Wed·Dec 10, 2025Wednesday·December 10, 2025

1. 01*

   Quadrupole spectra derived from 2.76 TeV Pb-Pb identified-hadron ${\mathbf{v}}_2({\mathbf{p}}_{\mathbf{t}})$ data

   Thomas A. Trainor🇺🇸

   $p_t$-differential quantity $v_2(p_t)$ is meant to measure elliptic flow manifested by a dense QCD medium formed in high-energy nucleus-nucleus collisions. Elliptic flow may be referred to more neutrally as a cylindrical quadrupole component of the transverse motion of particle sources within a collision. As defined, $v_2(p_t)$ relies on an implicit assumption that almost all produced particles emerge from a single source. This article describes a detailed study of the algebraic structure of $v_2(p_t)$. A procedure is developed to derive a common monopole boost (radial flow) value and quadrupole $p_t$ spectra for several hadron species. The method is applied to $v_2(p_t)$ data for three hadron species from 2.76 TeV Pb-Pb collisions. According to available $v_2(p_t)$ data the assumption of a single dominant particle source within A-A collisions is unjustified. Combined with a previous study of quadrupole amplitude variation for 200 GeV $p$-$p$ collisions these results demonstrate that quadrupole structure is related to a novel QCD process separate from projectile-nucleon dissociation and jet production. Given quadrupole evolution it is unlikely that a hydrodynamic description is relevant to that process.

   hep-ph2 citations
2. 02*

   (3+1)D event-by-event pre-equilibrium dynamics in heavy-ion collisions

   Xiaojian Du🇨🇳 · Sören Schlichting🇩🇪 · Jie Zhu🇨🇳

   So far a major source of uncertainty in the study of heavy-ion collisions arises from the early time dynamics which includes initial state and pre-equilibrium dynamics. The state-of-the-art framework, KoMPoST, employs non-equilibrium Green's functions to propagate the initial energy-momentum tensor to the hydrodynamic phase, yet currently only treats transverse plane dynamics under boost-invariant conditions. In this work, we extend KoMPoST to include non-boost-invariant responses to initial conditions, essential for accurately capturing the longitudinal structures observed in heavy-ion collisions. Non-boost-invariant fluctuations on top of a homogeneous background are evolved using (3+1)D response functions calculated in kinetic theory. To assess kinetic theory's transition towards hydrodynamic evolution, we systematically compare the out-of-equilibrium shear-stress tensor from KoMPoST-3D with estimates based on Navier-Stokes hydrodynamics. Subsequently, a comprehensive (3+1)D framework, McDIPPER+KoMPoST-3D+CLVisc+SMASH, is utilized to simulate the complete spacetime evolution of heavy-ion collisions. The sensitivity of key observables, including longitudinal structure of anisotropic flow, to variations in the hydrodynamic initialization time is thoroughly investigated.

   hep-phnucl-thPRD(2026)·3 citations
3. 03*

   New Monopoles in Non-Abelian Gauge Theories

   Liping Zou🇨🇳 · Pengming Zhang🇨🇳 · Y. M. Cho🇰🇷

   The monopoles play important roles in physics. In this work we discuss the new monopoles in non-Abelian gauge theories, the standard model, the Georgi-Glashow model, and QCD. The standard model has two totally different types of monopoles, the Cho-Maison type monopoles which have the weak boson dressing and the electromagnetically neutral magnetic monopoles (the naked one and the one with the W boson dressing) which carries the neutral magnetic charge $4\pi /\text{bae}$. The Georgi-Glashow model has a new monopole, the Wu-Yang monopole which has the W boson dressing, in addition to the well known 'tHooft-Polyakov monopole. And QCD has a new monopole, the Wu-Yang monopole which has the chromon dressing. We show how to construct the new monopoles and clarify the origin of the topology of the new monopoles. The new monopoles could have deep implications not just in high energy physics but also in low energy physics.

   hep-ph2 citations
4. 04*

   Nucleon Structure from Basis Light-Front Quantization : Status and Prospects

   James P. Vary🇺🇸 · Chandan Mondal🇨🇳 · Siqi Xu🇨🇳 · Xingbo Zhao🇨🇳 · Yang Li🇨🇳

   We review recent advancements in understanding nucleon structure within the Basis Light-Front Quantization (BLFQ) framework--a fully relativistic, nonperturbative approach to solving quantum field theories. In its initial phase, we start with the leading Fock sector $|qqq⟩$ and an effective light-front Hamiltonian incorporating confinement and one-gluon exchange within which BLFQ can already successfully describe key nucleon observables. The framework has since been extended to include the next-to-leading Fock sector $|qqqg⟩$, enabling studies of gluonic contributions to the nucleon's internal structure, including gluon helicity, orbital angular momentum, and three-dimensional imaging through generalized and transverse momentum dependent parton distributions (GPDs and TMDs). Most recently, BLFQ has achieved a significant milestone by computing nucleon light-front wavefunctions as eigenstates of the QCD Hamiltonian without an explicit confining potential. These calculations, including Fock sectors up to $|qqqq\bar{q}⟩$, further develop the path to first-principles predictions of quark and gluon matter densities, helicity and transversity distributions, and spin observables, showing qualitative agreement with experimental and phenomenological results. Together, these developments highlight BLFQ's growing capacity to provide an increasingly complete and realistic picture of nucleon structure grounded in QCD.

   hep-phhep-thnucl-thEur.Phys.J.ST(2026)·14 citations
5. 05*

   Leading-twist gluon transverse momentum dependent distributions from large-momentum effective theory

