Wed·Nov 5, 2025Wednesday·November 5, 2025

1. 01*

   Single-spin measurements and heavy new physics in the $e^{+}{e}^{-}\to t\bar{t}$ process at an FCC-ee

   Haotian Cao🇺🇸 · Frank Petriello🇺🇸

   We investigate the potential of single-spin components of the spin-density matrix in the $e^{+}{e}^{-}\to t\bar{t}$ process at a future FCC-ee for probing heavy new physics parametrized using the SMEFT framework. We consider the full spectrum of spin observables and the complete angular decomposition of the $t\bar{t}$ production process in our study. We find that single-spin measurements generically provide stronger probes of SMEFT Wilson coefficients than measurements where the $t\bar{t}$ spins are correlated, and that single-spin observables are important for resolving flat directions that can appear in the Wilson-coefficient parameter space.

   hep-phPRD(2026)·5 citations
2. 02*

   Renormalisation

   Leonardo Di Giustino🇮🇹

   We give an introduction to renormalisation, focusing first on a pedagogical description of fundamental concepts of the procedure and its features, then we introduce the renormalisation group and its equations. We discuss then the case of gauge theories such as QCD summarising the current state of the art. We introduce the renormalisation scale setting problem in QCD and we give an illustration of the possible optimisation procedures currently in use.

   hep-phhep-th0 citations
3. 03*

   Underground Production of Electromagnetic Dark States by MeV-scale Electron Beams and Detection with CCDs

   Helmut Eberl🇦🇹 · Maximilian Fahrecker🇦🇹 · Josef Pradler🇦🇹

   In this work we explore the possibility of new light fermionic particles with millicharge or electromagnetic form factor interactions and their underground production via an electron beam in the 100 MeV range and their subsequent detection using a CCD-sensor. We evaluate the S-matrix elements and the phase spaces for production analytically, and then calculate the corresponding cross sections numerically. For millicharged fermions this set-up could be able to probe a window in parameter space, yet unconstrained by direct detection experiments. The electric or magnetic dipole moment of a light fermion could feasibly be probed with enough beam time or an increased beam energy.

   hep-phJHEP(2026)·3 citations
4. 04*

   Statistical Indications of Toponium Formation in Top Quark Pair Production

   Benjamin Fuks🇫🇷 · Aminul Hossain🇿🇦 · James Keaveney🇿🇦

   We present an analysis of six differential cross-section measurements of top-quark pair production in the dilepton channel from the ATLAS and CMS experiments. The data are compared to state-of-the-art QCD predictions with and without the inclusion of toponium formation effects. This contribution is modelled via a re-weighting of fixed-order matrix elements using the Green's function of the non-relativistic QCD Hamiltonian, and we employ a statistical model to quantify the preference of the data for the toponium hypothesis. All observables yield Bayes factors larger than unity, with two exceeding 20, yielding strong evidence for the toponium hypothesis in top-quark pair production at the LHC.

   hep-phhep-exPLB(2026)·13 citations
5. 05*

   Ultra-relativistic freeze-out: a bridge from WIMPs to FIMPs

   Stephen E. Henrich🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸

   We re-examine the case for dark matter (DM) produced by ultra-relativistic freeze-out (UFO). UFO is the mechanism by which Standard Model (SM) neutrinos decouple from the radiation bath in the early universe at a temperature $T_d\approx 1$ MeV. This corresponds to chemical freeze-out without Boltzmann suppression, such that the freeze-out (decoupling) temperature $T_d$ is much greater than $m_{\nu }$ and the neutrinos are therefore ultra-relativistic at freeze-out. While UFO has historically been rejected as a viable mechanism for DM production due to its association with hot DM and the accompanying incompatibility with $\Lambda$CDM, we show that when the approximation of instantaneous reheating after inflation is lifted, UFO can produce cold DM and account for the entire observed relic density in large regions of parameter space. In fact, DM with masses ranging from sub-eV to PeV scales can undergo UFO and be cold before structure formation, given only a simple perturbative, post-inflationary reheating period prior to radiation domination. For some interactions, such as a contact interaction between the Higgs and DM scalars, there is a seamless transition between the WIMP and FIMP regimes which excludes UFO. However, for many other interactions, such as SM fermions producing fermionic DM via a heavy scalar or vector mediator, the WIMP to FIMP transition occurs \textit{necessarily} via a large intermediate region corresponding to UFO. We characterize the general features of UFO in this paper, while we supply a more detailed analysis in a companion paper. We find that UFO during reheating can produce the correct relic density (${\Omega }_{\chi }{h}^2=0.12$) for DM masses spanning about 13 orders of magnitude, reheating temperatures spanning 17 orders of magnitude, and beyond the Standard Model (BSM) effective interaction scales spanning 11 orders of magnitude.

   hep-phastro-ph.COPRL(2025)·16 citations
6. 06*

   Baryon-number-violating nucleon decays in SMEFT extended with a light scalar

   Xiao-Dong Ma🇨🇳 · Michael A. Schmidt🇦🇺 · Weihang Zhang🇦🇺

   New light particles have received considerable attention in recent years. Baryon-number-violating (BNV) nucleon decays involving such light particles are able to provide stringent constraints. They exhibit distinctive experimental signatures that merit thorough investigation. We systematically investigate BNV nucleon decay with a light scalar in an effective field theory framework. Within this framework, we set stringent bounds on BNV operators using available experimental data and predict the occurrence of several BNV three-body nucleon decays. We further study contributions to dinucleon to dilepton transitions in a nucleus mediated by the scalar, which complements single nucleon decay. Finally, we provide three ultraviolet-complete models that can generate different subsets of BNV operators in leading order. Our theoretical framework will facilitate experimental searches for those exotic nucleon decays.

