Tue·Feb 24, 2026Tuesday·February 24, 2026

1. 01*

   Mixed Freeze-In and Freeze-Out Histories and Dark-Sector Decays in a ${\mathbb{Z}}_4$ Two-Scalar Model

   J. P. Carvalho-Corrêa🇧🇷 · B. A. Couto e Silva🇧🇷 · B. L. Sánchez-Vega🇧🇷

   We present a systematic non-equilibrium analysis of a renormalisable ${\mathbb{Z}}_4$ Higgs-portal dark sector with a complex scalar $S_A$ and a real scalar $S_B$, including conversion, semi-annihilation, and, when kinematically allowed, the dark-sector decay $S_B\to S_A{S}_A$. We impose theoretical consistency, Higgs invisible-decay limits, relic-fraction-rescaled LZ bounds, and an a posteriori thermalisation check of the WIMP/FIMP assignments. Allowing one or both dark states to remain out of equilibrium qualitatively enlarges the set of viable cosmological histories. In the stable regime, FIMP--FIMP and mixed WIMP--FIMP configurations can share the observed relic density between the two components, while the WIMP-like state remains subject to the usual Higgs-portal correlation between freeze-out and spin-independent scattering and the FIMP-like state can provide a substantial abundance with a negligible direct-detection rate. For $M_{S_B}>2M_{S_A}$, the decay of the unstable $S_B$ opens three distinct abundance-transfer mechanisms: SuperWIMP production, injection-assisted freeze-out, and sequential freeze-in. Because the decay proceeds entirely within the dark sector, the usual electromagnetic and hadronic BBN energy-injection bounds do not apply; we instead track the parent energy fraction and use an equivalent thermal-WDM mass to diagnose the warmness of the decay-produced daughter population. The minimal ${\mathbb{Z}}_4$ Higgs portal thus supports thermal, mixed, and fully non-thermal relic histories within the same renormalisable framework, with dark-sector decay linking relic-density production to small-scale structure.

   hep-phhep-th0 citations
2. 02*

   Cosmological Constraints on Long-Lived Particles Using Dimension-Six Effective Operators

   Mickael V. S. de Farias🇧🇷 · Rodrigo Holanda🇧🇷 · Matheus M. A. Paixao🇧🇷 · Farinaldo S. Queiroz🇧🇷 · Priscila V. dos Santos🇧🇷

   Long-lived particles (LLPs) provide an interesting window into physics beyond the Standard Model, offering characteristic signatures at colliders and in cosmology. In this work, we investigate LLPs decays into dark matter. If the lifetime of LLPs are longer than $10^4$ s, the decay products can disrupt the synthesis of light nuclei in the early universe and alter Big Bang Nucleosynthesis (BBN) predictions. If the LLP is much heavier than the dark matter particle, the decay contributes to the number of effective neutrino species, $N_{eff}$. We describe these decays via dimension-six effective operators and outline the parameter space in which such decays obey cosmological bounds stemming from BBN, structure formation, Cosmic Microwave Background, and Baryon Acoustic Oscillation data.

   hep-phastro-ph.COhep-thAnnals Phys.(2026)·0 citations
3. 03*

   Scaling solutions for varying tension strings

   C. S. C. M. Coelho🇵🇹 · A.-L. Y. Gschrey🇩🇪 · C. J. A. P. Martins🇵🇹

   We use the Velocity-dependent One Scale Model for topological defect evolution to explore and classify the possible scaling solutions for string networks with time-varying tension, in cosmological and non-cosmological settings and under two different phenomenological assumptions for the behavior of these variations, which rely on different stretching and damping contributions to the string dynamics. We discuss how these assumptions impact the standard scaling solutions, as well as the evolution of the string network density. In addition to simple power-law cosmological epochs solutions, we also discuss the behavior of the network during the radiation-to-matter and matter-to-acceleration transitions. Overall, our results show that for the same amount of tension variation, a change in the stretching length scale tends to have a more significant impact on the network than a change in the damping length.

   hep-phastro-ph.COgr-qcPRD(2026)·2 citations
4. 04*

   Dark Glueball Direct Detection

   Ji-Wei Li🇨🇳 · Roman Pasechnik🇸🇪 · Wei Wang🇨🇳 · Zhi-Wei Wang🇨🇳

   We consider glueball dark matter (DM) in a Yang-Mills dark sector confined at ${\Lambda }_D$ scale and coupled to the Standard Model through electrically and dark-color charged vector-like fermion portals, with the mass scale $m_{\psi }$. In a simple case with two lightest mass-degenerate vector-like fermions with opposite electric charges the effective amplitudes with one $C$-odd glueball (oddball) and odd number of photons vanish, rendering the lightest $C$-odd spin-1 state with mass $m_{\chi }$ a viable DM candidate provided that $m_{\psi }\gtrsim 5.5{\Lambda }_D$. We develop a controlled effective field theory framework with non-perturbative information supported by QCD phenomenology leading to a quantitative prediction for coherent elastic glueball scattering off nuclei. We find a steep scaling of the spin-independent cross section ${\sigma }_{\mathrm{SI}}\propto {\Lambda }_D^{2.15}{m}_{\psi }^{-8}$. This implies that the sensitivity of the current and next-generation xenon experiments in the range of ${\sigma }_{\mathrm{SI}}\sim 10^{-46}-10^{-48}$ cm${}^2$ corresponds to $m_{\psi }\simeq 3-30$ GeV, respectively, for ${\Lambda }_D\simeq 0.55-5.5$ GeV. We provide a minimal UV completion of the portal sector compatible with collider phenomenology. Our results pave a quantitative foundation for testing glueball DM in direct-detection experiments.

   hep-phastro-ph.COhep-lathep-th2 citations
5. 05*

   A limit on top quark pair production at future electron-proton colliders

   G.R.Boroun🇮🇷

   The ratio of the structure functions for deep inelastic scattering in top pair production at future electron-proton colliders is analyzed at a fixed $\sqrt{s}$ and $Q^2$ relative to the minimum value of $x$ given by $Q^2/s$ using collinear factorization. This compact formula for the ratio $F_{L2}(Q^2/s,Q^2,m_t)$ is useful for extracting a bound on the top structure function. The reduced cross-section for top production at this limit is determined, establishing a bound value for $t\overline{t}$ production at the LHeC and FCC-eh center-of-mass energies based on renormalization scales. The modification of the Bjorken scaling is applied to this bound of the reduced top cross-section at the renormalization scale ${\mu }^2=Q^2+4m_t^2$, which improves the scaling quantity at $Q^2<4m_t^2$. The dipole cross-section for top pair production is examined across a wide range of dipole sizes, denoted as $r$. It is expected that there will be limited behavior in observing top saturation in future electron-proton colliders according to the bound behavior. The probability of the Higgs boson in ${\gamma }^{\ast }g$ interactions is compared to the $gg$ process at the order of $\mathcal{O}({\alpha }^{\mathrm{em}}/{\alpha }_s)$.

