Tue·Apr 1, 2025Tuesday·April 1, 2025

1. 01*

   NNLOJET: a parton-level event generator for jet cross sections at NNLO QCD accuracy

   A. Huss🇨🇭 · L. Bonino🇨🇭 · O. Braun-White🇬🇧 · S. Caletti🇨🇭 · X. Chen🇨🇳 · J. Cruz-Martinez🇨🇭 · J. Currie🇬🇧 · Y.S. Dai🇨🇳 · W. Feng🇨🇭 · G. Fontana🇨🇭 · E. Fox🇬🇧 · R. Gauld🇩🇪 and 28 other authors

   The antenna subtraction method for NNLO QCD calculations is implemented in the NNLOJET parton-level event generator code to compute jet cross sections and related observables in electron-positron, lepton-hadron and hadron-hadron collisions. We describe the open-source NNLOJET code and its usage.

   hep-phSciPost Phys.Codeb.(2026)·61 citations
2. 02*

   One Born Oppenheimer Effective Theory to rule all Exotics

   Abhishek Mohapatra🇩🇪

   The discovery of XYZ exotic states in the hadronic sector with two heavy quarks constitute one of the most important open problems in particle theory. In this work, we demonstrate that the QCD derived Born-Oppenheimer effective field theory (BOEFT) framework, provides a systematic framework to describe exotic states of arbitrary composition. The BOEFT construction is based on QCD taking into consideration the scale separation and symmetry of systems containing two heavy quarks. We show the results for the coupled channel Schrödinger equations incorporating nonadiabatic mixing terms that describes exotic states for arbitrary quantum number of the light degrees of freedom: hybrids, tetraquarks, pentaquarks, doubly heavy baryons, and quarkonia at leading order. Additionally, we present the results of the predicted spin-symmetry multiplets, and the expression of the nonperturbative gauge-invariant correlators to be computed on lattice that are required for BOEFT: static energies, generalized Wilson loops, gluelumps, adjoint mesons or baryons, and triplet or sextext mesons or baryons. Moreover, for the static energies, we describe the short-distance behavior based on multipole expansion and the mixing with heavy-light thresholds at long distances based on the conserved quantum numbers.

   hep-phhep-exhep-latPoS(2025)·2 citations
3. 03*

   Probing and Knocking with Muons

   Leyun Gao🇨🇳 · Cheng-en Liu🇨🇳 · Qite Li🇨🇳 · Chen Zhou🇨🇳 · Qiang Li🇨🇳 · Liangwen Chen🇨🇳 · Xueheng Zhang🇨🇳 · Yu Xu🇨🇳 · Zhiyu Sun🇨🇳

   We propose here a set of new methods involving probing and knocking with muons (PKMu). There is a wealth of rich physics to explore with GeV muon beams. Examples include but not limited to: muon scattering can occur at large angles, providing evidence of potential muon-philic dark matter or dark mediator candidates; muon-electron scattering can be used to detect new types of bosons associated with charged lepton flavor violation; precise measurements of GeV-scale muon-electron scattering can be employed to probe quantum correlations.

   hep-phhep-exMod.Phys.Lett.A(2025)·5 citations
4. 04*

   General Formulas for Loop-Induced Decays of $A\to Z\gamma \gamma$ and Their Applications

   Dzung Tri Tran (Duy Tan Univ.)🇻🇳 · Thanh Huy Nguyen (HCMUS)🇻🇳 · Khiem Hong Phan (Duy Tan Univ.)🇻🇳

   Within the framework of the Standard Model Higgs extensions, including the Two-Higgs-Doublet Model with vector-like fermions and the Triplet-Higgs Model, we derive general one-loop contributions to the rare decay process $A\to Z\gamma \gamma$. The analytical expressions are formulated with Passarino-Veltman scalar functions, which represent the scalar coefficients of one-loop Lorentz-covariant tensor integrals. These functions are written in accordance with the input conventions of the {\tt LoopTools} and {\tt Collier} packages, facilitating the efficient numerical generation of decay rates and their distributions using these computational tools. As part of our phenomenological study, we examine the branching ratios of this decay channel within the viable parameter space of the considered models. Our results indicate that the branching ratio can reach $\mathcal{O}(10^{-4})$ in the Two-Higgs-Doublet Model and $\mathcal{O}(10^{-2})$ in the Triplet-Higgs Model at specific points within the allowed parameter regions. Furthermore, the inclusion of vector-like fermions in the loop leads to a significant modification of the partial decay rates, with an observed variation of approximately $10\%$. Additionally, we explore the dependence of the branching ratios on key model parameters, including the charged Higgs mass, mixing angles, and the soft-breaking scale, providing deeper insights into the phenomenological implications of these Higgs-extended frameworks.

   hep-phEPJC(2025)·0 citations
5. 05*

   Electromagnetic and axial-vector structure of singly heavy baryons in a pion mean-field approach

   Hyun-Chul Kim🇰🇷

   In this talk, we present a series of recent works on the electromagnetic and axial-vector structures of low-lying singly heavy baryons. We first explain the pion mean-field approach, in which light and singly heavy baryons can be considered on an equal footing. We then discuss the results for the electromagnetic and radiative transition form factors of the singly heavy baryons. We also demonstrate the results for the strong decay rates and quark spin content of the singly heavy baryons. Finally, we propose a consistent way of dealing with the $1/m_Q$ corrections in the pion mean-field approach.

   hep-phhep-exhep-latPoS(2025)·1 citation
6. 06*

   Gravitational form factors of the nucleon and their mechanical structure: Twist-2 case

   Hyun-Chul Kim🇰🇷 · June-Young Kim🇺🇸 · Ho-Yeon Won🇫🇷

   We present a series of recent works on the gravitational form factors (GFFs) of the nucleon within a pion mean-field approach, which is also called the chiral quark-soliton model. We investigate the flavor structure of the mass, angular momentum, and $D$-term form factors of the nucleon. The main findings of the present work are given as follows: the contribution of the strange quark is rather small for the mass and angular momentum form factors, it plays an essential role in the $D$-term form factors. It indicates that the $D$-term form factor is sensitive to the outer part of the nucleon. The flavor blindness, i.e, $D^{u-d}\simeq 0$, is valid only if the strange quark is considered. We also discuss the effects of twist-4 operators. Though the gluonic contributions are suppressed by the packing fraction of the instanton vacuum in the twist-2 case, contributions from twist-4 operators are significant.

   hep-phhep-exhep-latPoS(2025)·0 citations
7. 07*

   Probing the general 2HDM with flavor violation through $A\to ZH$

   Wei-Shu Hou🇹🇼 · Mohamed Krab🇹🇼

   We investigate the LHC discovery prospects for a second Higgs doublet through $A\to ZH$ weak decay. The latter is identified as the $\text{smoking gun signature}$ of two Higgs doublet models (2HDMs) with first-order electroweak (EW) phase transition, a necessary condition for EW baryogenesis. In the general 2HDM (G2HDM) that has flavor-changing neutral Higgs couplings, $H$ may decay dominantly via $t\bar{c}+\bar{t}c$ final states, giving rise to trilepton signals. By a phenomenological analysis, we show that $A\to ZH$ in ${\ell }^{+}{\ell }^{-}t\bar{c}$ or ${\ell }^{+}{\ell }^{-}\bar{t}c$ final states could be a promising probe of G2HDM at the LHC with flavor violation.

   hep-phPRD(2025)·4 citations
8. 08*

   Pion, Kaon and nucleon gravitational form factors

   Zhao-Qian Yao🇪🇸 · Yin-Zhen Xu🇪🇸 · Daniele Binosi🇮🇹 · Minghui Ding🇨🇳 · Zhu-Fang Cui🇨🇳 · Khépani Raya🇪🇸 · Craig D. Roberts🇨🇳 · José Rodríguez-Quintero🇪🇸

