Tue·Apr 15, 2025Tuesday·April 15, 2025

1. 01*

   Using the Virasoro conditions to revise the model of a quark-gluon string fragmentation

   Roman Nikolaenko🇷🇺

   Quark-gluon string fragmentation is usually seen as a universal process with its physics remaining unchanged for different colliding systems and center-of-mass energy. However, there is a way to go beyond this assumption by considering the angular momentum of the fragmenting system. An accurate calculation of the spin of the string requires a specific definition of the initial state of the string. In this paper, I present a new method for defining the initial data for the Nambu-Goto relativistic string and derive the basics of its fragmentation process using the so-called Virasoro conditions. It is shown that very non-trivial consequences arise for non-zero mass strings, including the discrete spectrum of string spin, the discreteness of the possible string breaking points, the close-to-Regge behavior of the spin-mass relation for the light string fragments, and the natural stopping mechanism for fragmentation.

   hep-phJHEP(2025)·1 citation
2. 02*

   Femtoscopy for exotic hadrons and nuclei

   Tetsuo Hyodo🇯🇵

   In high energy collision experiments with multiple hadron productions, the momentum distribution of the measured hadron pair shows a correlation due to the final state hadron interactions and the quantum statistics. In the past, this femtoscopy technique has been developed to extract the information of the emission source from the momentum correlation functions. Recently, correlation function measurement is utilized also as a new method to determine the hadron interactions. In fact, the ALICE collaboration at LHC measures the correlation functions with various hadron pairs, for which the standard scattering experiment is difficult, providing remarkable progress in the study of the hadron interactions. In this contribution, we introduce the theoretical method to calculate the correlation functions, and present recent results on the study of the antikaon-nucleon interactions and hyperon-nucleus interactions.

   hep-phnucl-thPoS(2025)·2 citations
3. 03*

   Superheavy Metastable Strings in SO(10)

   Rinku Maji🇰🇷 · Qaisar Shafi🇺🇸

   The spontaneous breaking of $SO(10)$ grand unified symmetry to $SU(3{)}_c\times SU(2{)}_L\times U(1{)}_Y\times U(1{)}_{\chi }$ yields the GUT monopole as well as a comparably heavy $U(1{)}_{\chi }$ monopole which also carries $U(1{)}_Y$ flux. A metastable string scenario in this case requires that the $U(1{)}_{\chi }$ symmetry is necessarily broken close to the GUT scale, thus resulting in a dimensionless string tension $G\mu \sim 10^{-6}$. We show that the $\chi$ monopole does not carry any unconfined flux following the electroweak symmetry breaking. Coupled with $G\mu \sim 10^{-6}$, this metastable string network appears to provide a good fit to the recent Pulsar Timing Array data on the stochastic gravitational background. Gauge coupling unification, especially in the presence of low scale supersymmetry, determines the GUT scale and, in combination with constraints from proton decay experiments, one is able to constrain some of the key parameters in this setup. The breaking of $SO(10)$ via $SU(5)\times U(1{)}_{\chi }$ also yields superheavy metastable strings with no unconfined flux associated with the monopoles. Finally, we consider $SO(10)$ breaking via $SU(4{)}_c\times SU(2{)}_L\times U(1{)}_R$, $SU(3{)}_c\times SU(2{)}_L\times SU(2{)}_R\times U(1{)}_{B-L}$ and flipped $SU(5)$ that yield metastable strings where the associated monopoles carry unconfined flux after the electroweak breaking.

   hep-phastro-ph.COhep-thJHEP(2025)·16 citations
4. 04*

   The importance of being discrete

   Goran Senjanović🇮🇹

   Although continuous symmetries may be more appealing, especially the local gauge ones, I argue that discrete symmetries may still play a fundamental role in shaping our understanding of the physics beyond the Standard Model. I exemplify this on the case of left-right symmetry and recall how its spontaneous breaking leads naturally to new weak interactions, and even more interestingly, to neutrino mass and the seesaw mechanism behind its smallness. The minimal realization of this program is shown to be a self-contained theory of the origin and nature of neutrino mass, and of quark mixing angles. I also discuss some new results on the extension of the theory based on Pati-Salam quark-lepton symmetry, and its embedding in $SO(10)$ grand unified theory, where LR symmetry becomes gauged discrete transformation in the form of charge conjugation.

