Fri·Jun 5, 2026Friday·June 5, 2026

1. 01*

   Interference effects in gluon-fusion Higgs boson production

   Federico Buccioni🇩🇪 · Federica Devoto🇺🇸

   In this contribution we summarize recent progress in higher-order computations of signal-background interference effects in Higgs boson production via gluon fusion. The focus is on the resonance region, where interference terms are most significant relative to the pure signal contribution when the Higgs boson decay is loop-induced. We present results for the well-studied $gg\to H\to \gamma \gamma$ process and for the rare $gg\to H\to Z\gamma$ mode. In both cases, the interference is destructive, reducing the resonant Higgs boson production rate by about 1.6\% in the diphoton channel and by roughly 3\% in the $Z\gamma$ decay mode.

   hep-phhep-ex0 citations
2. 02*

   Gravitational Wave Imprints of a High-Quality Axion and the Origin of Flavor Hierarchies

   K.S. Babu🇺🇸 · Sai Charan Chandrasekar🇺🇸 · Sudip Jana🇮🇳 · Sudip Manna🇮🇳

   Axions, arising from an anomalous global Peccei-Quinn symmetry $U(1{)}_{\text{PQ}}$, offer a compelling solution to the strong CP problem but are vulnerable to Planck-suppressed operators. Gauged abelian flavor symmetries $U(1{)}_F$, invoked to explain the flavor hierarchies via the Froggatt-Nielsen mechanism, can naturally shield the axion from such effects, yielding an accidental high-quality flavored axion with unit domain wall number. Such constructions predict two complementary signatures: (i) flavor-changing neutral currents from $K\to \pi a$ decays, typically associated with high flavor scales ${\Lambda }_{\text{FN}}\gtrsim f_a$, and (ii) stochastic Gravitational Waves (GWs) sourced by the evolution and decay of gauged flavonic and axionic cosmic-string networks. In addition, global axionic strings can efficiently radiate axions, potentially accounting for the observed dark matter relic abundance. We show that the resulting characteristic plateau--valley structure in the GW spectrum provides a distinctive and powerful probe of high-quality flavored axion dark matter models, complementary to low-energy flavor experiments.

   hep-phastro-ph.COastro-ph.HEhep-ex0 citations
3. 03*

   Muon-induced di-tau production as a probe of new physics

   Sudipta Das🇺🇸 · Luke Kupari🇺🇸 · Mary Hall Reno🇺🇸 · Sebastian Trojanowski🇵🇱

   The muon trident process, which involves coherent scattering to produce tau pairs, is a powerful tool for constraining dark sectors. We propose to explore this channel using future high-energy muon beams with the dedicated active-target detector, High-Energy Muon Electronic Research Apparatus (HEMERA). The detector would complement muon beam-dump searches by resolving prompt signatures and could operate from preparatory facilities involving an individual muon beam of the full Muon Collider. We illustrate its capabilities for a leptophilic scalar with Yukawa-like couplings that can mediate thermal dark matter production. With $10^{18}$ incident TeV-scale muons, even a compact 10 kg silicon-based HEMERA will extend current $B$-factory and $(g-2{)}_{\mu }$ bounds by over an order of magnitude in coupling strength. In the leptophilic thermal dark matter paradigm, this search offers a way to probe dark sector targets beyond the neutrino floor of dark matter direct detection. This provides an additional compelling motivation for the development of high-energy muon beam infrastructure.

   hep-ph2 citations
4. 04*

   BSMArt 2: simpler and faster parameter space scans

   Fernando Abreu de Souza🇵🇹 · Nuno Filipe Castro🇵🇹 · Miguel Crispim Romão🇬🇧 · Mark D. Goodsell🇫🇷 · Farid Ibrahimov🇬🇧 · Werner Porod🇩🇪

   We present version 2 of BSMArt, a powerful yet lightweight scanning tool designed to simplify the exploration of parameter spaces of new physics models. Aside from architectural improvements, simpler installation and expanded documentation with examples, the new version includes additional tools and new machine learning and Monte Carlo scanning algorithms: Affine MC, Contour Finding, MLScanner, DLScanner, MLS, and CMA-ES. We showcase two variants of CMA-ES scans with physics applications relevant for soft lepton excesses at the LHC. We demonstrate that it is easily possible to find diverse and interesting parameter points for future testing.

   hep-ph3 citations
5. 05*

   Diffractive open charm photoproduction in ultraperipheral lead-lead and proton-lead collisions at the LHC

   Vadim Guzey🇫🇮 · Gian Michele Innocenti🇺🇸 · Anna M. Staśto🇺🇸 · Mark Strikman🇺🇸

   We calculate diffractive $D^0$ photoproduction in ultraperipheral lead--lead (Pb--Pb) collisions at the Large Hadron Collider (LHC) within the recently developed G$\gamma$A--FONLL framework, where photon--lead diffraction is modeled using nuclear diffractive parton distributions obtained in the leading twist shadowing approach and the photon fluxes include corrections for independent electromagnetic dissociation accompanying the hard photoproduction process. We then use the predicted diffractive cross section to quantify the coherent diffractive contribution rejected by the $Xn0n$ neutron-tagged event selection adopted in the first measurement of $D^0$ photoproduction in Pb-Pb collisions at the LHC, which requires neutron emission from only one of the two lead nuclei. In this work, we also extend the G$\gamma$A--FONLL framework to proton--lead ($p$--Pb) UPCs and present predictions for inclusive and diffractive $D^0$ photoproduction at the LHC. In this case, the dominant configuration is photon emission from the lead ion followed by photon--proton scattering, and the diffractive contribution is evaluated using proton diffractive parton distributions constrained by HERA data.

