Fri·Oct 10, 2025Friday·October 10, 2025

1. 01*

   Sterile neutrino dark matter from a TeV Scale Seesaw

   Kunal Pandey🇮🇳 · Suhail Khan🇮🇳

   In this article, we investigate the phenomenological aspects of a feebly interacting sterile neutrino dark matter candidate within a low-scale seesaw framework. The Type-I seesaw model is augmented by a second complex scalar doublet (${\Phi }_{\nu }$), which couples exclusively to the heavy right-handed neutrinos and the lepton doublet, thereby generating the neutrino Dirac mass term while the first scalar doublet is responsible for giving mass to the remaining Standard Model particles. The lightest sterile neutrino ($N_1$) acts as a feebly interacting massive particle (FIMP), produced via decays of $W^{\pm }$, $Z$ and extra scalars present in the setup. We point out that $W^{\pm }$ and $Z$ contributions were overlooked in the previous studies, which actually dominate the $N_1$ production by a factor of $\sim 10^{13}$ and solely determines the relic abundance. Incorporating them leads to several novel consequences for the DM phenomenology like a new non-thermal condition which leads to smaller Yukawa couplings. We thoroughly discuss about the enhancement possibilities of $N_1$'s mass which is controlled by the small vacuum expectation value ($v_{\nu }$) of the second Higgs doublet. After incorporating the latest Lyman-$\alpha$ forest observations, this setup can accommodate both warm and cold dark matter scenarios.

   hep-phastro-ph.COPRD(2025)·1 citation
2. 02*

   Charged scalar bosons under rotation and acceleration

   M. Bordag🇷🇺 · D. N. Voskresensky🇷🇺

   Creation of charged spinless bosons from vacuum in the rigidly rotating frame is studied in presence of the external static electromagnetic fields, being formed either in the resting, or in the general rotating or in the local-flat frames. It is shown that the description remains the same in the resting and the local-flat frames. More specifically, the case of a solenoid (magnetic flux tube) embedded into the rotating empty cylinder (rotation frame) is studied in presence or absence of a static square electric potential well $e{A}_0$. A supervortex of a spinless-boson field can be created from vacuum when the rotation frequency exceeds a critical value ${\Omega }_c$. It is shown that ${\Omega }_c$ is smaller provided the solenoid rests in the resting frame. Then the case is considered when the rotating frame additionally moves with acceleration $\vec{w}(\vec{r})\ne 0$. A specific case $w(r)=G/r$ for $G=const$ is treated explicitly. It is shown that for $G<0$ the charged spinless-boson vortex can be created in rapidly rotating system even in the limit when the magnetic and electric fields tend to zero.

   hep-phcond-mat.quant-gasnucl-thPhys.Part.Nucl.Lett.(2026)·2 citations
3. 03*

   Simulation-based inference for neutrino interaction model parameter tuning

   Karla Tame-Narvaez🇺🇸 · Aleksandra Ćiprijanović🇺🇸 · Steven Gardiner🇺🇸 · Giuseppe Cerati🇺🇸

   High-energy physics experiments studying neutrinos rely heavily on simulations of their interactions with atomic nuclei. Limitations in the theoretical understanding of these interactions typically necessitate ad hoc tuning of simulation model parameters to data. Traditional tuning methods for neutrino experiments have largely relied on simple algorithms for numerical optimization. While adequate for the modest goals of initial efforts, the complexity of future neutrino tuning campaigns is expected to increase substantially, and new approaches will be needed to make progress. In this paper, we examine the application of simulation-based inference (SBI) to the neutrino interaction model tuning for the first time. Using a previous tuning study performed by the MicroBooNE experiment as a test case, we find that our SBI algorithm can correctly infer the tuned parameter values when confronted with a mock data set generated according to the MicroBooNE procedure. This initial proof-of-principle illustrates a promising new technique for next-generation simulation tuning campaigns for the neutrino experimental community.

   hep-ph2 citations
4. 04*

   Apparent Lorentz violation from disformally coupled ultralight dark matter

   Guillem Domènech🇩🇪 · Apostolos Tsabodimos🇩🇪 · Nathaniel Sherrill🇩🇪 · Alexander Ganz🇩🇪 · Fiona Kirk🇩🇪

