Mon·Jan 19, 2026Monday·January 19, 2026

1. 01*

   Maximizing Returns: Optimizing Experimental Observables at the LHC

   Jeffrey Davis🇺🇸 · Andrei V. Gritsan🇺🇸 · Lucas S. Mandacaru Guerra🇺🇸 · Lucas Kang🇺🇸 · Michalis Panagiotou🇺🇸 · Jeffrey Roskes🇺🇸 · Mohit Srivastav🇺🇸

   We introduce a framework that integrates both analytical and machine-learning approaches for calculating observables optimal for EFT and broader applications at the LHC. A new metric for evaluating the performance of these approaches has been introduced. In addition, we demonstrate how the majority of relevant information can be effectively stored in a limited number of bins, allowing for efficient data analysis, data preservation, and global data combination, while also providing tools to achieve these benefits. A key feature of this approach is the reduction in the dimensionality of the observable information, which enhances both the effectiveness and practicality of the data analysis while maximizing gains within limited resources. These features have been demonstrated through simulated analyses of the Higgs boson production and decay processes at the LHC.

   hep-phhep-ex2 citations
2. 02*

   Topic Modeling in New Physics Detection

   Alexandre Alves🇧🇷 · Eduardo da Silva Almeida🇧🇷 · Douglas Roberto Pimentel

   In this work, we apply topic modeling to detect new physics in proton-proton collisions at the LHC in an unsupervised way. We investigate three new physics scenarios where fully leptonic $t\bar{t}\to b\bar{b}{\ell }^{+}{\ell }^{-}{\nu }_{\ell }{\bar{\nu }}_{\ell }$ is the main source of background without relying on jet substructure variables. We demonstrate that the algorithm remains effective even in this low-particle multiplicity framework, complementing jet tagging studies, where it is typically employed. Moreover, we demonstrate that the performance of topic modeling is competitive or even better than well-known outlier detectors, such as isolation forest and variational autoencoders, with moderate and high background pollution in almost all new physics scenarios considered.

   hep-phhep-ex1 citation
3. 03*

   The Sensitivity of Higgs Factories to Composite Higgs Models via Precision Measurements

   Kamal Maayergi🇺🇸 · Devin G. E. Walker🇺🇸 · Ora Cullen🇺🇸 · Michael E. Peskin🇺🇸

   We investigate the potential of precision Higgs factory measurements to discover signatures of a representative model of electroweak symmetry breaking in which the Higgs boson arises as a composite Nambu-Goldstone boson. In this model, as in other models of the ``Little Higgs" or Natural Composite Higgs type, the primary perturbations of the Standard Model come from effects of vectorlike top quark partners. We carry out an explicit calculation of the Higgs potential in this model. Applying phenomenological constraints, we are left with a 3-dimensional parameter space. We then present results from a complete scan of this parameter space. The region in which significant departures from the Standard Model predictions extends to models in which the lightest top quark partner has a mass above 3~TeV. Little Higgs models with such heavy top partners also predict significant deviations from the Standard Model in the top quark electroweak couplings, in particular, in the model studied here, in the $t_L$ coupling to the $Z$ boson.

   hep-phPRD(2026)·1 citation
4. 04*

   Spectral Signatures of Heavy Quarkonia in a Rotating and Anisotropic Quark-Gluon Plasma: A Holographic Study

   Xiang-Wei Shi🇨🇳 · Sheng-Qin Feng🇨🇳

   We investigate the in-medium spectral functions and effective masses of heavy quarkonia charmonium ($J/\Psi$) and bottomonium (${\rm Y}(1S)$) in a quark-gluon plasma (QGP) possessing both global rotation and spatial anisotropy. Using a gauge/gravity holographic model incorporating finite temperature, chemical potential, and warp factor, we compute the spectral signatures non-perturbatively. Our results show that both rotation and anisotropy enhance quarkonium dissociation, manifesting as peak suppression and width broadening in the spectral functions. Crucially, their effects are directional: anisotropy primarily dissociates longitudinally polarized states, while rotation more strongly disrupts transversely polarized ones. A competitive interplay exists: for small anisotropy, rotational effects dominate at high angular velocity, whereas for large anisotropy, anisotropy governs the dissociation regardless of rotation strength. Furthermore, rotation induces a non-monotonic temperature dependence in the transverse effective mass of $J/\Psi$, while strong anisotropy causes similar non-monotonicity in the longitudinal effective mass of $J/\Psi$. These findings reveal how the distinct symmetry breaking patterns induced by QGP rotation and anisotropy reshape the heavy quarkonium spectrum, providing new insights into polarization-dependent suppression in non-central heavy-ion collisions.