   hep-phPRD(2026)·1 citation
6. 06*

   Pion structure in Holographic QCD

   Jiali Deng🇨🇳 · Defu Hou🇨🇳 · Xiaolong Wang🇨🇳 · Yang Zhou🇨🇳

   We employ a holographic model with a modified background that incorporates effective descriptions of key QCD features, including linear confinement and gluon condensation, to study the pion's internal structure, encompassing its mass spectrum as well as electromagnetic and gravitational form factors. This model is capable of simultaneously describing these diverse observables and reaches reasonable agreement with both experimental measurements and lattice QCD results. Our findings indicate that the model captures essential aspects of the pion. The description of multiple structure observables supports its potential as a useful tool for further investigations of pion properties.

   hep-phPLB(2026)·1 citation
7. 07*

   QCD Sum Rule Analysis of a Compact $D^{+}{D}^{-}{K}^{+}$-Like Hidden-Charm Hexaquark with $J^P=0^{-}$

   Jing-Yi Yan🇨🇳 · Wen-Shuai Zhang🇨🇳 · Liang Tang🇨🇳

   In this work, we study a compact hexaquark configuration motivated by the same quark content as $D^{+}{D}^{-}{K}^{+}$ using QCD sum rules, where the $DDK$ system has been extensively studied within theoretical frameworks of few-body hadronic dynamics and coupled-channel interactions. The state is constructed from three color-octet quark--antiquark clusters coupled to an overall color singlet. We construct six independent local interpolating currents with the quantum numbers $J^P=0^{-}$ and analyze the corresponding two-point correlation functions. Both perturbative contributions and nonperturbative condensates up to dimension ten are included in the operator product expansion. Our analysis indicates that, within Borel windows satisfying standard sum rule criteria and with a reasonable choice of continuum threshold, the mass of the $J^P=0^{-}$ hidden-charm hexaquark state is estimated to be in the range $3.94$--$4.41\mathrm{GeV}$. This prediction can provide a valuable theoretical reference for identifying such exotic hidden-charm hexaquark state in future experiments.

   hep-phhep-ex0 citations
8. 08*

   Probing Quantum Numbers and Decay Branching Ratios of Exotic States via Entanglement-Enabled Spin Interference

   Di Zhang🇨🇳 · Zhangbu Xu🇺🇸 · Chi Yang🇨🇳

   Ultra-peripheral heavy-ion collisions (UPCs) coherently photo-produce vector mesons through two spatially separated and quantum-mechanically indistinguishable production sites, whose separation far exceeds the lifetime of the created resonance. The superposition of these amplitudes generates production-site entanglement, observed experimentally as entanglement-enabled spin-interference patterns in the angular distributions of the decay products. We show that these interference signatures provide a sensitive probe of spin-alignment transfer in hadronic decay chains, enabling intermediate-state quantum numbers and relative branching ratios to be measured from observed angular modulations. Using the decay $\rho (1450)\to {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ as example, we simulate the $a_1(1260)\pi$, $h_1(1170)\pi$, $\rho (\pi \pi {)}_S$, and $\pi (1300)\pi$ channels and demonstrate that each produces a distinct azimuthal $\cos 2\varphi$ modulation. The $\pi (1300)\pi$ mode shows a uniquely separated response, allowing its branching fraction to be extracted directly. These results establish production-site entanglement in UPCs as a selective tool for hadron spectroscopy, particularly for broad or overlapping resonances that are otherwise difficult to disentangle.

   hep-ph1 citation
9. 09*

   Pion transitions in the Born-Oppenheimer Effective Field Theory: a long distance approach

   Joan Soto🇪🇸 · Sandra Tomàs Valls🇪🇸

   We address pion transitions involving heavy quarkonium and heavy exotic states in the Born-Oppenheimer effective field theory. Many of these states have a size similar or larger than the typical hadronic scale, and hence the usual QCD multipole expansion breaks down. Unknown low energy functions must be introduced, which at short distances must reproduce the known results of the multipole expansion. In order to determine the long distance behavior of these functions, we propose an interaction Lagrangian for pions and the QCD string. By matching the amplitudes obtained with this Lagrangian to the ones of the Born-Oppenheimer effective field theory in the static limit, we obtain the low energy functions in terms of three universal parameters. As a by product, we also obtain the light quark mass dependence of the string tension. Assuming that the low energy functions are long-distance dominated, we calculate several quarkonium-to-quarkonium and hybrid-to-quarkonium transitions. We estimate the universal constants and provide a phenomenological analysis of the most relevant transitions.

   hep-ph0 citations
10. 10*

    Search for heavy Majorana neutrinos at muon-proton colliders via lepton-number-violating signals