   hep-phJHEP(2026)·7 citations
7. 07*

   Dark Matter Freeze-in from a $Z^{\prime }$ Reheaton

   Avirup Ghosh🇦🇺 · Alexei H. Sopov🇦🇺 · Raymond R. Volkas🇦🇺

   We consider the Standard Model (SM) extended by a secluded $U(1{)}_D$ gauge sector encompassing a Dirac fermion ($\chi$) dark matter (DM), an abelian gauge boson $Z^{\prime }$ and a SM-singlet complex-scalar field $\Phi$, whose radial component drives cosmic inflation. When the Higgs portal coupling is small, the $Z^{\prime }$ then acts as a {\it ``reheaton''}, dominating the energy budget of the Universe before finally yielding the SM bath, with reheating temperature $<O(10)$ TeV, through the gauge portal interaction. We explore the possibility that DM freezes-in via non-thermal $Z^{\prime }$ decays before reheating ends, giving rise to substantial viable parameter space. We account for non-perturbative effects, relevant during the initial stages of reheating, using lattice simulations. We additionally show how the cosmological gravitational wave (GW) background produced by preheating and inflation allow for a direct probe of the reheating mechanism.

   hep-phastro-ph.COJCAP(2026)·2 citations
8. 08*

   Spectroscopy of $cc\bar{c}\bar{c}$ and $ss\bar{c}\bar{c}$ Tetraquarks within the Framework of Regge Phenomenology

   Vandan Patel🇮🇳 · Juhi Oudichhya🇮🇳 · Ajay Kumar Rai🇮🇳

   In this work, we investigate the mass spectra of all-charm ($cc\bar{c}\bar{c}$) and doubly strange- doubly charm ($ss\bar{c}\bar{c}$) tetraquark states using the framework of Regge phenomenology. Employing a quasi-linear Regge trajectory ansatz, we derive linear and quadratic mass inequalities for hadrons, which provide constraints on the masses of tetraquark states. We estimate the range of ground state masses of $cc\bar{c}\bar{c}$ tetraquarks and determine the Regge slope parameters by fitting the corresponding $(J,M^2)$ trajectories. These parameters are then utilized to predict the mass spectra of orbital excited states of both $cc\bar{c}\bar{c}$ and $ss\bar{c}\bar{c}$ systems in the $(J,M^2)$ plane. Furthermore, we extend our analysis to radial excitations by exploring Regge trajectories in the $(n,M^2)$ plane. The obtained mass predictions are compared with existing theoretical results from various models. Additionally, we discuss the possible identification of the experimentally observed $\psi (4660)$ and ${\chi }_{c0}(4700)$ resonances as tetraquark candidates. The results presented in this study offer useful benchmarks for future experimental investigations and may assist in the spin-parity assignment of exotic hadronic states. Our findings contribute to a deeper understanding of multiquark dynamics and the spectroscopy of exotic hadrons within the framework of Quantum Chromodynamics.

   hep-phFew Body Syst.(2025)·10 citations
9. 09*

   Searching for dark photons from dark-scalar decays at CEPC and FCC-ee

   Kingman Cheung🇹🇼 · Fei-Tung Chung🇹🇼 · Zeren Simon Wang🇨🇳

   We investigate the sensitivity of proposed CEPC and FCC-ee with a center-of-mass energy of 240 GeV to long-lived dark photons heavier than 2 GeV that are pair-produced via the prompt decays of a light scalar mixed with the Standard-Model Higgs boson. We compute the production and decay rates of both the light scalar and the dark photon, and develop two search strategies targeting displaced vertices within the inner tracker of the main detectors. Using Monte Carlo simulations, we evaluate the signal acceptance and projected sensitivity for each strategy. Our results show that, for the scalar-Higgs mixing angle set at $10^{-2}$ just below the current upper limit, the proposed searches at CEPC and FCC-ee can probe dark-photon kinetic-mixing parameter several orders of magnitude below existing bounds, for dark photons lighter than half the dark-scalar mass.

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

    Testing Electromagnetic Memory via Acceleration-Induced Phase Imprints in Superconductors

    Jie Sheng🇯🇵 · Tsutomu T. Yanagida🇯🇵 · Bo Gao🇨🇳 · Hong Ding🇨🇳

    Electromagnetic memory is an infrared observable of gauge theory associated with soft photons and large gauge transformations. Despite its fundamental theoretical importance, it has not yet been experimentally verified. From a phenomenological perspective, a transient electromagnetic configuration can leave a persistent gauge-invariant phase imprint on charged coherent states after the local field has vanished. We point out that the electric field and associated gauge potential induced inside a normal conductor by gravitational acceleration can provide a clean source for imprinting this phase, and it can then be read out through a superconducting protocol. For representative parameters, the predicted signal can lie within the range of present sensitivities, providing a possible tabletop route toward testing electromagnetic memory.

    hep-phquant-ph2 citations
11. 11*

    NLO heavy-quark contributions to DIS structure functions in the ACOT scheme

    Edoardo Spezzano🇩🇪 · Tomas Jezo🇩🇪 · Michael Klasen🇩🇪 · Peter Risse🇺🇸 · Ingo Schienbein🇫🇷