   A unified set of predictions for pion, kaon and nucleon gravitational form factors is obtained using a symmetry-preserving truncation of each relevant quantum field equation. A crucial aspect of the study is the self-consistent characterization of the dressed quark-graviton vertices, applied when probing each quark flavor inside mesons or nucleons. The calculations reveal that each hadron's mass radius is smaller than its charge radius, matching available empirical inferences; moreover, core pressures are significantly greater than those in neutron stars. This set of predictions is expected to be instrumental as forthcoming experiments provide opportunities for validation.

   hep-phPoS(2025)·4 citations
9. 09*

   The influence of electron-electron interaction on pair production in supercritical collisions of highly charged ions

   N. K. Dulaev🇷🇺 · D. A. Telnov🇷🇺 · R. V. Popov🇷🇺 · V. M. Shabaev🇷🇺 · Y. S. Kozhedub🇷🇺 · X. Ma🇨🇳 · I. A. Maltsev🇷🇺 · A. D. Mironov🇷🇺 · I. I. Tupitsyn🇷🇺

   The effect of electron-electron interaction on positron emission in supercritical collisions of highly charged ions is studied within the monopole approximation using the time-dependent density functional theory and the time-dependent Hartree-Fock-Slater methods. Positron production probabilities and energy spectra are calculated for U-U, U-Cm, and Cm-Cm collision systems, considering both bare nuclei and highly charged ions with partially filled electron shells. The results demonstrate that electron screening substantially reduces positron production and suppresses the characteristic signatures of spontaneous vacuum decay, previously found in collisions of bare nuclei.

   hep-phCPC(2025)·1 citation
10. 10*

    Vacuum polarization current in presence of intense Sauter field

    Deepak Sah🇮🇳 · Manoranjan P. Singh🇮🇳

    The quantum vacuum becomes unstable under an external field, leading to spontaneous particle-antiparticle pair creation. In canonical quantization, the time-dependent particle number, defined via Bogoliubov transformations lacks physical meaning until the external field vanishes. To address this, we explore dynamical quantities that remain well-defined at both asymptotic and intermediate times, focusing on the vacuum polarization current. Investigating this observable provides insights into the system's intermediate-time behavior. We consider pair creation in a spatially homogeneous, time-dependent, intense Sauter field. Specifically, we analyze the real and imaginary parts of the correlation function, linking them to vacuum polarization effects. The vacuum polarization current in an intense laser pulse is computed numerically, revealing that it correlates with the real part of the correlation function. Initially, the current changes sign and gradually decreases, but unlike the particle number, it does not reach a constant asymptotic value. Instead, for large times, it exhibits nearly undamped oscillations, a distinctive feature of scalar particles, oscillating strongly around zero. Additionally, we explore the uniqueness of the vacuum polarization current in the adiabatic basis, comparing different reference mode function choices. Notably, we find that the current remains independent of the basis choice.

    hep-phhep-thmath-phmath.MPEur.Phys.J.Plus(2025)·2 citations
11. 11*

    Leptogenesis and the relativistic degrees of freedom of the plasma

    Dimitrios Karamitros🇫🇮 · Thomas McKelvey🇬🇧 · Apostolos Pilaftsis🇬🇧

    We investigate the impact of the temperature dependence of the relativistic degrees of freedom (dofs) of the plasma on lepton and baryon asymmetry. Motivated by the significant effect of the varying dofs on the tri-resonant leptogenesis particle model in low-scale leptogenesis, we show how this effect impacts the evolution of the lepton asymmetry in a simplified setup. We provide analytical approximations as well as numerical results showing that the simplified setup exhibits similar behavior as the concrete model. As the dofs enter the transport equations via the expansion rate of the Universe and the temperature of the plasma, we argue that any analysis must take these effects into account in order to be consistent.

    hep-phPoS(2025)·0 citations
12. 12*

    Unstable molecular state with unstable constituent

    Yuqin Yin🇨🇳 · Zonghua Shi🇨🇳 · Hao Liu🇨🇳 · Xiurong Guo🇨🇳 · Xiaozhao Chen🇨🇳 · Xiaofu Lü🇨🇳

    Based on the developed Bethe-Salpeter theory for dealing with unstable state, we investigate unstable meson-meson molecular state in which at least one of the constituents is an unstable meson and provide a reasonable and feasible scheme to deal with this interesting problem in the framework of relativistic quantum field theory. The developed Bethe-Salpeter theory is applied to investigate the unstable meson composed of a quark and an antiquark, and we obtain the Green's function for unstable meson in the framework of relativistic quantum field theory, which is used to deal with unstable constituent of molecular state. We can obtain the physical mass and width of unstable molecular state composed of two heavy mesons, which contain the contribution from at least one unstable constituent of molecular state.

    hep-ph0 citations
13. 13*

    The effect of recoils on soft-drop-groomed observables in $\gamma$-tagged jets in a multistage approach

    Y. Tachibana🇯🇵 · C. Sirimanna🇺🇸 · A. Majumder🇺🇸 · A. Angerami🇺🇸 · R. Arora🇺🇸 · S. A. Bass🇺🇸 · Y. Chen🇺🇸 · R. Datta🇺🇸 · L. Du🇨🇦 · R. Ehlers🇺🇸 · H. Elfner🇩🇪 · R. J. Fries🇺🇸 and 40 other authors

    We investigate medium-induced modifications to jet substructure observables that characterize hard components in central Pb-Pb collisions at $\sqrt{s_{NN}}=5.02$~TeV. Using a multistage Monte Carlo simulation of in-medium jet shower evolution, we explore flavor-dependent medium effects through simulations of inclusive and $\gamma$-tagged jets. The results show that quark jets undergo a nonmonotonic modification compared with gluon jets in observables such as the Pb-Pb to $p$-$p$ ratio of the soft drop prong angle $r_g$, the relative prong transverse momentum $k_{T,g}$, and the groomed mass $m_g$ distributions. Due to this nonmonotonic modification, $\gamma$-tagged jets, enriched in quark jets, provide surprisingly clear signals of medium-induced structural modifications, distinct from effects dominated by selection bias. Further systematic studies demonstrate that these effects are dominated by recoil medium response. This work highlights the potential of hard substructures in $\gamma$-tagged jets as powerful tools for probing the jet-medium interactions in high-energy heavy-ion collisions, in particular by enabling detailed investigations of jet-medium parton scatterings via their associated medium response. All simulations for $\gamma$-tagged jet analyses carried out in this paper used triggered events containing at least one hard photon, which highlights the utility of these observables for future Bayesian analysis.

    hep-phnucl-exnucl-thPRC(2026)·9 citations
14. 14*

    Production of $K^{+}{K}^{-}$ Pairs Through Decay of $\varphi$ Meson

    Xin-Nan Zhu🇨🇳 · Xin-Li Sheng🇮🇹 · Defu Hou🇨🇳

    We develop a theoretical framework for the production of $K^{+}{K}^{-}$ pairs through the decay of $\varphi$ mesons produced from a thermal background, based on the Nambu-Jona-Lasinio (NJL) model. The differential production rate of $K^{+}{K}^{-}$ is related to the self-energy of the $\varphi$ meson, incorporating the contributions of the quark loop at leading order and the kaon loop at next-to-leading order in the $1/N_c$ expansion. We numerically evaluate the invariant mass spectrum of the $K^{+}{K}^{-}$ pair both in vacuum and at finite temperature. The inclusion of the kaon loop results in a finite width of the spectrum, improving agreement with experimental data. We also investigate the spin alignment of the $\varphi$ meson induced by its motion relative to the thermal background. In the NJL model with only chiral condensates, we find that deviations from the unpolarized limit of 1/3 are negligible.

    hep-phhep-thnucl-thPRD(2025)·2 citations
15. 15*

    Semileptonic baryon decays ${\Xi }_b\to {\Xi }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ in perturbative QCD

