Fri·Nov 14, 2025Friday·November 14, 2025

1. 01*

   The Unresolved Behaviour of Polarized Scattering Matrix Elements at NNLO in QCD

   Thomas Gehrmann🇨🇭 · Markus Löchner🇨🇭

   Spin asymmetries in collisions of spin-polarized hadrons probe polarized parton distributions, which encode the spin structure of the colliding hadrons. To perform precision physics studies with spin asymmetries, higher order QCD corrections to the underlying polarized cross sections are required. Their numerical implementation relies on the use of an infrared subtraction scheme, which extracts the infrared singular pieces from the real and virtual subprocesses. We derive the universal behaviour of longitudinally polarized real radiation matrix elements in their infrared-singular limits up to next-to-next-to-leading order (NNLO) in QCD, thereby enabling the construction of infrared subtraction schemes for generic polarized cross sections at NNLO.

   hep-phJHEP(2026)·4 citations
2. 02*

   CP violation

   Alexey A Petrov🇺🇸

   CP violation, which involves breaking the combined charge-conjugation (C) and parity (P) symmetries, is essential for understanding the observed matter-antimatter asymmetry in the universe. It is a key feature of the Standard Model, originating from complex phases in the Cabibbo-Kobayashi-Maskawa quark mixing matrix. Despite the successes of the SM, the amount of CP violation it predicts is not enough to explain baryogenesis, prompting searches for new sources of CP violation in other areas of particle physics. This article offers a pedagogical introduction to the theoretical foundations of C, P, and T symmetries and their combinations. It also emphasizes the importance of CP violation in modern particle physics and how it can be used to explore New Physics.

   hep-phhep-exnucl-th0 citations
3. 03*

   Searching for screened scalar forces with long-baseline atom interferometers

   Hannah Banks🇬🇧 · John Carlton🇬🇧 · Benjamin Elder🇬🇧 · Thomas Hird🇬🇧 · Christopher McCabe🇬🇧

   Screened scalars are ubiquitous in many dark-sector models. They give rise to non-trivial fifth forces whilst evading experimental constraints through density-dependent screening mechanisms. We propose equipping a 10\,m-scale long-baseline atom interferometer with an annular planar source mass inside the vacuum chamber to search for such screened fifth forces. Two key challenges arise: distinguishing the static fifth force from backgrounds, and isolating it from the plate's Newtonian gravity. We introduce the `$Q$-flip protocol', which alternates between interferometry sequences to induce controllable time-dependence, aiding signal extraction and de-trending of transient noise. We further develop an \emph{in situ} calibration procedure to characterise the plate's Newtonian gravity and reach shot-noise-limited sensitivity. We show that our proposal could test theoretically motivated parameter space, advancing existing bounds in chameleon and symmetron screened scalar models by $1$ to $1.5$ orders of magnitude. Our proposal is directly applicable to forthcoming experiments, such as AION-10 or VLBAI, and is readily extensible to broader theoretical models and longer baselines.

   hep-phastro-ph.COgr-qcphysics.atom-phPRD(2026)·3 citations
4. 04*

   Semi-visible higgs decay as a probe for new invisible particles

   Sally Dawson🇺🇸 · Arnab Roy🇦🇺 · German Valencia🇦🇺

   We discuss the HL-LHC sensitivity to probe new invisible particles including scalars and fermions using semi-visible Higgs decays in the $pp\to ZH,Z\to jj({\ell }^{+}{\ell }^{-}),H\to {\ell }^{+}{\ell }^{-}(jj)+\mathrm{E}{/}_{\mathrm{T}}$ production mode. The kinematics of these decays allow new particle masses below $m\lesssim 50$ GeV. We carry out our analysis using both a cut-based approach and a multivariate method based on a boosted decision tree. We work within the dark-SMEFT framework with operators up to dimension six and a discrete ${\mathbb{Z}}_2$ symmetry under which the new particles are odd and the SM particles are even. We compare our results to those obtained from considering the invisible $Z$-width, as well as perturbative unitarity arguments. Finally, we outline kinematic strategies at the LHC to distinguish different operator structures of the postulated invisible particles.

   hep-phPRD(2026)·3 citations
5. 05*

   Beam polarization precision requirements for future $e^{+}{e}^{-}$ Higgs factories

