evolution of structure functions without PDFs

    Tuomas Lappi🇫🇮 · Heikki Mäntysaari🇫🇮 · Hannu Paukkunen🇫🇮 · Mirja Tevio🇫🇮

    We formulate and numerically solve the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi~(DGLAP) evolution equations at next-to-leading order in perturbation theory directly for a basis of 6 physical, observable structure functions in deeply inelastic scattering. By expressing the evolution in the physical basis one evades the factorization scale and scheme dependence. Working in terms of observable quantities, rather than parametrizing and fitting unobservable parton distribution functions (PDFs), provides an unambiguous way to confront predictions of perturbative Quantum Chromodynamics with experimental measurements. We compare numerical results for the DGLAP evolution for structure functions in the physical basis to the conventional evolution with PDFs.

    hep-phEPJC(2025)·4 citations
29. 29*

    Probing a diffuse flux of axion-like particles from galactic supernovae with neutrino water Cherenkov detectors

    David Alonso-González🇪🇸 · David Cerdeño🇪🇸 · Marina Cermeño🇪🇸 · Andres D. Perez🇪🇸

    In this article, we claim that axion-like particles (ALPs) with MeV masses can be produced with semi-relativistic velocities in core-collapse supernovae (SNe), generating a diffuse galactic flux. We show that these ALPs can be detected in neutrino water Cherenkov detectors via $ap\to p\gamma$ interactions. Using Super-Kamiokande data, we derive new constraints on the ALP parameter space, excluding a region spanning one order of magnitude in the ALP-proton coupling above cooling bounds for ALP masses in the range of $1-70$~MeV and ALP-proton couplings between $\sim 2\times 10^{-5}-2\times 10^{-4}$. We show that the future Hyper-Kamiokande will be able to probe couplings as small as $\sim 10^{-5}$, considerably constraining the allowed region above SN 1987A cooling bounds.

    hep-phastro-ph.COPRD(2025)·18 citations
30. 30*

    Quantum stresses in the hydrogen atom

    Adam Freese🇺🇸

    Gravitational form factors are often interpreted as providing access to stresses inside hadrons, in particular through Fourier transforms of the form factors $D$ and $\bar{c}$. Some researchers, however, have expressed skepticism of this interpretation. I revisit the question, and argue that it is indeed appropriate to interpret these quantities as stress distributions. I consider the hydrogen atom's ground state as a familiar example, and use the pilot wave interpretation of quantum mechanics to give the distributions a clear meaning. A striking result is that $\bar{c}$ -- rather than $D$ -- quantifies the force law binding the system, which can be understood through Cauchy's first law of motion.

    hep-phnucl-thquant-phPRD(2025)·15 citations
31. 31*

    Renormalisation group evolution effects on global SMEFT analyses

    Riccardo Bartocci🇩🇪 · Anke Biekötter🇩🇪 · Tobias Hurth🇩🇪

    Global analyses in the Standard Model Effective Field Theory (SMEFT) framework serve as a tool to probe potential directions of new physics. To break degeneracies between the Wilson coefficients of the SMEFT, it is essential to combine observables from various experiments. Since different observables entering global fits may be measured at different energy scales, it becomes increasingly important to account for this fact through the renormalisation group evolution (RGE) of the Wilson coefficients. In this work, we investigate the effects of the RGE on a global SMEFT fit under the assumption of a $U(3{)}^5$ symmetry within the minimal flavour violation framework. We comment on the role of next-to-leading order SMEFT predictions for breaking potential degeneracies between Wilson coefficients arising as a result of RGE effects.

    hep-phJHEP(2025)·38 citations
32. 32*

    Higgs Potential from Instantons

    Hooman Davoudiasl🇺🇸 · Marvin Schnubel🇺🇸

    We propose that the Higgs potential, a key element in our understanding of Nature, is partially generated by the instantons of new confining dynamics, perhaps from a hidden sector. In this picture, while the Higgs itself is a fundamental field, it controls the strength of the non-perturbative interactions that give rise to its potential. We examine a simple setup in which this instanton contribution is augmented by a quartic term, which is sufficient for a realistic electroweak symmetry breaking mechanism. The minimum of the potential is given by the Lambert $W_0$ function, with these assumptions. We discuss the predictions of this model and how it may be tested through measurements of the Higgs self coupling. Given the connection with non-trivial dynamics, one may also consider the prospects of accessing hidden sector states at colliders; this seems to be typically challenging in our setup. Symmetry restoration in the early Universe in this scenario is briefly examined. We also comment on the possible connection of our general setup with recent work on the physics of field space end points.