   Xiupeng Xie🇨🇳 · Zhun Lu🇨🇳

   We present the perturbative calculation of the leading-twist gluon transverse momentum dependent distribution functions (TMDPDFs) at one-loop level within large-momentum effective theory. By employing the basis of circular polarizations, we generalize the gluon-gluon correlator to a matrix ${\Phi }_{\Lambda {\Lambda }^{\prime }}^{ij}(x,{\mathbf{k}}_T^2;S)$ in the gluon $\otimes$ hadron spin space. Incorporating the transverse momentum of external states, we derive the leading-twist gluon TMDPDFs and quasi-TMDPDFs at one-loop level. Our calculations reveal nonzero distributions for the gluon TMDPDFs $f_{1T}^{\perp g}(x,{\mathbf{k}}_T^2)$, $h_1^{\perp g}(x,{\mathbf{k}}_T^2)$, $h_{1T}^g(x,{\mathbf{k}}_T^2)$, and $h_{1T}^{\perp g}(x,{\mathbf{k}}_T^2)$. These findings enable future lattice QCD simulations to extract these gluon TMDPDFs, which will facilitate a complete determination of nucleon tomography.

   hep-phPRD(2026)·2 citations
6. 06*

   Impact of antiparticle degrees of freedom on neutrino flavor oscillations in frames of quantum field theory

   Maxim Dvornikov (IZMIRAN)🇷🇺

   We study neutrino flavor oscillations using the approach based on the quantum field theory (QFT), where neutrinos are taken to be virtual particles. One deals with the propagators of neutrino mass eigenstates in this formalism. Previously, while applying this approach to neutrino oscillations in external fields, we decomposed the propagators and used only the particle contribution in the calculation of the matrix element. In the present work, we carefully justify the validity of this kind of transformation by considering neutrino oscillations in vacuum. In principle, the results obtained can be extended for the QFT applied to neutrino oscillations in external fields.

   hep-phhep-thPhys.Part.Nucl.(2026)·1 citation
7. 07*

   $B\to PP$ decays with Light-Cone Sum Rules

   Yuanyuan Ma🇨🇳 · Yan-jun Sun🇨🇳

   We study factorizable contributions to two-body nonleptonic decays of $B$ mesons using the light-cone sum rule method. By constructing three-point correlation functions and incorporating light-cone distribution amplitudes, we compute the hadronic matrix elements and branching ratios for decay channels $B^0\to {\pi }^{+}{\pi }^{-}$, $B^{+}\to {\pi }^{+}{\pi }^0$, $B^0\to K^{+}{\pi }^{-}$, and $B^0\to K^{+}{K}^{-}$. The results are in agreement with experimental data within uncertainties. We also estimate the branching ratio of $B_s^0\to {\pi }^{+}{\pi }^{-}$ to be approximately $0.781\times 10^{-6}$.

   hep-ph0 citations
8. 08*

   Damped oscillation regular structures from the deuteron "effective" electromagnetic form factor data

   A.-Z. Dubničková🇸🇰 · S. Dubnička🇸🇰 · P. Weisenpacher🇸🇰

   The deuteron ``D'' is the simplest nucleus with the spin S=1, therefore its electromagnetic structure is completely described by three different, the charge $G_C(t)$, magnetic $G_M(t)$ and quadrupole $G_Q(t)$ form factors, where $t=-q^2$ is the momentum transfer squared of the electrons or the deuterons in the elastic scattering of electrons on deuterons. All three deuteron form factors are theoretically related to the functions $A(t)$, $B(t)$ and $T_{20}(t)$ to be numerically evaluated with errors, whereby $A(t)$ and $B(t)$ in a measurement of the differential cross section of elastic scattering of unpolarized electrons on unpolarized deuterons, and $T_{20}$ in measurements of the elastic scattering of the longitudinally polarized electrons, respectively also on polarized deuteron target. The obtained data are utilized to fix parameters of the deuteron electromagnetic form factors to be constructed in the form of the Unitary and Analytic model. Afterwards these form factors are analytically continued into the time-like region, with the aim to predict artificial behavior of the total cross section ${\sigma }_{tot}(e^{+}{e}^{-}\to D\bar{D})(s)$. By means of the latter artificial data with errors on the deuteron ``effective'' electromagnetic form factor are produced theoretically. Finally, such data render a possibility to investigate the deuteron damped oscillation regular structures.

   hep-phPRD(2025)·0 citations
9. 09*

   Reviving $Z^{\prime }$ Portal Dark Matter with Conversion Mechanism

   Zhen-Wei Wang🇨🇳 · Zhi-Long Han🇨🇳 · Fei Huang🇨🇳 · Honglei Li🇨🇳 · Ang Liu🇨🇳

   In many new physics models with extended gauge symmetry, the new gauge boson $Z^{\prime }$ could mediate the interactions between the dark matter and standard model particles. For the conventional $Z^{\prime }$ portal dark matter, the collider and the direct detection constraints typically pose a significant challenge. To address this pressing issue, we present in this paper a new benchmark model based on the gauged $U(1{)}_{B-L}$ symmetry, which introduces a Dirac dark fermion ${\tilde{\chi }}_1$ and a heavier partner ${\tilde{\chi }}_2$ with zero and nonzero $U(1{)}_{B-L}$ charge, respectively. Including the mass term $\delta m{\overline{\stackrel{~}{\chi }}}_1{\tilde{\chi }}_2$ results in the dark fermions ${\chi }_1$ and ${\chi }_2$ in the mass eigenstate, where the lighter one ${\chi }_1$ is regarded as the dark matter candidate. Various intriguing processes for the relic density arise with the compressed mass spectrum $m_{{\chi }_1}\simeq m_{{\chi }_2}$, such as the coscattering ${\chi }_{2}f\to {\chi }_{1}f$, the conversion ${\chi }_2{\chi }_i\to {\chi }_1{\chi }_j$, and the coannihilation ${\chi }_1{\chi }_2\to f\bar{f}$ processes. Suppressed by the small mixing angle $\theta$ between the dark fermions, the small effective gauge coupling of dark matter ${\chi }_1$ to the gauge boson $Z^{\prime }$ is one distinct feature of this model, rendering phenomenology in many aspects more promising. In this paper, we investigate the production of dark matter through new mechanisms within the frameworks of resonance and secluded scenarios. The impacts of phenomenological constraints from collider, dark matter, and cosmology are also taken into account. We report that the conversion mechanism is both favored by the resonance and secluded scenarios under current constraints.