    Yao-Bei Liu🇨🇳

    We propose a novel search strategy for heavy Majorana neutrinos based on the lepton-number-violating process ${\mu }^{-}p\to jN\to j({\ell }^{+}{W}^{-})$ at future muon-proton ($\mu p$) colliders equipped with 1 TeV muon beams and 7 TeV proton beams, yielding a center-of-mass energy of approximately 5.3 TeV. For heavy neutrinos with masses in the range $200\text{GeV}\lesssim m_N\lesssim 1000\text{GeV}$, this analysis targets the decay chain $N\to {\ell }^{+}{W}^{-}\to {\ell }^{+}jj$, producing a characteristic final state consisting of one charged lepton and three well-resolved jets. For TeV-scale Majorana neutrinos, the $W$ boson is highly boosted, such that its hadronic decay products coalesce into a prominent fat-jet ($J$) signature. We conduct comprehensive signal and background analyses that account for realistic detector effects to assess the search sensitivity. We derive the projected $2\sigma$ exclusion limits on the neutrino mixing parameter $|V_{\ell N}{|}^2$ based on two typical integrated luminosity scenarios of $100{\text{fb}}^{-1}$ and $1{\text{ab}}^{-1}$. The results demonstrate that the proposed search strategy can achieve constraints substantially superior to the existing bounds from the LHC and other high-energy colliders. This study demonstrates that future $\mu p$ colliders can provide competitive sensitivity for probing heavy Majorana neutrinos over the mass range $200\text{GeV}\le m_N\le 3000\text{GeV}$.

    hep-ph0 citations
11. 11*

    Bulk viscosity of a binary mixture: the role of the intra-species interaction

    Gabriele Parisi🇮🇹 · Vincenzo Nugara🇮🇹 · Shams Ul Arfeen🇵🇰 · Salvatore Plumari🇮🇹 · Vincenzo Greco🇮🇹

    The bulk viscosity $\zeta$ is a transport coefficient which is of central importance for various areas of modern physics. In particular, its determination for a mixture of more than one fluid is challenging, since it involves a complex interplay of multiple microscopic processes that operate on different time scales. Within the Chapman-Enskog framework, based on a series expansion of the Boltzmann distribution function, many previous works have derived the 1${}^{\text{st}}$ order result for the $\zeta$ of a mixture. However, such a result fails to reproduce relevant physical features of the system, especially when the masses of the two components are similar. In this work we improve the 1${}^{\text{st}}$ order Chapman-Enskog result by deriving the $\zeta$ at the 2${}^{\text{nd}}$ order in the expansion. We show that this improved formula encodes many physical properties that the 1${}^{\text{st}}$ order result misses: under specific conditions, the 2${}^{\text{nd}}$ order result can be qualitatively and quantitatively very different from the 1${}^{\text{st}}$ order one. Moreover, this result is compared against the $\zeta$ evaluated within the Green-Kubo formalism, by means of a numerical solution of the Relativistic Boltzmann equation. The agreement with respect to this benchmark is significantly improved when moving from the 1${}^{\text{st}}$ to the 2${}^{\text{nd}}$ order CE result.

    hep-phhep-th1 citation
12. 12*

    Vector charmonium(-like) states in the energy range of 4.1-4.6 GeV

    Xiang-Kun Dong🇩🇪 · Vadim Baru🇩🇪 · Leon von Detten🇩🇪 · Feng-Kun Guo🇨🇳 · Christoph Hanhart🇩🇪 · Teng Ji🇩🇪 · Ulf-G. Meißner🇩🇪 · Alexey Nefediev🇩🇪

    The spectrum of vector charmonium(-like) states in the 4.1\dash4.6~GeV energy region exhibits a long-standing tension between inclusive and exclusive measurements. While the inclusive $R$-value indicates only conventional vector charmonia such as $\psi (4160)$ and $\psi (4415)$, exclusive $e^{+}{e}^{-}$ cross sections reveal additional structures whose parameters strongly depend on the observed final states when fitted with Breit--Wigner functions. This puzzling pattern suggests that coupled-channel and threshold effects play an essential role. In this work, we develop a unified coupled-channel framework for the $1^{--}$ resonances in this energy region. The framework incorporates the $S$-wave open-charm channels $D{\bar{D}}_1$, $D^{\ast }{\bar{D}}_1$, and $D^{\ast }{\bar{D}}_2^{\ast }$ constrained by heavy-quark spin symmetry, optional bare poles associated with $\psi (4160)$ and $\psi (4415)$, and final-state interactions in the $Z_c$ channels. We perform simultaneous fits to the BESIII cross sections for $e^{+}{e}^{-}\to J/\psi {\pi }^{+}{\pi }^{-}$, $h_c{\pi }^{+}{\pi }^{-}$, $D{\bar{D}}^{\ast }\pi$, $D^{\ast }{\bar{D}}^{\ast }\pi$, $J/\psi \eta$, and ${\chi }_{c0}\omega$, together with invariant-mass distributions exhibiting the $Z_c(3900)$ and $Z_c(4020)$ structures. The benchmark models differ in the number of bare seed states and the fitting strategy. We show that even the purely dynamical scheme without bare charmonia captures the gross features of the analyzed distributions. The inclusion of bare compact states improves the fit quality but does not change the conclusion that the measured line shapes can be understood in terms of strong coupled-channel effects with dynamically generated poles. We also discuss possible heavy-quark spin partners of the exotic $1^{--}$ states.

    hep-phhep-exhep-lat2 citations
13. 13*

    Spin-orbit correlation of quarks within quarkonium

    Tianyang Hu🇨🇳 · Xianghui Cao🇨🇳 · Siqi Xu🇨🇳 · Weijie Du🇨🇳 · Qin-Tao Song🇨🇳 · Yang Li🇨🇳