   hep-phPRD(2026)·0 citations
5. 05*

   Spectroscopy of $\rho$-meson in symmetric nuclear medium

   Anshu Gautam🇮🇳 · Tanisha🇮🇳 · Satyajit Puhan🇮🇳 · Arvind Kumar🇮🇳 · Harleen Dahiya🇮🇳

   In this work, we investigate the behavior of the light vector \(\rho\) meson in the presence of a symmetric nuclear medium at zero temperature. We calculate the mass and decay constant of the $\rho$-meson as well as the leading twist distribution amplitudes (DAs) in the light-front quark model in vacuum, which are further investigated at different baryonic densities. We also predict the Mellin moments of the DAs and decay width of the ${\rho }^0\to e^{+}{e}^{-}$ process in both vacuum and medium. The evolution of DAs is carried out by the leading order (LO) Efremov-Radyushkin-Brodsky-Lepage method and compared with available predictions. For better understanding of medium effects on $\rho$-meson, we have also predicted the in-medium charge ($G_C(Q^2)$), magnetic ($G_M(Q^2)$), and quadrupole ($G_Q(Q^2)$) form factors. The in-medium charge radii, magnetic moment, and quadrupole moment have also been predicted in this work. We have found that the nuclear medium induces appreciable modifications on the mass, weak decay constant, decay width, and distribution amplitudes of the \(\rho\) meson. However, the charge radii, magnetic moment, and quadrupole moment are observed to exhibit weaker sensitivity to changes in baryonic density.

   hep-phPRD(2026)·2 citations
6. 06*

   The properties of strange quark matter and evolution of strange quark stars

   Huai-Min Chen🇨🇳 · Cheng-Jun Xia🇨🇳 · Guang-Xiong Peng🇨🇳

   In this work, we study the properties of strange quark matter and reveal the evolution process of strange quark stars employing a self consistent thermodynamic treatment. A comprehensive and reliable thermodynamic basis for the study of the dynamic evolution from proto-strange quark stars to stable strange stars at a zero temperature is provided. The relative abundance of particles, equation of state, temperature, and mass-radius relationship at each stage of the evolution of stars are discussed, where the cold strange quark star are consistent with the observational mass and radius of Hess J1731-347, PSR J1231-1411, PSR J0030+0451, PSR J0348+0432, and PSR J0740+6620, which could be difficult to be explained by the standard neutron star model. A schematic diagram is provided as well, illustrating the state of different stages along the evolution of stars at a fixed baryon-mass.

   hep-ph2 citations
7. 07*

   Elliptic flow of charm quarks produced in the early stage of pA collisions

   Gabriele Parisi🇮🇹 · Fabrizio Murgana🇫🇷 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹

   We investigate the build-up of elliptic flow of charm quarks produced in the early pre-equilibrium stage of high-energy proton--nucleus collisions. The initial stage is modeled within the Color Glass Condensate framework as an evolving glasma, initialized through the McLerran--Venugopalan model. Subnucleonic fluctuations have been implemented as constituent-quark hotspots for both the proton and the nuclear participants. Charm quarks are propagated in the evolving non-Abelian background by solving the relativistic Wong equations for their coordinates, momenta, and color charges. First, we compute the nuclear modification factor of charm quarks, finding a slight migration towards higher $p_T$ states in agreement with previous results in the literature. Then, we focus on the azimuthal anisotropies acquired through the interaction with glasma fields. We find that glasma-induced momentum anisotropies are efficiently transmitted to heavy quarks within $\tau \sim 0.4fm/c$, leading to a sizeable charm-quark $v_2$, with a magnitude that increases with the strength of the initial fields and with the number of nuclear participants. Remarkably, we show that the early-stage contribution alone can account for a significant fraction of the experimentally observed $J/\psi$ elliptic flow in p-Pb collisions, indicating that pre-hydrodynamic dynamics can play a non-negligible role in the final-state heavy-flavor collectivity, especially in small systems.