   hep-phhep-exPRD(2026)·0 citations
10. 10*

    On the existence of bound states in SIMP dark sectors

    Xiaoyong Chu🇨🇳 · Josef Pradler🇦🇹 · Daris Samart🇹🇭

    In strongly interacting massive particle (SIMP) scenarios, dark matter is comprised of stable dark pions whose $3\to 2$ or $4\to 2$ reactions set the dark matter relic abundance. Recent work has shown that shallow two-pion bound states significantly affect the freeze-out, but did not establish whether such states actually form. In this work we demonstrate that a scalar isosinglet bound state does exist in a well-defined region of parameter space by solving an on-shell Lippmann--Schwinger equation in a chiral-unitary framework and analyzing the $S$-wave $\pi \pi$ amplitude in the complex energy plane. We determine the range of $m_{\pi }/f_{\pi }$ for which a pole appears below the two-pion threshold, extract the corresponding residue, and, in the non-relativistic limit, obtain the bound-state wave function at the origin, $|\Psi (0)|$, which controls bound-state-assisted annihilation and decay rates relevant for catalyzed freeze-out. Comparing this T-matrix based result with variational estimates using simple finite-range potentials, we find agreement within order-one factors for shallow binding. For binding energies of order the freeze-out temperature, $E_B\sim m_{\pi }/20$, we obtain $|\Psi (0)|\sim \mathcal{O}(0.1)m_{\pi }^{3/2}$, thereby supporting the parametric assumptions used in previous phenomenological analyses.

    hep-phastro-ph.HEPRD(2026)·3 citations
11. 11*

    Superluminal constraints from ultra-high-energy neutrino events

    J. M. Carmona🇪🇸 · J. L. Cortés🇪🇸 · M. A. Reyes🇪🇸

    The $220_{-100}^{+570}$PeV neutrino detected by KM3NeT marks the beginning of ultra-high-energy neutrino astronomy and provides a powerful probe of Lorentz Invariance Violation (LIV). In superluminal scenarios, neutrinos can decay through vacuum $e^{-}{e}^{+}$ pair emission or neutrino splitting. Previous analyses of the KM3-230213A event relied on simplified survival-probability estimates and, in some cases, used inaccurate decay-width expressions or neglected redshift and threshold effects. In this work we present a unified and self-consistent framework that corrects these issues and applies to both the energy-independent ($n=0$) and quadratic ($n=2$) superluminal cases. We collect and recast the decay-width and threshold expressions, clarify their flavor dependence, and include a consistent treatment of cosmological propagation. We also assess the impact of cascade regeneration and show that cascade effects are negligible for the purpose of setting LIV bounds. The survival-probability approximation adopted in previous works is therefore justified, while our framework provides a coherent basis for future analyses of superluminal neutrino constraints, which should consistently include possible time-delay signatures.

    hep-phastro-ph.HEJCAP(2026)·1 citation
12. 12*

    Dark Photons in the Early Universe: From Thermal Production to Cosmological Constraints

    Xun-Jie Xu🇨🇳 · Boting Zhou🇨🇳

    Dark photons, a generic class of light gauge bosons that interact with the Standard Model (SM) exclusively through kinetic mixing, arise naturally in many gauge extensions of the SM. Motivated by these theoretical considerations, we present a comprehensive analysis of their thermal production in the early universe. Our calculation covers a broad range of dark photon masses from 0.1 keV to 100 MeV and include inverse decay, annihilation, and semi-Compton processes. Wherever possible, we present analytical estimates of the production rates and yields, and verify their accuracy numerically. For dark photons lighter than twice the electron masses (around 1 MeV), we find that our analytical estimate of the freeze-in yield based on resonant production is very accurate, implying that off-resonance contributions can be neglected in practice. For heavy dark photons, although this conclusion no longer holds, we derive an interesting ratio, $4\pi e/27\approx 0.14$, with $e$ the coupling constant of QED, that can be used to estimate the relative importance of on- and off-resonance contributions. Finally, using the calculated abundance of dark photons in the early universe, we derive cosmological constraints on the dark photon mass and kinetic mixing. Compared with bounds from stellar cooling and supernovae, the cosmological constraints are most stringent in the mass range from 0.1 MeV to 6 MeV, within which kinetic mixing at the level of $10^{-12}\sim 10^{-10}$ can be probed.

    hep-phastro-ph.COhep-exJHEP(2026)·5 citations
13. 13*

    Further study on the lepton mass spectra and flavor mixing with $S_{3L}\times S_{3R}$ flavor symmetry

    Chang-Qi Hu🇨🇳 · Chun-Yuan Li🇨🇳 · Xiao Liang🇨🇳 · Xing-Hua Yang🇨🇳 · Dai-Xing Zhang🇨🇳

    Neutrino oscillation experiments have confirmed that neutrinos are massive particles and lepton flavors are mixed. To explain the observed lepton mass spectra and flavor mixing patterns, flavor symmetry plays a crucial and unique role. In this paper, we propose a useful symmetry-breaking scheme by applying $S_{3L}\times S_{3R}\to S_{2L}\times S_{2R}\to \varnothing$ within both charged-lepton and neutrino sectors at the mass-matrix level. For the three distinct residual subgroups $S_{2L}^{(23)}\times S_{2R}^{(23)}$, $S_{2L}^{(13)}\times S_{2R}^{(13)}$ and $S_{2L}^{(12)}\times S_{2R}^{(12)}$ under consideration, we systematically analyze the various parameterizations of the lepton mass matrices. It is shown that all the three scenarios are in good agreement with current neutrino oscillation data. Notably, within the latest best-fit values of neutrino oscillation parameters, the predicted Dirac CP-violating phase $\delta$ is calculated to be $294.6^{\circ }$, $302.3^{\circ }$ and $287.0^{\circ }$, respectively. To further assess the viability of the model, a comprehensive numerical analysis is performed by utilizing neutrino oscillation parameters at the $3\sigma$ level. It is found that the allowed range of $\delta$ is $281.2^{\circ }\to 338.7^{\circ }$, $287.0^{\circ }\to 342.2^{\circ }$ and $282.7^{\circ }\to 297.0^{\circ }$, all fall within its $3\sigma$ range. These results indicate that the proposed symmetry-breaking scheme $S_{3L}\times S_{3R}\to S_{2L}\times S_{2R}\to \varnothing$ can naturally explain the realistic lepton mass hierarchy and mixing pattern, thereby providing valuable theoretical perspectives for future research.