   We study the impact of general disformal metric transformations on fermions, which shift the gravitational metric by an additional rank-2 tensor. This tensor can in principle be constructed from scalar-field gradients, vector fields, or field-strength contractions. We show this transformation results in the conventional Dirac action being modified by additional kinetic and axial-current couplings that are quadratic in the shifted field. When the field sourcing the metric shift takes on a non-trivial background value, apparent Lorentz-violating effects can result, which we identify as terms in an effective field theory. Assuming the well-motivated cases of scalar and vector ultralight dark matter, we demonstrate that experimental tests of rotation and boost violation imply constraints on the additional kinetic coupling. Even under conservative assumptions, the constraints for vector ultralight dark matter are extremely stringent.

   hep-phgr-qcPRD(2026)·2 citations
5. 05*

   The rare decays $h^0\to Z\gamma ,VZ$ in the NB-LSSM

   Xing-Xing Dong🇨🇳 · Cai Guo🇨🇳 · Wen Lu🇨🇳 · Shu-Min Zhao🇨🇳 · Tai-Fu Feng🇨🇳

   This study investigates the Higgs rare decays $h^0\to Z\gamma ,VZ$ within the next to minimum B-L supersymmetric model(NB-LSSM), where $V$ represents a vector meson $(\varphi ,J/\psi ,{\rm Y}(1S),{\rho }^0,\omega )$. Compared to the minimal supersymmetric standard model(MSSM), the NB-LSSM introduces three singlet Higgs superfields, which mix with the Higgs doublets and affect the lightest Higgs boson mass and the Higgs couplings. The loop-induced contributions resulting from the effective $h^{0}Z\gamma$ coupling can produce new physics(NP) contributions, thereby affecting the theoretical predictions of rare decays significantly through the new parameters such as $\kappa$, $\lambda$, ${\lambda }_2\cdot \cdot \cdot$. The results of this work can provide a reference for probing NP beyond standard model(SM).

   hep-phNPB(2026)·0 citations
6. 06*

   Multiplicity dependence of ${\rm Y}$(nS) mean transverse momentum in proton-proton collisions

   Luis Gabriel Gallegos Mariñez🇲🇽 · Lizardo Valencia Palomo🇲🇽 · Luis Cedillo Barrera🇲🇽

   Correct description of quarkonia production and kinematics are still one of the most challenging assignments for Quantum Chromodynamics. This document presents a study of the ${\rm Y}$(1S), (2S) and (3S) mean transverse momentum ($⟨p_{\mathrm{T}}^{{\rm Y}}⟩$) as a function of the charged particle multiplicity ($N_{\mathrm{Track}}$) in proton-proton collisions at $\sqrt{s}$ = 7 TeV generated with Pythia 8.312 CUETP8M1 tune. The comparison to real data collected by the CMS experiment indicates that the agreement is much better for the excited states than for the ground state. The observed fast increase of the $⟨p_{\mathrm{T}}^{{\rm Y}}⟩$ at small values of $N_{\mathrm{Track}}$ is mainly due to the contribution from the away region. Furthermore, when computing the $⟨p_{\mathrm{T}}^{{\rm Y}}⟩$ from jetty and isotropic events a clear $p_{\mathrm{T}}$ hardening is observed in jetty events. Finally, analyzing the fragmentation of jets containing an ${\rm Y}$(nS) it is proposed a method to test the new quarkonia shower present in the Monte Carlo event generator.

   hep-phUniverse(2026)·0 citations
7. 07*

   The low-lying light tetraquark states with quantum numbers $J^P=0^{+}$, $1^{+}$ and $2^{+}$

   Hao Wu🇨🇳 · Mao-Jun Yan🇨🇳 · Chun-Sheng An🇨🇳 · Cheng-Rong Deng🇨🇳

   The low-lying light tetraquark states are investigated in the non-relativistic quark model (NRQM) including the pseudoscalar meson exchange, where two different confinement potential schemes, the Cornell potential and the linear potential, are employed, along with the instanton-induced interaction serving as the residual spin-dependent interaction. The numerical results show agreement with masses of $f_0(500)$, $f_0(1370)$, $f_0(1500)$, $f_0(2020)$, $f_0(2200)$, $h_1(1170)$, $h_1(1595)$, $h_1(1900)$, $h_1(1965)$, $h_1(2215)$, $f_2(1430)$, $f_2(1640)$, $f_2(1810)$, $f_2(2010)$, $f_2(2150)$, $a_0(980)$, $a_0(1450)$, $a_0(1950)$, $a_1(1260)$, $a_1(1640)$, $a_2(1700)$, $K_0^{\ast }(1430)$, $K_0^{\ast }(1950)$, $K_1(1270)$, $K_1(1440)$, $K_1(1650)$, and $K_2^{\ast }(1980)$. The results shed light on the spectrum of these mesons and offer guidande to search for the tetraquarks in the future.