   Brendon Madison🇺🇸

   We present work on quantifying the minimum requirements for beam polarization precision at future $e^{+}{e}^{-}$ Higgs factories. We find that, under the assumption of a high electron beam polarization ($P_{-}$) that the positron polarization ($P_{+}$) is of key importance but for reasons both known and newly discovered. We have discovered that improved positron polarization leads to a less strict requirement on the beam polarization precision for measurements that scale only with the effective polarization, $P_{\mathrm{eff}}$. Conversely, measurements that scale with the product of beam polarizations, $P_{-}{P}_{+}$, such as those that contain the $eeZ$ or $ee\gamma$ vertex, have their polarization precision demands get more strict as positron polarization increases. We check the polarization precision demands for $10^{-3}$ on the Higgsstrahlung cross-section (${\sigma }_{ZH}$) at 250~GeV, $10^{-4}$ on the electron left-right asymmetry ($A_{\mathrm{e}}$) at the Z pole, and $10^{-4}$ on the di-photon cross-section (${\sigma }_{\gamma \gamma }$) from the Z pole to 3~TeV. We find that, for measurements away from the Z pole, the goals can plausibly be attained if one can achieve precision on beam polarization better than $0.1\%$. For measurements of $A_{\mathrm{e}}$ at $10^{-4}$, colliders must do better than $0.02\%$ on beam polarization precision, or determine ways to upgrade their beam polarization values towards unity, where the requirements decrease to better than $0.15\%$.

   hep-phhep-ex2 citations
6. 06*

   Sifting out the neutral and charged components of $X(3872)$ from a spin observable

   Ke Wang🇨🇳 · Yu-Fei Wang🇨🇳 · Bo-Chao Liu🇨🇳 · Fei Huang🇨🇳

   In this work, we propose a new method to detect the composition of the $X(3872)$ state. Based on a widely accepted interpretation that $X(3872)$ is a weakly bound $S$-wave molecule of the $D^{\ast 0}{\bar{D}}^0$ (neutral) and $D^{\ast +}{D}^{-}$ (charged) configurations, the process $X(3872)\to {\bar{D}}^{\ast 0}{D}^0$ is described by one-loop triangle diagrams with the corresponding components as intermediate particles, and with the parameters constrained by the experimental branching ratio. Unlike the mild behavior of the neutral component, the charged component manifests itself as a distinct structure near the $D^{\ast +}{D}^{-}$ threshold at $3.880$ GeV, in the $M_{{\bar{D}}^{\ast 0}{D}^0}$ invariant mass distribution of the spin density matrix element ${\rho }_{00}^{D^{\ast }}$. Hence the line shape of ${\rho }_{00}^{D^{\ast }}$ near this structure depends sensitively on the proportions of the two configurations. We propose high-precision measurements of this matrix element by future BESIII and Belle experiments to elucidate how a molecular $X(3872)$ state is composed.

   hep-phPRD(2025)·0 citations
7. 07*

   Masses of Purely Top-Quark Bound States: Toponium and the Triply-Top Baryon

   Z. Rajabi Najjar🇮🇷 · K. Azizi🇮🇷

   We investigate the pseudoscalar (${\eta }_t$) and vector (${\psi }_t$) toponium states, as well as the triply-top baryon (${\Omega }_{ttt}$), using the QCD sum-rule method. This study was motivated by the recent observation of a pseudoscalar enhancement near the $t\bar{t}$ threshold, reported by the CMS and ATLAS collaborations with a statistical significance exceeding $5\sigma$. In the calculations, we consider both the perturbative and nonperturbative contributions, with the nonperturbative operators taken into account up to dimension eight. The results obtained for the pseudoscalar toponium provide a theoretical estimate that is consistent with the near-threshold events observed in recent experimental studies. The calculated negative binding energy for both the pseudoscalar and vector toponium states reflects the strong correlation within the $t\bar{t}$ system and can be interpreted as $t\bar{t}$ bound states, while the calculated central mass for the ${\Omega }_{ttt}$ slightly exceeds the central value of the sum of the constituent top-quark masses. The results of this study can provide a precise theoretical guide for future experimental investigations of these states, which are composed entirely of top quarks, at high-energy colliders such as the LHC and future facilities like the FCC.

   hep-phhep-exhep-latEPJC(2026)·6 citations
8. 08*

   Trapped and Unstable: Axion-like particle fragmentation at finite temperature

   Nicklas Ramberg🇮🇹 · Daniel Schmitt🇩🇪

   We investigate the emergence of a resonant behavior in axion-trapped misalignment models featuring finite-temperature potential barriers. As the temperature decreases and the field is released from its trapped configuration, inhomogeneities are exponentially amplified through an instability in their equation of motion, leading to the fragmentation of the axion field. We show that this process constitutes a novel source of gravitational waves (GWs), analogous to those generated in zero-temperature axion fragmentation, but with distinct characteristics. We quantify the resulting GW spectrum, identifying the peak frequency and amplitude associated with the inhomogeneous axion dynamics. Our results indicate that the GW signal can be enhanced by up to two orders of magnitude compared to the standard fragmentation scenario, while exhibiting a markedly different spectral shape. The parameter space featuring both strong GW signals and reproducing the correct dark matter abundance is, however, limited.