   hep-ph0 citations
6. 06*

   Application of Selenium-82 for Short Base Neutrino Oscillations Searches

   Sergei Semenov🇷🇺

   Characteristics of neutrino absorption by ${}^{82}$Se nucleus reaction -- low threshold value, high absorption cross section of neutrinos, emitted by artificial sources, make selenium-82 perspective object to search for new neutrino species in calibration experiments. One of the interesting possibilities is usage of scintillating crystals. In (3+1) model for spherical geometry the expression for neutrino path length in a setup in the presence of oscillations is obtained and the scheme of experiment is proposed.

   hep-ph2 citations
7. 07*

   Two nearby states in the $X(3872)$ region: Resolving the radiative-decay ratio tension with ${\eta }_{c2}$

   Satoshi X. Nakamura (Shandong University)🇨🇳

   Recently, LHCb reported the radiative-decay ratio ${\mathcal{R}}^{\psi \gamma }\equiv \mathcal{B}[X(3872)\to {\psi }^{\prime }\gamma ]/\mathcal{B}[X(3872)\to J/\psi \gamma ]=1.67\pm 0.25$ extracted from $B^{+}\to K^{+}(J/\psi \gamma ,{\psi }^{\prime }\gamma )$. This result differs markedly ($\sim 4.6\sigma$) from the BESIII value obtained from $e^{+}{e}^{-}\to \gamma (J/\psi \gamma ,{\psi }^{\prime }\gamma )$, ${\mathcal{R}}^{\psi \gamma }=-0.04\pm 0.28$. Such a significant tension suggests that more than one state in the $X(3872)$ region contributes to the processes. We therefore propose a two-state scenario: a shallow $D^{\ast 0}{\bar{D}}^0$ bound state with $J^{PC}=1^{++}$ and a $2^{-+}$ charmonium candidate, ${\eta }_{c2}$, slightly above the $D^{\ast 0}{\bar{D}}^0$ threshold. We show that this hypothesis consistently describes these ratios along with other branching fractions and lineshapes across multiple processes. By contrast, fits without the ${\eta }_{c2}$ component fail to reproduce the radiative-ratio data. We also predict helicity-angle distributions that motivates the future experiments to test the two-state hypothesis and search for the so-far missing ${\eta }_{c2}$.

   hep-phhep-exnucl-thPRD(2026)·2 citations
8. 08*

   Reconstruction of Gravitational Form Factors using Generative Machine Learning

   Herzallah Alharazin🇩🇪 · Julia Yu. Panteleeva🇩🇪

   We develop a generative framework based on denoising diffusion for the model-independent reconstruction of hadronic form factors from sparse and noisy data. The generative prior is built from a large ensemble of synthetic curves drawn from ten distinct functional classes rooted in different theoretical approaches to hadron structure. Applied to the proton gravitational form factors $A(t)$, $J(t)$, and $D(t)$, the framework yields non-parametric reconstructions consistent with lattice QCD across the full kinematic range $0\le -t\le 2{\mathrm{GeV}}^2$, remaining robust even when only one or two conditioning points are retained. The densely sampled output enables a direct extraction of the chiral low-energy constants $c_8=-4.6\pm 0.8{\mathrm{GeV}}^{-1}$ and $c_9=-0.61\pm 0.19{\mathrm{GeV}}^{-1}$. Using these values at the physical pion mass, we obtain $D(0)=-4.3\pm 0.8$ for the nucleon $D$-term.

   hep-phhep-lathep-thPRD(2026)·3 citations
9. 09*

   Kaon decay constraints on vector bosons coupled to non-conserved currents

   Matheus Hostert🇺🇸 · Maxim Pospelov🇺🇸 · Adrian Thompson🇺🇸

   We study rare three- and four-body kaon decays as a probe of light vector and axial-vector bosons coupled to non-conserved currents. We find that searches for $K_L\to {\pi }^0{\pi }^0(X\to e^{+}{e}^{-})$ decays constrain the couplings of light $X$ bosons to light quarks to be as small as $\mathcal{O}(10^{-5})$. The charged-pion modes $K^{+}\to {\pi }^{+}{\pi }^0(X\to e^{+}{e}^{-})$ and $K_L\to {\pi }^{+}{\pi }^{-}(X\to e^{+}{e}^{-})$ provide weaker limits, but constrain complementary combinations of couplings to the $u$, $d$, and $s$ quarks at the level of $\mathcal{O}(10^{-4})$. Finally, we also find that double emission of $X$ in $K\to \pi XX$ decays can provide yet additional constraints on the parameter space of light $X$ bosons due to a double $(m_K/m_X{)}^2$ enhancement to the rate. For a 17 MeV boson, these limits add to the known tension between spin-1 bosons coupled to vector and axial-vector currents interpretations of the results of the ATOMKI experiment with meson decay data. Finally, we also comment on negative pion capture on hydrogen and deuterium as a source of light particles and discuss the prospects for testing the 17 MeV boson hypothesis.

   hep-phhep-exPRD(2026)·3 citations
10. 10*

    Form factors of $\Delta$(1232) and the electromagnetic $N-\Delta$ transition

    Jiaqi Wang🇨🇳 · Dongyan Fu🇨🇳 · Yubing Dong🇨🇳

    In this work, the electromagnetic and gravitational form factors of $\Delta$ isobars, as well as the electromagnetic $N-\Delta$ transition form factors are studied systematically and continuously using a covariant quark-diquark approach with the pion cloud effect. In our model, the baryon is treated as the two-body system to simplify calculations, and the quarks are assumed to be surrounded by the pion cloud. The related physical properties, such as the charge radius and magnetic moment of $\Delta$ and the helicity amplitudes of the $N-\Delta$ transition are obtained and discussed. Our results for the form factors of both $\Delta$(1232) and the electromagnetic $N-\Delta$ transition are in reasonable agreement with the experimental or lattice results. Moreover, we found that the pion cloud plays an important role in the results through enlarging the magnetic transition form factor $G_M(t)$ and shifting the sign of the D-term of $\Delta$ to negative.

    hep-phEPJC(2026)·0 citations
11. 11*

    Three-body molecular states composed of $D^{(\ast )}$ and two nucleons

    Si-Yi Chen🇨🇳 · Fei-Yu Chen🇨🇳 · Xu-Liang Chen🇨🇳 · Lu Meng🇨🇳 · Ning Li🇨🇳 · Wei Chen🇨🇳

    We study the three-body systems $DNN$ and $D^{\ast }NN$ within a hadronic molecular framework by combining a realistic nucleon-nucleon interaction with a $D^{(\ast )}N$ potential constrained by heavy-quark symmetry. The three-body Schrödinger equation is solved with the Gaussian Expansion Method, and the analytic structure of the spectrum is investigated using the Complex Scaling Method. We find that the $DNN$ system supports a robust and compact bound state in the $I(J^P)=\frac{1}{2}(1^{-})$ channel over a broad range of cutoff values, even when the corresponding $DN$ subsystem is weakly bound or unbound. For $D^{\ast }NN$, the spin-$1$ nature of the heavy meson and the associated spin-dependent forces generate a clear spin hierarchy: deeply bound states appear in both $0^{-}$ and $2^{-}$ channels, while the $1^{-}$ channel exhibits a characteristic two-branch pattern with a strongly bound compact branch and a more weakly bound, spatially extended branch. The root-mean-square radii indicate pronounced spatial compression compared with the deuteron scale, highlighting the cooperative roles of realistic $NN$ correlations, the $D^{(\ast )}N$ interactions, and heavy-quark symmetry in forming compact heavy-flavor few-body bound states. No three-body resonances under complex scaling are found in the explored parameter space. Our results provide quantitative benchmarks for future experimental searches for such charmed-meson-nuclear bound states.

