Wed·Oct 22, 2025Wednesday·October 22, 2025

1. 01*

   QINNs: Quantum-Informed Neural Networks

   Aritra Bal🇩🇪 · Markus Klute🇩🇪 · Benedikt Maier🇬🇧 · Melik Oughton🇬🇧 · Eric Pezone🇬🇧 · Michael Spannowsky🇬🇧

   Classical deep neural networks can learn rich multi-particle correlations in collider data, but their inductive biases are rarely anchored in physics structure. We propose quantum-informed neural networks (QINNs), a general framework that brings quantum information concepts and quantum observables into purely classical models. While the framework is broad, in this paper, we study one concrete realisation that encodes each particle as a qubit and uses the Quantum Fisher Information Matrix (QFIM) as a compact, basis-independent summary of particle correlations. Using jet tagging as a case study, QFIMs act as lightweight embeddings in graph neural networks, increasing model expressivity and plasticity. The QFIM reveals distinct patterns for QCD and hadronic top jets that align with physical expectations. Thus, QINNs offer a practical, interpretable, and scalable route to quantum-informed analyses, that is, tomography, of particle collisions, particularly by enhancing well-established deep learning approaches.

   hep-phcs.LGhep-exquant-ph0 citations
2. 02*

   Collider Searches for Near-Continuum Dark Matter

   Steven Ferrante🇺🇸 · Lillian Luo🇺🇸 · Maxim Perelstein🇺🇸 · Taewook Youn🇺🇸

   We study collider constraints on the near-continuum dark matter model, in which the dark sector consists of a tower of closely spaced states with weak-scale masses coupled to the Standard Model through a $Z$-portal. To capture this structure in a model-agnostic way, we introduce a minimal parameterization that encodes the dominant geometric information with three parameters. Using a custom-built Monte-Carlo tool for near-continuous spectra, we simulate DM-pair production at $\sqrt{s}=13$ TeV and subsequent cascade decays via on/off-shell $Z$ bosons, which yield events with large missing transverse momentum and high jet multiplicity. Recasting the CMS multijet$+H_T^{\mathrm{miss}}$ analysis of Run-2 data (35.9 fb${}^{-1}$), we derive bounds on the model parameter space. Extrapolating these bounds, we provide High-Luminosity LHC projections (3 ab${}^{-1}$). We also project sensitivities for future electron-positron colliders at $\sqrt{s}=365$ GeV and $\sqrt{s}=500$ GeV, showing substantial improvements over the HL-LHC. The current LHC sensitivity is beginning to approach the theoretically motivated region of the parameter space, while future colliders will be able to comprehensively test this model.

   hep-ph3 citations
3. 03*

   Systematic derivation of perturbative unitarity bounds for any models

   Nico Benincasa🇨🇳

   In this letter, we provide a simple algorithm, anyPUB, to systematically derive the $2\to 2$ scattering matrix in the high-energy limit for any kind of models, irrespective of their gauge group or their field representation. After computing the eigenvalues analytically and/or numerically from this matrix, we impose perturbative unitarity bounds on them. We tested our method on various models and validated the results against the literature. Finally, as a concrete application of our approach, we discuss the case of the minimal left-right symmetric model and derive, for the first time, the perturbative unitarity constraints in the Pati-Salam model.

   hep-phPLB(2026)·1 citation
4. 04*

   Solar Reflected Dark Matter under the Influence of a Dark Magnetic Field

   Haoming Nie🇨🇳

   The scattering of dark matter particles within the Sun's hot plasma can lead to the acceleration of dark matter, producing a high-energy solar-reflected DM flux detectable in ground-based experiments. In the vector portal model, the dark matter has a sub-MeV-scale mass, and interactions between the dark matter and Standard Model particles are mediated by a hidden vector field--referred to as a dark photon--which kinetically mixes with the conventional photon through a small mixing angle. Furthermore, the solar plasma generates intense magnetic fields. Due to the photon-dark photon mixing, this simultaneously sources a ``dark magnetic field". For sufficiently low dark photon masses, this dark magnetic field is capable of deflecting dark matter particles traversing the Sun. We found that if the dark magnetic force is sufficiently strong, the dark magnetic field becomes a wall, preventing the dark matter particles from reaching the deep core region, suppressing their reflected flux. This scenario corrects the sensitivity of the solar-reflected dark matter detection, offering critical insights for ground-based experiments aiming to probe dark matter.

   hep-phastro-ph.SRhep-exPRD(2026)·0 citations
5. 05*

   Theoretical Aspects of $b\to s\bar{\ell }\ell$ Decays

   Arianna Tinari🇨🇭

   Flavor-changing neutral current decays such as $b\to s\bar{\ell }\ell$ are highly suppressed in the Standard Model (SM) and therefore provide sensitive tests for new physics. Persistent tensions between SM predictions and experimental results in branching ratios and angular observables can be explained by a shift of the Wilson coefficient $C_9$ of the effective operator $O_9$ by $\sim 20\%$ relative to the SM value. This shift could arise from a non-standard short-distance contribution or from an inaccurate description of long-distance dynamics, particularly charm rescattering contributions. We therefore investigate charm rescattering contributions in $B^0\to K^0\bar{\ell }\ell$ using a model of fundamental hadronic degrees of freedom inspired by heavy-hadron chiral perturbation theory and improved by appropriate form factors as well as experimental data. Our analysis shows that such effects, with a high degree of fine-tuning, could shift $C_9$ by $\sim 20\%$, at the cost of introducing a more pronounced $q^2$ dependence, whereas experimental data are consistent with a $q^2$-independent shift of $C_9$ with the current experimental uncertainties. In the most natural scenario, we find these effects to be of the order of $\sim 5\%$. Connections with other flavor anomalies further illustrate the strong discovery potential of $b\to s\bar{\ell }\ell$ modes.

   hep-phPoS(2026)·0 citations
6. 06*

   Ultra-Strongly Self-Interacting Dark Matter: From Phenomenology to Astrophysical Observables