    We present next-to-leading-order (NLO) calculations of heavy-quark contributions to deep-inelastic scattering (DIS) structure functions $F_4$ and $F_5$ within the Aivazis--Collins--Olness--Tung (ACOT) scheme, implemented in the open source library \texttt{APFEL++} using \texttt{CT18NLO} parton distribution functions. These structure functions, suppressed by lepton mass effects in light-lepton processes, become significant in muon, tau-lepton and neutrino scattering at facilities such as SHiP, IceCube, and DUNE. Our results reveal NLO corrections up to 10\% relative to leading order, with pronounced heavy-quark effects at low Bjorken-$x$, impacting gluon and strange quark distributions. In the unpolarized case, $F_{4/5}^{\gamma Z}$ and $F_{4/5}^{\gamma }$ do not contribute to the cross section, while the $\gamma Z$ interference becomes accessible with longitudinally polarized lepton beams at the Electron-Ion Collider (EIC), offering enhanced sensitivity at low $Q^2$ due to reduced $Z$-boson propagator suppression. Analytical NLO expressions have also been derived for the polarized structure functions $g_1$, $g_4$, $g_5$, $g_6$, and $g_7$ in the ACOT framework. These developments enable precise theoretical predictions for upcoming experimental programs and global QCD analyses.

    hep-phhep-exhep-thPoS(2025)·1 citation
12. 12*

    Probing an extra Higgs boson at future linear $e^{+}{e}^{-}$ colliders

    Wei-Shu Hou🇹🇼 · Mohamed Krab🇹🇼

    We investigate the possibility of probing an extra Higgs boson at future linear $e^{+}{e}^{-}$ colliders. We consider the production process $e^{+}{e}^{-}\to H\nu \bar{\nu }$, followed by the decay $H\to W^{+}{W}^{-}$, where $H$ is the extra $\text{CP}$-even Higgs boson of the general two Higgs doublet model (G2HDM). This process is governed by the $\text{CP}$-even Higgs mixing angle, $\cos \gamma$, offering direct access to this parameter. We discuss constraints on $\cos \gamma$ using existing LHC data and test the viability of the G2HDM top-quark-driven scenario for electroweak baryogenesis. We perform a full Monte Carlo simulation of the signal and background, and show that an extra Higgs boson in the mass range $200\le m_H\le 400$ GeV could be probed at high energy linear $e^{+}{e}^{-}$ colliders. Promising results are found for CLIC running at 1.5 and 3 TeV collision energies.

    hep-ph2 citations
13. 13*

    Observability of an ultraheavy diquark decaying into vectorlike quarks at the LHC

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

    We present a comprehensive analysis of the discovery reach and exclusion limits for an ultraheavy diquark scalar (7-9.5 TeV) decaying into a pair of vectorlike quarks (1.5-2 TeV) at the HL-LHC. Building on an improved signal selection efficiency achieved using Machine Learning techniques, we extend our previous six-jet final-state study by providing a complete likelihood-based statistical treatment of this search topology. The analysis incorporates theoretical and systematic uncertainties through nuisance parameters within the likelihood framework, enabling a consistent statistical interpretation. The mass regions of interest were determined through scans of the local $p$-values, $C{L}_s$, and the upper limits on the model-dependent signal strength $\mu$. The results indicate a promising sensitivity to ultraheavy diquark scalars within the explored mass range, suggesting that the HL-LHC could either discover or set stringent exclusion limits on such particles.

    hep-phhep-exPRD(2026)·3 citations
14. 14*

    State-of-the-art electroweak Higgs boson pair production in association with two jets at the LHC in the Standard Model and beyond

    Jens Braun🇩🇪 · Pia Bredt🇩🇪 · Gudrun Heinrich🇩🇪 · Marius Höfer🇩🇪 · Barbara Jäger🇩🇪 · Alexander Karlberg🇨🇭 · Simon Reinhardt🇩🇪

    We present a systematic comparison of two state-of-the-art tools for the simulation of Higgs boson pair production via vector boson fusion (VBF) as implemented in the Monte-Carlo tools GoSam+Whizard and the POWHEG-BOX. Cross sections and distributions are provided within the Standard Model and beyond, within scenarios typical for experimental physics analyses, and for a range of energies of relevance to the LHC and its upcoming high luminosity phase. We further perform a detailed study of the so-called VBF approximation, in particular in the presence of anomalous Higgs boson couplings.

    hep-ph2 citations
15. 15*

    Masses of Light Flavor Mesons using Bethe-Salpeter Approach

    Iqra Liaqat🇵🇰 · Faisal Akram🇵🇰

    This work employs the approach based on the Bethe-Salpeter and Dyson-Schwinger equations to study the light meson spectrum. The Dyson-Schwinger equation of the quark propagator is truncated using the Maris-Tandy model for the dressed gluon propagator, which incorporates both the infrared enhancement and the perturbatively correct ultraviolet behavior. Additionally, for the dressed quark-gluon vertex, we apply its bare form and the Ball-Chiu model, which minimally satisfies the constraint imposed by the gauge symmetry through its Ward-Green-Takahashi identity. Consistent truncation of both Bethe-Salpeter and Dyson-Schwinger equations requires that axial-vector Ward-Takahashi identity, arising from chiral symmetry of the Lagrangian of quantum chromodynamics, must not be violated. We utilize this identity as an additional constraint to truncate the Bethe-Salpeter equation and examine the impact of two choices of quark-gluon vertex, along with the application of the Maris-Tandy model on the light meson spectrum. To extract the masses of flavored and unflavored light mesons, we solve the inhomogeneous Bethe-Salpeter equation using the Pad$\acute{e}$ approximation, which enables us to locate the poles of the Bethe-Salpeter amplitude without requiring a numerical solution in the timelike region of momentum space. We find that truncations of the Bethe-Salpeter equation based on bare and Ball-Chiu vertices, coupled with the Maris-Tandy model, yield consistent results.