    hep-phPRD(2025)·2 citations
33. 33*

    A comprehensive study of ALPs from $B$-decays

    Deepanshu Bisht🇮🇳 · Sabyasachi Chakraborty🇮🇳 · Atanu Samanta🇮🇳

    We present a comprehensive study of axion-like particles (ALPs) through flavor changing neutral current processes, such as $B\to Ka$ followed by $a\to \text{hadronic},\gamma \gamma ,{\mu }^{+}{\mu }^{-}$ channels. Our generic framework encompasses different ultraviolet scenarios similar to KSVZ, DFSZ and flavorful axions etc. Starting from the effective Lagrangian written at the high scale, we compute the anomalous dimension matrix, taking into account all one-loop and relevant two-loop contributions. The latter is most important for the KSVZ and heavy QCD axion scenarios. We recognized that such two-loop diagrams can have both ultraviolet (UV) and infrared (IR) divergences. We show explicitly that UV divergences cancel by inserting appropriate counterterms, which are new operators involving the axion field and required to be present at the UV itself, to renormalize the theory. On the other hand, the cancellation of IR divergences is subtle and demonstrated through matching with the effective theory at the electroweak scale. We also utilize chiral perturbation theory and vector meson dominance framework to compute the decay and branching fractions of the ALP pertaining to our framework. We find that for KSVZ-like scenario, axion decay constant, $f_a\lesssim 1$ TeV can be ruled out. The bound becomes stronger for the DFSZ and Flaxion-like models, reaching upto $10^4$ TeV and $10^6$ TeV, respectively. We also provide projections on the parameter space based on 3 ab${}^{-1}$ data from Belle II and 300 fb${}^{-1}$ data from LHCb.

    hep-phhep-exJHEP(2025)·15 citations
34. 34*

    Vector Portals at Future Lepton Colliders

    Sagar Airen🇺🇸 · Edward Broadberry🇺🇸 · Gustavo Marques-Tavares🇺🇸 · Lorenzo Ricci🇺🇸

    We assess the sensitivity of future lepton colliders to weakly coupled vector dark portals (aka ``$Z^{\prime }$ bosons'') with masses ranging from tens of GeV to a few TeV. Our analysis focuses on dark photons and $L_{\mu }-L_{\tau }$ gauge bosons. We consider both visible and invisible decay channels. We demonstrate that both high energy $\mu$ colliders and future $e^{+}{e}^{-}$ colliders, using the FCC-ee $Z$-pole and $ZH$ operation modes as a benchmark, offer significant improvements in sensitivity. We find that both colliders can enhance the sensitivity to $L_{\mu }-L_{\tau }$ bosons (for both visible and invisible decays) and to invisibly decaying dark photons by 1--2 orders of magnitude across the relevant mass range. Furthermore, we study the impact of forward $\mu$ detectors at the $\mu$-collider on the sensitivity to both models.

    hep-phJHEP(2025)·11 citations
35. 35*

    Bayesian evidence for two peaks in the sound speed in cold dense QCD

    Dake Zhou🇺🇸

    I show that in addition to the well-known peak inside massive neutron stars, the sound speed in cold dense QCD matter likely exhibits another peak above neutron star densities before it asymptotes to $c_s=\sqrt{C_s}=\sqrt{1/3}$. Based on the framework reported in arxiv:2408.16738, this approach does not rely on any assumption about the ultra-dense matter not realized in nature. Current multimessenger observation of neutron stars favors the two-peak scenario with a Bayes factor $5.1_{-0.7}^{+0.9}$, where the uncertainties are systematics due to models of neutron star inner cores. This evidence grows to $27_{-8}^{+11}$ if the $2.6M_{\odot }$ component of GW190814 is a neutron star. The trough in $C_s$ separating the two peaks is inferred to be below $0.05_{-0.02}^{+0.04}$ (at the $50\%$ level) if $2.6M_{\odot }$ neutron stars exist. The second peak above $1/3$ beyond baryon chemical potential ${\mu }_B=1.6-1.9$ GeV most likely signals non-perturbative effects in cold quark matter, for instance color superconductivity.