   M. Grant Roberts🇺🇸 · Wolfgang Altmannshofer🇺🇸 · Pierce Giffin🇺🇸 · Stefano Profumo🇺🇸

   We develop a minimal, testable framework for two-component self-interacting dark matter (SIDM) in which a dominant, moderately self-interacting species coexists with an ultra-strongly self-interacting subcomponent (uSIDM). A light vector mediator induces velocity-dependent self-scattering, while early-universe dynamics - standard $2\to 2$ annihilation supplemented by interconversion ${\chi }_1{\chi }_1\to {\chi }_2{\chi }_2$ - determine the relic abundance analytically. From observations of dwarf and low surface brightness galaxy rotation curves, as well as strong cluster lensing, we place constraints on the microphysics parameters. From these constrained regions, we map the microphysics to effective \texttt{ETHOS} parameters and evolve the linear power spectrum in \texttt{CLASS}. We identify a region where: (1) the SIDM dominant component attains ${\sigma }_{\mathrm{eff}}/m=20-40{\text{cm}}^2{\text{g}}^{-1}$ at dwarf velocities while satisfying cluster upper bounds ${\sigma }_{\mathrm{eff}}/m<0.13{\mathrm{cm}}^2{\mathrm{g}}^{-1}$; (2) a subpercent uSIDM fraction drives accelerated gravothermal collapse in early halos, providing seeds relevant to high-redshift quasar formation and ``little red dots''; and (3) the small-scale cutoff in the matter power spectrum remains consistent with Lyman-$\alpha$ and satellite counts, but exhibits non-standard features, potentially discernible with future observations. The allowed space can be organized by the mediator-to-DM mass ratio and the late-time uSIDM fraction, with a narrow window singled out by the combined cosmological and astrophysical requirements.

   hep-phastro-ph.CO3 citations
7. 07*

   Neutrino Dipole Portal

   Sin Kyu Kang🇰🇷 · C.J. Ouseph🇰🇷

   The neutrino dipole portal (NDP) is a minimal and predictive extension of the Standard Model, in which a transition magnetic moment operator couples an active neutrino to a heavy neutral lepton via the electromagnetic field. This higher-dimensional interaction gives rise to distinctive processes such as neutrino up-scattering, radiative decays, meson transitions, and modifications of recoil spectra, offering multiple avenues for discovery. In this review, we discuss the theoretical foundations of the NDP, its ultraviolet completions, and the associated production and decay mechanisms across laboratory, astrophysical, and cosmological settings. Current constraints arise from accelerator searches, recoil-based detectors, collider studies, and high energy neutrino observatories, complemented by robust bounds from Big Bang Nucleosynthesis, the Cosmic Microwave Background, and supernova cooling. Future experimental and observational efforts, including next-generation neutrino experiments, multi-ton dark matter detectors, and improved cosmological and astrophysical probes, are anticipated to test the remaining allowed regions. The NDP thus provides a simple, well-motivated, and broadly testable framework at the intersection of particle physics, astrophysics, and cosmology.

   hep-phhep-exhep-thInt.J.Mod.Phys.A(2026)·1 citation
8. 08*

   High-Quality Axion Models with the Anomalous $U(1{)}_X$ Gauge Symmetry

   Hongkun Gao🇨🇳 · Tianjun Li🇨🇳 · Lina Wu🇨🇳 · Wenxing Zhang🇨🇳

   We propose the generic high-quality axion models with anomalous $U(1{)}_X$ gauge symmetry and vector-like particles. We briefly review the gauge anomaly cancellations via the Green-Schwarz mechanism, study the breaking of the $U(1{)}_X$ gauge symmetry, as well as derive the Nambu-Goldstone boson, Peccei-Quinn (PQ) axion, and axion decay constant in general. The high-dimensional operators, which break the $U(1{)}_{PQ}$ global symmetry, have dimension eleven or higher due to the anomalous $U(1{)}_X$ gauge symmetry, and thus the axion quality problem is solved. In particular, unlike the high-quality axion models with anomaly free $U(1)$ gauge symmetry, we only need to introduce two pairs of vector-like particles. To be concrete, we present three specific models with two pairs of vector-like particles. We show that gauge anomalies in all three models can be canceled via the Green-Schwarz mechanism. To achieve gauge coupling unification, we need to introduce additional vector-like particles only in Model I. We find that gauge coupling unification is achieved at the unification scale around $10^{16}$ GeV with a relative error of less than 1\%. Notably, gauge coupling unification in Model II is achieved naturally with the smallest relative error of 0.1\%.

   hep-ph0 citations
9. 09*

   Direct Detection of Leptophobic Dark Matter with Electronic Collective Excitations

   Yuanlin Gong🇨🇳 · Yifan Hu🇨🇳 · Ning Liu🇨🇳 · Liangliang Su🇩🇪 · Bin Zhu🇨🇳

   Some new-generation dark matter detection experiments are primarily designed to search for the dark matter-electron interactions, but they can also be utilized to probe models in which dark matter couples exclusively to nucleon via the quantum effects. The hadronic loop-induced interactions can directly excite plasmons in semiconductors, thereby providing an additional channel for detecting the leptophobic dark matter. In this work, we investigate plasmon excitations in silicon detectors induced by boosted dark matter and cosmic-ray up-scattering dark matter via the hadronic loop process. By analyzing the available experimental data, we derive new exclusion limits on the leptophobic dark matter-nucleon scattering cross section in the sub-MeV mass range.

   hep-ph5 citations
10. 10*

    Heavy Neutral Lepton at Same-Sign Muon Collider

    Ryuichiro Kitano🇯🇵 · Ian Low🇺🇸 · Ryutaro Matsudo🇯🇵 · Shohei Okawa🇰🇷 · Subhojit Roy🇺🇸