    The spin-orbit correlation (SOC) provides a unique probe into the internal spin structure of hadrons. Defined via the parity-odd (P-odd) energy-momentum tensor (EMT), this observable can remain non-vanishing even in systems where the total angular momentum is zero. In this study, we connect the formal field-theoretical definition of the SOC to a non-perturbative quantum many-body framework utilizing light-front dynamics. Furthermore, we show how the SOC can be extracted directly from the hadronic matrix elements of the P-odd EMT, establishing a pathway to access this observable within the partonic picture. As a practical application, we compute the transverse and longitudinal SOC distributions for charmonium and $B_c$ mesons. While our findings align with rough estimates based on the Clebsch-Gordan decomposition, we demonstrate that these observables yield rich, non-trivial information regarding partonic dynamics.

    hep-phhep-thnucl-th0 citations
14. 14*

    Diffusion of multiple conserved charges from entropy production

    Samapan Bhadury🇮🇳 · Arpan Das🇮🇳 · Sandeep Chatterjee🇮🇳 · Hiranmaya Mishra🇮🇳

    We derive dissipative relativistic hydrodynamic equations in the presence of multiple conserved charges, i.e., baryon number ($B$), electric charge ($Q$), and strangeness ($S$), using the Chapman-Enskog (CE) method within the kinetic theory approach. The relativistic Boltzmann equation is solved within the relaxation-time approximation with a momentum-independent relaxation time in the collision term. We derive both first-order (Navier-Stokes limit) and second-order dissipative hydrodynamic equations. Within the kinetic theory framework, using the Boltzmann's H-theorem, and by demanding that for a dissipative system, the entropy must be produced, we find different transport coefficients at the first-order and second-order gradient expansion of the out-of-equilibrium distribution function around the local equilibrium. Apart from the well-known transport coefficients, the shear ($\eta$) and the bulk ($\zeta$) viscosities , we also find the diffusion matrix elements (${\kappa }_{q{q}^{\prime }}$) for the conserved charges $B$, $Q$ and $S$. The diffusion matrix elements (${\kappa }_{q{q}^{\prime }}$) are important to model the multi-component diffusion dynamics sourced by inhomogeneous baryon stopping in the initial state of heavy-ion collisions. We estimate the temperature ($T$) and chemical potential dependence of diagonal and off-diagonal elements of the diffusion matrix elements for the (2+1) flavor quark-gluon plasma. We further estimate the ratio ${\kappa }_{q{q}^{\prime }}T/\eta$ for a wide range of temperature and chemical potentials to show the relative importance of the diffusion matrix elements compared to other transport coefficients.

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

    Probing SU(2) Quark Flavor Asymmetry with W Bosons at RHIC

    Maximiliano Ponce-Chavez🇺🇸

    This work examines the effects of multiple parton radiation on proton-proton $W^{\pm }$ boson production at the Relativistic Heavy Ion Collider (RHIC), focusing on the ratio of charged lepton pseudorapidity differential cross sections to test the SU(2) flavor symmetry violation in the proton quark sea. I show that the measured ratio is marginally affected by the fiducial constraints imposed on the QCD recoil radiation by the STAR experiment, and that the ratio is also stable with respect to transverse momentum resummation effects. Hence, the STAR data on the $W^{+}/W^{-}$ cross section ratio provides a robust discrimination of $\bar{d}(x)$ and $\bar{u}(x)$ parton distribution functions (PDFs) at momentum fractions of order 0.1, shown by comparing predictions with various PDF models and using the $L_2$ sensitivity analysis and reweighting methods.

    hep-ph0 citations
16. 16*

    Wave-Tide Locking in Thin Stellar Streams: A Phenomenological Mass Spectrometer for an Intermediate Ultralight Axion

    Peter H. Tsang🇬🇧

    We propose a phenomenological mass estimator for an intermediate ultralight axion dark-matter component using thin stellar streams. The central observation is an analytic relation linking three length scales in a fuzzy-dark-matter stream progenitor: the tidal radius of a bound dark core, its gravitational Bohr radius, and the axion de Broglie wavelength evaluated at the stripped-star velocity scale. If the stream width is (w=C_w r_{\rm t}), with (C_w=O(1)), then [ \frac{r_{\rm t}}{r_{\rm B}} =========================== \frac{4\pi^2}{C_w^2} \left(\frac{w}{\lambda_{\rm dB}}\right)^2 . ] Thus (\lambda_{\rm dB}\sim w) automatically implies (r_{\rm t}/r_{\rm B}\sim25)--(40): the dark wave core survives well inside the tidal boundary while the extended stellar envelope is stripped into a thin stream. This wave--tide locking gives a no-simulation axion-mass estimator, [ m_a \simeq 2.69\times10^{-19},{\rm eV} \left(\frac{\sqrt{2}}{q_\kappa}\right) \left(\frac{R}{10,{\rm kpc}}\right) \left(\frac{38,{\rm pc}}{w}\right)^2 \left(\frac{w}{\ell_{\rm ripple}}\right) \left(\frac{220,{\rm km,s^{-1}}}{v_c}\right). ] In the simplest locked case (\ell_{\rm ripple}\sim w), a homogeneous first-pass set of narrow stream widths points to (m_a) of a few (10^{-19},{\rm eV}) and hidden-core masses of a few (10^3)--(10^4M_\odot). This is not a detection claim; it is a falsifiable phenomenological test for an ultralight axion component that can be sharpened by homogeneous stream catalogs and Schrödinger--Poisson simulations.