   hep-phastro-ph.COPRD(2026)·1 citation
9. 09*

   Boosting long lived particles searches at $\mu$TRISTAN

   Daniele Barducci🇮🇹

   We study the prospects of the proposed $\mu$TRISTAN experiment, running in the energy asymmetric ${\mu }^{+}{e}^{-}$ mode, in probing long lived particles (LLPs) arising from the decay of the Standard Model Higgs boson. We focus on the proposed runs with $\{E_{{\mu }^{+}},E_{e^{-}}\}=\{1\mathrm{TeV},30\mathrm{GeV}\}$ and $\{E_{{\mu }^{+}},E_{e^{-}}\}=\{3\mathrm{TeV},50\mathrm{GeV}\}$ and we show that, owing to the boosted nature of the produced events, a far detector placed along the beam line can collect a large fraction of the LLP flux. This allows one to set bounds on the exotic Higgs branching ratio which, for specific $\varphi$ decay modes, can surpass those expected at the end of the High Luminosity LHC in the regime of large LLPs proper decay lengths. On the other hand, we find that the proposed strategy will not be able to further extend the limits that might be set by proposed LHC far detectors such as CODEX-b, ANUBIS and MATHUSLA.

   hep-phhep-exJHEP(2026)·2 citations
10. 10*

    Possible $K{\bar{K}}^{\ast }$ and $D{\bar{D}}^{\ast }$ resonances by solving Schrödinger equation

    Bao-Xi Sun · Qin-Qin Cao🇨🇳 · Ying-Tai Sun

    The one-pion exchange interaction between the kaon and the vector antikaon is investigated by solving the Schrödinger equation in the S-wave approximation. In addition to the particle $f_1(1285)$, another bound state of $K{\bar{K}}^{\ast }$ is obtained, which is approximately 9 MeV below the threshold of $K{\bar{K}}^{\ast }$ and labeled $f_1(1378)$ for convenience in this manuscript. Under the outgoing wave condition, two resonance states of $K{\bar{K}}^{\ast }$ are produced with different coupling constants fixed with the binding energies of $f_1(1285)$ and $f_1(1378)$, respectively. Both of the resonance states are located in the vicinity of 1400 MeV, and thus it is reasonable to assume that these two resonance states correspond to the $f_1(1420)$ particle in the review of the Particle Data Group simultaneously. This method is extended to study the $D{\bar{D}}^{\ast }$ system analogously. When the particle ${\chi }_{c1}(3872)$ is treated as a bound state of $D{\bar{D}}^{\ast }$, the particles $T_{c\bar{c}1}(3900)$, $T_{c\bar{c}}(4020)$ and $X(3940)$ can be obtained as solutions of the Schrödinger equation under the outgoing wave condition, which implies the spin and parity of these particles are all $J^P=1^{+}$.

    hep-phnucl-thPoS(2026)·0 citations
11. 11*

    High-Energy Decays and Weak Quantum Measurements

    Alan J. Barr🇬🇧

    High-energy particle decays naturally realise informationally weak measurements of quantum spin. Decay kinematics act as continuous pointer variables whose overlapping angular distributions encode partial, non-projective information about the parent spin state. Ensemble averages of these pointers yield weak values, linking collider spin-density reconstruction to Aharonov-Vaidman measurement theory. This framework unifies spin tomography, entangled-decay correlations, and spin-correlation algorithms, showing that relativistic decays realise informationally weak measurements of spin and suggesting new ways to probe coherence and interference in high-energy processes.

    hep-phhep-exquant-phEPJC(2026)·2 citations
12. 12*

    Probing thermal leptogenesis and dark matter through primordial gravitational waves from a supercooled universe

    Peter Athron🇨🇳 · Satyabrata Datta🇨🇳 · Zhao-Yang Zhang🇨🇳

    We explore the cosmological dynamics of a supercooled first-order phase transition in the classically conformal $U(1{)}_{B-L}$ extension of the Standard Model, where radiative symmetry breaking simultaneously generates the right-handed neutrino (RHN) masses, and a strong stochastic gravitational-wave (GW) background. The slow decay of the scalar field into RHNs can induce an early matter-dominated (EMD) era whose duration is sensitive to the RHN mass and gauge coupling $g^{\prime }$. This non-standard cosmological phase reshapes the GW spectrum and leaves a distinctive RHN-mass-dependent spectral distortion that correlates with the flavour regime of thermal leptogenesis. Within this framework, one RHN can serve as a dark matter candidate produced nonthermally from scalar decays, while the remaining states generate the baryon asymmetry via thermal leptogenesis. For $g^{\prime }=0.5$, we identify such a parameter region, and show that with singlet extensions, even with a smaller gauge coupling, one can realise this mechanism for the three-flavour regime. The resulting GW signals, amplified by supercooling and modified by EMD, provide a unique window to probe the scale and flavour structure of leptogenesis in future high-frequency GW observations.