    We explore the discovery potential of heavy neutral leptons (HNLs), motivated by models addressing the origin of neutrino masses, at the proposed high-energy same-sign muon collider known as $\mu$TRISTAN. The study focuses on two complementary HNL-mediated signatures: (i) the lepton-flavor-violating (LFV) channel ${\mu }^{+}{\mu }^{+}\to W^{+}{\tau }^{+}{\bar{\nu }}_{\mu }$ and (ii) the lepton-number-violating (LNV) channel ${\mu }^{+}{\mu }^{+}\to W^{+}{W}^{+}$. The LNV process is the muon analogue of inverse neutrinoless double beta decay and, if observed, would provide strong evidence for Majorana neutrinos, while the LFV process offers a novel probe of flavor-changing neutral currents in the lepton sector. At the $\mu$TRISTAN collider with $\sqrt{s}\sim \mathcal{O}(10)\text{TeV}$, the resulting sensitivity to the HNL mixing with muon and tau neutrinos, as a function of mass, can surpass current bounds from the measurements of electroweak precision observables over a broad mass range. In particular, for the mixing with muon neutrinos, the collider bound can improve by an order of magnitude for $5$-$10$ TeV HNLs.

    hep-phhep-ex5 citations
11. 11*

    Electromagnetic characteristics as probes into the inner structures of the predicted ${\Xi }_c^{{(}^{\prime },\ast )}{D}_s^{(\ast )}$ molecular states

    Sheng-He Zhu🇨🇳 · Fu-Lai Wang🇨🇳 · Xiang Liu🇨🇳

    In this work, we conduct a systematic investigation of the electromagnetic properties, specifically the magnetic moments and the M1 radiative decay behavior, of the predicted ${\Xi }_c^{{(}^{\prime },\ast )}{D}_s^{(\ast )}$-type double-charm hidden-strangeness molecular pentaquarks. The study is carried out within the framework of the constituent quark model to evaluate these electromagnetic observables, and our analysis incorporates three distinct scenarios: single-channel analysis, $S$-$D$ wave mixing analysis, and coupled-channel analysis. The calculated magnetic moments reveal characteristic patterns that reflect their underlying constituent configurations and provide sensitive probes for their quantum number assignments. Furthermore, we identify several M1 radiative decay channels with sizable widths that may offer promising signatures for future experimental detection. These M1 transitions also act as sensitive probes into their inner structures, displaying distinctive features that help differentiate between their constituent configurations and quantum number assignments. We anticipate that this study will stimulate experimental interest in exploring the electromagnetic properties of the ${\Xi }_c^{{(}^{\prime },\ast )}{D}_s^{(\ast )}$ molecular states, thereby advancing our structural understanding of these exotic hadronic states.

    hep-phhep-exEPJC(2026)·8 citations
12. 12*

    Ontological Fluctuating Lattice Cut Off

    Holger Bech Nielsen🇩🇰

    Remarkably accurate fine structure constants are calculated from assumptions further developed from two earlier publications. We have put together a series of energy scales related to various physical phenomena such as the Planck scale, a scale, which we call ``fermion tip'' being a certain extrapolation related to the heaviest Fermions in the Standard Model, an approximate SU(5) unification scale (without susy); and then we found, that as function of the power of an imagined lattice link length supposedly relevant for the scale in question, these powers are rather well linearly related to the logarithms of the associated energy scales. The coincidence of these scales fitting a straight line is remarkable and in some cases quite intriguing. It is evidence for Nature truly having a fluctuating lattice, meaning, that the size of the links say fluctuate quantum mechanically. We review a self-reference obtaining the three fine structure constants via three theoretically predictable quantities, among which is a scale on our straight line plot, namely for an approximate SU(5)-like unification (SU(5) coupling relations are only true in a classical approximation). Concentrating on the four energy scales, for which most precise numbers make sense (this is new in the present article), we interpolate to the approximate unification scale to such an accuracy, that it combined with the quantum corrections making the deviation from genuine SU(5) delivers the differences between the three inverse fine structure constants agreeing within errors being a few units on the second place after the comma! E.g. we predict the difference between the non-abelian inverse fine structure constants at the Z-mass MZ to be (1/alpha2 - 1/alpha3)(M_Z)predict=29.62-8.42 =21.20, while the experimental difference is 29.57-8.44=21.13 both with uncertainties of order +/- 0.05.

    hep-ph0 citations
13. 13*

    Towards a Post-Inflationary Composite Axion Model

    Aleksandr Azatov🇮🇹 · Mohamed Mahdi Khalil🇮🇹 · Motoo Suzuki🇮🇹

    Composite axions offer a scenario where the axion emerges as a pion-like state, avoiding fine-tuning of elementary scalars and ameliorating the axion quality problem. Despite these advantages, their post-inflationary cosmology remains largely unexplored, with challenges including the domain wall problem and the presence of exotic relics. We propose two composite axion models with an effective domain wall number $N_{\text{DW}}=1$ and study the dilution of relics via a short period of inflation. One model is based on an $SU(5)$ chiral gauge theory, while the other employs a ``gauged'' $U(1)$ Peccei-Quinn symmetry in vector-like $SU(N)$ gauge theories. We identify the viable parameter space in which axion strings re-enter the horizon before or even after the QCD transition and axion dark matter is dominantly produced from the decay of the string-wall network.

    hep-phJHEP(2026)·5 citations
14. 14*

    The Muonic Portal to Vector Dark Matter:connecting precision muon physics, cosmology, and colliders