    hep-phEPJC(2025)·0 citations
16. 16*

    Searches for heavy neutrinos at a 3 TeV CLIC in fat jet final states

    Yao-Bei Liu🇨🇳 · Jing-Wei Lian🇨🇳

    Heavy Majorana neutrinos ($N$) are predicted in many models of physics beyond the Standard Model. In this work, we explore the production and detection prospects of TeV-scale heavy neutrinos ($m_N\gtrsim 1$ TeV) at a future 3 TeV Compact Linear Collider (CLIC). We focus on two distinct decay topologies: (i) $N\to {\ell }^{\pm }{W}^{\mp }$ with hadronic $W$ boson decay, leading to a final state with one charged lepton and a hadronic fat-jet $J_W$; and (ii) $N\to \nu h$ with subsequent Higgs decay $h\to b\bar{b}$, yielding a Higgs-tagged fat-jet $J_h$ and $\text{slashed}{E}_T$. Based on comprehensive detector-level simulations and background analysis, we present both $2\sigma$ exclusion limits and $5\sigma$ discovery reaches in the $m_N$-$|V_{\ell N}{|}^2$ plane. We further extract 95\% confidence level upper limits on the mixing parameter $|V_{\ell N}{|}^2$, and perform a detailed comparison with existing constraints from direct searches at future colliders and indirect global fits. Our findings demonstrate that a 3 TeV CLIC can improve the sensitivity to $|V_{\ell N}{|}^2$ by about two orders of magnitude compared to the projected reaches of future hadron colliders, while remaining competitive with other CLIC search channels.

    hep-phCPC(2026)·4 citations
17. 17*

    Progress on Constraining the Strange Quark Contribution to the Nucleon Spin

    S.F. Pate🇺🇸 · V. Papavassiliou🇺🇸 · J.P. Schaub🇺🇸 · D.P. Trujillo🇺🇸 · M.V. Ivanov🇧🇬 · M.B. Barbaro🇮🇹 · C. Giusti🇮🇹

    We report on a global fit of neutral-current elastic (NCE) neutrino-scattering data and parity-violating electron-scattering (PVES) data with the goal of determining the strange quark contribution to the vector and axial form factors of the proton. Knowledge of the strangeness contribution to the axial form factor, $G_A^s(Q^2)$, at low $Q^2$ will reveal the strange quark contribution to the nucleon spin, as $G_A^s(Q^2=0)=\Delta s$. Previous fits [1,2] of this form included data from a variety of PVES experiments (PVA4, HAPPEx, G0, SAMPLE) and the NCE neutrino and anti-neutrino data from BNL E734. These fits did not constrain $G_A^s(Q^2)$ at low $Q^2$ very well because there was no NCE data for $Q^2<0.45$ GeV${}^2$. Our new fit includes for the first time MiniBooNE NCE data from both neutrino and anti-neutrino scattering; this experiment used a hydrocarbon target and so a model of the neutrino interaction with the carbon nucleus was required. Three different nuclear models have been employed; a relativistic Fermi gas (RFG) model, the SuperScaling Approximation (SuSA) model, and a spectral function (SF) model [3]. We find a tremendous improvement in the constraint of $G_A^s(Q^2)$ at low $Q^2$ compared to previous work, although more data is needed from NCE measurements that focus on exclusive single-proton final states, for example from MicroBooNE [4]. This work has been published in Physical Review D [5]. [1] S.F. Pate, D. McKee, V. Papavassiliou, Phys. Rev. C78, 015207 (2008) [2] S.F. Pate, D. Trujillo, EPJ Web of Conferences 66, 06018 (2014) [3] C. Giusti and M.V. Ivanov, J. Phys. G: Nucl. Part. Phys. 47 024001 (2020) [4] L. Ren, NuFact 2021, PoS, 402, 205 (2022), 10.22323/1.402.0205 [5] S.F. Pate et al., Phys. Rev. D 109, 093001, 2024

    hep-phPoS(2026)·0 citations
18. 18*

    Model Parameter Reconstruction of Electroweak Phase Transition with TianQin and LISA: Insights from the Dimension-Six Model

    Aidi Yang🇨🇳 · Chikako Idegawa🇨🇳 · Fa Peng Huang🇨🇳

    We investigate the capability of TianQin and LISA to reconstruct the model parameters in the Lagrangian of new physics scenarios that can generate an electroweak SFOPT. Taking the dimension-six Higgs operator extension of the Standard Model as a representative scenario for a broad class of new physics models, we establish the mapping between the model parameter $\Lambda$ and the observable spectral features of the stochastic gravitational wave background. We begin by generating simulated data incorporating Time Delay Interferometry channel noise, astrophysical foregrounds, and signals from the dimension-six model. The data are then compressed and optimized, followed by geometric parameter inference using both Fisher matrix analysis and Bayesian nested sampling with PolyChord, which efficiently handles high-dimensional, multimodal posterior distributions. Finally, machine-learning techniques are employed to achieve precise reconstruction of the model parameter $\Lambda$. For benchmark points producing strong signals, parameter reconstruction with both TianQin and LISA yields relative uncertainties of approximately $20$-$30\%$ in the signal amplitude and sub-percent precision in the model parameter $\Lambda$. The sub-percent precision reflects the statistical reconstruction capability of the detectors in an idealized setting: it incorporates the machine-learning inference uncertainty and is established at a fixed bubble wall velocity, while theoretical uncertainties in the effective potential calculation are not included.