    hep-phastro-ph.COhep-thJHEP(2026)·7 citations
13. 13*

    Primer of Strong-Field Quantum Electrodynamics for Experimentalists

    Annabel Kropf🇩🇪 · Ivo Schulthess🇩🇪

    This document serves as a conceptual and practical introduction to Strong-Field Quantum Electrodynamics (SFQED), written from the standpoint of experimental physicists. Rather than providing a comprehensive theoretical review, the document focuses on the core ideas, terminology, and challenges in SFQED that are most relevant to experimental design and interpretation. Our goal is to offer a first point of contact with the subject, bridging the gap between foundational theory and hands-on experimental work, and complementing more formal literature in the field.

    hep-phhep-exhep-thMDPI Physics(2026)·3 citations
14. 14*

    Hydrogen-like symmetry in Regge spectrum of light mesons: selection of states

    S.S. Afonin🇷🇺 · A.V. Sarantsev🇷🇺 · A.M. Tsymbal🇷🇺

    We discuss the $(L,n)$-classification of excited light non-strange mesons, where $L$ and $n$ are orbital and radial quantum numbers. The selection of true non-strange quark-antiquark excited states and assigning to them definite $L$ and $n$ is a notoriously confusing problem. Three guiding principles for selection of correct observed states are formulated. They are applied for construction of a new $(L,n)$-classification. This classification is consistent both with the approximate Regge form of the spectrum and with the hydrogen-like degeneracy, i.e., the dependence of mass on the sum $L+n$.

    hep-phPhys.Part.Nucl.(2026)·2 citations
15. 15*

    Revealing dipion correlations for the observed substructure near the ${\pi }^{+}{\pi }^{-}$ mass threshold in $\psi (3686)\to J/\psi {\pi }^{+}{\pi }^{-}$

    Zhong-Yu Wang🇨🇳 · Zhe Liu🇨🇳 · Xiang Liu🇨🇳

    Based on the world's largest $\psi (3686)$ data sample, the BESIII Collaboration recently reported a substructure near the ${\pi }^{+}{\pi }^{-}$ mass threshold in the decay $\psi (3686)\to J/\psi {\pi }^{+}{\pi }^{-}$, challenging the established understanding of the dipion invariant mass spectrum. We propose that this substructure arises directly from dipion correlations. Using a chiral unitary approach, we successfully reproduce the observed anomaly, thereby providing strong evidence of dipion correlation in heavy quarkonium decays. This approach also allows us to predict the corresponding dipion correlation function.

    hep-phPRD(2026)·2 citations
16. 16*

    Updated branching ratios and $CP$ asymmetries in $D\to PV$ decays

    Hui Zheng🇨🇳 · Jia-Rui Dong🇨🇳 · Si-Hong Zhou🇨🇳

    Motivated by extensive new high-precision experimental data, we present an updated analysis of the two-body charm decays $D\to PV$ (with $P=\pi ,K,{\eta }^{(\prime )}$ and $V=\rho ,K^{\ast },\omega ,\varphi$) within the factorization-assisted topological-amplitude (FAT) approach. In the framework, flavor SU(3) symmetry breaking effect is incorporated into the topological amplitudes, allowing the nonfactorizable contributions from topological diagrams to be expressed as a minimal set of universal parameters determined through a global fit to experimental data. Thanks to the sufficient data with high precision, we are now able to quantify the nonfactorizable contribution of so-called ``factorization" $T$ diagram, which is essential for explaining the observed branching ratios. The parameters for the $C$, $E$, and $A$ diagrams are also updated with significant improved precision, and notably, the resulting strong phases differ substantially from those in the earlier FAT analysis. We find that the $C$ topological amplitude features substantial nonfactorizable effects in the charm sector. These refined parameters enable predictions of significantly improved accuracy, yielding branching ratios in good agreement with current data and the latest results in topological diagram approach, and the predicted direct $CP$ asymmetries differ distinctly form previous FAT results due to updated strong phases. In several modes, the $CP$ asymmetries are predicted to reach $\mathcal{O}(10^{-3})$, thereby making them promising observables for future high-precision experiments at LHCb, BESIII and Belle II. Predictions for unobserved decay modes, especially those with branching fractions of order $10^{-4}\sim 10^{-3}$, are also provided for forthcoming experimental tests.

    hep-phPRD(2026)·3 citations
17. 17*

    Bubble Friction in Symmetry-Restoring Transitions

    Andrew J. Long🇺🇸 · Bibhushan Shakya🇩🇪 · Julia Anabell Ziegler🇩🇪

    In standard (symmetry-breaking) first-order phase transitions, the frictional pressure on expanding bubble walls can be dominated by transition radiation -- the emission of a gauge boson with phase-dependent masses as particles present in the thermal plasma pass through bubble walls. This process is enhanced in the soft limit, and is known to produce a significant frictional effect that is proportional to the Lorentz factor $\gamma$ of the bubble wall, thereby prohibiting runaway behavior. We calculate the analogous pressure for phase transitions with symmetry restoration. In such transitions, we show that the pressure due to this process can be $\text{negative}$, producing the opposite effect. However, when the Lorentz factor of the wall gets very large, the result approaches the same scaling as the standard scenarios. Therefore, phase transitions with symmetry restoration can feature an intermediate negative friction regime even in the presence of significant interactions with the plasma, and the bubble wall terminal Lorentz factor can be significantly larger (by more than an order of magnitude) than in the corresponding symmetry-breaking scenarios. This can carry important implications for various phenomenological applications, from gravitational waves to physics beyond-the-Standard-Model.