   hep-phPRD(2025)·2 citations
8. 08*

   Emission of Nambu-Goldstone bosons from the semilocal string network

   Yukihiro Kanda🇯🇵 · Naoya Kitajima🇯🇵

   Semilocal cosmic string is a line-like non-topological soliton associated with the breakdown of the $SU(2{)}_{\mathrm{global}}\times U(1{)}_{\mathrm{gauge}}$ symmetry to the $U(1{)}_{\mathrm{global}}$ symmetry. The broken phase has two massless Nambu-Goldstone (NG) modes as dynamical fields, and they can be emitted by semilocal strings. In this paper, we numerically show that such NG bosons are copiously produced with the evolution of the semilocal string network in the early universe. Our numerical analysis shows that the spectrum of produced particles has a peak at low momenta corresponding to the horizon scale. If the emitted NG bosons acquire mass due to soft-breaking terms, they can take the role of dark matter. This scenario typically predicts very light pseudo NG boson dark matter.

   hep-phastro-ph.COhep-thPLB(2026)·2 citations
9. 09*

   Atomic Observables Induced by Cosmic Fields

   Sebastian Lahs🇫🇷 · Daniel Comparat🇫🇷 · Fiona Kirk🇩🇪 · Benjamin Roberts🇦🇺

   The existence of cosmic fields made from yet unknown light bosons is predicted in many extensions to the Standard Model. They are especially of interest as possible constituents of dark matter. To detect such light and weakly interacting fields, atomic precision measurements offer one of the most sensitive platforms. In this work, we derive which atomic observables are sensitive to what kind of cosmic field couplings. For this we consider fields that couple either through scalar, pseudoscalar, vector, axial vector, or tensor couplings. We derive the corresponding non relativistic atomic potentials. Based on their symmetry properties, these can induce direct energy shifts or induce atomic electric dipole, magnetic dipole, electric quadrupole as well as nuclear Schiff and anapole moments.

   hep-phastro-ph.COphysics.atom-phPRD(2026)·0 citations
10. 10*

    Bypassing Spin-Analyzing Power Dependence for Quantum Entanglement at Colliders: A Case Study of $\Lambda \bar{\Lambda }$

    Junle Pei🇨🇳 · Tianjun Li🇨🇳 · Lina Wu🇨🇳 · Xiqing Hao🇨🇳 · Xiaochuan Wang🇨🇳

    We study, as a concrete case study using the $\Lambda (\to p{\pi }^{-})\bar{\Lambda }(\to \bar{p}{\pi }^{+})$ system, whether quantum entanglement in fermion pairs produced at colliders can be certified solely using angular information from final-state decays, while remaining independent of the parity-violating decay parameters ${\alpha }_{\Lambda }$ and ${\alpha }_{\bar{\Lambda }}$. Building on a general decomposition of any angular observable in terms of Wigner d-functions, we show that the expectation value must take the form ${\mathcal{O}}_0+{\mathcal{O}}_1{\alpha }_{\Lambda }+{\mathcal{O}}_2{\alpha }_{\bar{\Lambda }}+{\mathcal{O}}_3{\alpha }_{\Lambda }{\alpha }_{\bar{\Lambda }}$, with coefficients ${\mathcal{O}}_i$ ($i=0,1,2,3$) linear in the spin-density matrix elements ${\alpha }_{k,j}{\alpha }_{m,n}^{\ast }$. We obtain the value ranges of observables over the general and separable spaces of ${\alpha }_{k,j}$, and demonstrate a sufficient entanglement condition for pure states, extending it to mixed states by convexity. In constructing an ${\alpha }_{\Lambda }$- and ${\alpha }_{\bar{\Lambda }}$-independent witness from angular observables alone, we find that there are obstacles to probe quantum entanglement via the inequality-type and ratio-type ways. In particular, for the ratio-type criterion $⟨A⟩/⟨B⟩$, the presence of zeros of $⟨B⟩$ in both the general and separable spaces of ${\alpha }_{k,j}(k,j=\pm \frac{1}{2})$ results in identical value ranges of $⟨A⟩/⟨B⟩$ in the two spaces (covering the entire real line), thereby precluding any effective criterion. Finally, for this specific system, we present the successful constructions with additional spin information.