    hep-phhep-exnucl-thPRD(2026)·1 citation
12. 12*

    Relative transverse activity as a probe of collectivity-like long-range correlations in pp collisions at $\sqrt{s}=13$ TeV

    Subhadeep Roy🇮🇳 · Sadhana Dash🇮🇳

    Understanding the origin of collectivity-like signatures in small collision systems is a central open question in high-energy nuclear physics, and two-particle correlation functions offer unique sensitivity to the underlying-event (UE) dynamics that may drive such behavior in proton--proton (pp) collisions. In this work, the two-particle number ($R_2$) and transverse-momentum ($P_2$) correlation functions are studied in pp collisions at $\sqrt{s}=13$ TeV using PYTHIA 8, for final state charged hadrons within $|\eta |<0.8$ and $0.2<p_{\mathrm{T}}<2.0$ GeV/$c$, with events classified by the relative transverse activity $R_{\mathrm{T}}$ to probe how UE activity shapes correlation structures in the soft-QCD-dominated regime. A collectivity-like long-range near-side component is observed in the charge-independent correlator $R_2^{\mathrm{CI}}$ exclusively for the highest $R_{\mathrm{T}}$ class ($2.5<R_{\mathrm{T}}\le 5.0$), while no corresponding structure appears in the charge-dependent correlators. This indicates that enhanced UE activity, driven by multiple partonic interactions and color reconnection, can generate collectivity-like long-range correlations without hydrodynamic evolution. These findings establish $R_{\mathrm{T}}$ as a differential event classifier to provide a non-hydrodynamic baseline for interpreting such signatures in small-system measurements at the LHC.

    hep-ph0 citations
13. 13*

    Directional recoil detection for CEvNS measurements with light nuclei at the Spallation Neutron Source

    Ciaran A. J. O'Hare🇦🇺 · Anirudh Chandra Shekar🇺🇸 · Chiara Lisotti🇦🇺 · Michael Litke🇺🇸 · Nityasa Mishra🇺🇸 · Jayden L. Newstead🇦🇺 · Louis E. Strigari🇺🇸 · Sven E. Vahsen🇺🇸

    The coherent elastic scattering of neutrinos on nuclei, also known as CEvNS, has been studied for several years by the COHERENT program of experiments using neutrinos from stopped-pion decays produced at the Spallation Neutron Source (SNS). We propose a new approach for CEvNS measurements at the SNS that aims to complement the COHERENT experiments in two main ways: by reconstructing the angular distribution of CEvNS-induced recoils, and by measuring CEvNS on much lighter target nuclei such as helium, carbon, and fluorine. The proposed detector would employ a gaseous time-projection chamber with a highly segmented charge readout to enable the spatial reconstruction of $\sim$10-500 keV ionisation tracks created by CEvNS-induced recoils. This would enable the simultaneous measurement of the CEvNS recoil energy and scattering angle, thereby allowing event-by-event reconstruction of the neutrino energy. We estimate that a 60:40 He:CF${}_4$ gas mixture at atmospheric pressure offers a good trade-off between total target mass and good directionality and could deliver a detection of the angular distribution of CEvNS, even under pessimistic background conditions. We project the sensitivity of 1 and 10 m${}^3$-scale detectors in the context of several physics cases, including: the measurement of the Standard Model CEvNS cross section, reconstruction of the flavour-dependent neutrino fluxes, observing the neutrino-induced Migdal effect, constraints on beyond-Standard Model neutrino interactions, and probing 10-eV-scale sterile neutrinos.

    hep-phhep-ex1 citation
14. 14*

    2025 EIC-France Workshop: Physics Highlights and Perspectives

    F. Arleo · V. Bertone · J. Bettane · B. Blossier · F. Bock · F. Bossù · R. Boussarie · F. Bouyjou · O. Brand-Foissac · N. L. Bucuru Rodriguez · V. Calvelli · P. Caucal and 66 other authors

    This document presents a synthesis of the theory contributions and discussions from the 2nd EIC-France Workshop, held at IJCLab (Orsay) on 1-3 December 2025. The workshop brought together members of the French hadron-physics community to review recent theoretical developments relevant to the future Electron-Ion Collider (EIC) and to coordinate national efforts in preparation for its early physics program. The report first summarizes the collider's initial running conditions and luminosity performance, as outlined in the EIC Early Science Matrix. It then provides concise overviews of the theoretical presentations on inclusive, semi-inclusive, exclusive, heavy-flavor, and small-x physics. Based on these discussions, two measurements emerged as especially well suited for early EIC operation and strongly aligned with areas of established French expertise: inclusive diffraction and inclusive quarkonium production. These channels offer clean signatures, robust theoretical interpretability, and direct sensitivity to fundamental QCD phenomena such as gluon saturation, heavy-quark dynamics, and the small-x structure of hadrons and nuclei. In addition, the workshop identified longer-term physics opportunities that will benefit from the full capabilities of the EIC after its ramp-up phase. These include accessing the three-dimensional structure of the pion through the Sullivan process and a broader program of exclusive three-body final states, both of which represent high-impact avenues for exploring hadronic structure and non-perturbative QCD. Together, the elements summarized in this report provide a coherent overview of the strategic priorities and scientific ambitions shaping the French community's contribution to the EIC physics program.

    hep-phhep-exnucl-exnucl-th0 citations
15. 15*

    Thermodynamically consistent treatment of repulsive corrections in HRG

    Somenath Pal🇮🇳

    We reformulate the treatment of density-dependent chemical potential shifts appearing in excluded-volume implementations of the hadron resonance gas model. An auxiliary classical representation is constructed in which a common energy shift is determined by preserving the scalar number density, ensuring thermodynamic consistency. Hadron radii are parametrized through a liquid-drop inspired mass-radius relation with two parameters: the pion radius and a scaling exponent. The resulting framework reproduces lattice QCD results for lower-order conserved-charge susceptibilities at zero chemical potentials with only two adjustable parameters.

    hep-phnucl-th0 citations
16. 16*

    MoCaNLO: a Monte Carlo integrator for NLO calculations

    A. Denner🇩🇪 · D. Lombardi🇮🇹 · S. Lopez Portillo Chavez🇩🇪 · M. Pellen🇩🇪 · G. Pelliccioli🇮🇹

    We present the Monte Carlo integration code MoCaNLO, which computes cross sections and distributions for processes at high-energy colliders like the LHC at leading and next-to-leading order (NLO) in the strong and electroweak couplings. It relies on the Recola package for the calculation of matrix elements and uses Catani-Seymour dipole subtraction for the treatment of infrared singularities. It has been used for several cutting-edge calculations of NLO QCD and electroweak corrections over the last years, such as NLO QCD corrections to off-shell top-antitop-quark production in association with a pair of bottom quarks and NLO electroweak corrections to vector-boson scattering processes.