    hep-phCPC(2026)·0 citations
14. 14*

    Bayesian Extraction of HQET Parameters from Inclusive Semi-Leptonic Decay of the ${\Lambda }_c^{+}$ Baryon

    Kangkang Shao🇨🇳 · Dong Xiao🇨🇳

    We extract the non-perturbative Heavy Quark Effective Theory (HQET) parameters from the inclusive semi-leptonic decay ${\Lambda }_c^{+}\to X{e}^{+}{\nu }_e$. Unlike charmed mesons produced near threshold, ${\Lambda }_c^{+}$ baryons produced in $e^{+}{e}^{-}$ annihilation exhibit a complex momentum distribution, making the transformation of the electron energy spectrum from the laboratory frame to the ${\Lambda }_c^{+}$ rest frame non-trivial. To address this, we develop a novel Bayesian inference method to reconstruct the electron energy moments in the ${\Lambda }_c^{+}$ rest frame. By performing a global fit of theoretical predictions in the 1S mass scheme to these extracted moments, we determine the HQET parameters ${\mu }_{\pi }^2({\Lambda }_c^{+})$ and ${\rho }_D^3({\Lambda }_c^{+})$ for the first time using a purely data-driven approach.

    hep-phhep-thCPC(2026)·0 citations
15. 15*

    Removal of the Tachyons from the Fermionic Sector of the Quadratic ZX Action for the Exotic Model (E8)

    John Anthony Dixon🇨🇦

    This paper contains an encouraging result for the development of the Exotic Model (the `XM'). The XM is made from the Supersymmetric Standard Model (the `SSM') by coupling it to the `Exotic Invariant'. This rather unique `Exotic Invariant' is suggested by the detailed form of the SSM, combined with the detailed form of the BRS cohomology of SUSY. The motivation for examining the XM is that the usual SSM has some well-known, and serious, problems in its generally accepted, but unsatisfactory, SUSY breaking mechanism. That mechanism is based on the spontaneous breaking of SUSY. The Exotic Model avoids all of these problems, easily, because its SUSY splitting mechanism does not use, or need, any kind of spontaneous breaking of SUSY. The XM contains a mechanism for SUSY mass splitting because the addition of the Exotic Invariant modifies the algebra of SUSY. This paper is E8 in a series of papers denoted En, n= 1,2, ... all devoted to the XM. There is a lot of work still required to elucidate how the XM functions, and to see if the XM is really a viable alternative to the SSM. The first crucial question, raised in E7, is whether it is possible to constrain the initial XM action, so that the result excludes tachyonic excitations at tree level. If the XM is to be a viable theory, it is essential to first remove the tachyonic excitations, in a sensible way, from the fermionic and the bosonic sectors of the quadratic ZX action. This paper E8 explains how to remove the tachyons from the basic fermionic `ZX sector' at tree level. There are four fermion fields in this ZX sector. The removal requires that all of these fields have the same mass. This result is shown using a Mathematica notebook, which is issued with this paper.

    hep-ph3 citations
16. 16*

    New dark matter production mechanism and the gravitational wave signals

    Fa Peng Huang🇨🇳

    The microscopic origin and production mechanism of dark matter (DM) remain central questions in cosmology and particle physics. While thermal freeze-out has long dominated DM model building, alternative non-thermal scenarios are gaining prominence. In this work, we explore novel production channels for heavy DM candidates, including pseudo-Nambu-Goldstone bosons (pNGBs), Q-balls, and filtered DM arising from early-universe phenomena such as primordial black hole (PBH) evaporation, superradiance, and first-order phase transitions. We demonstrate that these mechanisms naturally generate gravitational wave signals detectable by future observatories, such as LISA, TianQin, Taiji, and Cosmic Explorer. This multi-messenger approach offers a promising pathway to probe the origin and nature of DM beyond conventional paradigms.

    hep-ph0 citations
17. 17*

    Freeze-in Production of Non-Abelian Millicharged Vector Dark Matter

    Van Que Tran🇹🇼 · Tzu-Chiang Yuan🇹🇼

    We present the first predictive realization, to our knowledge, of vector freeze-in dark matter from a hidden non-Abelian $SU(2)$ gauge sector spontaneously broken by a Higgs triplet to a residual $U(1)$ symmetry with a massless dark photon mediator. A massive dark vector particle-antiparticle pair acquires small millicharges through a dimension-4 kinetic-mixing term with an induced coefficient $ϵ$, generated by an effective dimension-5 operator involved the Higgs triplet. The dark sector interactions are governed by the hidden gauge coupling $g_D$, providing a weak connection to the Standard Model to realize the freeze-in dark matter production mechanism. Solving the two-temperature Boltzmann evolution including plasmon decay, we find a wide region of parameter space consistent with the observed relic abundance while satisfying astrophysical and cosmological constraints. This minimal framework connects non-Abelian vector dynamics with long-range dark forces and may be probed by upcoming sub-GeV dark matter direct-detection experiments.

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

    Collider Probes of Four-Lepton Final States in Maximally Flavor-Violating $U(1{)}_{L_{\mu }-L_{\tau }}$ Model

    Jianing Qin🇨🇳 · Fei Huang🇨🇳 · Honglei Li🇨🇳 · Zhi-Long Han🇨🇳 · Jin Sun🇰🇷

    We investigate the collider signatures of the maximally flavor-violating $U(1{)}_{L_{\mu }-L_{\tau }}$ model, where a new gauge boson $Z^{\prime }$ and scalar triplets induce lepton flavor-changing interactions in the $\mu$-$\tau$ sector. Focusing on four-lepton final states at multi-TeV lepton colliders, we conduct a detailed analysis of cross sections, asymmetries, and polarization effects. We show that the signal cross section is highly sensitive to $m_{Z^{\prime }}$ and the effective parameters $\tilde{g}/m_{Z^{\prime }}$, while remaining largely insensitive to the triplet Yukawa couplings within the phenomenologically allowed region. The forward-backward asymmetry exhibits a characteristic monotonic dependence on $m_{Z^{\prime }}$, and beam polarization can significantly suppress Standard Model backgrounds while enhancing new physics contributions. We find that over the phenomenologically allowed parameter space, the predicted observables remain highly sensitive to the underlying model parameters. These results demonstrate that multi-lepton final states are powerful probes of the $U(1{)}_{L\mu -L_{\tau }}$ framework and offer valuable guidance for future searches at muon and electron-positron colliders.