    hep-phhep-thquant-phJHEP(2026)·14 citations
11. 11*

    Neutrinoless double beta decay in a supersymmetric left-right model

    Vivek Banerjee🇮🇳 · Sasmita Mishra🇮🇳

    Neutrinoless double beta ($0\nu \beta \beta$) decay, an important low-energy process, serves not only as a potential test of the Majorana nature of neutrinos, but also as a sensitive probe for new physics beyond the Standard Model. In this study, the supersymmetric left-right model is explored to investigate its impact on $0\nu \beta \beta$ decay. Although the process takes place at low energies as compared to the electroweak scale, it carries the potential to provide indirect hints about the parity-breaking scale ${\text{M}}_R$. In this work, we formulate the decay amplitude using an effective field theory approach by separating long- and short-range contributions, each expressed in terms of dimensionless particle physics parameters and nuclear matrix elements. The analysis shows that the ${\text{M}}_R$ must lie above $1$ TeV, and future experiments may push it beyond $4-5$ TeV region. Another important outcome of this work is the role played by the tentative dark matter candidates, the lightest neutralino and sneutrino, which contribute significantly to the half-life of $0\nu \beta \beta$ decay. This suggests that if any supersymmetric particle is detected in future experiments, dark matter candidates will gain a permanent position in these extensions of the Standard Model.

    hep-ph0 citations
12. 12*

    Recent advances in perturbative QCD at high density

    Pablo Navarrete🇫🇮 · Aleksi Vuorinen🇫🇮

    In these conference proceedings, we discuss recent progress in high-order perturbative studies of the thermodynamic and transport properties of dense quark matter. Special emphasis is placed on the introduction of a promising new computational tool, thermal Loop Tree Duality, which enables pushing the existing weak-coupling calculations to higher perturbative orders.

    hep-phnucl-thJ.Subatomic Part.Cosmol.(2026)·1 citation
13. 13*

    Beyond-the-Standard-Model Physics in the Neutrino Sector

    Kevin J. Kelly🇺🇸

    Neutrino oscillations are a phenomenon that has been observed for over two decades and leads to the conclusion that neutrinos have mass. The Standard Model predicts massless neutrinos, and so neutrinos require physics beyond the Standard Model. Other signatures of BSM physics are detectable in modern neutrino facilities -- this chapter explores those possibilities. These can range from new effects modifying neutrino oscillations (beyond the expectations when neutrinos have mass), to searches for new particles in neutrino facilities. Next-generation experiments are particularly powerful for these searches due to high-intensity neutrino beams and novel detection technologies. We give an introduction to these search strategies, giving a non-comprehensive overview of the field as it stands presently.

    hep-phhep-ex0 citations
14. 14*

    Gluon splitting at small $x$: a unified derivation for the JIMWLK, DGLAP and CSS equations

    Paul Caucal🇫🇷 · Edmond Iancu🇫🇷 · Farid Salazar🇺🇸 · Feng Yuan🇺🇸

    We revisit the calculation of the next-to-leading order (NLO) corrections to dijet production in electron-ion collisions at small $x$. We focus on the back-to-back configuration where the relative transverse momentum $P_{\perp }$ of the measured jets is much larger than both their momentum imbalance $K_{\perp }$ and the target saturation momentum $Q_s(x,A)$. In this regime, we present for the first time a complete calculation of the real NLO corrections at leading power in $1/P_{\perp }$. Our result exhibits TMD factorisation, with the same hard factor as at tree-level and a NLO correction to the Weiszäcker-Williams (WW) gluon transverse momentum dependent (TMD) distribution which involves four Wilson-line operators. By studying different kinematical regimes for $K_{\perp }$ and for the radiated gluon, we recover all the quantum evolutions that were previously identified for this process at NLO: the B-JIMWLK high-energy evolution and the CSS evolution of the gluon WW TMD, and the DGLAP evolution of the gluon PDF. When both $K_{\perp }$ and the transverse momentum transferred by the target are large compared to $Q_s$, all the Wilson-line operators boil down to the unintegrated gluon distribution and our NLO result for the gluon TMD can be used to isolate the transverse-momentum dependent gluon splitting function.

    hep-phnucl-thJHEP(2026)·13 citations
15. 15*

    Constraining the new contributions to electron $g-2$ in a radiative neutrino mass model

    Bayu Dirgantara🇮🇩 · J. Julio🇮🇩

    We examine electron and muon anomalous magnetic dipole moments within a radiative neutrino mass model featuring TeV-scale scalar leptoquarks $S(3,1,-1/3)$ and $R(3,2,1/6)$. We utilize textures with decoupling electron and muon sectors, so that both electron and muon anomalous magnetic dipole moments could receive internal chiral enhancements from different heavy up-type quarks while in the same time evading the stringent $\mu \to e\gamma$ constraint. A successful fit to neutrino oscillation data requires the simultaneous presence of one- and two-loop neutrino mass contributions. This severely constrains the parameter space of the model, which results in a negligible new physics correction to the muon $g-2$. The electron $g-2$ discrepancy implied by the rubidium experiment, on the other hand, can be resolved within $2\sigma$ uncertainty provided that neutrino mass ordering is inverted. Lepton-flavor-violating tau decay rates, such as $\tau \to e\gamma$ and $\tau \to 3e$, are predicted to be within the sensitivities of next-generation experiments.