    ↳ nucl-thastro-ph.HEhep-phhep-th2 citations
36. 36*

    Do ${\Lambda }_{CC}$ and $G$ run?

    John F. Donoghue🇺🇸

    No. In this brief pedagogic note, I describe why the cosmological constant and Newton's constant are not running parameters in physical reactions.

    ↳ hep-thgr-qchep-phActa Phys.Polon.B(2025)·12 citations
37. 37*

    Non-minimally coupled quintessential inflation

    Seong Chan Park🇰🇷

    We present a unified framework that simultaneously addresses the dynamics of early-time cosmic inflation and late-time cosmic acceleration within the context of a single scalar field non-minimally coupled to gravity. By employing an exponential coupling function and a scalar potential with dual asymptotic plateaus, our model naturally transitions from inflationary dynamics at small field values to a quintessence-like behavior at large field values. We derive the inflationary predictions for the spectral index ($n_s$) and tensor-to-scalar ratio ($r$) in agreement with current observational constraints. For late-time acceleration, the model produces a viable dark energy component with an equation of state $w_{\varphi }$ approaching $-1$ but retaining a measurable deviation that could serve as an observational signature. This work demonstrates that a single theoretical framework can reconcile both early inflation and the late-time accelerated expansion of the Universe.

    ↳ gr-qchep-phhep-thPTEP(2025)·5 citations
38. 38*

    Chiral phase transition: effective field theory and holography

    Yanyan Bu🇨🇳 · Zexin Yang🇨🇳

    We consider the chiral phase transition relevant for QCD matter at finite temperature but with vanishing baryon density. Presumably, the chiral phase transition is of second order for two-flavor QCD in the chiral limit. Near the transition temperature, we apply the Schwinger-Keldysh formalism and construct a low-energy effective field theory for the system, in which fluctuations and dissipations are systematically captured. The dynamical variables involve the chiral charge densities and order parameter (chiral condensate). Via the holographic Schwinger-Keldysh technique, the effective action is further confirmed within a modified AdS/QCD model. With higher-order terms suitably neglected, the stochastic equations derived from the effective field theory resemble those of model F in the Hohenberg-Halperin classification. Within the effective field theory, we briefly discuss the spontaneous breaking of chiral symmetry and Goldstone modes.

    ↳ hep-thcond-mat.mes-hallhep-phnucl-thPRD(2025)·4 citations
39. 39*

    Grassmann tensor renormalization group for the massive Schwinger model with a $\theta$ term using staggered fermions

    Hayato Kanno🇺🇸 · Shinichiro Akiyama🇯🇵 · Kotaro Murakami🇯🇵 · Shinji Takeda🇯🇵

    We use the Grassmann tensor renormalization group method to investigate the $N_f=2$ Schwinger model with the staggered fermions in the presence of a $2\pi$ periodic $\theta$ term in a broad range of mass. The method allows us to deal with the massive staggered fermions straightforwardly and to study the $\theta$ dependence of the free energy and topological charge in the thermodynamic limit. Our calculation provides consistent results with not only the analytical solution in the large mass limit but also the previous Monte Carlo studies in the small mass regime. Our numerical results also suggest that the $N_f=2$ Schwinger model on a lattice has a different phase structure, than the model in the continuum limit.