    hep-phhep-exEPJC(2026)·9 citations
17. 17*

    Thermal field theory and the QCD Equation of State

    Matteo Bresciani🇮🇪

    This Chapter introduces QCD at finite temperature and density. We first present the formulation of the thermal theory in the Euclidean path integral formalism. We then describe how the strong dynamics at high temperature can be inspected through thermal effective field theories. As a concrete example of thermodynamic quantity, we discuss the Equation of State, which characterises the equilibrium properties of the QCD plasma. We finally conclude with an overview of the phase diagram of strongly interacting matter.

    hep-phhep-lat0 citations
18. 18*

    Probing Doubly Charged Higgs Bosons with Three-Body Associated Production at Future $e^{+}{e}^{-}$ Colliders

    Brahim Ait-Ouazghour🇲🇦 · Abdesslam Arhrib🇲🇦 · Rachid Benbrik🇲🇦 · Mohammed Boukidi🇵🇱 · Mohamed Chabab🇲🇦 · Khalid Goure🇲🇦 · Stefano Moretti🇬🇧

    We study the discovery prospects for a doubly charged Higgs boson $H^{\pm \pm }$ in the 2-Higgs doublet model with type-II seesaw at future $e^{+}{e}^{-}$ colliders. Focusing on the three-body channels $e^{+}{e}^{-}\to H^{\pm \pm }{H}_1^{\mp }{H}_1^{\mp }$ and $e^{+}{e}^{-}\to H^{\pm \pm }{H}_1^{\mp }{W}^{\mp }$, we scan the model parameter space subject to theoretical consistency as well as current collider, flavor and electroWeak precision observables (EWPOs). We find that these $2\to 3$ production modes can exceed the conventional pair-production rate $e^{+}{e}^{-}\to H^{++}{H}^{--}$, followed by $H^{\pm \pm }\to H_1^{\pm }{H}_1^{\pm }$ and $H_1^{\pm }{W}^{\pm }$ decays, over wide regions, particularly above the $H^{\pm \pm }\to H_1^{\pm }{H}_1^{\pm }$ and $H^{\pm \pm }\to H_1^{\pm }{W}^{\pm }$ thresholds, reaching cross sections up to $\mathcal{O}(10^2)$~fb for $\sqrt{s}=500$--$1500$~GeV. A detector-level analysis of the $4\ell +E_T^{\text{miss}}$ signature, including dominant multiboson and top quark backgrounds, shows that discovery sensitivity is achievable for $\sqrt{s}=1000$-$1500$~GeV with integrated luminosities in the few ab${}^{-1}$ range, even in the presence of realistic systematic uncertainties.

    hep-phPRD(2026)·2 citations
19. 19*

    Unquenched Charmonium and Beyond

    Zi-Yue Bai🇨🇳 · Dian-Yong Chen🇨🇳 · Qi-Huang🇨🇳 · Xiang Liu🇨🇳 · Si-Qiang Luo🇨🇳 · Jun-Zhang Wang🇨🇳

    The year 2024 marked the 50th anniversary of the discovery of the $J/\psi$ particle, which unveiled the charm quark and the charmonium spectrum, instigating the "November Revolution" in particle physics. This discovery catalyzed the development of quenched potential models, most notably the Cornell model, which provided a foundational quantitative description of the hadronic spectrum. However, the landscape of hadron spectroscopy has been profoundly transformed since the turn of the 21st century with the observation of numerous charmonium-like states, such as $X(3872)$, which exhibit properties starkly at odds with quenched model predictions. These discrepancies, exemplified by the "$X(3872)$ low-mass puzzle" and the "$Y$ problem" associated with vector states like $Y(4260)$, underscore the critical limitations of the quenched approximation and signal the necessity for a new theoretical paradigm. This review synthesizes recent advances in hadronic spectroscopy, arguing that the unquenched picture, which incorporates coupled-channel effects such as hadronic loops, is essential for a unified description of these new states and associated anomalies. We demonstrate how unquenched effects provide compelling solutions to long-standing puzzles in charmonium decays (e.g., the "$\rho \pi$ puzzle" and anomalous dipion transitions), predict and explain the existence of exotic charged states like $Z_c(3900)$ and $Z_b(10610)$ via mechanisms such as Initial Single Pion Emission, and offer a framework for understanding interactions between charmonia and with nucleons. Furthermore, we emphasize the universality of unquenched effects, extending their application to bottomonium and light-flavor sectors. As experimental precision continues to improve, we advocate for the systematic development of unquenched hadronic spectroscopy.

    hep-phhep-exhep-latnucl-thPhys.Rept.(2027)·25 citations
20. 20*

    Gauge-Invariant Longitudinal Modes in the Herwig 7 Electroweak Parton Shower

    M.R. Masouminia🇬🇧 · P. Richardson🇬🇧

    Longitudinal electroweak gauge bosons are the most technically delicate ingredient of electroweak parton showers: in the broken Standard Model, the gauge component of a longitudinal polarisation does not cancel diagram by diagram, but is related by Ward identities to amplitudes with an insertion of the associated would-be Goldstone field. Building on the default Herwig 7 treatment based on a subtraction-defined longitudinal current, we construct a gauge-invariant scheme in which the subtraction remainder is retained as a well-defined contribution and completed by a Ward-identity-fixed Goldstone-matching term. We derive helicity-resolved building blocks and compact quasi-collinear splitting kernels for $q\to q^{\prime }V$ and $V\to V^{\prime }{V}^{\prime \prime }$ branchings, and implement the scheme in Herwig 7 as a switchable alternative to the default basis. The completion leaves the transverse sector unchanged and modifies only longitudinal entries through controlled symmetry-breaking terms, including Yukawa-sensitive contributions in massive-fermion channels. In shower-level studies, we find that the default and gauge-invariant prescriptions coincide at high evolution scales, while differing at lower scales precisely in channels where symmetry breaking is active. Exclusive single-emission observables can moreover display non-monotonic scheme dependence once Sudakov suppression and kinematic constraints are accounted for. A first multi-emission LHC-like study confirms numerical stability and yields controlled, interpretable shifts in observables that probe propagating electroweak shower currents, whereas quantities dominated by promptly contracted, near on-shell vector-boson matrix elements remain largely unchanged.

    hep-phJHEP(2026)·2 citations
21. 21*

    Leptophilic scalar dark matter in U(1)${}_{L_{\mu }-L_{\tau }}$: Evading direct detection and prospective neutron star heating