   hep-phnucl-thPRD(2026)·1 citation
8. 08*

   HL-LHC sensitivity to an ultraheavy $S_{uu}$ diquark in the $u\chi$ channel

   Matei S. Filip🇷🇴 · Calin Alexa🇷🇴 · Daniel C. Costache🇷🇴 · Ioan M. Dinu🇷🇴 · Ioana Duminica🇷🇴 · Gabriel C. Majeri🇷🇴

   We study the HL-LHC sensitivity to an ultraheavy diquark $S_{uu}$ produced in up-quark fusion and decaying as $S_{uu}\to u\chi$, $\chi \to Wb,Zt,h^{0}t$. For fully hadronic decays of the W, Z and top quark, this gives rise to multijet final states. Within the same model framework used previously for the $S_{uu}\to \chi \chi$ six-jet channel, we consider $S_{uu}$ masses in the multi-TeV range and vectorlike quark masses of order a few TeV, and simulate proton-proton collisions at $\sqrt{s}=13.6$ TeV with integrated luminosities up to the HL-LHC target. The analysis strategy employs a machine-learning-based discriminant adapted from the six-jet study to the new four-jet topology, which we use to derive the corresponding discovery reaches and exclusion limits. We find that this topology improves the overall sensitivity to $S_{uu}$ in regions where the branching ratio $B(S_{uu}\to u\chi )$ is sizable and provides a complementary signature for studying ultraheavy diquarks at the HL-LHC.

   hep-phhep-ex2 citations
9. 09*

   BabaYaga@NLO at present and future $e^{+}{e}^{-}$ colliders. Celebrating 25 years of BabaYaga

   Francesco P. Ucci🇮🇹

   Precise QED radiative corrections for low- and high-energy electron-positron colliders are essential for accurate simulations of luminosity processes and precision tests of the Standard Model. We review the historical formulation and the recent developments of the BabaYaga@NLO event generator, which implements a QED Parton Shower matched with fixed-order calculations. We discuss the theoretical formulation of the code, as well as the assessment of its theoretical accuracy. Applications at low- and high-energy $e^{+}{e}^{-}$ colliders are presented, including latest result, together with the perspectives for future improvements, in view of the demanding precision requirements of future machines at the intensity frontier.

   hep-phActa Phys.Polon.Supp.(2026)·0 citations
10. 10*

    Suppression of the jet quenching parameter near the critical temperature

    Haibo Ren🇨🇳 · Qianqian Du🇨🇳 · Yun Guo🇨🇳

    In this work, we study the jet quenching parameter $\hat{q}$ by using a background field effective theory. Particular attention is paid to its behavior near the critical temperature where nonperturbative effects induced by the deconfining phase transition are taken into account through a self-consistently introduced background field $\mathcal{Q}$. We adopt a theoretical approach in which the interaction rate between the energetic jet and medium partons is computed diagrammatically and the hard-thermal-loop resummed propagator is used to regulate the infrared divergence. In the presence of a background field, its influence on the jet quenching parameter manifests in two aspects. One is the modification on the screening mass in the resummed propagator, which leads to an enhanced $\hat{q}$. The other corresponds to the $\mathcal{Q}$-modified parton distribution function which is dominant and leads to a suppression of $\hat{q}$. Decreasing the temperature $T$, our result shows a nonmonotonic $T$ dependence of the dimensionless $\hat{q}/T^3$. In the high temperature region, $\hat{q}/T^3$ shows an increase with decreasing $T$ due to the running coupling effect. Near the critical temperature, the background field plays a significant role and a dramatic suppression of $\hat{q}/T^3$ is found which qualitatively agrees with the lattice simulation. In addition, the background field modification on the jet quenching parameter which is characterized by the $\hat{q}$ ratio can be simply parametrized by a polynomial expression depending only on the background field. This expression is expected to be useful for phenomenological applications in jet physics.