    ↳ hep-lathep-phhep-thJHEP(2025)·11 citations
40. 40*

    Magnetic polarisability of octet baryons near the physical quark-mass point

    Thomas Kabelitz🇦🇺 · Waseem Kamleh🇦🇺 · Derek Leinweber🇦🇺

    The magnetic polarisabilities of octet baryons are calculated close to the physical quark-mass point using the background field method in lattice QCD. This first calculation draws on the identification and elimination of exceptional configurations that have hindered previous attempts. The origin of the exceptional configuration problem lies in the use of a Wilson-type fermion action on electro-quenched gauge field configurations, where the dynamical-fermion gauge-field generation algorithm the electric charges of the quarks. Changes in the fermion determinant that would suppress some gauge fields in the background magnetic field are neglected, leaving improbable gauge fields that generate large additive mass renormalisations which manifest as significant outliers in correlation-function distributions. An algorithm for the systematic identification and removal of these exceptional configurations is described. We find the light up and down quarks to be problematic, particularly the up quark with its larger electric charge. The heavier mass of the strange quark protects the hyperon correlation functions to some extent. However, these also benefit from the removal of exceptional configurations. In many cases, the magnetic polarisability is calculated with good precision. We find our results to be in accord with the behaviour anticipated by chiral perturbation theory.

    ↳ hep-lathep-phnucl-thPRD(2025)·0 citations
41. 41*

    A comprehensive numerical study on four categories of holographic dark energy models

    Jun-Xian Li🇨🇳 · Shuang Wang🇨🇳

    Holographic dark energy (HDE), which arises from a theoretical attempt to apply the holographic principle (HP) to the dark energy (DE) problem, has attracted significant attention over the past two decades. We perform a comprehensive numerical study on HDE models that can be classified into four categories: 1) HDE models with other characteristic length scale, 2) HDE models with extended Hubble scale, 3) HDE models with dark sector interaction, 4) HDE models with modified black hole entropy. For theoretical models, we select seven representative models, including the original HDE (OHDE) model, Ricci HDE (RDE) model, generalized Ricci HDE (GRDE) model, interacting HDE (IHDE1 and IHDE2) models, Tsallis HDE (THDE) model, and Barrow HDE (BHDE) model. For cosmological data, we use the Baryon Acoustic Oscillation (BAO) data from the Dark Energy Spectroscopic Instrument (DESI) 2024 measurements, the Cosmic Microwave Background (CMB) distance priors data from the Planck 2018, and the type Ia supernovae (SNe) data from the PantheonPlus compilation. Using ${\chi }^2$ statistic and Bayesian evidence, we compare these HDE models with current observational data. It is found that: 1) The $\Lambda$CDM remains the most competitive model, while the RDE model is ruled out. 2) HDE models with dark sector interaction perform the worst across the four categories, indicating that the interaction term is not favored under the framework of HDE. 3) The other three categories show comparable performance. The OHDE model performs better in the BAO+CMB dataset, and the HDE models with modified black hole entropy perform better in the BAO+CMB+SN dataset. 4) HDE models with the future event horizon exhibit significant discrepancies in parameter space across datasets. The BAO+CMB dataset favors a phantom-like HDE, whereas the BAO+CMB+SN leads to an equation of state (EoS) much closer to the cosmological constant.

    ↳ astro-ph.COgr-qchep-phJCAP(2025)·55 citations
42. 42*

    Topological data analysis of the deconfinement transition in SU(3) lattice gauge theory

    Daniel Spitz🇩🇪 · Julian M. Urban🇺🇸 · Jan M. Pawlowski🇩🇪

    We study the confining and deconfining phases of pure $\mathrm{SU}(3)$ lattice gauge theory with topological data analysis. This provides unique insights into long range correlations of field configurations across the confinement-deconfinement transition. Specifically, we analyze non-trivial structures in electric and magnetic field energy densities as well as Polyakov loop traces and a Polyakov loop-based variant of the topological density. The Betti curves for filtrations based on the electric and magnetic field energy densities reveal signals of electromagnetic dualities. These dualities can be associated with an interchange in the roles of local lumps of electric and magnetic energy densities around the phase transition. Moreover, we show that plaquette susceptibilities can manifest in the geometric features captured by the Betti curves. We also compare these findings against earlier results for $\mathrm{SU}(2)$ and elaborate on the significant differences. Our results demonstrate that topological data analysis can identify clear differences between phase transitions of first and second order for non-Abelian lattice gauge theories and provides unprecedented insights into the relevant structures in their vicinity.