    Zhou Rui🇨🇳 · Zhi-Tian Zou🇨🇳 · Ya Li🇨🇳 · Ying Li🇨🇳

    We perform a detailed analysis of the semileptonic ${\Xi }_b\to {\Xi }_c{\ell }^{-}{\bar{\nu }}_{\ell }$ decays within the perturbative QCD framework. In our study, the ${\Xi }_b\to {\Xi }_c$ transition form factors are calculated using several popular models for baryonic light-cone distribution amplitudes. These form factors are then employed to analyze a range of observable quantities for the semileptonic processes via the helicity formalism. Our work presents predictions for the branching fractions of these decays for both the $\tau$ and $e$ channels. Notably, the obtained lepton flavor universality ratio, ${\mathcal{R}}_{{\Xi }_c}\approx 0.3$, may offer new insights into the ${\mathcal{R}}^{(\ast )}$ puzzle. Furthermore, we investigate various angular observables, such as forward-backward asymmetries, lepton-side convexity parameters, and polarization asymmetries, which provide complementary information regarding potential new physics in $b$-baryonic semileptonic transitions. The numerical results for these angular observables are presented as both functions of $q^2$ and as averaged values. We observe that the lepton mass plays a significant role in shaping the angular distributions, affecting most of the observables under consideration. These results are expected to be valuable for both current and future experimental investigations of semileptonic heavy-to-heavy baryon decays.

    hep-phPRD(2025)·10 citations
16. 16*

    Production of open and hidden charm in fixed-target experiments at the LHC

    Antoni Szczurek🇵🇱 · Anna Cisek🇵🇱 · Rafal Maciula🇵🇱

    We discuss the production of $D$ mesons and $J/\psi$ quarkonia in proton-nucleus collisions in the fixed-target LHCb experiment. We consider gluon-gluon fusion within $k_t$-factorization, processes initiated by intrinsic charm in the nucleon and perturbative recombination mechanism. All the mechanisms seem to be necessary to describe the LHCb experimental data. We get an upper limit for the probability of the large-$x$ $c\bar{c}$ Fock component in the nucleon, which is slightly less than 1 \%. The recombination mechanism allows the description of $D^0$ and ${\bar{D}}^0$ asymmetry observed by the LHCb collaboration.\\ We also discuss the production of $J/\psi$ quarkonia, including color singlet mechanisms. We include $g^{\ast }{g}^{\ast }\to J/\psi g$ and $g^{\ast }{g}^{\ast }\to {\chi }_c(1^{+},2^{+})(\to J/\psi \gamma )$ within $k_t$-factorization approach. Different unintegrated gluon distributions from the literature are used. A reasonable agreement is achieved with some distributions from the literature.

    hep-phActa Phys.Polon.Supp.(2025)·0 citations
17. 17*

    KNO scaling in quark and gluon jets at the LHC

    Xiang-Pan Duan🇨🇳 · Lin Chen🇪🇸 · Guo-Liang Ma🇨🇳 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸

    The Koba-Nielsen-Olesen (KNO) scaling of hadron multiplicity distributions, empirically confirmed to hold approximately in $e^{+}{e}^{-}$ collisions and Deep Inelastic Scattering, has been observed to be violated in hadron-hadron collisions. In this work, we show that the universality of KNO scaling can be extended to hadron-hadron collisions when restricted to QCD jets. We present a comprehensive study of KNO scaling in QCD jets produced in proton-proton collisions at the LHC. Using perturbative QCD calculations in the double logarithmic approximation and PYTHIA simulations, we find that KNO scaling approximately holds for both quark and gluon jets across a broad jet $p_T$ range, from $0.1$ TeV to $2.5$ TeV, at both the parton and hadron levels. Especially, we highlight characteristic differences between the KNO scaling functions of quark and gluon jets, with the quark-jet scaling function lying above that of gluon jets at both low and high multiplicities. This distinction is essential for interpreting inclusive jet data at the LHC. Furthermore, we propose direct experimental tests of KNO scaling in QCD jets at the LHC through quark-gluon discrimination using jet substructure techniques, as demonstrated by applying energy correlation functions to PYTHIA-generated data.

    hep-phhep-exnucl-thPRD(2025)·11 citations
18. 18*

    A possibility for grand unification and non-Higgs mass generation in a Nambu-Jona-Lasinio-like theory of fermions interacting with current metric field

    Sergii Kutnii

    Grand unification possibilities in Nambu-Jona-Lasinio-like models are studied. To address the problem of vector boson masses and nonrenormalizability of the theory, algebraic formalism encompassing the effective action, Schwinger-Keldysh path integral, and Bogoliubov-Parasiuk-Hepp-Zimmerman renormalization is constructed. A new NJL-like model: the theory of current metric field interacting with fermions is proposed. Bosonization in this model can produce massless vector bosons under certain conditions which makes it a candidate grand unified theory. Both Higgs and non-Higgs effects can contribute to particle masses.

    hep-phhep-th0 citations
19. 19*

    Quark production in the bottom-up thermalization

    Sergio Barrera Cabodevila🇪🇸 · Xiaojian Du🇪🇸 · Carlos A. Salgado🇪🇸 · Bin Wu🇪🇸

    We investigate the impact of quark production on bottom-up thermalization in heavy-ion collisions. First, we extend the parametric estimates of bottom-up thermalization in pure gluon systems by incorporating quark production in the weak-coupling (high-energy) limit. Our analysis reveals that quark production does not alter the qualitative features of the three-stage thermalization process in this limit. Furthermore, we obtain the scaling behavior of the quark number density over time at each stage. Then, by solving the Boltzmann equation in diffusion approximation (BEDA) for longitudinally boost-invariant systems, we demonstrate how our detailed numerical simulations approach the predicted three-stage thermalization picture as the strong coupling ${\alpha }_s$ decreases. Finally, we carry out a detailed comparison of our BEDA results with those obtained by solving the QCD effective kinetic theory for intermediate values of ${\alpha }_s$, observing remarkably good quantitative agreement between the two approaches.

    hep-phnucl-thPLB(2025)·8 citations
20. 20*

    Leading qT/Q correction for Drell-Yan in TMD factorization

    Arturo Arroyo-Castro🇪🇸 · Ignazio Scimemi🇪🇸 · Alexey Vladimirov🇪🇸

    The transverse momentum dependent (TMD) factorization theorem accommodates various types of power corrections. Among them, the least studied are qT/Q corrections, which become significant at large values of transverse momentum. These corrections partially originate from higher-twist TMD distributions, which exhibit singularity at small transverse distances. We propose a decomposition that reveals this singularity explicitly, and makes the qT/Q correction manifest. As a concrete application, we consider the next-to-leading power correction for the angular distributions in Drell-Yan, and determine the leading qT/Q corrections. These corrections are significant for the angular distributions A1 and A3, in complete agreement with the data.

    hep-phhep-exhep-latnucl-ex+1JHEP(2025)·7 citations
21. 21*

    Large CP violation in ${\Lambda }_b^0\to p{K}^{-}{\pi }^{+}{\pi }^{-}$ and its U-spin partner decays

    Xiao-Gang He🇨🇳 · Chia-Wei Liu🇨🇳 · Jusak Tandean🇨🇳

    The LHCb Collaboration has recently found a large CP-violating rate asymmetry in the $b$-baryon decay ${\Lambda }_b^0\to p{K}^{-}{\pi }^{+}{\pi }^{-}$. This is the first observation of CP violation in baryon processes, opening a new window to test its standard model origin. Many more baryon decays are expected to exhibit observable signals of CP violation. We show that there also exists large CP violation in the U-spin partner decay mode, ${\Xi }_b^0\to {\Sigma }^{+}{\pi }^{-}{K}^{+}{K}^{-}$, with rate asymmetry $$A_{CP}({\Xi }_b^0\to {\Sigma }^{+}{\pi }^{-}{K}^{+}{K}^{-})=-A_{CP}({\Lambda }_b^0\to p{K}^{-}{\pi }^{+}{\pi }^{-})\frac{Br({\Lambda }_b^0\to p{K}^{-}{\pi }^{+}{\pi }^{-})}{Br({\Xi }_b^0\to {\Sigma }^{+}{\pi }^{-}{K}^{+}{K}^{-})}\frac{{\tau }^{{\Xi }_b}}{{\tau }^{{\Lambda }_b}}$$ in the U-spin symmetry limit. By neglecting a subleading contribution in the amplitudes, we obtain $$A_{CP}({\Lambda }_b^0\to p{\pi }^{+}{\pi }^{-}{\pi }^{-})=A_{CP}({\Xi }_b^0\to {\Sigma }^{+}{\pi }^{-}{K}^{+}{K}^{-})=-(12\pm 3)\%.$$ These predictions provide crucial tests for the standard model.