    Alexander Belyaev🇬🇧 · Luca Panizzi🇮🇹 · Nakorn Thongyoi🇹🇭 · Franz Wilhelm🇸🇪

    We present a comprehensive study of the Muonic Portal to Vector Dark Matter (MPVDM), a minimal extension of the Standard Model featuring a new $SU(2{)}_D$ gauge symmetry and vector-like muons that mediate interactions between the dark sector and the muon sector. We show that the MPVDM can simultaneously reproduce the observed dark matter relic abundance and accommodate scenarios consistent with the current experimental determination of the muon anomalous magnetic moment, $(g-2{)}_{\mu }$, as well as scenarios allowing for a non-zero new physics contribution to $(g-2{)}_{\mu }$. One of the key results of this work is the identification of a generic off-resonance velocity-suppression mechanism that allows light ($\lesssim 1$ GeV) vector dark matter to evade stringent CMB constraints near $2m_{\mathrm{DM}}\simeq m_{H_D}$. A five-dimensional parameter scan combining cosmological, collider, and precision constraints shows that scenarios admitting a non-zero contribution to $(g-2{)}_{\mu }$ favour sub-GeV dark matter realised near the scalar resonance with a dark gauge coupling $g_D\sim 10^{-3}$ and TeV-scale vector-like muons, while scenarios consistent with a Standard-Model-like $(g-2{)}_{\mu }$ allow a broad viable dark matter mass range from sub-GeV to multi-TeV. By recasting ATLAS and CMS searches for ${\mu }^{+}{\mu }^{-}$ final states with missing transverse energy, we derive a lower bound of approximately 850~GeV on the vector-like muon masses. We further identify distinctive multi-lepton collider signatures, including six-, eight-, and ten-muon final states as well as mixed muon--electron topologies with displaced electron pairs, providing striking and well-motivated targets for searches at the LHC and future colliders.

    hep-phastro-ph.COhep-exhep-thJHEP(2026)·2 citations
15. 15*

    Constraints on Attractor Models of Inflation and Reheating from Planck, BICEP/Keck, ACT DR6, and SPT-3G Data

    John Ellis🇬🇧 · Marcos A. G. Garcia🇲🇽 · Keith A. Olive🇺🇸 · Sarunas Verner🇺🇸

    We analyze the latest cosmic microwave background (CMB) constraints on the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$ from Planck 2018, BICEP/Keck 2018, the Atacama Cosmology Telescope Data Release 6 (ACT DR6), and the South Pole Telescope (SPT-3G) data, focusing on their implications for attractor models of inflation. We compare systematically observational bounds with theoretical predictions for both E-model ($\alpha$-Starobinsky) and T-model potentials. The observational constraints accommodate E-models with $\alpha \lesssim 25$, with the canonical Starobinsky model ($\alpha =1$) predicting $n_s=0.958-0.963$ for reheating temperatures between $100-10^{10}$ GeV, in good agreement with Planck 2018 data and within the 95% CL region determined by the Planck-ACT-SPT combination, but below the 95% confidence region of the Planck-ACT-DESI combination. Higher reheating temperatures from near-instantaneous reheating improve the compatibility. T-models predict slightly lower $n_s$ values (0.956-0.961), in some tension with Planck 2018 data, and we find an upper limit of $\alpha \lesssim 11$ in these models. We extend our analysis to generalized $\alpha$-attractors with monomial potentials $V(\phi )\propto {\phi }^k$ near the minimum, demonstrating that models with $k\ge 6$ naturally predict $n_s\simeq 0.965-0.968$ for typical number of $e$-folds, in better agreement with the ACT DR6 data. We also consider deformed E- and T-models, which allow significantly higher values of $n_s$ for low values of $\alpha \simeq 1$.

    hep-phastro-ph.COPRD(2026)·45 citations
16. 16*

    Two-loop QCD corrections for real and off-shell diphoton and triphoton production via quark loops

    Dario Kermanschah🇨🇭 · Matilde Vicini🇨🇭

    We compute squared matrix elements at next-to-next-to-leading order in perturbative quantum chromodynamics for the production of two or three (on- or off-shell) photons mediated via (light or heavy) quark loops. Our method handles all cases in a unified framework, using simultaneous subtraction of infrared, ultraviolet, and threshold singularities in loop momentum space to produce a locally finite integrand suitable for numerical integration. We confirm agreement with available analytic benchmarks at fixed phase-space points and provide new results otherwise. We also compute the double-virtual corrections to the cross section for on- and off-shell diphoton and on-shell triphoton production by combining the Monte Carlo integration over loop and phase space.

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

    NLO analysis of the subleading-power $Q_1-Q_{7\gamma }$ interference in $\bar{B}\to X_s\gamma$ at large photon energies

    Riccardo Bartocci🇩🇪 · Philipp Böer🇨🇭 · Tobias Hurth🇩🇪

    We report on progress towards including next-to-leading order (NLO) radiative corrections to the subleading-power factorization formula for the $Q_1^q-Q_{7\gamma }$ interference contribution in $\bar{B}\to X_s\gamma$ at large photon energies, $m_b-2E_{\gamma }=\mathcal{O}({\Lambda }_{\mathrm{QCD}})$. The novel ingredients for a NLO analysis are the one-loop anomalous dimension of the subleading shape function $g_{17}(\omega ,{\omega }_1;\mu )$, which was recently computed by us, and the two-loop corrections to the jet function with an internal charm loop. Here we summarize the renormalization of $g_{17}(\omega ,{\omega }_1;\mu )$, and further discuss that our insights allow for a simplified renormalization of a specific generalization of a three-particle $B$-meson light-cone distribution amplitude, but with non-aligned light-like separations of the fields.

    hep-phPoS(2026)·3 citations
18. 18*

    Modelling $b\bar{b}H$ production for the LHC at 13.6 TeV

    Christian Biello🇩🇪 · Alessandro Gavardi🇩🇪 · Rebecca von Kuk🇩🇪 · Matthew A. Lim🇬🇧 · Stefano Manzoni🇨🇭 · Elena Mazzeo🇨🇭 · Javier Mazzitelli🇨🇭 · Aparna Sankar🇩🇪 · Michael Spira🇨🇭 · Frank J. Tackmann🇩🇪 · Marius Wiesemann🇩🇪 · Giulia Zanderighi🇩🇪 · Marco Zaro🇮🇹

    We present new state-of-the-art predictions for Standard Model Higgs boson production in association with a bottom-quark pair ($b\bar{b}H$). Updated cross sections are computed in accordance with the recommendations of the LHC Higgs Working Group, including the use of the PDF4LHC21 set of parton distribution functions, with a center-of-mass energy of 13.6 TeV. For the total inclusive cross section, we provide matched predictions of the massless five-flavour scheme and the massive four-flavour scheme at the fixed-order level. We further present recently obtained simulations matched to parton showers in both flavour schemes within the Standard Model, and also discuss them in the context of potential Beyond-the-Standard-Model scenarios. In the massless scheme, we compare different next-to-next-to-leading order predictions matched to parton showers obtained through the MiNNLOPS and GENEVA generators. In addition, the role of four-flavour scheme predictions is studied as a background to $HH$ searches, considering both the top-quark and bottom-quark Yukawa contributions to $b\bar{b}H$ production. Finally, we analyse the sensitivity of the Higgs transverse momentum spectrum to light-quark Yukawa couplings in the diphoton decay channel based on MiNNLOPS simulations.