    ↳ hep-latcond-mat.stat-mechhep-phhep-th+1PRD(2025)·4 citations
43. 43*

    Betwixt Annihilation and Decay: The Hidden Structure of Cosmological Stasis

    Jonah Barber🇺🇸 · Keith R. Dienes🇺🇸 · Brooks Thomas🇺🇸

    Stasis is a unique cosmological phenomenon in which the abundances of different energy components in the universe (such as matter, radiation, and vacuum energy) each remain fixed even though they scale differently under cosmological expansion. Moreover, extended epochs exhibiting stasis are generally cosmological attractors in many BSM settings and thus arise naturally and without fine-tuning. To date, stasis has been found within a number of very different BSM cosmologies. In some cases, stasis emerges from theories that contain large towers of decaying states (such as theories in extra dimensions or string theory). By contrast, in other cases, no towers of states are needed, and stasis instead emerges due to thermal effects involving particle annihilation rather than decay. In this paper, we study the dynamics of the energy flows in all of these theories during stasis, and find that these theories all share a common energy-flow structure which in some sense lies between particle decay and particle annihilation. This structure has been hidden until now but ultimately lies at the root of the stasis phenomenon, with all of the previous stases appearing as different manifestations of this common underlying structure. This insight not only allows us to understand the emergence of stasis in each of these different scenarios, but also provides an important guide for the potential future discovery of stasis in additional cosmological systems.

    ↳ astro-ph.COhep-phhep-thPRD(2025)·8 citations
44. 44*

    Constraining primordial black hole abundance with Insight-HXMT

    Chen Yang🇺🇸 · Jun-Da Pan🇺🇸 · Xin Zhang🇺🇸

    Primordial black holes (PBHs) are a major candidate for dark matter and they have been extensively constrained across most mass ranges. However, PBHs in the mass range of $10^{17}$ - $10^{21}$ g remain a viable explanation for all dark matter. In this work, we use observational data from the Hard X-ray Modulation Telescope (Insight-HXMT) to refine constraints on PBHs within the mass range of $2\times 10^{16}$ - $5\times 10^{17}$ g. Our analysis explores three scenarios: directly using observational data, incorporating the astrophysical background model (ABM), and employing the power-law spectrum with an exponential cutoff. Our results indicate that although Insight-HXMT does not have an advantage in the first two scenarios, when considering the power-law model, its exceptional sensitivity in the hard X-ray regime and sufficiently high upper energy limit significantly strengthen the constraints on PBHs with masses greater than $10^{17}$ g compared to previous limits. Furthermore, the exclusion limit for PBHs as dark matter has reached $4\times 10^{17}$ g, which is comparable to the current threshold.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phCommun.Theor.Phys.(2026)·5 citations
45. 45*

    Searching for New Physics in Ultradense Environment: a Review on Dark Matter Admixed Neutron Stars

    Francesco Grippa🇮🇹 · Gaetano Lambiase🇮🇹 · Tanmay Kumar Poddar🇮🇹

    Neutron Stars (NSs), among the densest objects in the Universe, are exceptional laboratories for investigating Dark Matter (DM) properties. Recent theoretical and observational developments have heightened interest in exploring the impact of DM on NS structure, giving rise to the concept of Dark Matter Admixed Neutron Stars (DANSs). This review examines how NSs can accumulate DM over time, potentially altering their fundamental properties. We explore leading models describing DM behavior within NSs, focusing on the effects of both bosonic and fermionic candidates on key features such as mass, radius, and tidal deformability. Additionally, we review how DM can modify the cooling and heating processes, trigger the formation of a black hole, and impact Gravitational Waves (GWs) emissions from binary systems. By synthesizing recent research, this work highlights how DANSs might produce observable signatures, offering new opportunities to probe DM properties through astrophysical phenomena.

    ↳ astro-ph.HEastro-ph.COgr-qchep-phUniverse(2025)·45 citations
46. 46*

    Extended Skyrme effective interactions with higher-order momentum-dependence for transport models and neutron stars