    hep-phPRD(2026)·0 citations
19. 19*

    The Price of a Large Electron Yukawa Modification

    Lukas Allwicher🇩🇪 · Matthew McCullough🇨🇭 · Sophie Renner🇬🇧 · Duncan Rocha🇺🇸 · Benjamin Smith🇬🇧

    The theoretical implications of an electron Yukawa modification are considered in the context of a possible Higgs pole run at FCC-ee, aimed at bounding this coupling. We start from an effective field theory viewpoint, considering the impact of renormalisation group effects on related observables and also examining assumptions on the broader UV flavour structure. We then give an overview of the landscape of simplified models, investigating phenomenological constraints arising at higher orders. A short discussion of fine-tuning is also included.

    hep-phJHEP(2026)·8 citations
20. 20*

    Infrared divergences and the photon mass in QED

    Orlando Oliveira🇵🇹

    The infrared properties of QED are investigated within the framework of the Dyson-Schwinger equations. Our study finds that, independently of the value of the coupling constant, requiring the photon self-energy to be finite for any momenta, combined with a smooth behavior for the photon-fermion vertex, is equivalent to state that the photon is massless and that the photon propagator diverges at low momenta as $1/k^2$. Furthermore, the Schwinger mechanism to generate, in a gauge invariant way, a photon mass is investigated and the form factors that can be at the origin of a possible photon mass are identified. For the Schwinger mechanism the link between the finiteness of the photon self-energy and the masslessness of the photon is lost. The infrared behavior of the fermion gap equation and the vertex equation are found to be infrared safe integral equations. Moreover, by studying chiral fermions within QED it is observed that the requirement of the finiteness of the photon self-energy translates into a fermion propagator that behaves as $\text{slashed}p/p^4$.

    hep-phPRD(2026)·0 citations
21. 21*

    Impact of the $a_1(1260)\pi$ cascade contribution on $D^0\to {\pi }^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$ decays

    Eleftheria Solomonidi🇨🇭 · Luiz Vale Silva🇪🇸

    We revisit the Standard Model description of the recently measured rare decays $D^0\to {\pi }^{+}{\pi }^{-}{\ell }^{+}{\ell }^{-}$. Because of the effectiveness of the Glashow-Iliopoulos-Maiani mechanism in charm flavour-changing neutral currents, those decays are driven by non-local insertions of four-quark operators. Following previous work, we consider the mediation of resonances both for the dipion and dilepton pairs. For the first time, we incorporate the effect of the cascade-type topology $D^0\to {\pi }^{-}{a}_1^{+}(1260)(\to {\pi }^{+}{\rho }^0(\to {\ell }^{+}{\ell }^{-}))$, which manifests distinctly in the invariant-mass and angular distributions. We find that this partial amplitude comprises one of the largest contributions to the decay rate and obtain an unprecedented agreement of the Standard Model prediction with the available LHCb data. Finally, we compare to the available CLEO-c, LHCb, and BESIII amplitude analyses for the analogous four-body hadronic decays and find that similar values of the hadronic parameters of our model successfully describe the two classes of decays.

    hep-phhep-exPRD(2026)·1 citation
22. 22*

    Dark Secrets of Baryons: Illuminating Dark Matter-Baryon Interactions with JWST

    Souradeep Das🇮🇳 · Ranjini Mondol🇮🇳 · Abhijeet Singh🇮🇳 · Ranjan Laha🇮🇳

    The James Webb Space Telescope (JWST) has discovered bright galaxies at high redshifts ($z\approx 10-14$) and various galaxy candidates extending to even higher redshifts ($z\approx 15-30$). Many astrophysical and beyond the Standard Model physics scenarios have been proposed to explain these observations. We investigate, {\it for the first time}, the implications of dark matter (DM) scattering with baryons (protons and electrons) in light of the JWST UV luminosity function (UVLF) observations. These interactions suppress structure formation on galactic scales, which may have an observable effect on the UVLF measurements at high redshifts. Using a recent galaxy formation model designed to explain high redshift observations, we obtain strong upper limits on DM-baryon scattering cross-sections and explore new regions of the parameter space. For DM-proton scattering with cross-section $\propto v^{-2}$ velocity dependence, we obtain the strongest limit for DM masses of $\sim$ 1 -- 500 MeV. For other cases that we study (DM-proton scattering cross-section $\propto v^0,v^{-4}$ and DM-electron scattering cross-section $\propto v^0,v^{-2},v^{-4}$, our limits are competitive with those obtained from other cosmological observables. Our study highlights the potential of JWST observations as a novel and powerful probe of non-gravitational interactions of DM.

    hep-phastro-ph.COastro-ph.GAhep-exPRL(2026)·7 citations
23. 23*

    Beyond the Daisy Chain: Running and the 3D EFT View of Supercooled Phase Transitions