    hep-phhep-exSciPost Phys.Comm.Rep.(2026)·3 citations
19. 19*

    Quantum Computing Hadron Fragmentation Functions in Light-Front Chromodynamics

    Juan José Gálvez-Viruet🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Nicolás Martínez de Arenaza🇪🇸 · María Gómez-Rocha🇪🇸 · Timothy J. Hobbs🇺🇸

    We deploy Quantum Chromodynamics (QCD) in Light-front Quantization (and Gauge), discretized and truncated in both Fock -- and momentum -- spaces with a particle-register encoding suited for quantum simulation; we show for the first time how to calculate fragmentation functions, a problem heretofore untractable in general from \emph{ab-initio} approaches. We provide a classical-simulator based proof-of-concept by computing the charm-to-charmonium fragmentation, $c\to J/\psi$, in a simplified setup, an interesting case where we can (reasonably) compare with the known 1993 perturbative evaluation within Nonrelativistic QCD.

    hep-phhep-th8 citations
20. 20*

    NNLO QCD$\otimes$QED corrections to unpolarized and polarized SIDIS

    Saurav Goyal🇮🇳 · Roman N. Lee🇷🇺 · Sven-Olaf Moch🇩🇪 · Vaibhav Pathak🇮🇳 · V. Ravindran🇮🇳

    We present the first computation of next-to-next-to-leading order (NNLO) pure QED and mixed QCD$\otimes$QED corrections to unpolarized and polarized semi-inclusive deep-inelastic scattering (SIDIS). Building on our previous NNLO QCD results, these corrections are crucial for improving the theoretical precision. The coefficient functions are derived within the QCD factorization framework using dimensional regularization, with consistent renormalization and mass factorization. A detailed phenomenological analysis shows that the NNLO QED and QCD$\otimes$QED terms enhance perturbative stability and reduce scale uncertainties. These results are essential for high-precision SIDIS predictions at future facilities such as the Electron-Ion Collider.

    hep-phhep-th7 citations
21. 21*

    Muon trident process at far-forward LHC detectors

    Reinaldo Francener🇧🇷 · Victor P. Goncalves🇧🇷 · Gabriel Rabelo-Soares🇧🇷

    The electromagnetic production of a dilepton pair in the muon - ion scattering, usually denoted muon trident process, is investigated considering the feasibility of studying processes induced by muons at LHC using its far-forward detectors. The total and differential cross - sections are estimated taking into account of the Bethe-Heitler and bremsstrahlung channels, and predictions for the event rates expected for muon - tungsten ($\mu W$) collisions at the LHC energies are presented. Our results indicate that the observation of the muon trident process is feasible at FASER$\nu$. In particular, our results indicate that the electromagnetic production of ${\tau }^{+}{\tau }^{-}$ pairs in the $\mu W$ scattering can, in principle, be observed for the first time ever at the LHC. In addition, we present our predictions for the production of QED bound states. Finally, results for the trident process at the FASER$\nu$2 detector are also presented.

    hep-phhep-exNPB(2026)·2 citations
22. 22*

    Axion Production and Detection Using a Dual NMR-type Experiment

    Jeff A. Dror🇺🇸 · Qiushi Wei🇺🇸 · Fengwei Yang🇺🇸

    Axions that couple to nuclear spins via the axial current interaction can be both produced and detected using nuclear magnetic resonance (NMR) techniques. In this scheme, nuclei driven by a real oscillating magnetic field in one device act as an axion source, which can drive NMR in a nearby spin-polarized sample interrogated with a sensitive magnetometer. We study the prospects for detecting axions through this method and identify two key characteristics that result in compelling detection sensitivity. First, the gradient of the generated axion field can be substantial, set by the inverse distance from the source. Near the source, it reduces to the inverse of the source's geometric size. Second, because the generated axion field is produced at a known frequency, the detection medium can be tuned precisely to this frequency, enabling long interrogation times. We show that the experimental sensitivity of a pair of centimeter-scale NMR devices operating over a 15-day integration time can already surpass existing astrophysical bounds on the axion-nucleon coupling. A similar sensitivity can be achieved with 10 centimeter-scale NMR devices with only 1 hour of integration time. These dual NMR configurations are capable of probing a wide range of axion masses, up to values comparable to the inverse distance between the source and the sensor.

    hep-phastro-ph.COhep-exPRD(2026)·1 citation
23. 23*

    Unified Resummation of Soft Gluon Radiation in Heavy Meson Pair Photoproduction

    Cyrille Marquet🇫🇷 · Yu Shi🇫🇷 · Bo-Wen Xiao🇨🇳

    We develop a unified resummation framework for heavy-meson pair photoproduction that treats soft-gluon radiation in a massive scheme for $|\mathbf{q}|\lesssim m_Q$ and is consistent with the massless limit $m_Q\ll |\mathbf{q}|$, where $\mathbf{q}$ denotes the transverse momentum of the pair and $m_Q$ the quark mass. This framework describes the full correlation regime $|\mathbf{q}|\ll |\mathbf{P}|$, with $\mathbf{P}$ the pair's relative transverse momentum. Next, within the Color Glass Condensate framework, we quantify the impact of soft gluon radiation on two important phenomenological observables, namely, the azimuthal $\Delta \varphi$ correlation and the harmonic asymmetries $⟨\cos (2n{\varphi }_{qP})⟩$. Our results show that the resummation provides an excellent description of the H1 $\Delta \varphi$ data. We then find that the angular-asymmetry harmonics are sizable and their ratios in $\gamma A$ to $\gamma p$ collisions are highly sensitive to gluon saturation. We further find a clear mass hierarchy in both observables, indicating that heavy-quark masses suppress soft radiation and thereby enhance genuine small-$x$ saturation signals. Our work demonstrates that heavy-quark pair photoproduction provides a quantitative probe of gluon saturation, directly measurable in forthcoming EIC and UPC measurements. Finally, the unified resummation is readily extendable to other processes involving massive particles and jets in both $eA$ and $pA$ collisions.