    Si-Pei Wang🇨🇳 · Xin Li🇨🇳 · Rui Wang🇮🇹 · Jun-Ting Ye🇨🇳 · Lie-Wen Chen🇨🇳

    The recently developed extended Skyrme effective interaction based on the so-called N3LO Skyrme pseudopotential is generalized to the general N$n$LO case by incorporating the derivative terms up to 2$n$th-order into the central term of the pseudopotential. The corresponding expressions of Hamiltonian density and single-nucleon potential are derived within the Hartree-Fock approximation under general nonequilibrium conditions. The inclusion of the higher-order derivative terms provides additional higher-order momentum dependence for the single-nucleon potential, and in particular, we find that the N5LO single-nucleon potential with momentum dependent terms up to $p^{10}$ can give a nice description for the empirical nucleon optical potential up to energy of $2$ GeV. At the same time, the density-dependent terms in the extended Skyrme effective interaction are extended correspondingly in the spirit of the Fermi momentum expansion, which allows highly flexible variation of density behavior for both the symmetric nuclear matter equation of state and the symmetry energy. Based on the Skyrme pseudopotential up to N3LO, N4LO and N5LO, we construct a series of interactions with the nucleon optical potential having different high-momentum behaviors and with the symmetry potentials featuring different linear isospin-splitting coefficients for nucleon effective mass, by which we study the properties of nuclear matter and neutron stars. Furthermore, within the lattice BUU transport model, some benchmark simulations with selected interactions are performed for the Au+Au collisions at a beam energy of $1.23$ GeV/nucleon, and the predicted collective flows for protons are found to nicely agree with the data measured by HADES collaboration.

    ↳ nucl-thastro-ph.HEhep-phnucl-exPRC(2025)·13 citations
47. 47*

    Bubble dynamics in a QCD-like phase diagram

    Yago Bea🇪🇸 · Mauro Giliberti🇮🇹 · David Mateos🇪🇸 · Mikel Sanchez-Garitaonandia🇫🇷 · Alexandre Serantes🇧🇪 · Miguel Zilhão🇵🇹

    A line of first-order phase transitions is conjectured in the phase diagram of Quantum Chromodynamics at non-zero baryon density. If this is the case, numerical simulations of neutron star mergers suggest that various regions of the stars may cross this line multiple times. This results in the nucleation of bubbles of the preferred phase, which subsequently expand and collide. The resulting gravitational wave spectrum is highly sensitively to the velocity of the bubble walls. We use holography to perform the first microscopic simulation of bubble dynamics in a theory that qualitatively mirrors the expected phase diagram of Quantum Chromodynamics. We determine the wall velocity in the metastable regions and we compare it to theoretical estimates. We discuss implications for gravitational wave production.

    ↳ hep-thhep-phJHEP(2026)·13 citations
48. 48*

    Effective temperatures of the QGP from thermal photon and dilepton production

    Olaf Massen🇳🇱 · Govert Nijs🇨🇭 · Mike Sas🇳🇱 · Wilke van der Schee🇨🇭 · Raimond Snellings🇳🇱

    Thermal electromagnetic radiation is emitted by the quark-gluon plasma (QGP) throughout its space-time evolution, with production rates that depend characteristically on the temperature. We study this temperature using thermal photons and dileptons using the Trajectum heavy ion code, which is constrained by Bayesian analysis. In addition we present the elliptic flow of both the thermal photons and thermal dileptons including systematic uncertainties corresponding to the model parameter uncertainty. We give a comprehensive overview of the resulting effective temperatures $T_{\mathrm{eff}}$, obtained from thermal photon transverse momentum and thermal dilepton invariant mass distributions, as well as the dependence of $T_{\mathrm{eff}}$ on various selection criteria of these probes. We conclude that the $T_{\mathrm{eff}}$ obtained from thermal photons is mostly insensitive to the temperature of the QGP with a value of $T_{\mathrm{eff}}\sim$ 250-300 MeV depending on their transverse momentum, almost independent of collision centrality. Thermal dileptons are much better probes of the QGP temperature as they do not suffer from a blue shift as their invariant mass is used, allowing for a more precise constraint of the QGP temperature during different stages of the evolution of the system. By applying selection criteria on the dilepton transverse momentum and the invariant mass we are able to extract fluid temperatures on average times ranging from late emission ($⟨\tau ⟩=5.6$fm$/c$) to very early emissions ($⟨\tau ⟩<1.0$fm$/c$). Furthermore, we show how these selection criteria can be used to map the elliptic flow of the system all throughout its evolution.

    ↳ nucl-thhep-phnucl-exEPJC(2025)·17 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.