    Chengfeng Cai🇨🇳 · Hong-Hao Zhang🇨🇳

    Leptophilic dark matter (DM) is a well-motivated thermal weakly interacting massive particle framework that can evade stringent nuclear-recoil searches while remaining testable via DM-induced heating of neutron stars (NSs). In this work, we study leptophilic scalar DM in a $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge extension of the Standard Model, which provides a common leptophilic portal for all scenarios considered. To reproduce the observed relic abundance while suppressing direct-detection signals, we investigate three benchmark realizations: (i) a secluded DM scenario in which the relic density is set by annihilation into $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge bosons and two pseudo-Nambu-Goldstone boson (pNGB) DM models based on (ii) an $SO(4)$ symmetry and (iii) an $SO(3)$ symmetry. In the $SO(4)$ pNGB model, the DM mass arises at tree level from a soft breaking term, while the elastic scattering amplitude is suppressed by a symmetry-protected cancellation. In the $SO(3)$ pNGB model, the DM mass is generated radiatively at one loop via the $U(1{)}_{L_{\mu }-L_{\tau }}$ gauge interaction, and we show that this gauging preserves the same cancellation mechanism, maintaining compatibility with direct-detection null results. We perform a systematic parameter scan imposing relic density, direct and indirect detection, and neutrino trident constraints and identify viable sub-TeV to TeV DM candidates. Under the optimistic maximal-heating assumption that the capture rate reaches the geometric limit and that the captured DM population efficiently thermalizes and attains capture-annihilation equilibrium inside NSs, we find that the remaining parameter space can be tested by near-infrared observations of old NSs, providing sensitivity complementary to terrestrial searches in regions that are currently weakly constrained.

    hep-phastro-ph.COastro-ph.HEPRD(2026)·1 citation
22. 22*

    Energy dependence of cross sections in proton-proton and antiproton-proton collisions

    V. A. Okorokov (National Research Nuclear University MEPhI)🇷🇺

    Energy dependence of global scattering parameters, mostly of total cross section, is studied for proton-proton and antiproton-proton collisions. Results are presented for physical analysis updated with taken into account the recent data from accelerator experiments as well as from cosmic ray measurements. The analytic parameterizations suggested within Axiomatic Quantum Field Theory (AQFT) provide the quantitative description of energy dependence of global scattering parameters for rather wide energy range. Detailed scan on low boundary of the fitting range for energy dependence of global scattering parameters allows the observation of the onsets for regions in which Pomeranchuk theorem and / or Froissart-Martin one is valid. It is obtained that global scattering parameters show the behavior corresponded to any formulations of Pomeranchuk theorem and closed to (modified) Froissart-Martin limit in functional sense in multi-TeV energy region. Bosonic condensation is considered as one of the possible dynamical mechanisms which would be provide the total cross section approaches to (modified) Froissart-Martin limit at quantitative level but not functionally only.

    hep-ph0 citations
23. 23*

    Production of dark matter in association with a Higgs boson via exclusive photon fusion in $pp$ collisions at $\sqrt{s}=13$ TeV

    M. A. Arroyo-Ureña🇲🇽 · H. Hernández-Arellano · I. Pedraza · S. Rosado-Navarro🇻🇪 · T. A. Valencia-Pérez🇲🇽

    In this work we study the production of a dark matter (DM) particle in association with a Higgs boson via a central exclusive photon-fusion initiated process. We explore this type of production through the Inert Doublet Model plus a complex Singlet (IDMS), where an extension of the Standard Model by an additional $U(1{)}_X$ gauge symmetry and a $SU(2)$ inert scalar doublet gives rise to a DM candidate $\chi$. This particular process involves the collision of two protons exchanging two colorless particles (in our case, photons), from which a central process occurs. Such interaction can be detected in the LHC using forward proton detectors, where the resulting missing mass spectrum can be observed after proton reconstruction, thus allowing a search for physics Beyond the Standard Model (BSM). We present results for different values of the difference of masses of a heavy scalar coming from the complex singlet, the DM candidate and the Higgs boson, $\Delta =M_S-M_{\chi }-M_h$, which is the phase space available for the final state in the central exclusive process.

    hep-ph0 citations
24. 24*

    A Rating Quality Methodology for the Theoretical Description of Experimental Data

    S.O. Omelchenko🇺🇦 · V.M. Pugatch🇺🇦

    We introduce a novel multi-parameter rating methodology for comparing theoretical models with experimental data in heavy-ion collisions, addressing limitations of the global ${\chi }^2$/ndf criterion. The methodology divides phase space into seven physically motivated kinematic zones. Each zone receives a quality score $Q_i\in [10,1000]$ via logarithmic transformation of local ${\chi }_i^2/{\nu }_i$ statistics. A composite rating $R$ aggregates weighted average, geometric mean, and minimum scores with a bounded dispersion penalty. The seven-zone division is validated through boundary significance tests on CMS PbPb data at $\sqrt{s_{NN}}=5.02$ TeV: four of six physical boundaries are confirmed significant ($p<0.05$) while none of the data-driven $K=9$ candidates carry independent physical significance. Coefficient sensitivity: $\pm 20\%$ variations produce $\Delta R<2\%$ with zero rank changes. Applied to ALICE data for $K_S^0$ mesons and $\Lambda$ hyperons in p-Pb at $\sqrt{s_{NN}}=5.02$ TeV, the methodology reveals a hierarchy of model universality: PHSD (microscopic QGP transport + coalescence) achieves near-universal performance ($R=911$ for mesons, $R=893$ for baryons on a synthetic LHCb-kinematics benchmark), while PYTHIA8 ($R=878$) leads in the hard-fragmentation regime via nuclear PDFs. The baryon anomaly peak in zones 3--4 yields $Q_i\sim 950$--$1000$ for coalescence models versus $Q_i\sim 400$--$600$ for fragmentation generators. The near-universal performance of PHSD demonstrates that coalescence mechanisms are critical not only for baryon production but also for a globally consistent description of meson spectra. The methodology is transparent, reproducible, and ready for integration into standard analysis frameworks.

    hep-phEPJA(2026)·0 citations
25. 25*

    Tailored PDFs for New Physics searches

    Ella Cole🇬🇧 · Mark N. Costantini🇬🇧 · Elie Hammou🇳🇱 · Luca Mantani🇪🇸 · Francesco Merlotti🇨🇭 · Manuel Morales-Alvarado🇮🇹 · Maria Ubiali🇬🇧

    Given the non-negligible interplay between parton distribution functions (PDFs) at large x and potential New Physics (NP) effects in the high-energy tails of hadron collider observables, a central question is which PDFs can be reliably employed in beyond-the-Standard-Model (BSM) analyses. In this work, we examine the fine balance between using PDF sets with small uncertainties in the large-x region -- crucial for maximising BSM sensitivity -- and adopting conservative PDF fits that exclude high-energy data potentially contaminated by unaccounted NP contributions. We systematically assess a range of conservative PDF fitting strategies designed to mitigate such biases and provide a recommendation for the class of PDFs best suited for robust BSM searches. In addition, we investigate the alternative approach of performing simultaneous fits of Standard Model Effective Field Theory (SMEFT) Wilson coefficients and PDFs, thereby consistently accounting for their mutual correlations. Starting from a toy model to illustrate the underlying mechanisms, we then analyse two realistic NP scenarios: one modifying high-mass Drell-Yan production and another affecting the high-invariant-mass tail of top-quark pair production. Both cases are representative of measurements that will be probed with high precision during the High-Luminosity phase of the LHC.

    hep-phJHEP(2026)·9 citations
26. 26*

    Linking Leptogenesis and Asymmetric Dark Matter: A Testable Framework for Neutrino Mass and the Matter-Antimatter Asymmetry