    hep-phPRD(2026)·1 citation
16. 16*

    Exploring rapidity regularization schemes at low $x$ with the DIS longitudinal structure function

    Tolga Altinoluk🇵🇱 · Guillaume Beuf🇵🇱 · Jani Penttala🇺🇸

    We propose three possible rapidity regulators for higher-order calculations in low $x$ QCD with gluon saturation, as alternatives to the usual lower cut-off for the integrals over the light-cone momentum $k^{+}$. These rapidity regulators are closely related to the $\eta$ regulator and to the pure rapidity regulator, which have been used primarily in studies of transverse-momentum-dependent (TMD) factorization within the soft-collinear effective theory (SCET). By choosing one of the three rapidity regulators that we propose, formulated in terms of $k^{+}$, $k^{-}$ or rapidity respectively, one can set from the start of the calculation in which of these three variables one wishes to formulate the low $x$ evolution equations, which is one of the main advantages of our approach. As a test of the viability of these rapidity regulators and of their practical implementation in higher order calculations with gluon saturation effects, we use them to revisit the calculation of the NLO corrections to the dipole factorization of the $F_L$ structure function in inclusive DIS at low $x$.

    hep-phJHEP(2026)·7 citations
17. 17*

    Expanding the Landscape of Exotic Muon Decays

    Admir Greljo🇨🇭 · Ajdin Palavrić🇨🇭 · Mirsad Tunja🇧🇦 · Jure Zupan🇺🇸

    We chart new-physics models that produce exotic, high-multiplicity muon decays featuring prompt or displaced $e^{+}{e}^{-}$ pairs and/or photons, with or without missing energy, such as $\mu \to 5e$, $\mu \to 7e$, etc. Starting from an effective-field-theory perspective, we estimate the reach on the ultraviolet scale and identify conditions under which lower-multiplicity modes are suppressed or occur at comparable rates. We then construct explicit realizations in minimal dark-sector models with light, feebly interacting particles, such as flavor-protected scalars, dark photons, inelastic dark matter, and axion-like particles. The predicted novel signatures can be probed at MEG II and Mu3e, as well as during calibration runs of COMET and Mu2e. A future discovery would provide valuable insights into short-distance dynamics and the mechanism of lepton-flavor symmetry breaking.

    hep-phhep-exPRD(2026)·8 citations
18. 18*

    Dark matter Simplified models in the Resonance Region

    Mattia Di Mauro🇮🇹 · Bohan Xie🇨🇳

    The particle-physics nature of dark matter (DM) remains one of the central open questions in modern physics. A widely used framework to investigate DM properties is provided by simplified models (DMSimps), which extend the Standard Model with a DM particle and a mediator that connects the visible and dark sectors. Much of the DMSimps parameter space is already constrained by direct and indirect detection, collider searches, and the measured DM relic abundance. We show, however, that the resonant regime $m_{\mathrm{DM}}\simeq m_{\mathrm{med}}/2$ remains viable under current bounds and will be stringently tested by forthcoming experiments. Using a full Boltzmann treatment that allows for departures from kinetic equilibrium near resonance, we demonstrate that this regime can reproduce the observed relic density with couplings compatible with direct-detection limits. We also show that models with s-wave-dominated annihilation can explain the Fermi-LAT Galactic Center Excess with couplings consistent with relic-density and direct-detection constraints. Finally, we propose two minimal constructions that naturally realize $m_{\mathrm{med}}\approx 2m_{\mathrm{DM}}$, making the resonant scenario generic rather than fine-tuned.

    hep-phastro-ph.HEPRD(2026)·10 citations
19. 19*

    Revealing signals of higher-order nonlinear showers in particle-laser collisions

    T. G. Blackburn🇸🇪 · B. King🇬🇧 · M. Samuelsson🇸🇪

    Several high power laser facilities are reaching field strengths where leading order strong-field quantum electrodynamical (QED) processes can be measured in the non-perturbative regime for the first time. At very high, as yet unobtainable in the laboratory, field strengths, the contribution of higher-order processes is predicted to dominate, implying a breakdown of current calculational methods. Focusing on nonlinear showers and considering currently available experimental parameters, we find that if the momentum spectrum of the \emph{incident} particles is well known, asymmetries in the \emph{outgoing} particle spectrum may provide a useful signature of higher orders of nonlinear phototrident, trident and Compton scattering. These signatures could be used by experiment to test how accurate the current calculational framework is when applied to strong-field QED at higher orders.