    hep-phastro-ph.COJHEP(2026)·4 citations
18. 18*

    Phenomenology of Non-Abelian Gauge and Goldstone Bosons in a U(2) Flavor Model

    Lorenzo Calibbi🇨🇳 · Jiangyi Yi🇨🇳

    We investigate the phenomenological implications of the bosons associated with the $SU(2{)}_F$ subgroup in a simple and realistic $U(2{)}_F$ flavor model. While the Nambu-Goldstone boson of the $U(1{)}_F$ factor behaves as a standard QCD axion (an axiflavon) with suppressed flavor-violating couplings, the three degrees of freedom from $SU(2{)}_F$ have not been studied before. This work focuses on these states, considering both the case where $SU(2{)}_F$ is a global symmetry, yielding pseudo-Nambu-Goldstone bosons (PNGBs), and the case where it is a gauge symmetry with a potentially small coupling, yielding a triplet of (possibly) light gauge bosons. In both scenarios, these new bosons naturally feature unsuppressed flavor-violating couplings to Standard Model fermions in the mass basis. We derive the resulting predictions for flavor-changing neutral currents and lepton flavor violation, including exotic decays of mesons and leptons. Our analysis shows that processes like $K\to \pi X$ and $\mu \to eX$ place the most stringent constraints, probing the flavor symmetry breaking scale $v_{\varphi }$ up to $10^{11}-10^{12}$~GeV for light bosons, while heavier states are tested in $B$ and $\tau$ decays, as well as by $K-\bar{K}$ mixing and $\mu \to e\gamma$. We demonstrate that low-energy flavor experiments provide a powerful probe of this framework, capable of testing ultra-high symmetry breaking scales that surpass the limits set by astrophysical observations.

    hep-phhep-exPRD(2026)·8 citations
19. 19*

    Toward a Comprehensive Exploration of Flavored Dark Matter Models

    Benedetta Belfatto🇩🇪 · Monika Blanke🇩🇪 · Jan Heisig🇩🇪 · Michael Krämer🇩🇪 · Lena Rathmann🇩🇪 · Felix Wilsch🇩🇪

    We present a comprehensive framework for the study of flavored dark matter models, combining relic density calculations with direct and indirect detection limits, collider constraints, and a global analysis of flavor observables based on SMEFT matching and renormalization-group evolution. The framework applies to scalar or fermionic dark matter, including both self-conjugate and non-self-conjugate cases. As a proof of principle, we analyze two scenarios with Majorana dark matter coupling to right-handed charged leptons and to right-handed down-type quarks, assuming a thermal freeze-out. In the leptophilic case, flavor-violating decays such as $\mu \to e\gamma$ dominate the constraints, while LHC searches still leave sizable parameter space. For quark couplings, direct detection bounds and meson mixing severely restrict the allowed couplings, favoring hierarchical flavor structures. The toolchain presented in this paper is publicly available on GitHub (https://github.com/lena-ra/Flavored-Dark-Matter).

    hep-phEPJC(2026)·6 citations
20. 20*

    A Fast Earth-scattering Formalism for Light Dark Matter with Dark Photon Mediators

    Agustín Lantero-Barreda🇪🇸 · Carlos Centeno-Lorca🇪🇸 · Bradley J. Kavanagh🇪🇸 · Núria Castello-Mor🇪🇸

    While Dark Matter (DM) is typically assumed to interact only very weakly with the particles of the Standard Model, many direct detection experiments are currently exploring regions of parameter space where DM can have a large scattering cross section. In this scenario, DM may scatter in the atmosphere and Earth before reaching the detector, leading to a distortion of the DM flux and a daily modulation of the signal rate as the detector is shielded by more or less of the Earth at different times of day. This modulation is a distinctive signature of strongly-interacting DM and provides a powerful method of discriminating against time-independent backgrounds. However, the calculation of these Earth-scattering effects by Monte Carlo methods is computationally intensive, inhibiting a systematic exploration of the DM parameter space. Here, we present a semi-analytic formalism for calculating Earth-scattering effects, for models of MeV-mass DM which interacts via a dark photon mediator, and release the associated code Verne2. This formalism assumes that DM travels along straight-line trajectories until it scatters and is reflected back along its incoming path, along us to taking into account the affects of both attenuation and reflection in the Earth. We compare this formalism with the results of full Monte Carlo simulations for cross sections within reach of current and future DM-electron scattering searches. We find that Verne2 is accurate to better than 10-30%, making it suitable for performing signal modeling in the search for daily modulation, while reducing the computational cost by a factor of $\sim 10^4$ compared to full Monte Carlo simulations.