    hep-phPRD(2026)·3 citations
11. 11*

    Hadronic tau decays at higher orders in QCD

    Gauhar Abbas🇮🇳 · Vartika Singh🇮🇳

    We investigate higher-order perturbative corrections to hadronic $\tau$ decays by applying nonlinear sequence-transformation techniques to the QCD correction ${\delta }^{(0)}$. In particular, we employ the Shanks transformation and several of its generalisations constructed through Wynn's $\epsilon$-algorithm, which are known to accelerate the convergence of slowly convergent or divergent series. These methods are used to extract higher-order information from the fixed-order perturbative expansion of ${\delta }^{(0)}$. Within this framework, we estimate the perturbative coefficients $c_{5,1}$-$c_{12,1}$. In particular, we obtain $c_{5,1}=298\pm 15$, $c_{6,1}=3431\pm 256$, and $c_{7,1}=2.29\pm 0.29\times 10^4$, where the quoted uncertainties reflect the spread among the different sequence transformations employed. Moreover, we predict the QCD correction ${\delta }_{\text{FOPT}}^{(0)}=0.2119\pm 0.0040\pm 0.0065_{{\alpha }_s}$. Our analysis demonstrates that non-linear sequence transformations, such as the Shanks-type, provide an efficient and systematic tool for probing higher-order perturbative effects in hadronic $\tau$ decays in the absence of explicit multi-loop calculations.

    hep-phhep-ex1 citation
12. 12*

    Projections of H$\to \tau \tau$ cross-section at FCC-ee

    Sofia Giappichini🇩🇪 · Markus Klute🇩🇪 · Matteo Presilla🇩🇪 · Xunwu Zuo🇩🇪 · Maria Cepeda🇪🇸

    The Future Circular Collider (FCC) stands at the forefront of the European Strategy for Particle Physics as the future flagship project at CERN. The H$\to \tau \tau$ decay, featuring a large branching ratio, clean identification in the FCC-ee environment, and the possibility to reconstruct polarization information, is an excellent channel to measure Higgs boson properties. This work shows the expected precision for the H$\to \tau \tau$ cross-section measurement at the FCC-ee in the ZH production mechanism at $\sqrt{s}=$240 GeV and $\sqrt{s}=$365 GeV, as well as via the vector boson fusion process at $\sqrt{s}=$365 GeV. Furthermore, we explore and evaluate a set of methods for reconstructing tau decays. These techniques are critical for unlocking the full physics potential of the FCC-ee and for improving the understanding of tau-related observables in both Standard Model measurements and New Physics searches. The results obtained significantly enhance the FCC-ee outlook in the H$\to \tau \tau$ channel, improving it by at least an order of magnitude compared to the current sensitivity of measurements' performance at the LHC.

    hep-phEPJC(2026)·2 citations
13. 13*

    Energy levels of multiscale bound states from QED energy-momentum trace

    Michael I. Eides🇺🇸 · Vladimir A. Yerokhin🇩🇪

    Energy levels of QED bound states, which depend on a number of independent mass parameters, can be calculated as matrix elements of the QED energy-momentum tensor trace. As an example of such system we consider muonic hydrogen. The leading one-loop corrections to its energy levels depend on the electron and muon masses. These corrections are calculated as matrix elements of the energy-momentum tensor trace. Respective one-loop trace diagrams are different from the standard Lamb shift diagrams. We explain analytically and diagrammatically why two different sets of diagrams lead to the same results. Similar relationships should also hold beyond the one-loop approximation.

    hep-phphysics.atom-phPRD(2026)·0 citations
14. 14*

    Globally Optimal Contour Deformations with Neural Networks

    Stephen Jones🇬🇧 · Daniel Maître🇬🇧 · Anton Olsson🇬🇧

    In this article, we explore the use of contour deformation for the numerical evaluation of Feynman integrals after sector decomposition. In existing codes, the contour of integration is determined heuristically for each phase-space point by sampling the integrand. In this work, we introduce a method for choosing the contour deformation for an entire phase-space region using only an initial sampling or training step. We demonstrate that the resulting integrand has a lower variance than that obtained with heuristic methods and show that optimising a contour to reduce the estimated error of a Quasi-Monte Carlo sample is an ill-defined problem. The a priori knowledge of the integration path obtained in this work can be used to improve the speed of conventional integration methods or be leveraged for integration using neural networks, where, crucially, it removes the need to retrain the neural network for each phase-space point. The techniques described in this work can be adapted to other problems where a non-trivial integration path has to be chosen subject to a set of constraints.