    hep-phhep-exPRD(2025)·10 citations
22. 22*

    Exotic Decays and Collider Signatures of pNGB Scalars in the $SU(5)/SO(5)$ Composite Higgs Model

    Nilanjana Kumar🇮🇳 · Vandana Sahdev🇮🇳

    The nature of the Higgs boson, whether it is elementary or composite, will be investigated through precision measurements at the collider experiments. In composite Higgs scenarios, the Higgs may manifest as a pseudo Nambu-Goldstone boson (pNGB) arising from a strongly interacting sector. The $SU(5)/SO(5)$ Composite Higgs Model features a rich scalar sector, with the decay patterns of the scalars being heavily influenced by the way fermions are embedded in various representations of $SU(5)$. We discuss how masses of the pNGB scalars and their couplings depend functionally on the compositeness scale and the parameters of the strong sector. Unique decay modes of the scalars emerge from the model when the mixing among the various pNGB scalars is non-negligible. We present a comprehensive and thorough analysis of the fermiophilic and fermiophobic decay modes of the pNGB scalars. Significant differences are observed in the decay patterns of the two singly charged scalars. Further, the decay of one pNGB to another on-shell pNGB when masses exceed about $1$ TeV presents a rich phenomenology, leading to distinctive signatures at the colliders. In this context, the future muon collider offers a promising avenue for detecting pNGB scalars with masses larger than $1$ TeV, especially in final states involving $W/Z$ fatjets.

    hep-phPRD(2026)·1 citation
23. 23*

    Transverse Energy--Energy Correlators at Small $x$ for Photon--Hadron Production

    Zhong-Bo Kang🇺🇸 · Robert Kao🇺🇸 · Meijian Li🇪🇸 · Jani Penttala🇺🇸

    We study the transverse energy--energy correlator (TEEC) observable in photon--hadron and photon--jet production in p+p and p+A collisions at small $x$. We derive the relevant expressions in the high-energy limit of the scattering where the dipole picture is applicable and show how the dependence on the fragmentation function of the hadron cancels due to the momentum-sum rule. The nonperturbative scattering with the target nucleus is expressed in terms of the dipole amplitude, which also describes nonlinear gluon saturation effects. The TEEC observable is computed in the RHIC and LHC kinematics, and we show that it can be sensitive to the dipole amplitude, making it a potentially good observable for studying saturation effects.

    hep-phhep-exnucl-exnucl-thPRD(2025)·9 citations
24. 24*

    Naturally Resonant Dark Matter from Extra Dimensions

    Taegyu Lee🇺🇸 · Yu-Dai Tsai🇺🇸

    We explore the mass resonance structure that naturally arises from extra-dimensional models. The resonance can enhance the dark matter annihilation as well as self-interaction. We demonstrate such a resonance structure by considering the fermionic dark matter and dark photon models on an $S^1/(Z_2\times Z_2^{\prime })$ orbifold. We also note that this model embeds dark matter axial vector coupling to the dark photon, which opens up the viable dark matter parameter space. We then present the unique predictions for direct-detection experiments and accelerator searches.

    hep-phastro-ph.COhep-exhep-thPRD(2026)·4 citations
25. 25*

    Discovery Prospects for a Minimal Dark Matter Model at Cosmic and Intensity Frontier Experiments

    Ahmed Alenezi🇺🇸 · Cari Cesarotti🇺🇸 · Stefania Gori🇺🇸 · Jessie Shelton🇺🇸

    We explore the detection prospects for a minimal secluded dark matter model, where a fermionic dark matter particle interacts with the Standard Model (SM) via a kinetically mixed dark photon. We focus on scenarios where the dark photon decays visibly, making it a prime target for beam-dump experiments. In this model, the dark matter relic abundance can be achieved by a variety of mechanisms: freeze-in, out-of-equilibrium freeze-out, and secluded freeze-out. We demonstrate that the secluded freeze-out regime in the considered mass range is now entirely excluded by a combination of direct and indirect detection constraints. Moreover, we show that future direct detection and intensity frontier experiments offer complementary sensitivity to this minimal model in the parameter space where the hidden sector never enters equilibrium with the SM. In out-of-equilibrium freeze-out scenarios, nuclear-recoil direct detection experiments can still access signals above the neutrino fog that are mediated by dark photons that are too weakly coupled to be detected in future beam dump experiments. Meanwhile, future beam dump experiments provide a powerful probe of the freeze-in parameter space in this model, which is largely inaccessible to direct detection experiments. Notably, even in the absence of a future observation in direct detection experiments, a dark photon discovery remains possible at SHiP, DUNE, LHCb, and DarkQuest within this minimal dark matter model.

    hep-phJHEP(2026)·8 citations
26. 26*

    The International Axion Observatory (IAXO): case, status and plans. Input to the European Strategy for Particle Physics

    A. Arcusa🇪🇸 · S. Ahyoune🇪🇸 · K. Altenmuller🇪🇸 · I. Antolin🇪🇸 · S. Basso🇮🇹 · P. Brun🇫🇷 · V. Burwitz🇩🇪 · F. R. Candon🇪🇸 · J. F. Castel🇪🇸 · S. Cebrian🇪🇸 · D. Chouhan🇩🇪 · R. Della Ceca🇮🇹 and 111 other authors

    The International Axion Observatory (IAXO) is a next-generation axion helioscope designed to search for solar axions with unprecedented sensitivity. IAXO holds a unique position in the global landscape of axion searches, as it will probe a region of the axion parameter space inaccessible to any other experiment. In particular, it will explore QCD axion models in the mass range from meV to eV, covering scenarios motivated by astrophysical observations and potentially extending to axion dark matter models. Several studies in recent years have demonstrated that IAXO has the potential to probe a wide range of new physics beyond solar axions, including dark photons, chameleons, gravitational waves, and axions from nearby supernovae. IAXO will build upon the two-decade experience gained with CAST, the detailed studies for BabyIAXO, which is currently under construction, as well as new technologies. If, in contrast to expectations, solar axion searches with IAXO ``only'' result in limits on new physics in presently uncharted parameter territory, these exclusions would be very robust and provide significant constraints on models, as they would not depend on untestable cosmological assumptions.

    hep-phastro-ph.HEastro-ph.SRhep-ex16 citations
27. 27*

    Importance of Loop Effects in Probing Lepton Number Violation

    Lukáš Gráf🇳🇱 · Chandan Hati🇪🇸 · Ana Martín-Galán🇪🇸 · Oliver Scholer🇩🇪

    The discovery of the lepton number violation would be a smoking gun signal for physics beyond the Standard Model, and its most sensitive probe is the search for neutrinoless double beta decay ($0\nu \beta \beta$). Working in the framework of the Standard Model Effective Field Theory (SMEFT), we show that one-loop effects can remarkably improve the tree-level bounds on the new-physics scales for several dimension-7 operators. Using ultraviolet model examples, we then showcase the competition among $0\nu \beta \beta$ contributions induced by dimension-7 and loop-level dimension-5 SMEFT operators.

    hep-phPRD·8 citations
28. 28*

    Quantum Information meets High-Energy Physics: Input to the update of the European Strategy for Particle Physics