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

    Systematic investigation of the spectroscopy and decay behaviors of doubly-charmed pentaquarks

    Hong-Tao An🇨🇳 · Yu-Shuai Li🇨🇳

    Building upon the discoveries of the ${\Xi }_{cc}^{++}(3621)$ and $T_{cc}^{+}(3875)$, we undertake a comprehensive investigation into the mass spectra, internal structures, and decay properties of doubly-charmed pentaquarks. By treating the two light quarks as a tightly bound diquark, the five-body system reduces to a four-body heavy quark-heavy quark-diquark-antiquark configuration. Within the constituent quark model framework, we calculate their mass spectra in the range of 4.7-5.4 GeV and corresponding internal mass contributions via the Gaussian expansion method. The root-mean-square radii, typically between 1.1-1.6 fm, indicate compact spatial structures. Furthermore, we also calculate the rearrangement decay widths via the quark-interchange model, finding that all states are unstable and decay into a singly-charmed baryon and a singly-charmed meson. Several narrow resonances have been identified, some of which have a total width even below 10 MeV. We hope that our study could provide valuable guidance for future theoretical investigations and experimental searches targeting doubly-charmed pentaquarks.

    hep-phEPJC(2026)·3 citations
20. 20*

    $J/\psi$-Meson Nucleon Scattering Length from Threshold Photoproduction on Light Nuclei

    Igor I. Strakovsky (GWU)🇺🇸 · William J. Briscoe (GWU)🇺🇸 · Philipp Gubler (JAEA)🇯🇵 · Jackson R. Pybus (LANL)🇺🇸 · Axel Schmidt (GWU)🇺🇸 · Alexander Somov (JLab)🇺🇸

    The quality of recent SRC/CT Collaboration $J/\psi$ photoproduction data off a ${}^4$He target from Hall~D at Jefferson Laboratory, combined with the feasibility of measuring the reaction close to the free-nucleon energy threshold, opens the door to using incoherent $J/\psi$ photoproduction to access a variety of interesting physics aspects. An example is an estimate of the $J/\psi p$ scattering length $|{\alpha }_{J/\psi p}|$ on the bound proton obtained using the Vector Meson Dominance model. This value can be compared with that of the free proton from the GlueX Collaboration. One may then project what would be expected from the SRC/CT Collaboration Experiment E12--25--002, which was recently approved by the JLab PAC. Using a plane-wave theoretical model to generate quasi-data, we find the experiment could achieve a result of $|{\alpha }_{J/\psi p}|=3.08\pm 0.45\mathrm{mfm}$, an uncertainty competitive with that of the free-proton measurement. A comparison between the two would allow an evaluation of the effects of medium modification in the case of light nuclei.

    hep-phhep-exnucl-exnucl-thPRC(2026)·4 citations
21. 21*

    The bound state of dark atom with the nucleus of substance

    T. E. Bikbaev🇷🇺 · M. Yu. Khlopov🇫🇷 · A. G. Mayorov🇷🇺

    The hypothesis of composite $XHe$ dark atoms offers a compelling framework to address the challenges in direct dark matter particles detection, as their neutral, atom-like configuration evades conventional experimental signatures. A critical issue may arise in interaction between $XHe$ and atomic nuclei due to the unshielded nuclear attraction, which could destabilize the dark atom's bound state. To resolve this, we propose a novel numerical quantum mechanical approach that accounts for self-consistent electromagnetic-nuclear couplings. This method addresses to eliminate the inherent complexity of the $XHe$-nucleus three-body system, where analytical solutions are intractable. By reconstructing the effective interaction potential - including dipole Coulomb barrier and shallow potential well - we demonstrate how these features lead to the formation of $XHe$-nucleus bound states and modulate low-energy capture processes. Our model enables validation of the dark atom hypothesis, particularly in interpreting experimental anomalies like annual modulation signals observed in DAMA/LIBRA. These findings advance the theoretical foundation for dark matter interactions and provide a robust framework for future experimental design.

    hep-phquant-ph0 citations
22. 22*

    Interpreting the current Higgs excesses at the LHC in the 2HD+a framework

    Giorgio Arcadi🇮🇹 · Abdelhak Djouadi🇪🇸

    There are several excesses of events in current LHC data, yet not exceeding the level of significance which would make them to be considered as firm. They point to the possibility of the presence of a new Higgs particle in the spectrum, in addition to the already observed 125 GeV state. In particular, there are excesses involving a diphoton resonance at invariant masses of about 95 GeV, 152 GeV and 650 GeV and an extra scalar might accompany the recent observation of a toponium at a mass of about 350 GeV. Several interpretations of these excesses have been attempted in extensions of the Standard Model. In this paper, we aim to explain them in the framework of a two Higgs doublet model supplemented by a relatively light pseudoscalar Higgs boson $a$ which would correspond to the putative resonance in most cases. This realistic 2HD+a scenario is attractive as it is has the virtue to pass all experimental constraints from high-precision experiments and collider searches and, at the same time, to allow for a viable explanation of the dark matter in the universe. We first update the present constraints on the model, in particular taking into account the latest results on dark matter and Higgs searches, as well the high-precision measurements, including those from Higgs and flavor physics. We then show that the additional Higgs states with the proper mass spectrum and adjusted couplings to fermions, would explain all the LHC excesses (but individually) while passing the former experimental constraints as well as the theoretical ones.