    hep-ph0 citations
17. 17*

    Machine Learning for Predicting the Proton Structure Function $F_2^P$ in QCD

    Shahin Atashbar Tehrani🇮🇷 · Elham Astaraki🇮🇷 · Fatemeh Arbabifar🇮🇷

    We present a comparative study of four supervised machine learning regression algorithms -- Support Vector Regression (SVR), Gradient Boosting Regression (GBR), Gaussian Process Regression (GPR), and Multilayer Perceptron (MLP) -- for predicting the proton structure function $F_2^p(x,Q^2)$ using high-precision BCDMS experimental data. Unlike conventional methods that solve the DGLAP evolution equations, our data-driven framework directly captures the complex nonlinear dynamics of partonic structure. To ensure statistical robustness, we employ $k$-fold cross-validation and perform thorough hyperparameter optimization. Our results show that the MLP and GPR models achieve superior predictive accuracy. In particular, MLP exhibits the highest sensitivity to nonlinear gradients, while SVR proves most stable against experimental uncertainties. The close convergence of training and validation metrics confirms that the models learn the underlying QCD physics without overfitting to statistical fluctuations. This work highlights the potential of ML-based regression as a complementary tool for structure function analysis and kinematic extrapolation in high-energy physics.

    hep-ph0 citations
18. 18*

    Probing anomalous quartic gauge couplings in same-sign $W$ boson scattering with polarization and spin correlation

    Oscar J. P. Éboli🇧🇷 · Rafiqul Rahaman🇧🇷 · Amir Subba🇨🇳

    The study of quartic couplings of electroweak gauge bosons not only provides a test of the Standard Model (SM) predictions, but also can look for signals of new physics beyond the SM. We present a comprehensive study of anomalous quartic gauge couplings in same-sign $W^{\pm }{W}^{\pm }$ production via vector boson scattering at the LHC. The analysis is carried out within the framework of the SM Effective Field Theory, exploiting polarization and spin-correlation effects encoded in angular asymmetries in addition to conventional kinematic observables. We demonstrate that spin-correlation asymmetries provide sensitivity to anomalous $WWWW$ interactions that is comparable to that obtained from the transverse mass distribution of the $WW$ system. By identifying a minimal set of the most sensitive asymmetries, we show that the dominant constraints on the Wilson coefficients can be captured with a reduced number of observables. A combined analysis of angular asymmetries and kinematic information leads to improved limits compared to either approach alone. The impact of unitarity considerations is also examined by imposing invariant-mass cut-offs on the $WW$ system, allowing us to determine unitarity-safe regions for the anomalous couplings.

    hep-phhep-exhep-th0 citations
19. 19*

    Method to study $CP$ violation in $B_s^0\to K_S{K}^{\pm }{\pi }^{\mp }$ decays

    Chen Chen🇬🇧 · Tim Gershon🇬🇧 · Thomas Latham🇬🇧

    The $B_s^0\to K_S{K}^{\pm }{\pi }^{\mp }$ decays are of interest to test the Standard Model and search for new sources of $CP$ violation. A full study of these decays requires a tagged decay-time-dependent Dalitz-plot analysis performed simultaneously in the two final states. Such an analysis has never previously been performed. The method to carry out such an analysis, relating the amplitudes for decays to resonances in the two final-states to each other, is set out and its feasibility is demonstrated using pseudoexperiments. The sensitivity to the weak phase difference, ${\varphi }_s^{\mathrm{eff}}$, between $B_s^0\to K_S{K}^{\ast }(892{)}^0$ decays with and without $B_s^0$-${\bar{B}}_s^0$ mixing is studied. Good precision on ${\varphi }_s^{\mathrm{eff}}$ is found to be achievable with a dataset corresponding to LHCb Runs 1-3, with further improvement expected with datasets to be collected in future. The method is implemented in the Laura++ Dalitz-plot analysis package, and can be applied to other multibody decays with multiple final states.

    hep-phhep-ex0 citations
20. 20*

    Soft UV Completion of a Preon Model

    Risto Raitio🇫🇮

    We build a framework for Regge trajectories from the Nambu-Goto action. We compute the 6-preon Regge trajectory in a preon model, include the worldsheet conformal anomaly, and build the parameter-free Veneziano amplitude. The amplitude has s-channel poles matching the spectrum to 0.5%, and at fixed-angle scattering decays exponentially with a negative Gross-Mende coefficient, realized numerically to 0.03%. This is a soft, genuinely non-perturbative ultraviolet completion of the preon model - and thereby of the Standard Model, which emerges as its low-energy limit. The Virasoro-Shapiro amplitude and the significance of worldsheet diffeomorphism are briefly discussed.

    hep-ph0 citations
21. 21*

    Neutrino mass ordering from the next Galactic supernova at DUNE, HK, and JUNO

    Prantik Sarmah🇨🇳 · Sovan Chakraborty🇮🇳 · Abinash Medhi🇮🇳 · Debanjan Bose🇮🇳 · Moon Moon Devi🇮🇳