    hep-phastro-ph.CO4 citations
21. 21*

    Dark Matter and Baryon Asymmetry from Monopole-Axion Interactions

    Raymond T. Co🇺🇸 · Keisuke Harigaya🇺🇸 · Isaac R. Wang🇺🇸 · Huangyu Xiao🇺🇸

    We introduce a novel mechanism where the kinetic energy of a rotating axion can be dissipated by the interactions with dark magnetic monopoles. This mechanism leads to a framework where the QCD axion and dark monopoles account for the dark matter density, and the observed baryon asymmetry is generated through the rotating QCD axion via axiogenesis. The monopoles acquire masses from a nonzero axion field, and they can transition between different quantized dyonic levels in the presence of a rotating axion field. The axion kinetic energy is dissipated by the transition, and thus the axion abundance is depleted to the observed dark matter abundance. We predict that the axion decay constant should be below $10^9$ GeV to explain the observed dark matter and baryon densities.

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

    Quantifying vacuum-like jets in heavy-ion collisions: a Machine Learning study

    Miguel Crispim Romão🇬🇧 · João Arruda Gonçalves🇵🇹 · José Guilherme Milhano🇵🇹

    The modification of jets by interaction with the Quark Gluon Plasma has been extensively established through the comparison of observables computed for samples of jets produced in nucleus-nucleus collisions and proton-proton collisions. The presence of vacuum-like jets, jets that experienced little interaction with the Quark Gluon Plasma, in the nucleus-nucleus samples dilutes the overall observed modification hindering the detailed study of the underlying physical mechanisms. The ability to ascertain on a jet-by-jet basis the degree of modification of a jet would be an invaluable step in overcoming this limitation. We consider a Transformer classifier, trained on a low-level representation of jets given by the 4-momenta of all its constituents. We show that the Transformer is able to capture discriminating information not accessible to other architectures which use high-level physical observables as input. The Transformer allows us to identify, in the experimentally relevant case where both medium response and underlying event contamination are accounted for, a class of jets that have been unequivocally modified. Further, we perform a robust estimate of the upper bound for the fraction of jets in nucleus-nucleus collisions that are, for all purposes, indistinguishable from those produced in proton-proton collisions.

    hep-phEPJC(2026)·2 citations
23. 23*

    Keeping It Renormalizable: Minimal Baryogenesis induced Asymmetric Dark Matter

    Miguel Escudero🇨🇭 · Thomas Hambye🇧🇪 · Chandan Hati🇪🇸

    Many asymmetric dark matter scenarios have been proposed to date. Among them, perhaps the most motivated ones are those in which the dark matter asymmetry is induced from the baryon/lepton asymmetries via chemical equilibration without any new sources of CP violation. However, most of the models put forward along these lines have been excluded by now and/or are based on complicated setups. In this letter, we present a new, simple, and viable scenario. It assumes only two new fields: a scalar singlet and an inert scalar doublet, and is based only on renormalizable interactions, that slowly generate the dark matter asymmetry from the Standard Model Higgs asymmetry. The model allows for the direct detection of dark matter in the upcoming generation of experiments, and the inert doublet is predicted to be light enough to be potentially produced and observed at the LHC and future colliders, $m_{H^{\prime }}<580\mathrm{GeV}$.

    hep-phastro-ph.COhep-ex0 citations
24. 24*

    FeynRules and UFO models for $\nu$SMEFT: operators of dimensions five and six

    Arsenii Titov🇮🇹

    We release FeynRules and UFO model files for the $\nu$SMEFT -- the effective field theory of the Standard Model extended with right-handed neutrinos, $N_R$. These model files include operators with $N_R$ up to dimension six. In particular, we provide a UFO implementation of four-fermion operators with Majorana $N$ compatible with MadGraph5_aMC@NLO. It relies on introducing auxiliary, non-propagating fields. All the model files are made publicly available on https://github.com/arsenii-titov/vSMEFT.

    hep-phhep-ex1 citation
25. 25*

    Heptagon Symbols at Five Loops and All-Loop Sequences

    Song He🇨🇳 · Xuhang Jiang🇨🇳 · Xiang Li🇨🇳 · Jiahao Liu🇨🇳

    We revisit the symbol bootstrap program for the seven-particle MHV and NMHV amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills (SYM) based on the alphabet associated with the $E_6$ cluster algebra. After imposing integrability, cluster adjacency (or extended Steinmann), first- and last-entry conditions, the solution space is already highly restrictive: e.g. for MHV case there are exactly $1,1,2,3,4$ parity-invariant solutions for $L=1,2,\cdots ,5$, which automatically satisfy dihedral symmetry. Remarkably, after further requiring a well-defined collinear limit, we find a unique solution for both MHV and NMHV sectors where all coefficients (e.g. more than $3.1\times 10^{10}$ for MHV at $L=5$) turn out to be integers. Furthermore, we observe recurrent patterns for coefficients of special words in $E_6$ symbols mirroring those found for the $C_2$ symbol of three-point form factors, which lead to numerous predictions in the form of all-loop sequences. As an initial application, we show that these sequences uniquely fix the MHV symbol through five loops without input from collinear limits. Given the simplicity and surprisingly strong constraining power of both physical constraints and the newly observed sequences, we conjecture that there is a unique symbol satisfying these constraints at any loop order.