    hep-phEPJC(2026)·3 citations
23. 23*

    Two-loop renormalization of general bosonic effective field theories

    Guilherme Guedes🇨🇭 · Jasper Roosmale Nepveu🇹🇼

    The renormalization of higher-dimensional operators in quantum field theory is essential for phenomenological analyses in particle physics, and plays a significant role in the study of critical phenomena. We present a framework for renormalizing general bosonic effective field theories beyond one loop, with arbitrary gauge symmetry and scalar field content. In particular, we calculate the renormalization group equations in such theories up to two loops and dimension six. When specialized to the bosonic sector of the Standard Model effective field theory (SMEFT) using simple replacement rules, our general expressions reproduce recent results from the literature. Due to the broad applicability of effective field theory, our general results can readily be applied to obtain the anomalous dimensions in extensions of the bosonic SMEFT and in a plethora of other theories. We also envision our results to provide useful data on the scaling dimensions of composite operators in conformal field theories without fermions.

    hep-phhep-thJHEP(2026)·11 citations
24. 24*

    New light mediators and the neutrino fog: Implications from XENONnT nuclear recoil data

    Valentina De Romeri🇪🇸 · Anirban Majumdar🇮🇳 · Dimitrios K. Papoulias🇪🇸 · Rahul Srivastava🇮🇳

    Current ton-scale, xenon-based dark matter (DM) direct detection experiments have now reached the sensitivity required to observe solar neutrinos, marking the onset of the so-called neutrino fog. In this work, we explore how this fog is modified when either neutrinos or DM interact with nuclei through a new scalar, vector or axial-vector interaction, considering both heavy and light mediators. Using the latest nuclear-recoil data from XENONnT, which show indications of coherent elastic neutrino-nucleus scattering from ${}^8$B solar neutrinos, we derive new strong bounds on couplings of light mediators. We find that these limits are significantly more stringent when the mediator couples to DM, rather than when new physics affects only neutrino interactions. Building on these results, we recompute the expected neutrino fog and compare it with the corresponding constraints on spin-independent and spin-dependent DM-nucleon interactions. We show that the morphology of the neutrino fog can be markedly modified if either neutrinos or DM interact with nuclei through light mediators, even in light of these recent constraints.

    hep-phJCAP(2026)·15 citations
25. 25*

    Update of the nonlocal sub-leading $O_1$-$O_7$ contribution to $\bar{B}\to X_s\gamma$ at LO

    Michael Benzke🇩🇪 · Maria Vittoria Garzelli🇩🇪 · Tobias Hurth🇩🇪

    In all previous calculations of the non-local sub-leading contribution to the inclusive penguin decay $\bar{B}\to X_s\gamma$ due to the interference of the electroweak operators $O_1^c$ - $O_{7\gamma }$ the local Voloshin term was subtracted. In view of the ongoing analysis at order ${\alpha }_s$, we present a calculation of the complete non-local contribution which takes into account the high correlation between the uncertainties of the local Voloshin and the non-local term of the previous analyses. The new calculation has a high impact on the range of the non-local contribution.

    hep-phPRD(2026)·2 citations
26. 26*

    Search for Dark Matter Annihilation and Decay with H$\alpha$ Line Emission

    Rebecca K. Leane🇺🇸

    I present a new indirect search for dark matter (DM) using Hydrogen-$\alpha$ (H$\alpha$) recombination emission. DM annihilation or decay products can ionize neutral gas; subsequent recombination cascades generate H$\alpha$ photons through the $3\to 2$ transition. In quiet gas-rich dwarf galaxies, the $n=2$ population is negligible, so H$\alpha$ is effectively unabsorbed and traces the DM-energy injection site. Using the non-detection of extended H$\alpha$ emission in the Leo T dwarf galaxy with Multi Unit Spectroscopic Explorer (MUSE) observations, I derive the first H$\alpha$-based limits on DM annihilation and decay, reaching leading sensitivity for parts of the eV-GeV mass range. Existing and upcoming telescopes can further extend this reach, establishing H$\alpha$ imaging as a powerful DM search strategy.

    hep-phastro-ph.GAastro-ph.HEPRL(2026)·2 citations
27. 27*

    Testing lepton non-unitarity with the next generation of Germanium-based CE$\nu$NS reactor experiments

    Salvador Centelles Chuliá🇪🇸 · Manfred Lindner🇩🇪 · Thomas Rink🇩🇪

    Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) has been experimentally confirmed using neutrinos from pion decay at rest, solar neutrinos and reactor antineutrinos. Future CE$\nu$NS experiments will foreseeable lead to precision measurements which will be a powerful tool to search for new physics beyond the Standard Model. In this work, we investigate possible deviations from unitarity in the $3\times 3$ leptonic mixing matrix that controls the propagation of active neutrinos. Such deviations may originate from the mixing with additional gauge singlet fermions and depending on their mass scale and mixing, the resulting phenomenology can differ substantially. We explore two well-motivated regimes: the \textit{seesaw limit}, where the new fermions are heavy and kinematically inaccessible, leading to effective deviations from unitarity in the active sector; and the \textit{light sterile limit}, where they are light enough to be produced and participate in neutrino propagation and scattering processes. We show how these scenarios modify both CE$\nu$NS and elastic neutrino--electron scattering (E$\nu e$S), and we present the corresponding sensitivity projections for a future CE$\nu$NS reactor experiment obtained by upscaling the CONUS+ experiment, which reported the first observation of reactor CE$\nu$NS. We identify the leading experimental systematics relevant for such an upscaling and demonstrate the resulting capability to probe TeV-scale new physics. Our results highlight the strong potential of CE$\nu$NS to test the structure of the lepton sector and to search for physics beyond the Standard Model.