    Yoav Afik🇺🇸 · Federica Fabbri🇮🇹 · Matthew Low🇺🇸 · Luca Marzola🇪🇪 · Juan Antonio Aguilar-Saavedra🇪🇸 · Mohammad Mahdi Altakach🇫🇷 · Nedaa Alexandra Asbah🇨🇭 · Yang Bai🇺🇸 · Hannah Banks🇬🇧 · Alan J. Barr🇬🇧 · Alexander Bernal🇪🇸 · Thomas E. Browder🇺🇸 and 59 other authors

    Some of the most astonishing and prominent properties of Quantum Mechanics, such as entanglement and Bell nonlocality, have only been studied extensively in dedicated low-energy laboratory setups. The feasibility of these studies in the high-energy regime explored by particle colliders was only recently shown and has gathered the attention of the scientific community. For the range of particles and fundamental interactions involved, particle colliders provide a novel environment where quantum information theory can be probed, with energies exceeding by about 12 orders of magnitude those employed in dedicated laboratory setups. Furthermore, collider detectors have inherent advantages in performing certain quantum information measurements, and allow for the reconstruction of the state of the system under consideration via quantum state tomography. Here, we elaborate on the potential, challenges, and goals of this innovative and rapidly evolving line of research and discuss its expected impact on both quantum information theory and high-energy physics.

    hep-phhep-exquant-phEur.Phys.J.Plus(2025)·75 citations
29. 29*

    Flavored Peccei-Quinn symmetries in the minimal $\nu$DFSZ model

    J. R. Rocha🇵🇹 · H. B. Câmara🇵🇹 · F. R. Joaquim🇵🇹

    We consider a Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axion model extended with two right-handed neutrino fields to realize the minimal type-I seesaw. In this $\nu$DFSZ scheme we systematically determine the simplest quark and lepton flavor patterns compatible with masses, mixing and charge-parity violation data, realized by flavored U(1) Peccei-Quinn (PQ) symmetries. We discuss axion dark matter production in pre and post-inflationary cosmology in this context, and predictions for the axion couplings to photons and fermions. In particular, helioscopes and haloscopes are able to probe our models via their distinct axion-to-photon couplings, while in the quark sector the most stringent constraints on axion-fermion couplings are set by $K^{+}\to {\pi }^{+}+a$. Flavor-violating constraints in the lepton sector are not as relevant as those stemming from star cooling that restrict the diagonal $ee$ and $\mu \mu$ axion couplings to charged leptons. We also obtain axion mass bounds for the most interesting models and discuss how minimal flavored PQ symmetries provide a natural framework to suppress flavor-violating couplings.

    hep-phPRD(2025)·7 citations
30. 30*

    Atoms as Electron Accelerators for New Physics Searches

    Fernando Arias-Aragón🇮🇹 · Giovanni Grilli di Cortona🇮🇹 · Enrico Nardi🇮🇹 · Léo Veissière🇫🇷

    Due to Heisenberg's uncertainty principle, atomic electrons localized around the nucleus exhibit a characteristic momentum distribution that, in elements with high atomic number, remains significant up to relativistic values. Consequently, in fixed-target experiments, atoms can effectively act as electron accelerators, increasing the centre-of-mass energy in collisions with beam particles. In this work, we leverage this effect to explore its potential for new physics searches. We consider positrons from beams of various energies annihilating with atomic electrons in a ${}^{74}$W fixed target. We compute the production rates of new vector bosons and pseudoscalar particles as functions of their couplings and masses. We show that the electron-at-rest approximation significantly underestimates the mass reach for producing these new states compared to the results obtained by properly accounting for atomic electron momenta. In particular, we estimate the sensitivity for detecting these new particles using the positron beam at the Beam Test Facility linac at the Laboratori Nazionali di Frascati, the H4 beamline in the CERN North Area, and the proposed Continuous Electron Beam Accelerator Facility of Jefferson Laboratory.

    hep-phhep-exJHEP(2025)·3 citations
31. 31*

    Open quantum system approach to inclusive jet production in heavy-ion collisions

    Yacine Mehtar-Tani🇺🇸 · Felix Ringer🇺🇸 · Balbeer Singh🇺🇸 · Varun Vaidya🇺🇸

    We derive a factorization formula for inclusive jet production in heavy-ion collisions using the tools of Effective Field Theory (EFT). We show how physics at widely separated scales in this process can be systematically separated by matching to EFTs at successively lower virtualities. Owing to a strong scale separation, we recover a vacuum-like DGLAP evolution above the jet scale, while the additional low-energy scales induced by the medium effectively probe the internal structure of the jet. As a result, the cross section can be written as a series with an increasing number of subjets characterized by perturbative matching coefficients each of which is convolved with a {\it distinct} function. These functions encode broadening, medium-induced radiations as well as quantum interference such as the Landau-Pomeranchuk-Migdal effect and color coherence dynamics to all orders in perturbation theory. As a first application of this EFT framework, we investigate the case of an unresolved jet and show how the cross section can be factorized and fully separate the jet dynamics from the universal physics of the medium. To compare to the existing literature, we explicitly compute the medium jet function at next-to-leading order in the coupling and leading order in medium opacity.

    hep-phnucl-exnucl-thJHEP(2026)·11 citations
32. 32*

    Axion forces in axion backgrounds

    Yuval Grossman🇺🇸 · Bingrong Yu🇺🇸 · Siyu Zhou🇺🇸

    Axions can naturally be very light due to the protection of an (approximate) shift symmetry. Because of their pseudoscalar nature, the long-range force mediated by the axion at tree level is spin dependent, which cannot lead to observable effects between two unpolarized macroscopic objects. At the one-loop level, however, the exchange of two axions does mediate a spin-independent force. This force is coherently enhanced in the presence of an axion background. In this work, we study the two-axion exchange force in a generic axion background. We find that the breaking of the axion shift symmetry plays a crucial role in determining this force. The background-induced axion force $V_{\mathrm{bkg}}$ vanishes in the shift-symmetry restoration limit. The shift symmetry can be broken either explicitly by non-perturbative effects or effectively by the axion background. When the shift symmetry is broken, $V_{\mathrm{bkg}}$ scales as $1/r$ and could be further enhanced by a large occupation number of the background axions. We investigate possible experimental probes of this effect in two distinct scenarios: an axion dark matter background and a solar axion flux, using fifth-force searches and atomic spectroscopy experiments. In the axion dark matter case, we find that the background-induced axion force can place strong constraints on axion couplings and masses, comparable to existing astrophysical bounds.

    hep-phastro-ph.COhep-thJHEP(2026)·27 citations
33. 33*

    Verifiable type-III seesaw and dark matter in a gauged $\mathbf{U}(1{)}_{\mathrm{B}-\mathrm{L}}$ symmetric model

    Satyabrata Mahapatra🇰🇷 · Partha Kumar Paul🇮🇳 · Narendra Sahu🇮🇳 · Prashant Shukla🇮🇳

    We propose a new extension of the Standard Model that incorporates a gauged \( U(1)_{\rm B-L} \) symmetry and the type-III seesaw mechanism to explain neutrino mass generation and provide a viable dark matter (DM) candidate. Unlike the type-I seesaw, the type-III seesaw extension under \( U(1)_{\rm B-L} \) is not automatically anomaly-free. We show that these anomalies can be canceled by introducing additional chiral fermions, which naturally emerge as DM candidates in the model. We thoroughly analyze the DM phenomenology, including relic density, direct and indirect detection prospects, and constraints from current experimental data. Furthermore, we explore the collider signatures of the model, highlighting the enhanced production cross-section of the triplet fermions mediated by the \( \rm B-L \) gauge boson, as well as the potential disappearing track signatures. Additionally, we investigate the gravitational wave signals arising from the first-order phase transition during \( \rm B-L \) symmetry breaking, offering a complementary cosmological probe of the framework.

    hep-phastro-ph.COhep-thEPJC(2026)·3 citations
34. 34*

    United States Early Career Researchers in Collider Physics input to the European Strategy for Particle Physics Update

    Oz Amram🇺🇸 · Grace Cummings🇺🇸

    This document represents a contribution of the United States early career collider physics community to the 2025--2026 update to the European Strategy for Particle Physics. Preferences with regard to different future collider options and R&D priorities were assessed via a survey. The early career community was defined as anyone who is a graduate student, postdoctoral researcher, untenured faculty member, or research scientist under 40 years of age. In total, 105 participants responded to the survey between February and March 10th, 2025. Questions were formulated primarily to gauge the enthusiasm and preferences for different collider options in line with the recommendations of the United States' P5 report, relevant to the European Strategy Update.