    Martin Christiansen🇩🇪 · Eric Madge🇪🇸 · Cristina Puchades-Ibáñez🇩🇪 · Maura E. Ramirez-Quezada🇩🇪 · Pedro Schwaller🇩🇪

    Pulsar timing arrays have recently observed a stochastic gravitational wave background at nano-Hertz frequencies. This raises the question whether the signal can be of primordial origin. Supercooled first-order phase transitions are among the few early Universe scenarios that can successfully explain it. To further scrutinise this possibility, a precise theoretical understanding of the dynamics of the phase transition is required. Here we perform such an analysis for a dark sector with an Abelian Higgs model in the conformal limit, which is known to admit large supercooling. We compare simple analytic parametrisations of the bounce action, one-loop finite temperature calculations including Daisy resummation, and results of a dimensionally reduced (3D) effective theory including up to two-loop corrections using the DRalgo framework. Consistent renormalisation group evolution (RGE) of the couplings is essential for a meaningful interpretation of the results. We find that the 3D EFT with consistent expansion in the 4D parameters gives a significantly reduced scale dependence of the phase transition parameters. With a suitable choice of RGE scale, the 4D high temperature expanded effective potential yields results consistent with the 3D calculations, while the analytic parametrisation deviates significantly in the limit of large supercooling.

    hep-phJHEP(2026)·9 citations
24. 24*

    Bulk-boundary decomposition of neural networks

    Donghee Lee🇰🇷 · Hye-Sung Lee🇰🇷 · Jaeok Yi🇰🇷

    We present the bulk--boundary decomposition as a new framework for understanding the training dynamics of deep neural networks. Starting from the stochastic gradient descent formulation, we show that the Lagrangian can be reorganized into a data-independent bulk term and a data-dependent boundary term. The bulk captures the intrinsic dynamics set by network architecture and activation functions, while the boundary reflects stochastic interactions from training samples at the input and output layers. This decomposition exposes the local and homogeneous structure underlying deep networks. As a physical consequence of locality and homogeneity, we derive the energy continuity equation within a deep neural network.

    ↳ cs.LGcond-mat.dis-nnhep-ph0 citations
25. 25*

    Charged-Current Elastic Scattering at the Electron-Ion Collider

    Henry T. Klest🇺🇸

    We discuss the measurement of the charged-current elastic scattering process $e^{-}p\to {\nu }_{e}n$ at the Electron-Ion Collider (EIC). This process provides sensitivity to the poorly constrained axial form factor of the nucleon, which encodes the spatial distribution of weak charge. Collisions of electrons with polarized protons enable measuring the axial form factor via the $e^{-}\vec{p}\to {\nu }_{e}n$ target-spin asymmetry for the first time. We conclude that a measurement of charged-current elastic scattering at the EIC will, perhaps unsurprisingly, prove very challenging. However, with dedicated instrumentation at a second EIC detector, the measurement may be possible.

    ↳ nucl-exhep-exhep-phPRD(2026)·5 citations
26. 26*

    Testing Quantum Gravity with Gravitational Waves from the ringdown of binary Black Holes coalescences: A New Frontier in Fundamental Physics

    Marco Danilo Claudio Torri🇮🇹 · Fulvio Ricci🇮🇹 · Marco Giammarchi🇮🇹 · Lino Miramonti🇮🇹 · Valerio Toso🇮🇹 · Chiara Sigala🇮🇹

    The observation of gravitational waves emitted during the merging phase of compact binary coalescing objects has opened a new field of investigation in fundamental physics. It is now possible to test the predictions of General Relativity with unprecedented precision in the strong gravitational field regime. These initial observations therefore call for further research, as the detection of gravitational waves emitted by coalescing black holes may allow the investigation of the properties of spacetime near the event horizon, also providing valuable information on the structure of these objects. This also opens the possibility of testing predictions from quantum gravity models regarding the presumed quantized structure of black holes, related to the quantization of their surface and, consequently, their entropy. In the future, the considerable amount of data obtained by the LIGO-Virgo-KAGRA collaboration will be followed by observations from next-generation interferometers such as the Einstein Telescope or the Cosmic Explorer. It is therefore of great interest to explore the potential of gravitational wave observations for investigating aspects of quantum gravity, which we will address considering the special case of the ringdown emission following the coalescence of binary black hole systems.

    ↳ gr-qchep-phhep-th0 citations
27. 27*

    Euler-Heisenberg actions for gauge-axial background vectors: Hessian diagonalization, sector classification, and applications

    Lucas Pereira de Souza🇧🇷

    We derive the closed-form one-loop Euler-Heisenberg effective actions for Dirac fermions coupled simultaneously to classical electromagnetic vector and massive pseudo-vector backgrounds within a controlled quasi-static approximation. Through complete diagonalization of the functional Hessian, we systematically delineate the parameter space into distinct sectors characterized by stability properties and spectral structure. We identify subspaces that encompass and extend results from previous studies into a broader class, admitting propagating axial fields as physically viable regimes; strikingly, we note sectors presenting chirality-asymmetric instability. This addresses long-standing questions regarding the well-defined nature, diagonalizability, and stability of these models. From the effective actions, we derive novel nonperturbative pair-production rates for simultaneously propagating electromagnetic and axial vector backgrounds; remarkably, we find pronounced vacuum stabilization compared to previous results. Furthermore, we derive the non-perturbative contributions to the chiral current divergence, which enables dynamical chiral symmetry breaking and show that the electromagnetic coupling induces instanton-like configurations for the axial field, even when it is not a fundamental gauge field. As a proof-of-concept, we analyze a cosmological toy model of baryogenesis driven by an axial vector, providing numerical estimates that support the viability of this hypothesis. Additionally, we outline qualitative predictions for Weyl/Dirac semi-metals and briefly discuss potential applications in related phenomena, such as Quark-Gluon plasma, Electroweak scenarios and the Strong-CP problem.