    hep-phhep-exhep-thnucl-th12 citations
24. 24*

    Clearing up the Strong $CP$ problem

    Joshua N. Benabou🇺🇸 · Anson Hook🇺🇸 · Claudio Andrea Manzari🇺🇸 · Hitoshi Murayama🇺🇸 · Benjamin R. Safdi🇺🇸

    The absence of a neutron electric dipole moment (EDM) constrains the quantum chromodynamics (QCD) theta angle to be less than one part in ten billion, posing the Strong $CP$ problem. We revisit two classes of proposed solutions. First, we show that when $P$ or $CP$ is realized as a gauged discrete symmetry - as can arise in quantum gravity - the vacuum necessarily preserves $CP$, contrary to recent claims that discrete-symmetry solutions fail. Gauged discrete models face model-building challenges, such as avoiding contributions to the neutron EDM after spontaneous $P$ or $CP$ breaking, but in principle have no fundamental obstructions. Second, we critically examine recent arguments that the Strong $CP$ problem is illusory, demonstrating that a nonzero neutron EDM at finite $\bar{\theta }$ follows directly from well-understood QCD dynamics. Taken together, our results reinforce the reality of the Strong $CP$ problem and highlight gauged discrete-symmetry realizations of $P$ or $CP$ as plausible solutions.

    hep-phhep-th29 citations
25. 25*

    The $B^{+}\to K^{+}\nu \bar{\nu }$ decay as a search for the QCD axion

    Merna Abumusabh🇫🇷 · Giulio Dujany🇫🇷 · Diego Guadagnoli🇫🇷 · Axel Iohner🇫🇷 · Claudio Toni🇫🇷

    We introduce a model-independent framework to reinterpret Belle II results using only public data, analytically reconstructing the mapping between true and reconstructed kinematic variables within the statistically dominant Inclusive Tagging Analysis. This enables rare-decay measurements to probe light invisible particles -- such as the QCD axion or axion-like particles, collectively denoted $a$ -- without relying on internal simulations. Applying the method to $B^{+}\to K^{+}\nu \bar{\nu }$ yields the strongest bound on the branching fraction for $B^{+}\to K^{+}a$, improving existing limits by about a factor of nine and constraining the axion's fundamental flavour-changing coupling to $b$ and $s$ quarks. The approach establishes $B^{+}\to K^{+}\nu \bar{\nu }$ as a dual probe -- simultaneously testing short-distance new physics and light invisible states, the two probes working independently to an excellent approximation -- and provides a general strategy for model-independent reinterpretation of collider data.

    hep-phhep-exPRResearch(2026)·13 citations
26. 26*

    Sensitivity forecasts for gravitational-wave detectors to dark matter decaying into gravitons

    Jose A. R. Cembranos🇪🇸 · Álvaro Cendal🇪🇸

    Dark matter may not be perfectly stable, and its decay could generate distinctive gravitational-wave signatures. In this work, we present model-independent predictions for the stochastic gravitational-wave background arising from the decay of ultralight dark matter into gravitons. Within this framework, we forecast the sensitivity reach of current and forthcoming gravitational-wave detectors to such signals.

    hep-phastro-ph.COgr-qcJCAP(2026)·1 citation
27. 27*

    A beginner's guide to functional methods in particle physics

    Markus Q. Huber🇩🇪

    Functional methods like Dyson-Schwinger equations, the $n$PI effective action formalism, bound state equations and the functional renormalization group are versatile tools to study quantum field theories. They are exact, nonperturbative equations but have to be truncated for practical calculations. After a general introduction, I focus on their use in particle physics and discuss common truncations and solution techniques. The complete process from choosing a truncation to calculating observable quantities is exemplified by means of the glueball spectrum.

    hep-ph11 citations
28. 28*

    Generalised Casas-Ibarra Parametrisation for Majorana Neutrino Masses

    Juan Herrero-García🇪🇸 · Simone Marciano🇪🇸 · Juan Racker🇦🇷 · Drona Vatsyayan🇨🇦

    We present a simple and broadly applicable extension of the Casas-Ibarra parametrisation that captures the structure of all Majorana neutrino mass models. Building directly on the original formulation, our approach naturally accommodates additional degrees of freedom and provides a unified, minimal framework for parametrising the Yukawa sector. It significantly simplifies both analytical treatments and numerical scans, and can be universally applied to any Majorana neutrino mass model, regardless of the underlying dynamics. The approach also offers a unified framework for classifying neutrino mass models according to the structure of the neutrino mass matrix, which naturally motivates the proposal of an extended version of the Scotogenic Model. This classification scheme yields tree-level (loop-level) representative models: the seesaw (Scotogenic Model), the linear seesaw (the Generalised Scotogenic Model), and the linear plus inverse seesaw (the Extended Scotogenic Model). We provide ready-to-use explicit expressions for several well-known scenarios, including the Zee model where one of the Yukawa matrices is antisymmetric.

    hep-phPRD(2026)·7 citations
29. 29*

    Freeze-in and Freeze-out in a Right-Handed Neutrino Extended MSSM with a Seesaw Mechanism

    Tushar Gupta🇫🇮 · Matti Heikinheimo🇫🇮 · Katri Huitu🇫🇮 · Harri Waltari🇸🇪

    We investigate the possibility of saturating the relic density bound with light Higgsinos. When the minimal supersymmetric Standard Model is extended with right-handed neutrino superfields and the seesaw scale is very low, right-handed sneutrinos can be produced via the freeze-in mechanism. In such a case we can have essentially two independent sources for dark matter, the traditional freeze-out of Higgsinos and the freeze-in of right-handed sneutrinos. The heavier of these two will decay to the lighter species with a delay. We rule out such a scenario for all seesaw models as the lifetime of sterile neutrinos produced over-abundantly via Dodelson-Widrow mechanism exceeds the age of the universe and will contribute to the relic density.