    hep-phPRA(2026)·1 citation
20. 20*

    Two-loop anomalous dimensions for baryon-number-violating operators in SMEFT

    Sumit Banik🇨🇭 · Andreas Crivellin🇨🇭 · Luca Naterop🇨🇭 · Peter Stoffer🇨🇭

    We compute the two-loop renormalization-group equations for the baryon-number-violating dimension-six operators in the SMEFT. This includes all three gauge interactions, the Yukawa, and Higgs self-interaction contributions. In addition, we present the one-loop matching of the $S_1$ scalar leptoquark on the SMEFT, which can generate the Wilson coefficients of all four gauge-invariant baryon-number-violating SMEFT operators. Using this example, we demonstrate the cancellation of scheme and matching-scale dependences. Together with the known two-loop renormalization-group evolution below the electroweak scale in the LEFT, as well as the one-loop matching of SMEFT onto LEFT, our results enable consistent next-to-leading-log analyses of nucleon decays, provided that the relevant matrix elements are known at next-to-leading-order accuracy.

    hep-phhep-exhep-latJHEP(2026)·22 citations
21. 21*

    Hydrodynamic models of reheating

    Juan Pablo Elía🇦🇷 · Lucas Cantarutti🇦🇷 · Nahuel Mirón-Granese🇦🇷 · Esteban Calzetta🇦🇷

    We develop a causal hydrodynamic model that provides an effective macroscopic description of the field-theoretic dynamics during the early stages of reheating. The inflaton condensate is treated as a homogeneous background coupled to a relativistic fluid that represents its inhomogeneous fluctuations. Within the divergence-type theory framework derived from kinetic considerations, the model captures essential dissipative and non-equilibrium effects while remaining stable and causal. We find that the coupling between the oscillating condensate and the fluid induces a parametric resonance in the tensor sector, leading to the amplification of the viscous stress tensor and the generation of gravitational waves with a characteristic spectral peak. The predicted spectrum agrees with lattice simulations performed with CosmoLattice. This hydrodynamic approach offers an effective bridge between microscopic field dynamics and macroscopic cosmological observables.

    hep-phastro-ph.COgr-qcPRD(2026)·2 citations
22. 22*

    Revisiting the soft-hard separation in the transverse momentum spectra of $pp$ collisions

    Gábor Bíró🇭🇺 · Guy Paić🇲🇽 · Leonid Serkin🇲🇽 · Gergely Gábor Barnaföldi🇭🇺

    We study the separation of soft and hard components in the transverse momentum spectra of charged particles as measured by ALICE in proton-proton collisions at $\sqrt{s}$ = 2.76, 5.02 and 13 TeV at the LHC. The soft component is described by a Boltzmann fit, while the residual spectra are identified as a hard QCD-like fragmentation contribution. After separation, the subtracted spectra show no significant evolution in shape or peak position with multiplicity, consistent with a two-component interpretation. Mean transverse momenta for both contributions remain nearly constant across multiplicity classes, while Pythia 8 Monte Carlo simulations confirm these trends. The robustness of the decomposition is demonstrated by a comparison between simulations with and without color reconnection, yielding consistent results. The terms `soft' and `hard' are used as operational labels within this framework and should not be interpreted as uniquely identified dynamical components. Our results are consistent with the two-component description as a viable and physically motivated alternative to hydrodynamical interpretations.

    hep-phnucl-thEPJC(2026)·0 citations
23. 23*

    Weakly turbulent saturation of the nonlinear scalar ergoregion instability

    Nils Siemonsen🇺🇸

    We perform time-domain evolutions of the ergoregion instability on a horizonless spinning ultracompact spacetime in scalar theories with potential-type and derivative self-interactions mimicking the nonlinear structure of the Einstein equations. We find that the instability saturates by triggering a weakly turbulent direct cascade, which transfers energy from the most unstable and large-scale modes to small scales. The cascade's nonlinear timescales of each mode are orders of magnitude shorter than the corresponding linear e-folding times. Through this mechanism, the counter-rotating stable light ring is filled with a spectrum of higher-order azimuthal modes forming a ring-like shape. Thereby we demonstrate that turbulent processes are likely also important during the fully gravitational saturation of the instability, leaving imprints in the gravitational wave emission.