    hep-ph2 citations
15. 15*

    Gravitational Baryogenesis from Entropy Production and Parity Violation: A Unified Framework

    Yakov Mandel

    We present a unified framework for gravitational baryogenesis combining two mechanisms: (i) an entropy-clock source that generates a sign-definite baryon chemical potential mu_B proportional to d ln S/dt during irreversible entropy production, and (ii) CP violation from a gravitational theta term theta R Rtilde analogous to the QCD vacuum angle. The entropy-clock evades adiabatic cancellation that suppresses purely oscillatory chemical potentials under smooth freeze-out; we quantify this with a universal low-pass transfer function F(x)=1/sqrt(1+x^2), where x=omega*tau_off. A minimal UV completion via a dilaton coupled to the conformal anomaly yields the entropy-clock coupling with decay constant f_sigma ~ 10^17-10^18 GeV. The theta term provides CP violation through interference between topologically distinct gravitational configurations; we estimate an instanton suppression factor kappa_inst ~ 10^-2-10^-1. The combined mechanism predicts Y_B ~ c*kappa*Pi_eff*epsilon_eff, linking the baryon asymmetry to the reheating temperature, the theta angle, and the entropy-production history. For Loop Quantum Cosmology bounces we derive an analytic expression for the circular polarization of the stochastic gravitational-wave background, with |Pi| ~ pi*|theta| for horizon-crossing modes, potentially testable by future space-based detectors.

    hep-phgr-qc2 citations
16. 16*

    Probing super-heavy dark matter with ultra-high-energy gamma rays

    Marco Chianese🇮🇹 · Ninetta Saviano🇮🇹 · Sara Cesare🇮🇹 · Vincenzo M. Grieco🇮🇹 · Valentina Nasti🇮🇹 · Francesca Spinnato🇮🇹 · Alessandro Tiano🇮🇹

    We refine the constraints on the lifetime of decaying super-heavy dark matter particles (SHDM), with masses ranging from $10^7$ to $10^{15}$ GeV, by analyzing ultra-high-energy (UHE) gamma-ray data. Our approach involves an accurate comparison of the primary gamma-ray emissions resulting from prompt SHDM decays in the galactic halo with the most recent upper limits on isotropic UHE gamma-ray fluxes provided by various extensive air shower experiments. We demonstrate that a precise consideration of the field of view and the geometric acceptance of different UHE gamma-ray observatories has significant implications for the inferred limits of dark matter lifetime. In addition, we examine the influence of uncertainties linked to the current models of the galactic dark matter distribution, employing diverse halo density profiles while varying both their radial extent and the local dark matter density. Our findings indicate that the newly established UHE gamma-ray constraints are marginally less stringent than earlier evaluations, thereby revisiting the SHDM parameter space and allowing for observable neutrino fluxes.

    hep-phastro-ph.COastro-ph.HE4 citations
17. 17*

    Bayesian optimisation for Bayesian evidence (BOBE) -- a fast and efficient likelihood emulator for model selection

    Nathan Cohen · Jan Hamann🇦🇺 · Ameek Malhotra

    The formalism of Bayesian model selection provides a very elegant way of ranking different physical models in terms of how compatible they are with a given set of observed data. However, its practical application is often hampered by the challenge of having to compute the Bayesian evidence - a multi-dimensional integral over the product of likelihood and prior probability. This usually necessitates a large number of function calls to the likelihood, which may become prohibitive in case of "slow", costly to evaluate likelihoods. A possible solution to this problem lies in approximating the slow full likelihood by a fast emulated likelihood. In this paper, we introduce BOBE (Bayesian Optimisation for Bayesian Evidence), a method to construct a Gaussian Process Regression (GPR)-based emulator. BOBE utilises a Bayesian Optimisation algorithm designed specifically to (i) provide a realistic estimate of the emulator's uncertainty and its impact on the evidence calculation, and (ii) minimise the number of likelihood evaluations required in order to meet a given evidence accuracy goal. We apply it to a number of toy examples as well as actual cosmological likelihoods, and demonstrate that training the emulator to a sufficient accuracy takes a factor of $O(10^3)$ fewer direct likelihood evaluations than would be needed if one were to directly compute the evidence integral via nested sampling. BOBE's overhead is independent of the likelihood computation time $t_L$, making it particularly useful for "expensive" likelihoods with $t_L\gtrsim 1$~s. BOBE is written in Python, supports MPI parallelisation, takes advantage of automatic differentiation and just-in-time-compilation provided by JAX, can straightforwardly be implemented with cosmological data analysis frameworks such as Cobaya, and is available for download from https://github.com/Ameek94/BOBE.