    ↳ hep-exhep-phphysics.acc-phphysics.ins-det3 citations
35. 35*

    Separating non-collective effects in d-Au collisions

    Satya Ranjan Nayak🇮🇳 · Akash Das🇮🇳 · B.K. Singh🇮🇳

    In this work, we present the multiplicity and yield of charged hadrons and particle ratios in d-Au collisions at $\sqrt{s_{NN}}=200$ GeV using the PYTHIA8/Angantyr. The model reproduces the multiplicity ($N_{ch}$) and pseudo-rapidity distribution reasonably well in minimum-biased d-Au collisions without assuming the formation of a thermalized medium. The invariant yield from Angantyr underpredicts the data in central collisions. We discussed the similarity between the nuclear modification factor $R_{AA}$ and data/MC from Angantyr and the possibility of using it as a model-dependent observable to check in-medium effects. The data/MC suggests that the central d-Au collisions exhibit signals like baryon enhancement, but no high $p_T$ suppression was found. The d-Au collisions have a much smaller invariant yield than the thermal model calculation for similar $N_{part}$.

    ↳ nucl-thhep-phEPJC(2026)·2 citations
36. 36*

    Quantum signatures and decoherence during inflation from deep subhorizon perturbations

    Francescopaolo Lopez🇮🇹 · Nicola Bartolo🇮🇹

    In order to shed light on the quantum-to-classical transition of the primordial perturbations in single field inflation, we investigate the decoherence and associated quantum corrections to the correlation functions of superhorizon scalar curvature perturbations. The latter are considered as an open quantum system which undergoes quantum decoherence induced by a time-dependent environment of deep subhorizon tensorial modes through the trilinear interactions predicted by General Relativity. We first prove that, in full generality, a time dependent subhorizon environment can be relevant for decoherence during inflation, by considering derivativeless interactions, which, in our case, give the most important results. For the first time, the time dependence of the environment is properly taken into account by modifying the quantum master equation. Important non-Markovian effects pop up, instead, when dealing with derivative interactions. We adopt a possible way to treat them which has been recently proposed and seems well suited for our case. Our results show that when considering the interplay between derivativeless and derivative interactions, decoherence is slowed down. This underlines the importance of accounting for all the interactions in open quantum-system calculations in an inflationary setting. We finally compute the quantum corrections to cosmological correlation functions, by solving the transport equations induced by the quantum master equation. We also compare the results to the solutions obtained by an alternative method previously used in the literature. We observe a resummation of the quantum corrections to the power-spectrum, which is a general property of quantum master equations. We extend these results to the bispectrum, showing a decay of this correlation function in time which is analogous to the one found, previously, for the power-spectrum.

    ↳ astro-ph.COgr-qchep-phhep-th+1JCAP(2026)·29 citations
37. 37*

    New constraints on interacting dark energy from DESI DR2 BAO observations

    Emanuelly Silva🇧🇷 · Miguel A. Sabogal🇧🇷 · Mateus Scherer🇧🇷 · Rafael C. Nunes🇧🇷 · Eleonora Di Valentino🇬🇧 · Suresh Kumar🇮🇳

    In its second data release (DR2), the Dark Energy Spectroscopic Instrument (DESI) publicly released measurements of Baryon Acoustic Oscillations (BAO) from over 13.1 million galaxies and 1.6 million quasars, covering the redshift range $0.295\le z\le 2.330$. In this work, we investigate the impact of this new dataset on dark sector interaction models, which are motivated by non-gravitational interactions between dark energy (DE) and dark matter (DM), commonly referred to as interacting dark energy models (IDE). We focus on two frameworks: the traditional IDE model and the recently proposed sign-switching Interacting model (S-IDE), aiming to derive new and robust constraints on both scenarios. After carefully selecting the sample for the joint analysis, ensuring compatibility among the data without significant tension, our main results indicate that both models can alleviate the $H_0$ tension, reducing it to moderate tension approximately $2.7\sigma$. The IDE model shows compatibility with the latest $S_8$ constraints from cosmic shear surveys, while the S-IDE model predicts lower values of $S_8$, which align with alternative perspectives on the $S_8$ tension. For the traditional IDE model, we derive new bounds for the coupling parameter, marking the strongest constraints to date through geometric measurements. This highlights the crucial role that supernova samples can play in refining these constraints. For the S-IDE model, we find mild evidence (over $2\sigma$) for a non-zero coupling, once the PantheonPlus dataset calibrated with Cepheid-based magnitude measurements is included in the analysis.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·144 citations
38. 38*

    Quantum Simulations of Fundamental Physics

    Martin J. Savage🇺🇸

    Simulating the dynamics of non-equilibrium matter under extreme conditions lies beyond the capabilities of classical computation alone. Remarkable advances in quantum information science and technology are profoundly changing how we understand and explore fundamental quantum many-body systems, and have brought us to the point of simulating essential aspects of these systems using quantum computers. I discuss highlights, opportunities and the challenges that lie ahead.

    ↳ nucl-thhep-lathep-phquant-phPoS(2026)·3 citations
39. 39*

    Bayesian method for quantifying the non-Gaussian fluctuations in low-intermediate energy heavy ion collisions

    Xinyu Wang🇨🇳 · Xiang Chen🇨🇳 · Junping Yang🇨🇳 · Ying Cui🇨🇳 · Zhuxia Li🇨🇳 · Kai Zhao🇨🇳 · Yingxun Zhang🇨🇳

    In this work, we present a model-independent method to quantify the non-Gaussian fluctuations in the observable distributions, which are assessed by the difference between the measured observable distributions and reconstructed observable distributions via the Bayesian method. Our results indicate that the strength of non-Gaussian fluctuation increases with the beam energy, and is primarily driven by non-central collision mechanisms. The experimental measurement of the strength of non-Gaussian fluctuation of the observable distributions will provide valuable insights into understanding the nonequilibrium effects in heavy ion collisions and the liquid-gas phase transition in finite nuclei.

    ↳ nucl-thhep-exhep-phnucl-exPLB(2025)·0 citations
40. 40*

    United States Muon Collider Community White Paper for the European Strategy for Particle Physics Update

    A. Abdelhamid (University of Tennessee) · D. Acosta (Rice University) · P. Affleck (University of Florida) · G. Agarwal (University of Notre Dame) · K. Agashe (University of Maryland) · P. Agrawal (University of Oxford) · R. Alharthy (University of Wisconsin) · B. Allmond (Kansas State University) · D. Ally (University of Tennessee) · G. Ambrosio (Fermilab) · O. Amram (Fermilab) · A. Apresyan (Fermilab) and 293 other authors

    This document is being submitted to the 2024-2026 European Strategy for Particle Physics Update (ESPPU) process on behalf of the US Muon Collider community, with its preparation coordinated by the interim US Muon Collider Coordination Group. The US Muon Collider Community comprises a few hundred American scientists. The purpose of the document is to inform ESPPU about the US plans for Muon Collider research and development (R&D), explain how these efforts align with the broader international R&D initiatives, and present the US community vision for the future realization of this transformative project.