    Henry G. F. McKenna🇬🇧 · Juri Smirnov🇬🇧 · Martin Gorbahn🇬🇧

    We investigate a minimal extension of the Leptogenesis framework that simultaneously explains the observed baryon asymmetry and dark matter (DM) abundance through the decay of a heavy Majorana neutrino. In this scenario, CP violation arises from complex Yukawa couplings, enabling the generation of asymmetries in both the Standard Model (SM) and DM sectors. We explore two regimes: (i) wash-in, where an initial dark asymmetry is transferred to SM leptons by $2\leftrightarrow 2$ scattering processes; and (ii) co-genesis, featuring a hierarchical coupling structure that allows enhanced CP violation while supporting a low-scale seesaw mechanism at order $\mathcal{O}(2)$ TeV. This setup not only links light neutrino masses to the Majorana mass term but also suggests that lepton-number violation may occur at experimentally accessible energy scales. In the co-genesis scenario, we show spin-independent cross sections for DM heavier than 10 GeV that can be tested in current direct detection experiments and motivate the exploration of cross sections inside the neutrino fog for lighter DM masses, establishing asymmetric leptogenesis as a predictive benchmark framework for direct-detection experiments and identifying a new hierarchical-coupling regime enabling TeV-scale leptogenesis.

    hep-phastro-ph.COhep-ex0 citations
27. 27*

    Warm dark matter from freeze-in at stronger coupling

    Duarte Feiteira🇫🇮 · Oleg Lebedev🇫🇮 · Vinícius Oliveira🇵🇹

    We study warm Higgs portal dark matter (DM) in the framework of freeze-in at stronger coupling. This scenario assumes that the Standard Model thermal bath temperature has always been relatively low, which suppresses dark matter production. As a result, a significant DM-Higgs coupling is allowed, enabling warm dark matter detection via Higgs decay at colliders. We find that the Lyman-{\alpha} bound on the DM mass is particularly strong, excluding masses below 50-100 keV, depending on further details. The shape of the DM momentum distribution is highly non-thermal, with low momenta being effectively cut off, and not captured by the common {\alpha}{\beta}{\gamma}-parametrization.

    hep-phastro-ph.HEPLB(2026)·5 citations
28. 28*

    Unitarity violation and restoration in radiative bound-state formation

    Marcos M. Flores🇫🇷 · Kalliopi Petraki🇫🇷

    State-of-the-art calculations motivated by dark matter exhibit severe violation of partial-wave unitarity in the non-relativistic regime in radiative bound-state-formation processes. It has been recently shown, in a model-independent fashion, that unitarity is restored by the proper resummation of the inelastic contributions to the self-energy of the incoming state. In this work, we first derive Kramers-like formulae for individual partial waves, demonstrating that existing calculations of bound-state formation severely violate unitarity. We then discuss how unitarity is restored through the resummation of the absorptive contributions to the incoming-state self-energy, generated by bound-state formation processes, taking into account their analytic structure in the complex momentum plane. Our results can be generalized to a variety of theories and employed in phenomenological studies, such as dark-matter freeze-out, indirect detection and self-interactions.

    hep-phastro-ph.COhep-thJHEP(2026)·3 citations
29. 29*

    Charged Higgs Decay to Bottom and Charm Quarks from $Z_3$-Flavored Two Higgs Doublet Models

    Alfredo Aranda🇲🇽 · J. Hernández-Sánchez🇲🇽 · Andrea Montiel🇲🇽 · R. Noriega-Papaqui🇲🇽

    The phenomenology of a charged Higgs present in a model with two Higgs SU(2) doublets and a $Z_3$ flavor symmetry is analyzed. It is shown that it is possible to generate an enhancement of its flavor changing coupling to c and b quarks and also to reproduce the ATLAS excess associated to the process $H^{\pm }\to bc$ for a charge Higgs mass of $130$~GeV. Furthermore, by considering the possibility of a search at the future LHeC, the analysis suggests viability for its detection.

    hep-phPLB(2026)·0 citations
30. 30*

    Supercooled Phase Transitions with Radiative Symmetry Breaking

    Alberto Salvio🇮🇹

    First-order phase transitions produce gravitational waves and primordial black holes. They always occur in field theories where symmetries are radiatively broken and masses are correspondingly generated. These theories predict a period of supercooling: phase transitions become effective at temperatures much smaller than the symmetry-breaking scale. This paper reviews a model-independent approach to study phase transitions in this scenario, which can be adopted if supercooling is strong enough. Perturbative methods can be used to determine the effective action and such model-independent approach allows us to obtain ready-to-use formulas that can be applied to any specific model of this sort.

    hep-phhep-thInt.J.Mod.Phys.A(2026)·4 citations
31. 31*

    Resummed azimuthal decorrelation and transverse momentum imbalance of dijets at the LHC

    Rong-Jun Fu🇨🇳 · Rudi Rahn🇦🇹 · Ding Yu Shao🇨🇳 · Wouter J. Waalewijn🇳🇱 · Bin Wu🇪🇸

    We present a theoretical study of the azimuthal decorrelation $\delta \varphi$ and transverse momentum imbalance $q_T$ in dijet production at the LHC, offering intriguing insights into the dynamics of quantum chromodynamics. We define the jet axes using the recoil-free winner-take-all (WTA) recombination scheme. For the azimuthal decorrelation $\delta \varphi$, this axis choice eliminates non-global logarithms (NGLs) entirely. For the transverse momentum imbalance $q_T$, NGLs emerge specifically in the small jet radius limit ($R\ll 1$). In this regime, the WTA scheme simplifies the theoretical framework by restricting jet radius logarithms to the soft sector. We derive factorization formulae for both observables within soft-collinear effective theory. To address the small-$R$ NGLs in the $q_T$ distribution, we refactorize the soft function into global soft, collinear-soft, and ultra-collinear-soft modes. We perform the resummation of global large logarithms $\ln (\delta \varphi )$ and $\ln (q_T/Q)$ up to next-to-next-to-leading logarithmic accuracy. For the $q_T$ distribution, this is combined with a leading-logarithmic resummation of the non-global $\ln R$ terms. We match our predictions to leading fixed-order $O({\alpha }_s^3)$ calculations. We also numerically investigate the structure of the first subleading power corrections. Comparisons with PYTHIA8 simulations demonstrate that the observables we consider are robust against non-perturbative multi-parton interactions and hadronization effects.

    hep-phhep-exnucl-thJHEP(2026)·5 citations
32. 32*

    Electromagnetic Radiation from Cosmic-Ray Scatterings on Relic Neutrinos

    Gonzalo Herrera🇺🇸 · Abraham Loeb🇺🇸

    Cosmic-ray scatterings on the cosmic neutrino background induce a flux of gamma-rays and X-rays from boosted meson decays and charged lepton processes. Here we present the first estimate of this flux and its cumulative cosmological contribution. Confronting expectations with Fermi-LAT diffuse gamma-ray data, we find a limit on the cosmic neutrino background overdensity at the level of $\eta \lesssim 2\times 10^4$ for a lightest neutrino mass of $m_{\nu }\gtrsim 0.1$ eV, orders of magnitude stronger than current direct laboratory probes, and comparable to constraints on the cosmic neutrino background obtained with IceCube. We further show that X-ray synchrotron emission from cascade electron-positron pairs in intergalactic magnetic fields provides a complementary, albeit weaker, constraint. We discuss how anisotropic signatures and future gamma-ray data from CTA could further improve bounds on the relic neutrino overdensity, approaching in sensitivity the $\Lambda$CDM expected density.