    ↳ astro-ph.COgr-qchep-phJCAP(2026)·2 citations
18. 18*

    Fine-tunings in radiative $\alpha$-particle capture on ${}^{12}$C at astrophysical energies

    Ulf-G. Meißner🇩🇪 · Bernard Ch. Metsch🇩🇪 · Helen Meyer🇩🇪

    We investigate the fine-tuning of radiative alpha-particle capture on carbon, $\alpha {(}^{12}\mathrm{C}{,}^{16}\mathrm{O})\gamma$, at astrophysical energies. Utilizing results from cluster effective field theory for this reaction, we find that the low-energy data of the astrophysical S-factor allow for only very small variations in the electromagnetic fine-structure constant $\alpha$, namely $|\delta \alpha /\alpha |\le 0.2$ per mille, in both the $E1$ and the $E2$ radiative capture.

    ↳ nucl-thastro-ph.SRhep-phhep-thCommun.Theor.Phys.(2026)·0 citations
19. 19*

    Light Dark Matter Search with 7.8 Tonne-Year of Ionization-Only Data in XENONnT

    E. Aprile🇺🇸 · J. Aalbers🇳🇱 · K. Abe🇯🇵 · M. Adrover🇨🇭 · S. Ahmed Maouloud🇫🇷 · L. Althueser🇩🇪 · B. Andrieu🇫🇷 · E. Angelino🇮🇹 · D. Antón Martin🇺🇸 · S. R. Armbruster🇩🇪 · F. Arneodo🇦🇪 · L. Baudis🇨🇭 and 165 other authors

    We report on a blinded search for dark matter (DM) using ionization-only (S2-only) signals in XENONnT with a total exposure of $7.83\mathrm{tonne}\times \mathrm{year}$ over 579 days in three science runs. Dedicated background suppression techniques and the first complete S2-only background model in XENONnT provide sensitivity to nuclear recoils of [0.5, 5.0] $\mathrm{ke}{\mathrm{V}}_{\mathrm{nr}}$ and electronic recoils of [0.04, 0.7] $\mathrm{ke}{\mathrm{V}}_{\mathrm{ee}}$. No significant excess over the expected background is observed, and we set 90\% confidence level upper limits on spin-independent DM--nucleon and spin-dependent DM--neutron scattering for DM masses between 3 and 8 $\mathrm{GeV}/c^2$, as well as on DM--electron scattering, axion-like particles, and dark photons, improving on previous constraints. For spin-independent DM--nucleon scattering, we exclude cross sections above $6.0\times 10^{-45}$cm${}^2$ at a DM mass of 5 $\mathrm{GeV}/c^2$, pushing the XENONnT sensitivity closer to the region where coherent elastic neutrino-nucleus scattering ($\text{CE}\nu \text{NS}$) becomes an irreducible background.

    ↳ hep-exastro-ph.COastro-ph.IMhep-ph+1PRL(2026)·19 citations
20. 20*

    Constraining the inflaton potential with gravitational waves from oscillons

    Kaloian D. Lozanov🇧🇬 · Misao Sasaki🇯🇵 · Jan Tränkle🇩🇪

    Under certain conditions, the oscillating inflaton condensate filling the Universe after inflation can fragment and form so-called oscillons. These long-lived soliton-like field configurations can dominate the Universe for several $e$-folds of expansion, leading to an early matter-dominated phase preceding the standard radiation era. In this paper we show how the rapid final decay of the oscillons leads to an enhanced production of induced gravitational waves, whose energy density can saturate the observational bound on the effective number of relativistic species. We leverage this bound to constrain the inflaton mass, cubic, and quartic self-coupling in generic models that admit oscillon formation, providing novel and complementary constraints in regions of parameter space that are inaccessible with cosmic microwave background observations alone.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·4 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.