    ↳ hep-thhep-ph13 citations
26. 26*

    Geometry Induced Chiral Transport and Entanglement in $Ad{S}_2$ Background

    Kazuki Ikeda🇺🇸 · Yaron Oz🇮🇱

    We study the real-time chiral dynamics of Dirac fermions in AdS${}_2$ and AdS${}_2$ black hole backgrounds. The spacetime curvature generates a spin connection term, acting as an effective magnetic field and a position-dependent chiral chemical potential. This leads to strongly asymmetric wave propagation, confined within an inhomogeneous Lieb-Robinson cone. The front velocities decrease with increasing fermion mass and horizon radius. The entanglement entropy grows inside the causal cone, and it saturates due to screening/dephasing in the finite inhomogeneous chain. In dipole-dipole collision, the central bipartite entropy rises when the inward Lieb-Robinson fronts intersect, forming a bright ridge in the local entanglement profile. Charge and current correlators peak at the front arrival, providing a real-time diagnostic of chiral transport. These results establish a causality-respecting framework, linking curvature and horizons to transport and entanglement in (1+1)-dimensional fermionic matter.

    ↳ hep-thcond-mat.mes-hallhep-phnucl-th+1JHEP(2026)·4 citations
27. 27*

    Composite Dissipation in Warm Inflation: Implications for the Primordial Power Spectrum

    Ayush Sahu · Richa Arya🇮🇳 · Sergio E. Jorás · Karim H. Seleim

    Warm inflation is a well-motivated and generalized framework of inflation, describing a coupled inflaton-radiation bath. In this work, we investigate a warm inflation model with a quartic potential and a composite dissipation coefficient ${\rm Y}(\varphi ,T)=C_1\frac{T^3}{M_{\text{Pl}}^2}+C_2\frac{T^3}{{\varphi }^2}.$ The two terms in ${\rm Y}$ dominate at different scales: the first term governs the early inflationary dynamics at large (CMB) scales, while the second term becomes significant at smaller scales. The model features two distinct stages of inflation: an initial phase where strong dissipation ($Q\gg 1$) generates a red-tilted primordial spectrum consistent with CMB observations (from ACT), followed by a second phase producing a blue-tilted spectrum with a significant amplification of power at small scales, leading to primordial black hole formation. We analyze the effects of key parameters -- like the duration of each inflationary phase, the slow-roll parameter at the end of the first phase, the dissipation strength at the pivot scale, and the choice of the growth function -- on the primordial power spectrum and its spectral index. Additionally, we examine the consistency of the model with the swampland distance conjecture and trans-Planckian conjecture, needed for embedding these models with some UV complete theories. This work highlights the potential of warm inflation with a composite dissipation coefficient to reconcile large-scale CMB measurements with small-scale structure formation.

    ↳ astro-ph.COgr-qchep-ph1 citation
28. 28*

    Shedding Light on (Anti-)nuclei Production with Pion-Nucleus Femtoscopy

    Li-Yuan Zhang🇨🇳 · Ze-Hua Zhang🇨🇳 · Che Ming Ko🇺🇸 · Yu-Gang Ma🇨🇳 · Qi-Ye Shou🇨🇳 · Kai-Jia Sun🇨🇳 · Zhan-Duo Tang🇨🇳 · Rui Wang🇮🇹 · Song Zhang🇨🇳

    High-energy nuclear collisions provide a unique environment for synthesizing both nuclei and antinuclei (such as $\bar{d}$ and ${}^4\overline{\text{He}}$) at temperatures ($k_{B}T\sim 100$ MeV) much higher than their binding energies per nucleon of a few MeV. The underlying production mechanism, whether through statistical hadronization, nucleon coalescence, or dynamical regeneration and disintegration, remains unsettled. Here we address this question using pion-nucleus femtoscopy. By solving relativistic kinetic equations for pion-catalyzed reactions ($\pi NN\leftrightarrow \pi d$) for deuteron production and including final-state $p-$wave scatterings derived from an established effective interaction, we successfully reproduce the resonance peaks of both ${\pi }^{+}-p$ and ${\pi }^{+}-d$ femtoscopic correlations observed in $pp$ collisions at $\sqrt{s}=13\mathrm{TeV}$. The interplay between $\Delta$ resonance and $p$-wave scatterings shifts both correlation peaks downward by about $70\text{ MeV}$ relative to vacuum $\Delta$ decay. Conversely, both the nucleon coalescence model and the statistical hadronization model significantly underestimate the data and produce additional dips that are absent from the data. These results provide compelling evidence that pion-catalyzed reactions play a dominant role in the production of light (anti-)nuclei in high-energy nuclear collisions and cosmic rays.