    ↳ gr-qchep-phhep-thPRL(2026)·11 citations
24. 24*

    Constraints on inelastic dark matter from the CDEX-1B experiment

    Y. F. Liang🇨🇳 · L. T. Yang🇨🇳 · Q. Yue🇨🇳 · K. J. Kang🇨🇳 · Y. J. Li🇨🇳 · H. P. An🇨🇳 · Greeshma C.🇹🇼 · J. P. Chang🇨🇳 · H. Chen🇨🇳 · Y. H. Chen🇨🇳 · J. P. Cheng🇨🇳 · J. Y. Cui🇨🇳 and 76 other authors

    We present limits on spin-independent inelastic weakly interacting massive particles (WIMP)-nucleus scattering using the 737.1 kg$\cdot$day dataset from the CDEX-1B experiment. Expected nuclear recoil spectra for various inelastic WIMP masses $m_{\chi }$ and mass splittings $\delta$ are calculated under the standard halo model. An accurate background model of CDEX-1B is constructed by simulating all major background sources. The model parameters are then determined through maximum likelihood estimation and Markov chain Monte Carlo fitting. The resulting 90\% confidence level upper limits on the WIMP-nucleon cross section ${\sigma }_{\mathrm{n}}$ exclude certain DAMA/LIBRA allowed regions: the ${\chi }^2<4$ regions for $\delta <30$ keV at $m_{\chi }=250$ GeV and the ${\chi }^2<9$ region for $\delta <50$ keV at $m_{\chi }=500$ GeV. The method is applicable to other inelastic dark matter scenarios, and the upcoming CDEX-50 experiment is expected to improve sensitivity by four orders of magnitude.

    ↳ hep-exhep-phphysics.ins-detPRD(2025)·2 citations
25. 25*

    Probing the Neutron Skin with Extreme Collision Geometries in Heavy-Ion Collisions

    Hui Zhang🇨🇳 · Alex Akridge🇺🇸 · Charles J. Horowitz🇺🇸 · Jinfeng Liao🇺🇸 · Hongxi Xing🇨🇳

    Understanding how protons and neutrons are located differently in an atomic nucleus can provide fundamental information on nuclear structure and have far-reaching implications for astrophysics. A precise determination of this important difference, often quantified by the so-called neutron skin thickness, is challenging both theoretically and experimentally. Here we show how one can use a new category of observables in heavy ion collisions to probe the neutron skin thickness of nuclei like ${}^{208}$Pb and ${}^{48}$Ca, by utilizing the asymmetry between neutrons and protons of spectator nucleons in super-central collisions as well as that of participant nucleons in peripheral collisions. Using quantitative simulations, we demonstrate their sensitivity and great potential in constraining neutron skin thickness for both ${}^{208}$Pb and ${}^{48}$Ca nuclei in these extreme event geometries. Furthermore, we propose the asymmetric collisions between ${}^{48}$Ca and ${}^{40}$Ca nuclei as a unique and powerful way to nail down the neutron skin thickness.

    ↳ nucl-thhep-exhep-phnucl-ex5 citations
26. 26*

    Elliptic flow of deuterons from simulations with hybrid model

    Tomas Polednicek🇸🇰 · Radka Vozabova🇸🇰 · Boris Tomasik🇸🇰

    Elliptic flow of deuterons is measured on simulated collisions events of Pb+Pb at CMS energy of 2.76 TeV per colliding nucleon pair. We use hybrid model that includes hydrodynamics for the deconfined phase and hadron transport as an afterburner. For deuterons, two production mechanisms are examined: coalescence, and direct thermal production during hadronisation and subsequent transport through the hadronic phase. Differential elliptic flow of deuterons in different centrality bins is evaluated for both implemented production models. In this approach, coalescence describes the experimental data better than direct deuteron production.

    ↳ nucl-thhep-phPRC(2026)·1 citation
27. 27*

    The large-$N$ limit of the topological susceptibility of $\mathrm{SU}(N)$ Yang-Mills theories via Parallel Tempering on Boundary Conditions

    Claudio Bonanno🇪🇸

    I present a large-$N$ determination of the topological susceptibility $\chi$ of $\mathrm{SU}(N)$ Yang--Mills theories using non-perturbative numerical Monte Carlo simulations of the lattice-discretized theory for $3\le N\le 6$, and adopting the Parallel Tempering on Boundary Conditions (PTBC) algorithm to bypass topological freezing for $N>3$. Thanks to this algorithm I am able to explore a uniform range of lattice spacings across all values of $N$, and to precisely determine $\chi$ for finer lattice spacings compared to previous studies with periodic or open boundary conditions. By taking the continuum limit at fixed smoothing radius in physical units, I am also able to show the independence of the continuum limit of $\chi$ from this choice. I conclude providing a comprehensive comparison of my new PTBC results with previous determinations of the topological susceptibility in the literature, both at finite $N$ and in the large-$N$ limit.