    ↳ hep-exhep-ph9 citations
41. 41*

    On an approach to canonicalizing elliptic Feynman integrals

    Jiaqi Chen🇨🇳 · Li Lin Yang🇨🇳 · Yiyang Zhang🇨🇳

    We present generic expressions for the integrands of canonical bases under maximal cut in elliptic Feynman integral families with multiple kinematic scales. Such integrals frequently arise in phenomenologically relevant scattering processes. The derivation of our results starts from the Legendre normal form of elliptic curves, where the geometric properties of the curves are simple and explicit, and further kinematic singularities are presented as marked points. The simplicity of the normal form allows a straightforward construction of canonical bases with an arbitrary number of marked points. They can then be mapped into any univariate elliptic integral families via an appropriate Möbius transformation, leading to universal expressions for the integrands. As a demonstration, we discuss the application of our method to several concrete examples, including two new integral families whose canonical bases were not available in the literature. In several examples, we derive canonical bases for the full integral families without any cuts, demonstrating the simplicity of the sub-sector dependence of our canonical bases.

    ↳ hep-thhep-phJHEP(2026)·20 citations
42. 42*

    Classification of Modular Symmetries in Non-Supersymmetric Heterotic String theories

    Shuta Funakoshi🇯🇵 · Yuichi Koga🇯🇵 · Hajime Otsuka🇯🇵

    We study modular symmetries in non-supersymmetric heterotic string theories on toroidal backgrounds with Wilson line modulus, constructed by stringy Scherk-Schwartz compactification. In particular, we focus on a subgroup of the T-duality group $O(D+16,D,\mathbb{Z})$ with $D=2$ given by an outer automorphism of the Narain lattice, which can be mapped to the Siegel modular group $\mathrm{Sp}(4,\mathbb{Z})$. We classify the modular symmetries and a $CP$-like symmetry on $T^2$ and its orbifolds with symmetric and asymmetric orbifold twists. It turns out that the non-supersymmetric heterotic string theories only enjoy a part of modular symmetries in contrast to supersymmetric ones. Furthermore, the gauge symmetry is maximally enhanced at fixed points of modular symmetries on $T^2$ on which we analyze the vacuum structure of eight-dimensional tachyon-free vacua.

    ↳ hep-thhep-phJHEP(2026)·6 citations
43. 43*

    Nuclear clustering process in heavy-ion collisions : experimental constraints on the low-temperature region of the QCD phase diagram

    E. Bonnet🇫🇷 · B. Borderie🇫🇷 · R. Bougault🇫🇷 · A. Chbihi🇫🇷 · Q. Fable🇫🇷 · J.D. Frankland🇫🇷 · D. Gruyer🇫🇷 · M. La Commara🇮🇹 · A. Le Fèvre🇩🇪 · N. Le Neindre🇫🇷 · I. Lombardo🇮🇹 · J. Łukasik🇵🇱 and 3 other authors

    In this article, we study the production of Hydrogen and Helium isotopes in heavy-ion collisions in the incident energy range between 80 and 150 MeV/nucleon. We compare their inclusive multiplicities emitted in the transverse plane of the reaction with the predictions given by the thermal model. As a first step, we validate the choice of this approach to describe the experimental measurements. We also show that the transient states have to be explicitly taken into account for a good statistical description of the experimental multiplicities. From the thermodynamical parameter values obtained we complete the existing database built with the use of thermal-statistical models to reproduce particle production in the (ultra-)relativistic-energy measurements. We then proposed a new constraint on the so-called freeze-out region in the temperature (T) versus baryonic chemical potential (muB) phase diagram of the quantum chromodynamics. These new results indicate that there is a common framework to describe the hadron production and nuclear clustering processes in heavy-ion collisions.

    ↳ nucl-thhep-phnucl-exPRC(2025)·4 citations
44. 44*

    Science4Peace: A Plea for Continued Peaceful International Scientific Cooperation (Input to the European Strategy for Particle Physics -- 2026 update)

    A. Ali🇨🇦 · M. Barone · D. Britzger🇩🇪 · A. Cooper-Sarkar🇬🇧 · J. Ellis🇬🇧 · S. Franchoo🇫🇷 · A. Giammanco🇧🇪 · A. Glazov🇩🇪 · H. Jung🇩🇪 · D. Käfer🇩🇪 · J. List🇩🇪 · L. Lönnblad🇸🇪 and 7 other authors

    The European Strategy for Particle Physics (ESPP) - 2026 update is taking place in a turbulent international climate. Many of the norms that have governed relations between states for decades are being broken or challenged. The future progress of science in general, and particle physics in particular, will depend on our ability to maintain peaceful international scientific collaboration in the face of political pressures. We plead that the ESPP 2026 update acknowledge explicitly the importance of peaceful international scientific collaboration, not only for the progress of science, but also as a precious bridge between geopolitical blocs. "Scientific thought is the common heritage of mankind" - Abdus Salam

    ↳ physics.soc-phhep-exhep-phhep-th0 citations
45. 45*

    Physics case for low-$\sqrt{s}$ QCD studies at FCC-ee

    David d'Enterria🇨🇭 · Pier Francesco Monni🇨🇭 · Peter Skands🇦🇺 · Andrii Verbytskyi🇩🇪

    Measurements of hadronic final states in $e^{+}{e}^{-}$ collisions at centre-of-mass (CM) energies below the Z peak can notably extend the FCC-ee physics reach in terms of precision quantum chromodynamics (QCD) studies. Hadronic final states can be studied over a range of hadronic energies $\sqrt{s_{\mathrm{had}}}\approx 20\text{mbox}--80\mathrm{GeV}$ by exploiting events with hard initial- and final-state QED radiation (ISR/FSR) during the high-luminosity Z-pole run, as well as in dedicated short (about one month long) $e^{+}{e}^{-}$ runs at CM energies $\sqrt{s}\approx 40\mathrm{GeV}$ and $60\mathrm{GeV}$. Using realistic estimates and fast detector simulations, we show that data samples of about $10^9$ hadronic events can be collected at the FCC-ee at each of the low-CM-energy points. Such datasets can be exploited in a variety of precision QCD measurements, including studies of light-, heavy-quark and gluon jet properties, hadronic event shapes, fragmentation functions, and nonperturbative dynamics. This will offer valuable insights into strong interaction physics, complementing data from nominal FCC-ee runs at higher center-of-mass energies, $\sqrt{s}\approx 91,160,240,$ and $365\mathrm{GeV}$.

    ↳ hep-exhep-phhep-thSciPost Phys.(2026)·8 citations
46. 46*

    Modelling Gaia photometry signals of dark halos

    George Pappas🇬🇷 · Ippocratis D. Saltas🇨🇿 · Laurent Eyer🇨🇭

    We use the framework of microlensing to show that observations of binary systems, such as those made by {\it Gaia}, combined with follow-up weak lensing measurements, can provide a means to probe halos of exotic matter, possibly clumped around compact objects such as black holes. This could potentially cover a broad range of physical scenarios - from dark matter mini-halos to black holes with bosonic configurations around them, known as hair. In a dark halo-regular star binary system, assuming that light can freely propagate through the halo of the exotic matter, the companion star will produce characteristic, sizable lensing signatures due to the lens's potential deviating from a point mass gravitational potential. The signature of the multiple images, the magnification and the light-curve could be the smoking gun of such a dark halo structure. We discuss how the precise observations of the {\it Gaia} survey offer an opportunity to search for new, yet undiscovered fundamental fields interacting gravitationally with baryons.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·1 citation
47. 47*

    Exclusion of a diquark-antidiquark structure for the lightest positive-parity charmed mesons

    Eric B. Gregory🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Stefan Krieg🇩🇪 · Thomas Luu🇩🇪

    The nature of low-lying scalar and axial-vector charmed mesons has been debated for decades, with hadronic molecular and compact tetraquark models being prominent candidates. These two models predict quite different features for the accessible SU(3) multiplets in the scalar and axial-vector sectors, which can be tested through lattice calculations at SU(3) symmetric points. In this work, we perform lattice calculations for both scalar and axial-vector charmed mesons with an SU(3) symmetric pion mass about 613 MeV for the SU(3) $[6]$ and $[\overline{15}]$ multiplets. We find that the $[6]$ multiplet exhibits attractive interactions in both scalar and axial-vector sectors, while the $[\overline{15}]$ multiplet shows repulsive interactions in both sectors. The energy shifts in the scalar and axial-vector sectors are compatible with each other within uncertainties. These results are fully consistent with the hadronic molecular picture, while challenging the compact tetraquark model, which predicts the existence of low-lying $[\overline{15}]$ states in the axial-vector sector but not in the scalar sector.