    The next Galactic core-collapse supernova (CCSN) will offer a unique opportunity to determine the neutrino mass ordering. We focus on two observables: the electron neutrino (${\nu }_e$) neutronization burst and the rise-time of the electron antineutrino (${\bar{\nu }}_e$) flux during the accretion phase. The neutronization burst, a sharp ${\nu }_e$ peak within $\sim 20$-$30$ ms, provides a clean and robust signature of mass ordering through its appearance or disappearance. During the accretion phase, the faster rise of heavy lepton flavor neutrinos (${\nu }_x$) leads to a distinct faster rise-time behavior of the oscillated ${\bar{\nu }}_e$ signal, resulting in mass ordering discrimination. Using realistic CCSN simulations for multiple progenitor masses, we compute event rates and perform a statistical analysis for a Galactic ($10$~kpc) CCSN event at DUNE, Hyper-Kamiokande (HK), and JUNO detectors. The neutronization burst remains largely independent of SN hydrodynamic simulation models, with DUNE and HK achieving $\gtrsim 6\sigma$ and $\gtrsim 4\sigma$ sensitivity for normal (NO) to inverted ordering (IO) discrimination, respectively. However, the rise-time observable is prone to progenitor degeneracies. To mitigate this cumulative and ratio-based observables constructed at characteristic timescales ($20$ ms & $100$ ms) are used. The resulting confidence levels from the rise-time analysis to discriminate IO/NO in HK and JUNO are $\sim 5\sigma$ and $\sim 3\sigma$, respectively. Our results highlight the complementarity of detectors and observables, and demonstrate that combining neutronization burst and accretion phase information will be crucial for a definitive determination of the neutrino mass ordering in the next Galactic supernova.

    hep-phastro-ph.HE0 citations
22. 22*

    A New Origin of the Big Bang from Dark-Sector-Induced Vacuum Decay and Its Gravitational-Wave Signal

    Haipeng An🇨🇳 · Tingyu Li🇨🇳

    We propose a novel scenario for the onset of the thermal Big Bang. In this framework, the inflaton transfers its energy exclusively into a dark sector, leaving the Standard Model (SM) sector temporarily trapped in a false vacuum. As the Hubble expansion rate rapidly decreases, the SM phase transition eventually completes, and the standard thermal Big Bang era commences upon the thermalization of the highly energetic bubble walls. We demonstrate that the large Lorentz boost of these bubble walls, combined with their Hubble-scale macroscopic size, generates distinctive gravitational-wave signatures from the SM vacuum decay. This stochastic gravitational-wave background provides a powerful new probe of the early Universe's expansion history, with a present-day energy density fraction that can reach ${\Omega }_{\text{GW}}\sim 3\times 10^{-8}$.

    hep-phastro-ph.CO1 citation
23. 23*

    Reweighting Adversarial Networks for Unbinned Unfolding

    Umar Sohail Qureshi🇺🇸 · Krish Desai🇺🇸 · Jesse Thaler🇺🇸 · Benjamin Nachman🇺🇸

    Differential cross sections are the currency of scientific exchange in particle and nuclear physics. Recently, machine learning methods have enabled unbinned and high-dimensional cross section measurements through new approaches to unfolding. A key challenge with unfolding is that it is a bi-level optimization problem where constraints are available at the detector level while the target is at the particle level, linked by a stochastic detector response. Further complications arise when the particle-level and detector-level distributions have non-overlapping or only partially overlapping support, which can destabilize training and degrade unfolding performance. In this paper, we introduce a new unbinned unfolding technique called the Reweighting Adversarial Network (RAN), which can be viewed as a generalization of the Moment Unfolding protocol to accommodate full phase-space unfolding. RANs address the bi-level optimization problem through a particle-level reweighting function steered by a Wasserstein critic at the detector level. RANs do not require overlapping support at the detector level, nor multiple iterations of training. We evaluate the performance of RANs with Gaussian data and jet substructure studies, including cases specifically designed to stress test the method under vanishing support overlap. We demonstrate that RANs outperform state-of-the-art methods in accuracy and have a lower computational overhead.

    hep-phhep-exphysics.data-an2 citations
24. 24*

    Running Vacuum in the expanding Universe: a unified QFT paradigm for Inflation and Dark Energy

    Joan Solà Peracaula🇪🇸

    The concordance $\Lambda$CDM model, based on a rigid $\Lambda$-term for the entire cosmic history, has been in crisis for a long time. In our expanding Universe, an evolving $\Lambda$ with the expansion is intuitively much more reasonable. In the running vacuum model (RVM) framework, based on quantum field theory (QFT) in curved spacetime, quantum effects induce a vacuum energy density (VED) ${\rho }_{\mathrm{vac}}=\Lambda /(8\pi G)$ which is a function of the Hubble rate $H$ and its time derivatives, ${\rho }_{\mathrm{vac}}={\rho }_{\mathrm{vac}}(H,\dot{H},\ddot{H},\dots )$. Currently, ${\rho }_{\mathrm{vac}}$ evolves very slowly with the expansion, $\delta {\rho }_{\mathrm{vac}}\sim \mathcal{O}(m_{Pl}^2{H}^2)$, and this fact provides a possible fundamental origin of dark energy (DE), conceived as dynamical vacuum energy. In the RVM, Newton's $G$ is also evolving, but much more slowly (logarithmically with $H$): $G=G(\ln H)$. In the very early universe, the vacuum fluctuations induce higher (even) powers, e.g. $\sim H^4$, capable of triggering fast inflation in a very short period, in which $H$ is very large and approximately constant. This is the mechanism of `RVM-inflation'. It does not require an `inflaton' field since inflation is brought about by pure QFT effects on the dynamical background. It differs from Starobinsky's inflation, where $H$ is never constant. Furthermore, the dynamics of ${\rho }_{\mathrm{vac}}(H)$ and $G(H)$ can also have implications on the frequently discussed possibility that the fundamental `constants' of Nature can be mildly evolving with the cosmic expansion. Putting things together, a unified QFT framework of dark energy and inflation ensues as a realistic theory for the description of the universe as a whole on fundamental grounds. In it, dynamical VED is predicted and is much welcomed, since it fits in with current DESI measurements, preferring dynamical DE over a rigid $\Lambda$ term.