    ↳ hep-lathep-phhep-thJHEP(2026)·11 citations
28. 28*

    Iterated Agent for Symbolic Regression

    Zhuo-Yang Song🇨🇳 · Zeyu Cai🇨🇳 · Shutao Zhang🇨🇳 · Jiashen Wei🇨🇳 · Jichen Pan🇨🇳 · Shi Qiu🇨🇳 · Qing-Hong Cao🇨🇳 · Tie-Jiun Hou🇨🇳 · Xiaohui Liu🇨🇳 · Ming-xing Luo🇨🇳 · Hua Xing Zhu🇨🇳

    Symbolic regression (SR), the automated discovery of mathematical expressions from data, is a cornerstone of scientific inquiry. However, it is often hindered by the combinatorial explosion of the search space and a tendency to overfit. Popular methods, rooted in genetic programming, explore this space syntactically, often yielding overly complex, uninterpretable models. This paper introduces IdeaSearchFitter, a framework that employs Large Language Models (LLMs) as semantic operators within an evolutionary search. By generating candidate expressions guided by natural-language rationales, our method biases discovery towards models that are not only accurate but also conceptually coherent and interpretable. We demonstrate IdeaSearchFitter's efficacy across diverse challenges: it achieves competitive, noise-robust performance on the Feynman Symbolic Regression Database (FSReD), outperforming several strong baselines; discovers mechanistically aligned models with good accuracy-complexity trade-offs on real-world data; and derives compact, physically-motivated parametrizations for Parton Distribution Functions in a frontier high-energy physics application. IdeaSearchFitter is a specialized module within our broader iterated agent framework, IdeaSearch, which is publicly available at https://www.ideasearch.cn/.

    ↳ physics.comp-phastro-ph.IMcs.AIcs.LG+14 citations
29. 29*

    Primordial Black Holes, Charge, and Dark Matter: Rethinking Evaporation Limits

    Sebastian Schuster (Stockholm University)🇸🇪 · Jessica Santiago (National Taiwan University)🇹🇼 · Justin Feng (CEICO Prague)🇨🇿 · Matt Visser (Victoria University of Wellington)🇳🇿

    Limits on the dark matter fraction of small mass primordial black holes from Hawking radiation are predominantly derived from the assumption of a Schwarzschild black hole evaporating. However, astrophysical black holes are usually much more realistically modelled by the rotating Kerr black hole solution. Meanwhile, electromagnetically charged black holes are astrophysically of little importance due to their fast neutralisation in the present universe. Dark matter is not just a possible solution to issues of astrophysics and cosmology, but also to issues of the standard model of particle physics. Extensions of this model thus can lead to charges present in the early universe which remain preserved in the charge of primordial black holes - even when the corresponding particles have disappeared from the particle content of the present epoch of the universe. Here, we report on a thorough proof-of-concept that such charges can greatly change evaporation limits for primordial black hole dark matter. Special emphasis is placed on (near-)extremal black holes, for which this effect is especially pronounced.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-phJ.Phys.Conf.Ser.(2026)·1 citation
30. 30*

    Effects of dark dipole radiation on eccentric supermassive black hole binary inspirals

    Mu-Chun Chen🇨🇳 · Yan Cao🇨🇳

    The final-parsec problem has long posed a central challenge in understanding the merger of supermassive black hole binaries. In this paper, we investigate a scenario in which a dark scalar or vector field is sourced by eccentric binaries, leading to accelerated mergers through additional dipole radiation, and thereby extending the range of masses for which the binary can merge within a Hubble time. The Newtonian-order radiation fluxes from an eccentric charged Keplerian binary are derived using general results for localized periodic sources in flat spacetime. We find that dipole radiation, although insufficient to fully resolve the final-parsec problem, can alter the low-frequency spectrum of the stochastic gravitational-wave background from supermassive black hole binary inspirals. We construct a simplified model for the spectrum and perform a Bayesian analysis using the current pulsar timing array data.

    ↳ gr-qcastro-ph.COastro-ph.GAastro-ph.HE+1PRD(2026)·2 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.