    hep-phastro-ph.COastro-ph.HE3 citations
33. 33*

    INFLAVON: CMB as cosmic tracer of Flavor physics

    Mu-Chun Chen🇺🇸 · Anish Ghoshal🇬🇧 · V. Knapp-Perez🇺🇸 · Xueqi Li🇺🇸 · Xiang-Gan Liu🇺🇸 · Cameron Moffett-Smith🇺🇸

    We unify one of the most widely studied frameworks to explain the hierarchical structure of the flavor sector in the Standard Model, the Froggatt-Nielsen mechanism, with cosmic inflation. We propose that the complex scalar field, the so-called flavon, which breaks the Froggatt-Nielsen $U(1)$ symmetry and generates the Yukawa couplings of the Standard Model, to also drive inflation, which we dub as Inflavon. After inflation ends, the decay of the inflavon reheats the Universe, establishing a novel link between early Universe cosmology and flavor physics. As concrete examples, we present realizations where the inflavon potential is described by an $\alpha$-attractor potential. We then compute the resulting CMB observables, specifically the spectral index ($n_s$), the tensor-to-scalar ratio ($r$), and the amplitude of scalar perturbations ($A_s$) as functions of the underlying Froggatt-Nielsen model parameters. We identify the parameter space in Froggatt-Nielsen models involving the scale of Flavor symmetry breaking ${\Lambda }_{\mathrm{FN}}$ and FN charges which is ruled out by Planck and ACT data, as well as the region that could be probed by next-generation CMB experiments like CMB-S4, SO and LiteBIRD. We also discuss inflavon as dark matter and its isocurvature constraints.

    hep-phastro-ph.COhep-th0 citations
34. 34*

    Earth Matter Enhanced Axion Dark Matter Search

    Xiaofei Huang🇨🇳 · Xiaolin Ma🇯🇵 · Zitong Xu🇸🇬 · Itay M. Bloch🇨🇭 · Kai Wei🇨🇳

    Laboratory searches for ultralight axion dark matter (DM) have traditionally assumed the terrestrial density of axions is equal to the average density of DM in the solar system. However, quadratic couplings to matter introduce a non-trivial field profile near the Earth. In this work, we present the first dedicated experimental implementation of this environment-aware axion DM wind search framework. Leveraging the extreme sensitivity of a K--Rb--${}^{21}$Ne comagnetometer to pseudo-magnetic fields induced by axion DM, we analyzed our data in the context of the massively enhanced local gradient of axions due to interactions with matter, though no signal candidates were found. Consequently, we have set the most stringent limits on axion-neutron derivative interactions for masses $m_a\in [0.041,28.9]\mathrm{feV}$, improving from previous experiments that ignore terrestrial matter effects by as much as three orders of magnitude for certain masses. Our work highlights the necessity of accounting for environmental modifications in precision frontier experiments and demonstrates how geophysical variations can be harnessed to act as a natural amplifier for DM possibly enabling future detection in parts of the parameter space that were previously beyond reach.

    hep-phhep-exphysics.atom-ph2 citations
35. 35*

    Charmonium suppression in fixed target proton-nucleus collisions

    Sourav Kanti Giri🇮🇳 · Partha Pratim Bhaduri🇮🇳 · Biswarup Paul🇮🇳 · Santosh K. Das🇮🇳

    In this article, we perform a systematic investigation of the cold nuclear matter (CNM) effects, operative on charmonium ($J/\psi$, $\psi (2S)$) production, in fixed target proton-nucleus (p+A) collisions. Influence on charmonium production cross section due to the interplay of three different plausible CNM effects namely the initial-state parton energy loss, nuclear shadowing, and final-state absorption of the resonant states, are evaluated in detail. The available data on charmonium production in fixed target p+A collision experiments from SPS, Fermilab and HERA-B are examined for this purpose. The beam energy dependence of the observed $J/\psi$ production patterns are utilized to anticipate level of "normal" absorption in the upcoming proton induced collisions by the NA60+ experiment at CERN SPS and the CBM experiment at FAIR SIS100 accelerator facilities.

    ↳ nucl-thhep-phEPJC(2026)·1 citation
36. 36*

    Gravitational Baryogenesis in $f(R)$ Cosmologies

    Ian B. Whittingham🇦🇺

    The generation of a baryon-antibaryon asymmetry in the Universe via gravitational baryogenesis is investigated for two f(R) modified theories of gravity, the widely used Starobinsky $f(R)=R+R^2/M^2$ model, and the recently proposed power-law model $f(R)=c_1{R}^{2+k/4}+c_{2}R+c_3$ of Odintsov and Oikonomou (2025) that is constructed from the slow-roll inflation parameters, and fits the new high-multipole CMB observations reported by the Planck and ACT collaborations for $k\sim -0.03$. The present investigation is undertaken in the Einstein frame. The motion of the scalaron is studied for the slow roll inflationary era using analytic approximate solutions obtained from its potential and, from these solutions, analytic expressions for the Ricci scalar, its time derivative, the Hubble parameter and the scale factor of the Universe. These expressions for the Starobinsky model were obtained first by Motohashi and Nishizawa (2012) but the expressions for the power-law model of Odintsov and Oikonomou and its generalization are new. The calculated values of the baryon asymmetry factor $\eta$ for the Starobinsky model vary from $(1.05-1.46)\times 10^{-11}$, and for the power-law model, from $(1.06-1.53)\times 10^{-11}$. The power-law values depend upon the unknown fitting parameters $c_1$ and $c_2$, and a future fit of the Odintsov and Oikonomou model to data could yield enhanced values. The values for $\eta$ depend upon a mass parameter $M_{\ast }$ which is expected to be of the order of $M_{Pl}=2.435\times 10^{18}$ GeV. The values of $\eta$ for both models have been calculated for $M_{\ast }=M_{Pl}$ and are quite close to the observed value $\eta =8.65\times 10^{-11}$. Since $\eta \propto (M/M_{\ast }{)}^2$, reducing $M_{\ast }$ slightly from $M_{Pl}$ to $0.4M_{Pl}$ would bring the calculated values into agreement with the observed value.