    ↳ nucl-thhep-ph7 citations
29. 29*

    Emulation of Proton-Deuteron Scattering via the Reduced Basis Method and Active Learning: Detailed Description

    Alex Gnech🇺🇸 · Xilin Zhang🇺🇸 · Christian Drischler🇺🇸 · R. J. Furnstahl🇺🇸 · Alessandro Grassi🇮🇹 · Alejandro Kievsky🇮🇹 · Laura E. Marcucci🇮🇹 · Michele Viviani🇮🇹

    Nucleon-deuteron ($Nd$) scattering can be used to constrain three-nucleon forces in chiral effective field theory ($\chi$EFT). However, high-fidelity calculations, such as the Hyperspherical Harmonic (HH) method, are computationally expensive, making it difficult or even prohibitive to explore the vast parameter space of $\chi$EFT\xspace. To address this challenge, specifically for proton-deuteron ($pd$) scattering below the deuteron breakup threshold, we developed model-driven emulators based on the Reduced Basis Method (RBM) and active learning techniques, as presented in \href{https://arxiv.org/abs/2511.01844}{arXiv:2511.01844}. The method exploits the similarities between solutions at different parameter points to significantly reduce computational costs. In this companion paper, we provide a comprehensive description of our HH-based high-fidelity calculations and implementation of both variational-method-based and Galerkin-projection-based scattering emulators. We demonstrate the effectiveness of active learning in the form of greedy algorithms for selecting optimal training points in the parameter space, and the high accuracy and speed of the emulators, for two different nucleon forces and two scattering channels (${1/2}^{+}$ and ${1/2}^{-}$). For example, in a two-dimensional parameter space, the relative emulation errors can be reduced to $10^{-7}$ with fewer than 10 training points. Our work paves the way for the efficient calibration of $\chi$EFT\xspace nucleon interactions using Bayesian statistics, and the methodology can be applied to other nuclear scattering processes (including neutron-deuteron scattering), as well as other finite quantum systems.

    ↳ nucl-thhep-phnucl-ex6 citations
30. 30*

    Friction terms in multi-fluid description of heavy-ion collisions

    Clemens Werthmann🇧🇪 · Iurii Karpenko🇨🇿 · Pasi Huovinen🇵🇱

    In multi-fluid description of heavy-ion collisions, the primary scatterings and particle production are described in terms of interaction between fluids, so called friction. These friction terms can be derived from kinetic theory, but they are not unique. We compare different approaches to derive the friction terms, introduce a new ``charge transfer" friction, which allows to move charge to the midrapidity fireball, and implement them in the MUFFIN model. The charge transfer friction is more consistent with the assumption of three fluids clearly separated in momentum space, and allows better comparisons of the experimental data and underlying equation of state. It also leaves room for entropy generation due to dissipation in individual fluids, and we present the first results obtained using viscous multi-fluid dynamics.

    ↳ nucl-thhep-phnucl-exPRC(2026)·2 citations
31. 31*

    New multiprobe analysis of modified gravity and evolving dark energy

    Zhiyu Lu🇨🇳 · Théo Simon🇫🇷

    We study the $(w_0,w_a)$ parametrization of the dark energy (DE) equation of state, with and without the effective field theory of dark energy (EFTofDE) framework to describe the DE perturbations, parametrized here by the braiding parameter ${\alpha }_B$ and the running of the Planck mass ${\alpha }_M$. We combine the EFTofLSS full-shape analysis of the power spectrum and bispectrum of BOSS data with the tomographic angular power spectra $C_{\ell }^{gg}$, $C_{\ell }^{\kappa g}$, $C_{\ell }^{Tg}$ and $C_{\ell }^{T\kappa }$, where $g$, $\kappa$ and $T$ stand for the DESI luminous red galaxy map, Planck PR4 lensing map and Planck PR4 temperature map, respectively. To analyze these angular power spectra, we go beyond the Limber approximation, allowing us to include large-scale data in $C_{\ell }^{gg}$. The combination of all these probes with Planck PR4, DESI DR2 BAO and DES Y5 improves the constraint on the 2D posterior distribution of $\{w_0,w_a\}$ by $\sim 50\%$ and increases the preference for evolving dark energy over $\Lambda$ from $3.8\sigma$ to $4.6\sigma$. When we remove BAO and supernovae data, we obtain a hint for evolving dark energy at $2.3\sigma$. Regarding the EFTofDE parameters, we improve the constraints on ${\alpha }_B$ and ${\alpha }_M$ by $\sim 40\%$ and $50\%$ respectively, finding results compatible with general relativity at $\sim 2\sigma$. We show that these constraints do not depend on the choice of the BAO and supernovae likelihoods.

    ↳ astro-ph.COhep-phPRD(2026)·8 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.