    hep-phPRD(2026)·1 citation
30. 30*

    Spurion Analysis of ${\mathbb{Z}}_M/{\mathbb{Z}}_2$ Non-Invertible Selection Rules: Low-Order versus All-Order Zeros

    Motoo Suzuki🇮🇹 · Ling-Xiao Xu🇮🇹

    Motivated by recent progress in the spurion analysis of non-invertible selection rules (NISRs) arising from near-group fusion algebras, we further generalize the framework to a class of NISRs obtained from ${\mathbb{Z}}_2$ orbifolding of a ${\mathbb{Z}}_M$ symmetry, denoted as ${\mathbb{Z}}_M/{\mathbb{Z}}_2$. Many structural features are carried over: for instance, our labeling scheme enables systematic tracking of all couplings when constructing composite amplitudes from simpler building blocks at arbitrary loop orders in perturbation theory. Our analysis provides a transparent understanding of both low-order and all-order zeros of couplings under radiative corrections. Furthermore, we examine the fate of low-order zeros when the fusion algebra is not faithfully realized -- a situation not captured by the vanilla argument of ``loop-induced groupification'' -- and formulate a conjecture on the related aspects of particle decoupling and effective theory. Finally, we discuss the low-order versus all-order zeros in Yukawa textures from the perspective of spurion analysis.

    hep-phhep-thJHEP(2026)·13 citations
31. 31*

    Constraining a de Broglie--Bohm quantum bounce cosmology with Planck data

    Micol Benetti🇮🇹 · Rudnei O. Ramos🇧🇷 · Renato Silva🇧🇷 · Gustavo S. Vicente🇧🇷

    This work investigates a singularity-free early Universe within the paradigm of quantum cosmology. We develop a bouncing model where the singularity is resolved via the de Broglie--Bohm interpretation of quantum mechanics, which provides a deterministic trajectory for the scale factor through a quantum bounce. The primordial power spectrum for scalar perturbations is derived, incorporating a characteristic modulation (distortion function) imprinted by the nonstandard quantum gravitational dynamics near the bounce. We confront this model with the Planck 2018 cosmic microwave background data, establishing its strong compatibility with observations. Our analysis places a stringent upper bound on the fundamental scale of the bounce $k_B$, constraining the parameter space of such quantum cosmological scenarios. {}Furthermore, the model's specific scale-dependent anticorrelation between the spectral index and amplitude of perturbations offers a potential mechanism for mitigating the $H_0$-${\sigma }_8$ tension, presenting a testable signature for future cosmological surveys.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2026)·1 citation
32. 32*

    Towards a unified viewpoint of Gribov--Zwanziger and Serreau--Tissier gauge fixing

    Rodrigo Carmo Terin🇪🇸

    We investigate a unified Landau--gauge fixing that continuously interpolates between the viewpoints of the Serreau--Tissier (ST) copy-averaged formulation and the (Refined) Gribov--Zwanziger (RGZ) restriction to the first Gribov region. By combining the ST weight with a GZ-type horizon term and localizing both through the replica trick and the BRST-invariant $A_{\mu }^h$ formulation, we obtain a single, local, BRST-invariant, power-counting renormalizable action. Algebraic renormalization shows that all counterterms are reabsorbed by a common set of field and parameter renormalizations, therefore the unification is algebraic rather than merely additive. The replica sector yields a radiatively generated gluon screening mass, while the RGZ parameters are fixed by the horizon and condensate gap equations; we also give infrared matching conditions that link both descriptions at small momentum. We present a compact BRST-superspace rewriting of the RGZ block and a simple hybrid superspace that hosts the ST replicas and RGZ side by side; these add no dynamics and organize the Ward-identity analysis. The resulting gluon propagator interpolates among the massive Faddeev--Popov--ST and the RGZ decoupling forms. This framework offers a controlled way to study how infrared Yang--Mills correlators depend on the balance between copy averaging and horizon suppression, and it suggests practical lattice tests through tunable copy weighting.

    ↳ hep-thhep-lathep-phPLB(2026)·3 citations
33. 33*

    Comprehensive analysis of dissipative effects in the induced gravitational waves

    Yan-Heng Yu🇨🇳 · Zhe Chang🇨🇳 · Sai Wang🇨🇳

    Dissipation is an intrinsic property of the cosmic fluid, leading to the damping of curvature perturbations at small scales. In this paper, we comprehensively study dissipative effects in gravitational waves induced by curvature perturbations, known as induced gravitational waves (IGWs). We find dissipative effects become especially significant at wavenumber $k\sim k_{\mathcal{H},\mathrm{dec}}$, where $k_{\mathcal{H},\mathrm{dec}}$ corresponds to the horizon scale at the decoupling of weakly-interacting particles. They can leave characteristic features on the IGW spectrum, including a notable suppression with a ``double-valley'' structure at $k\sim k_{\mathcal{H},\mathrm{dec}}$ and a modified infrared behavior without logarithmic running at $k\lesssim k_{\mathcal{H},\mathrm{dec}}$. Within the Standard Model of particle physics, dissipative effects caused by neutrinos at the nanohertz frequencies can be important in the analysis of pulsar timing array data. Furthermore, dissipation-induced features associated with possible new weakly-interacting particles can be detectable by a wide range of gravitational-wave experiments, serving as a promising probe of new physics at extremely high energy scales. As an extension, we also discuss dissipative effects in the presence of primordial non-Gaussianity and their impacts on the anisotropies of IGWs and the poltergeist mechanism. These dissipative effects not only provide a more realistic description of IGWs but also exhibit rich phenomenology and profound physical implications, opening a new window into understanding the early Universe and fundamental physics.