    ↳ gr-qcastro-ph.COhep-phhep-thInt.J.Mod.Phys.A(2026)·5 citations
25. 25*

    Charting the different phases of Yang-Mills-Chern-Simons-Higgs theories

    Daniel O. R. Azevedo🇺🇾 · Gustavo P. de Brito🇧🇷 · Philipe De Fabritiis🇧🇷 · Antonio D. Pereira🇧🇷

    We explore Yang-Mills-Chern-Simons theories coupled to a Higgs-like field in the fundamental representation of $SU(2)$ quantized in linear covariant gauges in three Euclidean dimensions. We analyze the modifications in the analytic structure of the gluon propagator due to the elimination of infinitesimal Gribov copies. The interplay between the Higgs, the Chern-Simons and Gribov mass parameters is investigated. Two different phases are identified: a confining one, where all poles are complex, and a deconfined one, where would-be physical gluon excitation can appear. Unlike previous works, the Gribov parameter is consistently fixed by its gap equation as a function of the other mass parameters and the gauge coupling. This imposes a constraint in the parameter space and makes transparent how the competition of the mass parameters affects the relevance of the Gribov parameter for the characterization of the spectrum of the theory.

    ↳ hep-thhep-phPRD(2026)·0 citations
26. 26*

    Chiral symmetry breaking in models with unconventional supersymmetry

    Pedro D. Alvarez🇨🇱 · Cristian Villavicencio🇨🇱 · Jorge Zanelli🇨🇱

    We investigate dynamical mass generation in a geometrically constructed gauge theory based on the super Lie algebra $su(2,2|3)$, in which gravity, Yang-Mills fields, and fermions are unified as components of a single gauge connection. The model contains no elementary scalar fields and no ad hoc four-fermion interactions. Instead, fermionic self-interactions arise unavoidably from the geometric structure of the theory, through nonminimal couplings and torsion associated with the unified connection. Upon reduction to an effective low-energy description, these interactions generate a Nambu-Jona-Lasinio--type potential that triggers chiral symmetry breaking and the formation of a fermion mass gap. In this framework, mass generation emerges as a direct consequence of the underlying gauge-geometric and algebraic structure, rather than as an independent dynamical assumption.

    ↳ hep-thhep-ph0 citations
27. 27*

    $\mathtt{BlackHawk}$ $v3.0$: Hawking Radiation from Regular Black Holes

    Alexandre Arbey🇫🇷 · Marco Calzà🇮🇹 · Léa Malacher🇫🇷 · Davide Pedrotti🇮🇹 · Yuber F. Perez-Gonzalez🇪🇸

    We present $\mathtt{BlackHawk}$ $v3.0$, a major update of the public code designed to compute Hawking radiation spectra of black holes. Building upon previous versions, this release considerably extends the range of black hole geometries that can be studied by implementing several new spherically symmetric metrics: the Bardeen and Hayward regular black holes, the Simpson-Visser and Peltola-Kunstatter black-bounces, the D'Ambrosio-Rovelli black hole-to-white hole metric, and the Babichev-Charmousis-Lehébel black hole. For each metric, we compute the corresponding Hawking temperatures and greybody factors, enabling the determination of primary Hawking emission spectra for particles of different spins. The greybody factors are obtained through dedicated numerical routines based on the companion code $\mathtt{GrayHawk}$. Additionally, $\mathtt{BlackHawk}$ $v3.0$ introduces several technical improvements aimed at enhancing precision and efficiency, providing a highly versatile tool. The code is publicly available at https://blackhawk.hepforge.org/

    ↳ gr-qcastro-ph.COhep-phPhys.Dark Univ.(2026)·6 citations
28. 28*

    On the Possibility of a Strong First-Order Phase Transition in Neutron Stars

    Zheng Cao🇨🇳 · Lie-Wen Chen🇨🇳

    Whether cold dense QCD matter undergoes a strong first-order phase transition remains an open question. In nature, neutron stars provide the most direct probe of cold dense QCD matter. Theoretically, chiral effective field theory constrains the equation of state of dense matter near nuclear saturation density, while perturbative QCD calculations constrain it at densities well beyond stable neutron-star interiors. We perform Bayesian inference with non-parametric Gaussian-process equation of state for $\beta$-equilibrated neutron-star matter under the assumption with and without a strong first-order phase transition, using the tidal deformability from GW170817, the NICER mass--radius measurements of PSR~J0740$+$6620, PSR~J0030$+$0451, PSR~J0437$-$4715, PSR~J0614$-$3329, chiral effective field theory, and perturbative QCD. Within this Bayesian inference framework, the model comparison mildly to moderately favors a strong first-order phase transition, with its onset most likely lying \emph{above} the central density of the most massive neutron star. Such an onset reconciles the stiffness required to support massive neutron stars with the softening favored by perturbative QCD from asymptotically high density.