    hep-phhep-exPRD(2026)·1 citation
28. 28*

    Dispersive determination of resonances from $\pi \pi$ scattering data

    José Ramón Peláez🇪🇸 · Pablo Rabán🇪🇸 · Jacobo Ruiz de Elvira🇪🇸

    We provide a precise, model- and parametrization-independent dispersive determination of the $f_0(500)$, $\rho (770)$, $f_0(980)$, $f_2(1270)$, $f_0(1370)$, $\rho (1450)$, $f_0(1500)$, and ${\rho }_3(1690)$ resonance pole parameters. They are obtained from the analytic continuation, by means of continued fractions, of forward dispersion relations, whose input is a recent global dispersive analysis of $\pi \pi$ scattering data. From this dispersive study, we find no indications of other resonant poles below 1.7 GeV. Beyond this energy, we also provide resonance pole parameters from the direct analytic continuation of Global Fits to the three existing incompatible datasets. Depending on the dataset we find poles for the $\rho (1700)$, $f_0(1710)$, $\rho (1900)$, $f_2(1950)$, and $f_0(2020)$ resonances. We also present the Argand diagrams of these Global Fits and illustrate that each resonance does not necessarily have to trace a full circle in the diagram.

    hep-phhep-exhep-latnucl-thPRD(2026)·8 citations
29. 29*

    Rapidly Spinning Massive Pulsars as an Indicator of Quark Deconfinement

    Christoph Gärtlein🇵🇹 · Violetta Sagun🇬🇧 · Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Ilídio Lopes🇵🇹

    We study rotating hybrid stars, with particular emphasis on the effect of spin on the deconfinement phase transition and star properties. Our analysis is based on a hybrid equation of state with a phase transition from hadronic matter containing hyperons to color-superconducting quark matter, where the quark phase is modeled within a relativistic density functional approach. By varying the strength of the vector repulsion and diquark pairing couplings in the microscopic quark Lagrangian, we construct a set of hybrid star sequences with different quark-matter onset densities. This framework ensures consistency with astrophysical and gravitational wave constraints on mass, radius, and tidal deformability.

    ↳ nucl-thastro-ph.HEhep-phJ.Subatomic Part.Cosmol.(2026)·3 citations
30. 30*

    Isocurvature Induced Gravitational Waves at Pulsar Timing Arrays

    Yi-Fu Cai🇨🇳 · Peizhi Du🇨🇳 · Jiahang Zhong🇨🇳

    Gravitational waves (GWs) are powerful probes of new physics in the early Universe. In particular, GWs induced by primordial isocurvature perturbations encode information of novel dynamics beyond the standard $\Lambda$CDM model. Existing studies of isocurvature induced GWs focus on a particular type: cold dark matter (CDM) isocurvature. In this work, we present a more comprehensive study of four kinds of isocurvature involving CDM, baryons, neutrinos and free-streaming dark radiation (DR). We first reformulate initial conditions of isocurvature with coupled neutrinos because modes relevant for observations at Pulsar Timing Arrays enter the horizon before neutrino decoupling. With these new initial conditions, neutrino isocurvature is phenomenologically similar to CDM isocurvature up to an overall coefficient, which leads to an interesting conversion of isocurvature between radiation and matter sectors. We then find that the spectrum of isocurvature induced GWs from free-streaming DR is qualitatively different than that from CDM due to the presence of anisotropic stress. Unlike GWs induced by CDM isocurvature that are suppressed at high frequencies due to matter density being suppressed at early times, DR isocurvature induced GWs is proportional to the constant ratio between DR density and total radiation. Finally, we utilize two general parametrizations of the isocurvature power spectrum: a delta function and a broken power law, and derive novel constraints with recent NANOGrav data. Our results set stringent constraints on isocurvature around $10^6{\text{Mpc}}^{-1}$, which are complementary to cosmological observations at large scales.

    ↳ astro-ph.COhep-phJCAP(2026)·2 citations
31. 31*

    Emergence of dynamical tensor fields in composite models of gravity

    Yadikaer Maitiniyazi🇨🇳 · Masatoshi Yamada🇯🇵

    We investigate composite models of gravity and explore how dynamical tensor fields can emerge within the functional renormalization group framework. We consider two prototype models: a fermionic theory and a scalar theory. In both cases, an auxiliary tensor field is introduced via a Hubbard-Stratonovich transformation, corresponding to the composite channel associated with the energy-momentum tensor. We derive the flow equations for the field renormalization factors of the auxiliary tensor field and demonstrate that finite kinetic terms are dynamically generated in the infrared regime. Agreement with the diffeomorphism-invariant quadratic Einstein-Hilbert structure can be established in the transverse-traceless spin-2 sector, while the remaining contributions reside in the longitudinal and trace sectors. Although these terms can be cast into a form reminiscent of gauge-fixed presentations of the quadratic Einstein-Hilbert action, we do not interpret them as originating from a genuine gauge-fixing procedure within the present truncation.

    ↳ hep-thgr-qchep-phPRD(2026)·1 citation
32. 32*

    Neutrino mass constraints in the context of 4-parameter dark energy equation of state and DESI DR2 observations

    Gowri S Nair · Amlan Chakraborty🇮🇳 · Luca Amendola · Subinoy Das🇮🇳

    Cosmological constraints on the total neutrino mass, $\sum m_{\nu }$, are strongly shaped by assumptions about the dark-energy equation of state due to the well-known degeneracy between massive neutrinos and late-time cosmic acceleration. In this work, we move beyond the two-parameter Chevallier-Polarski-Linder (CPL) form adopted in recent DESI analyses and re-examine neutrino mass constraints using a flexible four-parameter dark energy equation of state (4pDE). We implement the 4pDE model in a modified version of CLASS and perform a full MCMC analysis using Planck, DESI DR2 BAO, and Pantheon+ data. Relative to our previous 4pDE study based on pre-DESI BAO datasets, the inclusion of DESI DR2 substantially tightens the constraints on the transition parameters while still yielding a relaxed neutrino-mass bound compared to $\Lambda$CDM, $\sum m_{\nu }<0.101$ eV ($95\%$ C.L.). This upper limit is more stringent than the DESI DR2 constraint obtained within the $w_0{w}_a$CDM framework. From the best-fit parameters, we reconstruct the evolution of the 4pDE equation of state along with both $68\%$ and $95\%$C.L. We do not find a statistically significant phantom-crossing at $z\sim 0.5$, consistent with the conclusion from the DESI collaboration; at higher redshifts, the reconstructed $w(z)$ follows the CPL evolution and deviates only at low redshift. Additionally we also find reduction in $\Delta {\chi }_{\min }^2=-7.3$ compared to $\Lambda$CDM model.