    ↳ gr-qcastro-ph.COhep-phJCAP(2026)·7 citations
34. 34*

    Charm-strange meson production in relativistic heavy ion collisions

    Sungtae Cho🇰🇷 · Su Houng Lee🇰🇷

    We study charm-strange mesons, or $D_s$, $D_s^{\ast }$, $D_{s0}^{\ast }(2317)$, and $D_{s1}(2460)$ mesons by focusing on their production by coalescence from a quark-gluon plasma in relativistic heavy ion collisions at $\sqrt{s_{NN}}=5.02$ TeV. Starting from the investigation of the transverse momentum distribution of both charm and strange quarks through transverse momentum distributions of $\varphi$ and $D^0$ mesons, we calculate the transverse momentum distributions and yields of $D_s$, $D_s^{\ast }$, $D_{s0}^{\ast }(2317)$, and $D_{s1}(2460)$ mesons based on the coalescence model. We find that the yield and transverse momentum distribution of the $D_s$ meson agree well with the experimental measurements at $\sqrt{s_{NN}}=5.02$ TeV at LHC. We further evaluate the transverse momentum ratio between $D_s$ and $D^0$ mesons, and investigate the role of light and strange quarks in the production of charmed mesons in heavy ion collisions. Finally, we calculate the transverse momentum distribution and yield of the $D_{s0}^{\ast }(2317)$ meson in a four-quark state, and compare to those of $D_{s0}^{\ast }(2317)$ meson in a two-quark state.

    ↳ nucl-thhep-phnucl-ex2 citations
35. 35*

    Analysis note: measurement of thrust and track energy-energy correlator in $e^{+}{e}^{-}$ collisions at 91.2 GeV with DELPHI open data

    Jingyu Zhang🇺🇸 · Tzu-An Sheng🇺🇸 · Yu-Chen Chen🇺🇸 · Hannah Bossi🇺🇸 · Anthony Badea🇺🇸 · Austin Baty🇺🇸 · Chris McGinn🇺🇸 · Yen-Jie Lee🇺🇸 · Yi Chen🇺🇸

    Recent theoretical developments, as well as experimental measurements at hadron collisions, have renewed interest in studying event shape variables in $e^{+}{e}^{-}$ collisions. We present a measurement of thrust and track-based energy-energy correlator in $e^{+}{e}^{-}$ collisions at center-of-mass energy of 91.2 GeV, using newly released open data from the DELPHI experiment. The event shapes, measured with unprecedented resolution and precision, are compared to various Monte Carlo and analytic predictions. Leveraging DELPHI's unique detector geometry and reconstruction capabilities, the track energy-energy correlator measurement provides data with the highest angular resolution, offering critical inputs for precision tests of QCD in both collinear and back-to-back limits. This note presents the first physics analysis using DELPHI open data and establishes benchmarks necessary for future studies exploiting this legacy dataset.

    ↳ hep-exhep-phnucl-ex11 citations
36. 36*

    AT2025ulz and S250818k: zooming in with the Hubble Space Telescope

    Yu-Han Yang · Eleonora Troja · Marko Ristić🇺🇸 · Muskan Yadav🇮🇳 · Massine El Kabir · Rubén Sánchez-Ramírez · Rosa L. Becerra · Chris L. Fryer🇺🇸 · Brendan O'Connor · Simone Dichiara · Alberto J. Castro-Tirado🇪🇸 · Camila Angulo-Valdez and 10 other authors

    AT2025ulz is an optical/near-infrared transient discovered during follow-up of the candidate gravitational wave (GW) event S250818k. Its young age ($\lesssim$1 d), rapid decline and strong color evolution over the first 48 hr classify it as a potential kilonova candidate. In this work, we present the results of our observing campaign, carried out with the Gran Telescopio Canarias (GTC) and the Hubble Space Telescope (HST). Although the early time evolution of AT2025ulz resembles some aspects of a kilonova, its rapid onset ($\sim$3 hr after the GW trigger) and luminosity (a factor of $\sim 5$ brighter than AT2017gfo in $g$-band) are difficult to reproduce. Only a small subset of our kilonova models matches its multi-color light curve, and the inferred ejecta mass is uncomfortably large given the low chirp mass ($\lesssim 0.87$ M${}_{\odot }$) of the GW candidate. HST observations place the transient within a nearby ($z=0.08489$) spiral galaxy with on-going star-formation and measure a color ($F336W-F160W\approx 1.4$ mag) that is too blue to match with a kilonova. Our data support the classification of AT2025ulz as a supernova, initially undergoing a shock-cooling phase and later entering its photospheric phase, and spectroscopically identified via its broad absorption features.

    ↳ astro-ph.HEhep-phApJL(2026)·12 citations
37. 37*

    Repulsively Bound Hadrons in a ${\mathbb{Z}}_2$ Lattice Gauge Theory

    Sayak Guha Roy🇺🇸 · Vaibhav Sharma🇺🇸 · Kaidi Xu🇩🇪 · Umberto Borla🇩🇪 · Jad C. Halimeh🇩🇪 · Kaden R. A. Hazzard🇺🇸

    The ${\mathbb{Z}}_2$ lattice gauge theory is a paradigmatic model that exhibits gauge-field-mediated-confinement of pairs of particles into mesons, drawing connections to quantum chromodynamics. In the absence of any additional attractive interactions between particles, mesons are not known to bind in this model. Here, we show that resonant pair-production terms give rise to two separate mechanisms to form stable ``hadron'' bound states of two mesons: either induced by an effective attractive interaction, or a new dynamical binding mechanism induced by an effective repulsion. The repulsively bound hadron is a high-energy state stabilized by being energetically separated from the two-meson continuum through quantum fluctuations of the gauge fields. We study the dynamical formation of this bound state starting from local excitations. We use matrix product state techniques based on the time-evolving block decimation algorithm to perform our numerical simulations and analyze the effect of model parameters on hadron formation. Furthermore, we derive an effective model that explains its formation. Our findings are amenable to experimental observation on modern quantum hardware such as superconducting qubits, trapped ions, and Rydberg atom arrays.

    ↳ hep-latcond-mat.quant-gashep-phquant-ph1 citation

* 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.