    ↳ nucl-thastro-ph.HEhep-phnucl-exApJ(2026)·2 citations
29. 29*

    Short Gravitational-Wave Transients as Probes of Cosmic Domain Walls

    Tore Boybeyi🇺🇸 · Doga Veske🇹🇷 · David Maibach🇩🇪

    GW190521 and GW231123 have been reported as short-duration gravitational-wave transients consistent with very massive binary black hole (BBH) coalescences whose inferred parameters, i.e., exceptionally high total masses and spin magnitudes, challenge standard isolated binary stellar evolution. We test a topological dark matter (TDM) interpretation invoking cosmic domain walls by fitting a physically motivated domain wall template to the LIGO Hanford and Livingston strain data. The BBH hypothesis is individually favored, with ${\log }_{10}{\mathcal{B}}_{BBH/TDM}=12.2$ and $11.3$ for GW231123 and GW190521, respectively. However, these values are lower than those typically recovered from matched maximum a posteriori BBH waveforms injected into nearby noise segments. We further perform, for the first time, a joint fit in which domain wall signals from a single underlying scalar field are constrained simultaneously by both events. Although not favored over BBH signals, we find the two events are consistent with a common scalar field, with shared TDM parameters agreeing across independent noise realizations and sky locations. We further find that injected TDM transients are systematically recovered under the BBH hypothesis with large spin parameters, revealing a morphological degeneracy that could mask genuine domain wall signals. This analysis demonstrates that multi-event parameter consistency tests provide a new discriminant for domain wall dark matter searches in upcoming observing runs.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-ph0 citations
30. 30*

    Phenomenology of Inflaton-Driven Early QCD Confinement and Solution to Axion Isocurvature Problem

    Evangelos I. Sfakianakis🇺🇸 · Barmak Shams Es Haghi🇺🇸 · Katherine Freese🇺🇸

    We study the phenomenology of early QCD confinement during inflation, driven by a direct coupling between the inflaton and Standard Model gluons. This coupling dynamically raises the QCD confinement scale, making the axion sufficiently heavy to suppress isocurvature perturbations during the CMB epoch. As inflation proceeds, the confinement scale decreases and the axion becomes light, allowing de Sitter fluctuations during the late stages of inflation or post-inflationary thermal fluctuations to generate the observed dark matter abundance. In addition, QCD-induced corrections to the inflationary potential can shift the scalar spectral index towards smaller values, providing a further observational handle. We embed this mechanism in an $\alpha$-attractor model of inflation and explore the resulting parameter space. We show that, in the minimal scenario with reheating into gluons, successful dark matter production requires deconfinement to occur shortly after the CMB window. Extensions involving reheating through heavy right-handed neutrinos generally require large Yukawa couplings, which induce sizable loop corrections that spoil inflationary dynamics. We show that this tension can be resolved in the presence of supersymmetry and derive constraints on the SUSY breaking scale that allow the mechanism to remain viable within plateau models of inflation. Treating the reheat temperature as a free parameter further enlarges the viable parameter space.

    ↳ astro-ph.COhep-phhep-th1 citation
31. 31*

    Hyperon-Nucleon Spectrometer

    Xiaozhi Bai🇨🇳 · Xu Cao🇨🇳 · Zhe Cao🇨🇳 · Jinhui Chen🇨🇳 · Kai Chen · Qibo Chen🇨🇳 · Shi Chen🇨🇳 · Xin Chen🇨🇳 · Yuquan Chen · Zhenyu Chen🇨🇳 · Jianping Dai🇨🇳 · Heng-Tong Ding🇨🇳 and 228 other authors

    Chirality lies at the heart of low-energy QCD, governing the symmetry structure that shapes hadron masses and strong interaction dynamics. Among the most compelling open questions tied to chiral dynamics and spontaneous chiral symmetry breaking is the longstanding $\Lambda$ polarization puzzle, in which $\Lambda$ hyperons produced in unpolarized hadronic collisions exhibit a surprisingly large transverse polarization that remains theoretically unexplained. This whitepaper presents the proposal for the Hyperon-Nucleon Spectrometer (H-NS) at the High-Intensity heavy-ion Accelerator Facility (HIAF). Leveraging the high energy and high intensity of HIAF's proton and heavy-ion beams, the H-NS experiment will perform systematic studies of hyperon polarization phenomena and their underlying mechanisms in proton-proton ($pp$), proton-nucleus ($pA$), and nucleus-nucleus ($AA$) collisions in the fixed target mode. A wide-range beam energy scan, including proton beams from 3 GeV up to 9.3 GeV (HIAF) and up to 32 GeV (upgraded HIAF), will be conducted to examine the dependence of polarization on collision energy. The spectrometer is designed with specialized detectors capable of high-precision reconstruction of final-state baryon polarizations. Among its many interesting and important measurements, H-NS will simultaneously measure hyperon and proton spin observables to explore the polarization mechanism in hadronic interactions and the spin structure of baryons. Furthermore, the use of $pA$ and $AA$ collisions will enable detailed investigations of cold and hot nuclear matter effects on spin polarization. Its physics program and detector development will significantly benefit the future Electron-ion Collider in China.

    ↳ physics.ins-dethep-exhep-phhep-th+23 citations
32. 32*

    Three Advanced Lectures on Inflation

    Martin S. Sloth🇩🇰

    Lecture notes on inflation. The lectures are three double lectures, held for the first time at the Nordita Winter School 2024 - Particle Physics and Cosmology, covering an advanced introduction to the theory of primordial inflation, as well as the linear and non-linear perturbation theory of slow-roll inflation/quasi-de Sitter spacetimes.

    ↳ hep-thastro-ph.COhep-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.