    ↳ hep-thastro-ph.COcond-mat.othergr-qc+1EPJC(2026)·1 citation
28. 28*

    Roper Resonance Structure and Exploration of Emergent Hadron Mass from CLAS Electroproduction Data

    V.I. Mokeev🇺🇸 · D.S. Carman🇺🇸

    The $N(1440)1/2^{+}$ nucleon resonance, first identified in 1964 by L.D. Roper and collaborators in analyses of $\pi N$ hadroproduction data have continued to provide pivotal insights that serve to advance our understanding of nucleon excited states. In this contribution, we present results from studies of the structure of the Roper resonance based on exclusive $\pi N$ and ${\pi }^{+}{\pi }^{-}p$ electroproduction data measured with the CLAS detector at Jefferson Lab. These analyses have revealed the Roper resonance as a complex interplay between an inner core of three dressed quarks and an external meson--baryon cloud. Analyses of the CLAS results on the evolution of the Roper resonance electroexcitation amplitudes with photon virtuality $Q^2$, within the framework of the Continuum Schwinger Method, have conclusively demonstrated the capability to gain insight into the strong interaction dynamics responsible for generating more than 98\% of hadron mass. Further extension of such studies to higher $Q^2$--through experiments currently underway with the CLAS12 detector and in the future with a potential CEBAF energy upgrade to 22 GeV--offers the only foreseeable opportunity to explore the full range of distances where the dominant portion of hadron mass and resonance structure emerges.

    ↳ nucl-exhep-phActa Phys.Polon.B(2026)·3 citations
29. 29*

    Fundamental structure of string geometry theory

    Matsuo Sato🇯🇵

    String geometry theory is one of the candidates of a non-perturbative formulation of string theory. In this theory, the ``classical'' action is almost uniquely determined by T-symmetry, which is a generalization of the T-duality, where the parameter of ``quantum'' corrections $\beta$ in the path-integral of the theory is independent of that of quantum corrections $\hslash$ in the perturbative string theories. We distinguish the effects of $\beta$ and $\hslash$ by putting " " like "classical" and "loops" for tree level and loop corrections with respect to $\beta$, respectively, whereas by putting nothing like classical and loops for tree level and loop corrections with respect to $\hslash$, respectively. A non-renormalization theorem states that there is no ``loop'' correction. Thus, there is no problem of non-renormalizability, although the theory is defined by the path-integral over the fields including a metric on string geometry. No ``loop'' correction is also the reason why the complete path-integrals of the all-order perturbative strings in general string backgrounds are derived from the ``tree''-level two-point correlation functions in the perturbative vacua, although string geometry includes information of genera of the world-sheets of the stings. Furthermore, a non-perturbative correction in string coupling with the order $e^{-1/g_s^2}$ is given by a transition amplitude representing a tunneling process between the semi-stable vacua in the ``classical'' potential by an ``instanton'' in the theory. From this effect, a generic initial state will reach the minimum of the potential.

    ↳ hep-thgr-qchep-phmath.DG+14 citations
30. 30*

    Precision determination of nucleon iso-vector scalar and tensor charges at the physical point

    Ji-Hao Wang🇨🇳 · Zhi-Cheng Hu🇨🇳 · Xiangdong Ji🇺🇸 · Xiangyu Jiang🇨🇳 · Yushan Su🇺🇸 · Peng Sun🇨🇳 · Yi-Bo Yang🇨🇳

    We report a high precision calculation of the isospin vector charge $g_{S,T}$ of the nucleon using recently proposed ``blending" method which provides a high-precision stochastic estimate of the all-to-all fermion propagator. Through multiplying the current operator by the traditional nucleon interpolator, we create a new operator that captures the major excited state contaminations. The linear combination of this new operator and traditional nucleon interpolator reduces these excited states and improves the robustness of the multi-state fit. Using 15 $N_f=2+1$ lattice ensembles which cover 5 lattice spacing, 5 combinations with the same quark masses and lattice spacing but multiple volumes, including three at the physical pion mass, we report so far most precise lattice QCD prediction $g_T^{\mathrm{QCD}}=1.0264[77{]}_{\mathrm{tot}}(53{)}_{\mathrm{stat}}(13{)}_a(46{)}_{\mathrm{FV}}(01{)}_{\chi }(28{)}_{\mathrm{ex}}(04{)}_{\mathrm{re}}$ and $g_S^{\mathrm{QCD}}=1.106[43{]}_{\mathrm{tot}}(31{)}_{\mathrm{stat}}(03{)}_a(28{)}_{\mathrm{FV}}(01{)}_{\chi }(08{)}_{\mathrm{ex}}(08{)}_{\mathrm{re}}$ at $\overline{\mathrm{MS}}$ 2~GeV, with the systematic uncertainties from continuum, infinite volume, chiral extrapolations, excited state contamination and also renormalization.