    ↳ astro-ph.COgr-qchep-phhep-th4 citations
33. 33*

    Backwards Gamma-Ray Bursts: Searching for Exploding Primordial Black Holes in Short-Duration GRB Catalogs

    Stefano Profumo🇺🇸 · Kally Wen🇺🇸

    We present a systematic search for signatures of terminal black-hole evaporation in short gamma-ray burst (sGRB) catalogs. An exploding primordial black hole (PBH) undergoing final-stage Hawking radiation is predicted to produce a distinctive "backwards burst"-a very short, spectrally hard transient with monotonically increasing flux and little or no longer-wavelength afterglow. We develop a forward-modeling framework that directly compares theoretical PBH evaporation light curves, computed with full Standard Model particle content and detector response folding, against empirical GRB pulse templates. Analyzing 39 well-characterized Swift sGRBs with non-detected or extremely faint afterglows, we find that all events exhibit fast-rise, slow-decay temporal profiles inconsistent with the PBH prediction. Model comparison via Akaike and Bayesian information criteria decisively favors conventional FRED or ERCA fits over the PBH template for every burst. No candidates for terminal PBH evaporation are identified. The null result yields an upper bound on the local PBH explosion rate density $R_{\mathrm{PBH}}\lesssim 10^5{\mathrm{pc}}^{-3}{\mathrm{yr}}^{-1}$, comparable to constraints from dedicated TeV $\gamma$-ray searches. Our methodology establishes a robust template-matching approach that can be scaled to larger multi-instrument catalogs, providing a foundation for future searches targeting this unique signature of quantum gravity and early-Universe physics.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-ph+1JHEAp(2026)·0 citations
34. 34*

    Neutrino pair bremsstrahlung due to electromagnetic collisions in neutron star cores revisited

    P.S. Shternin🇷🇺

    We reconsider the problem of neutrino pair bremsstrahlung emission originating from the electromagnetic collisions of charged particles in nucleonic ($npe\mu$) neutron star cores. Two limiting cases are considered: (i) protons are in the normal state and (ii) protons are in the superconducting state. In both cases, the dominant contribution to the bremsstrahlung emissivity $Q_{\mathrm{Br}}^{\mathrm{em}}$ comes from the transverse part of in-medium electromagnetic interactions. For non-superconducting matter, we obtain an unusual $Q_{\mathrm{Br}}^{\mathrm{em}}\propto T^{23/3}$ temperature dependence due to the dynamical character of plasma screening in the transverse channel, but considerably smaller values of $Q_{\mathrm{Br}}^{\mathrm{em}}$ than in previous studies, rendering the considered process unimportant in practice. In contrast, for superconducting and superfluid matter, the neutrino emission processes involving nucleons are suppressed and $Q_{\mathrm{Br}}^{\mathrm{em}}$ due to lepton collisions provides the residual contribution to the neutrino emissivity of neutron star core matter. In the superconducting case, the plasma screening becomes static and the standard $Q_{\mathrm{Br}}^{\mathrm{em}}\propto T^8$ temperature scaling is restored. Simple analytical expressions for $Q_{\mathrm{Br}}^{\mathrm{em}}$ in both limiting cases are provided.

    ↳ astro-ph.HEhep-phParticles(2025)·2 citations
35. 35*

    The Strong-$CP$ Problem and its Gauge Axion solution as Evidence for Fundamental Strings

    Gia Dvali🇩🇪 · Lucy Komisel🇩🇪 · Otari Sakhelashvili🇦🇺 · Anja Wachowitz🇩🇪

    The topological susceptibility of the QCD vacuum provides an understanding of $\theta$-vacua as vacua of a Chern-Simons gauge theory. In this way, it gives an immediate proof of the physicality of the boundary $\theta$-term. This makes the essence of the strong-$CP$ puzzle very transparent and offers a solution in form of the gauge axion, which has exact quality. This axion represents an intrinsic part of the QCD gauge redundancy without any reference to an anomalous global symmetry. It is a two-form transforming under the QCD gauge symmetry. Due to its pure gauge nature, the gauge axion represents a powerful tool to monitor physics of $\theta$-vacua in various regimes. Unlike the ordinary Peccei-Quinn axion, which is UV-completed into a Goldstone phase of a complex scalar and thereby suffers from the quality problem, the gauge axion is UV-completed directly into a fundamental theory of gravity. We study the domain wall and string structure of the gauge axion and show that the strings sourcing it must be a part of this fundamental theory. We thus observe that the absence of the axion quality problem motivates the presence of fundamental strings. This provides a new argument for a connection between the axion and gravity.

    ↳ hep-thastro-ph.COhep-ph4 citations
36. 36*

    Asymptotic Behavior of Diagram Classes

    Luen Clingerman🇺🇸 · Matthew D. Schwartz🇺🇸

    The asymptotic nature of perturbative expansions in quantum field theory can arise from the factorial growth in the number of Feynman diagrams with loop order, as with instantons, or from a series of individual diagrams whose values grow factorially, as with renormalon chains in QED. Other classes of diagrams are known also to grow factorially, such as the Hopf series of graphs in ${\varphi }^3$ theory. This Hopf series was studied using Schwinger-Dyson equations and the Connes-Kreimer Hopf algebra of decorated rooted trees. We review the Hopf algebra approach and show that the same results can be obtained using analytic QFT techniques as with Hopf-algebraic ones. We present an efficient method to extract the asymptotic behavior and thereby generalize the analysis of the Hopf series to other classes of diagrams in other theories. We confront the question of whether these classes correspond to new types of asymptotic growth beyond instantons and renormalons, and find that they appear to be incomplete calculations of what would be renormalons in these theories if all diagrams were included. Although the Hopf algebra approach is not essential to deriving asymptotic behavior from Schwinger-Dyson equations, it does provide some other insights into quantum field theory. We therefore attempt also to provide a map between some relevant aspects of the Hopf algebra and quantum field theory.

    ↳ hep-thhep-phJHEP(2026)·3 citations

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