    ↳ hep-lathep-phEPJA(2025)·12 citations
48. 48*

    Dynamics of Spinning Test Body in quadratic Einstein-Cartan Theory and its Free-fall Test

    Kun Hu🇨🇳 · Zhiyuan Yu🇨🇳 · Taotao Qiu🇨🇳 · Zhongkun Hu🇨🇳

    We study the dynamics of the non-relativistic spinning test body (STB) in the framework of Einstein-Cartan theory(ECT), in which the weak equivalence principle is violated by the spin-gravitational interaction. We derive the general equation of geodesic in terms of comoving tetrads. More concretely, we consider the case of the quadratic form of the lagrangian, within the environment of weak and static spherically symmetric space-time. We find that the trajectories of STB deviate from the traditional Mathisson\textendash Papapetrou equation, which is due to the coupling of the spin of the test particle to the torsion field of the environment. This allows us to test the theory with free-fall experiment in the laboratory, such as atom interferometer. By using the previous data, we find the upper bound of the possible torsion field on Earth is given by up to $2.0\times 10^1{\mathrm{m}}^{-1}$ and torsion gradient up to $3.1\times 10^{-6}{\mathrm{m}}^{-2}$. This result may enable us to provide a theoretical foundation for future precision measurements of the existence of the fifth force.

    ↳ gr-qchep-phhep-thphysics.atom-ph+1PRD(2025)·3 citations
49. 49*

    The Belle II Experiment at SuperKEKB -- Input to the European Particle Physics Strategy

    The Belle II Collaboration

    Belle II is an intensity-frontier experiment at the SuperKEKB collider in Tsukuba, Japan. Over the coming decades, it will record the decays of billions of bottom mesons, charm hadrons, and tau leptons produced in 10 GeV electron-positron collisions. The experiment's low-background environment and precisely known kinematics enable high-precision measurements of hundreds of Standard Model (SM) parameters while probing for new particles at mass scales far beyond the direct reach of high-energy colliders. We project Belle II's sensitivity for key measurements - where it will be uniquely positioned or world-leading - over datasets ranging from 1 to 50 ab${}^{-1}$. By exploring previously uncharted regions of non-SM parameter space with high precision, Belle II will either reveal new physics or set stringent constraints, guiding future experimental and theoretical efforts. Additionally, we outline near-term upgrades to the Belle II detector and SuperKEKB accelerator, which will enhance sensitivity in searches for new physics beyond the SM across flavor, tau, electroweak, and dark sector physics. These improvements will ensure that Belle II remains both complementary to and competitive with the LHC and other experiments.

    ↳ hep-exhep-ph9 citations
50. 50*

    Current status of real-time imaging of antiproton annihilation in biological targets

    Zlatko Dimcovski · Michael Doser🇨🇭

    Following a successful pioneering study of the biological effects of antimatter ( the AD-4/ACE experiment at CERN), the use of antiprotons in clinical radiotherapy became a very serious possibility. A major part of any future radiotherapy using antiprotons will be real-time imaging of antiproton annihilation in biological targets. In principle, real-time imaging is possible thanks to the secondary particles, neutral pions and charger pions, produced by the annihilation of antiprotons in the cells they come to a stop in.Neutral pions decay dominantly and almost instantaneously into a photon pair, and one approach to real-time imaging is based on the detection of these high-energy gammas. An alternative is based on the detection of charged pions, which have lifetimes almost a billion times longer than neutral pions. This paper is a brief review of this field of research, from the first real-time imaging achieved by the AD-4/ACE experiment in 2004 to the present day.

    ↳ physics.med-phhep-ph1 citation
51. 51*

    Worldvolume fermion as baryon with homogeneous instantons in holographic ${\mathrm{QCD}}_3$

    Si-wen Li🇨🇳 · Xiao-tong Zhang🇨🇳

    (ArXiv version) We investigate holographically the effective theory of the worldvolume fermion on the flavor branes in the D3/D7 model with homogeneously smeared D(-1)-branes. As a top-down approach in gauge-gravity duality, the D(-1)-branes are instantons and violate the CP symmetry in the dual theory. In the confined geometry, we introduce a baryon vertex as a D5-brane wrapped on $S^5$, then identify the fermionic fluxes produced by the $N_c$ open strings on the D7-brane as a baryonic operator. Afterwards, we study the spectrum and the holographic correlation function of the baryonic fermion on the D7-branes. Remarkably, the fermionic spectrum is in agreement with the dispersion curves obtained from the confined correlation function, and the mass ratio of the lowest baryon and meson in our model is close to the associated experimental data. Moreover, the effective interaction terms of the holographic baryon and meson are derived and all the coupling constants take order of $N_c^{1/2}$ agreeing with the evaluation from the large $N_c$ field theory. In the deconfined geometry, the holographic correlation function is also evaluated numerically while the fermion on D7-brane is identified to plasmino instead of baryon. The dispersion curves from the deconfined correlation function basically covers the results from the hard thermal loop approximation and may imply the instanton-induced interaction with spin. Overall, this work constructs a holographic theory about baryonic fermion and mesonic boson with instantons or CP violation.

    ↳ hep-thhep-phnucl-thPRD(2025)·4 citations
52. 52*

    Massive Black Holes Seeded by Dark Matter -- Implications for Little Red Dots and Gravitational Wave Signatures

    Tingwei Shen🇨🇳 · Xuejian Shen🇺🇸 · Huangyu Xiao🇺🇸 · Mark Vogelsberger🇺🇸 · Fangzhou Jiang🇨🇳

    Observations of supermassive black holes (SMBHs) at high redshifts challenge standard seeding scenarios. We examine a dissipative self-interacting dark matter (dSIDM) model in which gravothermal collapse leads to the formation of massive BH seeds ab initio. We utilize a semi-analytical framework to predict properties of the dSIDM-seeded SMBH population. Billion solar mass quasars are reproduced along with low-mass faint active galactic nuclei (known as little red dots) with SMBH-to-galaxy stellar mass ratios consistent with recent James Webb Space Telescope observations. To match the abundance of the observed bright quasars, a percent-level duty-cycle is suggested, implying a large population of dormant SMBHs. The gravitational wave (GW) signals from mergers of these massive SMBHs can be detected by LISA while remaining within the NANOGrav constraints on the GW background. These results provide testable signatures of DM-driven SMBH formation, offering a pathway to probe hidden-sector physics through SMBH and GW observables.

    ↳ astro-ph.GAastro-ph.COhep-phPRD(2026)·21 citations
53. 53*

    French HEP community input to the European Strategy for Particle Physics

    Yasmine Amhis🇫🇷 · Jeremy Andrea🇫🇷 · Etienne Augé🇫🇷 · Sara Bolognesi🇫🇷 · Maarten Boonekamp🇫🇷 · Samuel Calvet🇫🇷 · Emilien Chapon🇫🇷 · Didier Contardo🇫🇷 · Fabrice Couderc🇫🇷 · Sabine Crépé-Renaudin🇫🇷 · Louis D'Eramo🇫🇷 · Cristinel Diaconu🇫🇷 and 14 other authors

    In view of the European Strategy for Particle Physics process, the French HEP community has organized a national process of collecting written contributions and has pursued a series of workshops culminating with a national symposium held in Paris on January 20-21, 2025 that involved over 280 scientists https://indico.in2p3.fr/event/34662/. The present document summarises the main conclusions of this bottom-up approach centred on the physics and technology motivations.

    ↳ hep-exhep-lathep-phhep-th0 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.