    ↳ hep-lathep-ph11 citations
31. 31*

    Revisiting the three-kaon interaction and its relation with $K(1460)$

    Michael Döring🇺🇸 · Kanchan P. Khemchandani🇧🇷 · Alberto Martínez Torres🇧🇷

    We test the hypothesis of $K(1460)$ being a hadronic $J^P=0^{-}$ molecule through nonperturbative $S$-wave $KK\bar{K}$, $K\pi \pi$, $K\pi \eta$ coupled-channel dynamics in a three-body unitary isobar approach. The scalar two-body coupled-channel resonances $f_0(500)$, $f_0(980)$, $a_0(980)$ and $K_0^{\ast }(700)$ are generated in the subsytems in amplitudes that match phase shifts from experiment. In a first step, previous results in the limit of mass-degenerate, stable $f_0$ and $a_0$ isobars are reproduced. Once the full seven-coupled channel model is switched on, other $S$-matrix effects obscure and modify the resonance signal, including complex thresholds, a two-body cusp, and a triangle singularity at threshold.

    ↳ nucl-thhep-phnucl-exPRD(2026)·5 citations
32. 32*

    A Bayesian Inference of Hybrid Stars with Large Quark Cores

    Milena Albino🇵🇹 · Tuhin Malik🇵🇹 · Márcio Ferreira🇵🇹 · Constança Providência🇵🇹

    Neutron stars (NSs) are interesting objects capable of reaching densities unattainable on Earth. The properties of matter under these conditions remain a mystery. Exotic matter, including quark matter, may be present in the NS core. In this work, we explore the possible compositions of NS cores, in particular, the possible existence of large quark cores. We use the Relativistic Mean Field (RMF) model with nonlinear terms for the hadron phase and the Nambu-Jona-Lasinio (NJL) model and Mean Field Theory of Quantum Chromodynamics (MFTQCD) for the quark phase. Through Bayesian inference, we obtain different sets of equations: four sets with hybrid equations and one set with only the hadron phase. We impose constraints regarding the properties of nuclear matter, X-ray observational data from NICER, gravitational wave data from the binary neutron star merger GW170817, perturbative QCD (pQCD) calculations, and causality. The MFTQCD allows for a phase transition to quark matter at low densities, just above saturation density, while for the NJL sets, the phase transition occurs above twice the saturation density. As a result, the MFTQCD model predicts the presence of quark matter in the inner core of 1.4 M${}_{\odot }$ NSs, while NJL models suggest a low probability of quark matter in the interior of a 1.4 M${}_{\odot }$ NS. Both models predict the existence of quark matter in 2 M${}_{\odot }$ NSs. The slope of the mass-radius curve has been shown to carry information about the presence of quark matter. In particular, a positive slope at 1.8 M${}_{\odot }$ indicates the presence of non-nucleonic matter. A hybrid star with a stiff quark equation of state could explain a larger radius in more massive stars, such as two solar mass stars, compared to canonical NSs.

    ↳ nucl-thastro-ph.HEgr-qchep-phPRD(2026)·13 citations
33. 33*

    Fixed points of semi-simple supersymmetric gauge theories

    Andrew D. Bond🇬🇧 · Daniel F. Litim🇬🇧 · Gabriel Picanço🇬🇧

    We study fixed points and phase diagrams of semi-simple supersymmetric gauge theories coupled to chiral superfields and a superpotential. Particular emphasis is put on new phenomena which arise due to the semi-simple nature of gauge interactions and the constraints dictated by supersymmetry, unitarity, and the $a$-theorem. Using field multiplicities as free parameters, we find all superconformal fixed points and classify theories according to their phase diagrams. Highlights include asymptotically free theories displaying a range of interacting fixed points in the IR, asymptotically non-free theories that become asymptotically safe due to residual interactions, UV-complete theories with gauge sectors that are simultaneously UV-free and IR-free, and theories that remain interacting both in the asymptotic UV and IR. Estimates for the sizes of conformal windows are also provided, and implications for model building are discussed.

    ↳ hep-thhep-phJHEP(2026)·1 citation
34. 34*

    Accuracy of ringdown models calibrated to numerical relativity simulations

    Francesco Crescimbeni🇮🇹 · Gregorio Carullo🇬🇧 · Emanuele Berti🇺🇸 · Giada Caneva Santoro🇪🇸 · Mark Ho-Yeuk Cheung🇺🇸 · Paolo Pani🇮🇹

    The ''ringdown'' stage of gravitational-wave signals from binary black hole mergers, mainly consisting of a superposition of quasinormal modes emitted by the merger remnant, is a key tool to test fundamental physics and to probe black hole dynamics. However, ringdown models are known to be accurate only in the late-time, stationary regime. A key open problem in the field is to understand if these models are robust when extrapolated to earlier times, and if they can faithfully recover a larger portion of the signal. We address this question through a systematic time-domain calculation of the mismatch between non-precessing, quasi-circular ringdown models parameterised by the progenitor binary's degrees of freedom and full numerical relativity inspiral-merger-ringdown waveforms from the Simulating eXtreme Spacetimes (SXS) simulation catalog. For the best-performing models, the mismatch is typically in the range $[10^{-6},10^{-4}]$ for the $(\ell ,|m|)=(2,2)$ harmonic, and $[10^{-4},10^{-2}]$ for higher-order modes. Our findings inform ongoing observational searches for quasinormal modes, and underscore the need for improved modeling of higher-order modes to meet the sensitivity requirements of future gravitational-wave detectors.

    ↳ gr-qcastro-ph.HEhep-phPRD(2026)·9 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.