    ↳ astro-ph.COhep-ph3 citations
37. 37*

    Exponential Quintessence Model: Analytical Quantification of the Fine-Tuning Problem in Dark Energy

    Naoto Maki🇯🇵 · Kazunori Kohri🇯🇵

    In this paper, we investigate a quintessence field with an exponential potential motivated by the suggestion of time-varying dark energy from the DESI galaxy survey. Assuming a kination epoch in the early Universe, we analytically derive constraints on initial conditions that are consistent with Big Bang Nucleosynthesis and the current dark energy density. Compared to the severe 120-digit fine-tuning required for dark energy to be a cosmological constant, our result suggests that the degree of fine-tuning is naturally relaxed by dozens of orders of magnitude. Furthermore, we discuss the method for testing this model through future observations of the gravitational wave background.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2026)·4 citations
38. 38*

    AI Agents for Variational Quantum Circuit Design

    Marco Knipfer🇺🇸 · Alexander Roman🇺🇸 · Konstantin T. Matchev🇺🇸 · Katia Matcheva🇺🇸 · Sergei Gleyzer🇺🇸

    Variational quantum circuits (VQCs) constitute a central building block of near-term quantum machine learning (QML), yet the principled design of expressive and trainable architectures remains a major open challenge. The VQC design space grows combinatorially with the number of qubits, layers, entanglement structures, and gate parameterizations, rendering manual circuit construction inefficient and often suboptimal. We introduce an autonomous agent-based framework for VQC architecture search that integrates high-level reasoning with a quantum simulation environment. The agent proposes candidate circuit architectures, evaluates them through fully automated training and validation pipelines, and iteratively improves its design strategy via performance-driven feedback. Empirically, we show that the agent autonomously evolves circuit architectures from simple initial ansätze toward increasingly expressive designs, progressively trying to improve task performance. This demonstrates that agentic AI can effectively navigate and refine the VQC design landscape with minimal human intervention, providing a scalable methodology for automated quantum model development in the Noisy Intermediate-Scale Quantum (NISQ) regime.

    ↳ quant-phcs.EThep-exhep-lat+14 citations
39. 39*

    Symbolic syzygy-constrained reduction rules for Feynman integrals and the LoopIn framework

    Sid Smith🇮🇹

    We present a new algorithm for integration-by-parts (IBP) reduction of Feynman integrals with high powers of numerators or propagators, a demanding computational step in evaluating multi-loop scattering amplitudes. The algorithm allows us to avoid a large intermediate system of equations and instead focus on applying direct reduction rules to the integrals. We demonstrate the application of our algorithm with some highly non-trivial examples, namely rank-20 integrals for the double box with an external mass and the massless pentabox. We also achieve much faster IBP reduction for an example of scattering amplitudes for spinning black hole binary systems. Finally, we present LoopIn, a modular framework for automating multi-loop calculations, where the IBP techniques described here can be interfaced.

    ↳ hep-thhep-ph0 citations
40. 40*

    Cosmic strings and domain walls: the impact of CMB $B$-mode data

    Luca Caloni🇵🇹 · Ricardo Z. Ferreira🇵🇹 · Lara Sousa🇵🇹 · Clara Winckler🇵🇹

    We analyse CMB constraints on stable networks of cosmic strings and domain walls using for the first time full Planck 2018 data together with BICEP/Keck 2018 $B$-mode measurements. The defect-induced anisotropies are computed using the Unconnected Segment Model for Nambu-Goto and Abelian-Higgs strings, as well as for stable domain walls, and included in a full Markov Chain Monte Carlo analysis jointly varying all $\Lambda$CDM parameters, the tensor-to-scalar ratio, and the string/domain wall tension. No statistically significant evidence for defects is found, although we observe a mild preference for non-zero cosmic string tension. Our results improve previous constraints on the cosmic string power spectrum and correct previous CMB analyses with domain walls that overestimated the constraints. In the particular case of strings, the improvement is driven by the $B$-mode data, and is especially pronounced for Abelian-Higgs strings. We also present forecasts for the Simons Observatory and the LiteBIRD satellite: the former will improve string tension constraints by about a factor of three, while the latter those on the domain wall tension by about a factor of five. Finally, we assess the impact of Nambu-Goto string loops on CMB anisotropies in light of both current and future observations.

    ↳ astro-ph.COhep-phJCAP(2026)·5 citations
41. 41*

    IceCube's convex all-sky neutrino spectrum consistent with the magnetically powered corona scenario for active galactic nuclei

    Kohta Murase🇺🇸 · Shigeo S. Kimura🇯🇵 · Mainak Mukhopadhyay🇺🇸 · Mukul Bhattacharya🇮🇳

    High-energy multimessenger background analyses over the past decade have provided evidence for a population of hidden neutrino sources that are opaque to GeV-TeV gamma rays, a picture bolstered by recent observations of the nearby active galaxy NGC 1068. The coronal regions in the hearts of active galactic nuclei (AGNs) have been proposed as the most promising sites for such hidden nonthermal particle production, and NGC 1068 is expected to be the most neutrino-active galaxy for IceCube. We demonstrate that the latest all-sky neutrino spectrum, exhibiting a spectral bend around 3-30 TeV, is consistent with predictions of the magnetically powered corona scenario, and the models for the all-sky neutrino flux can simultaneously explain the multimessenger data from NGC 1068 within observational and modeling uncertainties. We further show, in a largely model-independent way, that the contribution from NGC 1068-like sources does not overshoot the observed medium-energy neutrino flux. Finally, we highlight the key role of the Eddington ratio, which can drive substantial variations in the predicted neutrino fluxes of nearby AGNs, and we encourage systematic multimessenger searches for the neutrino-brightest AGNs.

    ↳ astro-ph.HEastro-ph.GAhep-ph9 citations
42. 42*

    Cloaking Cosmic Light

    Nemanja Kaloper🇺🇸

    Light crossing dark domain walls that source a top form coupled to gauge Chern--Simons terms mixing visible and dark $U(1)$ gauge fields generically converts into dark photons. The effect is entirely localized on the wall and requires no additional ingredients. The conversion rate is a sharp function of the photon frequency in the wall rest frame, vanishing above the ultraviolet cutoff of the top form sector. Partial cloaking may also induce a rotation of the polarization of transmitted light of order $\Delta \vartheta \sim 10^{-3}$ radians, modify the cosmic microwave background power spectrum, and violate Etherington's reciprocity relation at low frequencies. These effects can impact cosmological determinations of the Hubble rate.

    ↳ astro-ph.COgr-qchep-phhep-th2 citations
43. 43*

    Galactic Center gamma-ray excess from a generic triaxial halo

    Leo Qiyuan Hu🇨🇳 · Ilias Cholis🇺🇸 · Yi-Ming Zhong🇨🇳

    Recent studies of Galactic surveys, such as Gaia, have revealed that the Milky Way's gravitational potential comes from a matter distribution that is triaxial and rotated with respect to the Galactic center-Sun axis. This, in turn, could mean that the dark matter halo also shares these properties. In this work, by fitting to the Fermi-LAT gamma-ray observations, we test the compatibility of the morphology of the Galactic Center Excess (GCE) from dark matter annihilation with a triaxial dark matter halo. In particular, we consider both untilted triaxial halos and halos whose principal axes are tilted with respect to the Galactic disk. In our fits of the Fermi-LAT data, by testing over a large library of galactic diffuse emission models, we quantify how the halo triaxiality and tilt affect the line-of-sight-integrated annihilation signal and, consequently, the preferred GCE spatial templates. We find that the GCE spectrum and inner cuspiness are robust against variations in the triaxiality and tilt of the dark matter halo. However, in terms of its overall morphology, the GCE in the gamma-ray data can discriminate between choices for the dark matter halo's triaxiality and tilt. Finally, we find that the GCE is more compatible with originating from a triaxial and tilted halo of dark matter than originating from a triaxial and tilted halo of stars, a result important for understanding the GCE's origin.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phPRD(2026)·2 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.