   hep-phhep-exPoS(2025)·1 citation
5. 05*

   Discovery of High-momentum Nucleon Correlations in Nuclei -- an Early History

   Leonid Frankfurt🇮🇱 · Mark Strikman🇺🇸

   We summarize the reasons for using the light-cone mechanics of nuclei for description of high-energy nuclear processes and describe the steps, which have led to the discovery of high-momentum correlations in nuclei.

   hep-phnucl-thActa Phys.Polon.B(2025)·0 citations
6. 06*

   Extracting Meson Distribution Amplitudes from Nonlocal Euclidean Correlations at Next-to-Next-to-Leading Order

   Yao Ji🇩🇪 · Fei Yao🇺🇸 · Jian-Hui Zhang🇨🇳

   We present the first complete result for the next-to-next-to-leading order (NNLO) hard matching kernel indispensable for a precision extraction of light meson distribution amplitudes from lattice calculations of equal-time nonlocal Euclidean correlation functions. The results are given in both coordinate and momentum space, with the renormalization and matching accomplished in a state-of-the-art scheme. Our results can be used in both large-momentum effective theory and short-distance factorization approaches. Notably, our coordinate space kernel is directly applicable to nonsinglet quark unpolarized and helicity generalized parton distributions as well. We also illustrate the numerical impact of the NNLO matching, using the pion distribution amplitude as an example.

   hep-phhep-latnucl-exnucl-th7 citations
7. 07*

   Prompt and non-prompt production of charm hadrons in proton-proton collisions at the Large Hadron Collider using machine learning

   Raghunath Sahoo🇮🇳 · Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Kangkan Goswami🇮🇳 · Gagan B. Mohanty🇮🇳

   In this contribution, we use machine learning (ML) based models to separate the prompt and non-prompt production of heavy flavour hadrons, such as $D^0$ and J/$\psi$, in proton-proton collisions at LHC energies. For this purpose, we use PYTHIA~8 to generate events, which provides a good qualitative agreement with experimental measurements of charm hadron production. The input features for the ML models are experimentally measurable. The prediction accuracy of the ML models used in this study reaches up to 99\%. The ML models can be useful in providing precise track-level identification, which is not possible in experiments with traditional methods. The contribution also discusses future applications of the ML models to understand the production of prompt and non-prompt heavy quark hadrons.

   hep-phhep-exhep-thnucl-ex+1J.Subatomic Part.Cosmol.(2025)·0 citations
8. 08*

   Probing Millicharged Dark Matter with Magnetometer Coupled to Circuit

   Yuanlin Gong🇨🇳 · Hongliang Tian🇨🇳 · Lei Wu🇨🇳 · Bin Zhu🇨🇳

   We present a novel approach to detect millicharged dark matter (mDM) by using a high-sensitivity magnetometer coupled with the resonant and broadband readout circuits. In the external magnetic field, the interaction between mDM and the photon field introduces an effective current corresponding to the mDMs annihilation into photons that produces a faint oscillating magnetic field signal, with a frequency uniquely determined by twice the mDM mass. By calculating the expected signal for two experimental configurations -- toroidal and solenoidal magnetic fields -- we show the potential to explore the uncharted regions of mDM parameter space. Our analysis establishes unprecedented constraints on the mDM coupling constant across the mass range $1\times 10^{-12}\mathrm{eV}$ to $6\times 10^{-8}\mathrm{eV}$, surpassing existing experimental limits by more than ten orders of magnitude.

   hep-phSCPMA(2025)·3 citations
9. 09*

   Multicomponent Dark Matter with Collider Implications

   Laura Covi🇩🇪 · Shyamashish Dey🇮🇳 · Sarif Khan🇰🇷 · Santosh Kumar Rai🇮🇳

   The present work aims to study an extension of the Standard Model (SM) that addresses the prominent SM shortcomings, i.e., can explain the neutrino mass, the dark matter (DM) content, and the matter-antimatter asymmetry of the Universe. The model introduces the possibility of a multicomponent DM scenario leading to distinctive signals at colliders. The SM is extended by a ``dark" $SU(2{)}_D$ gauge symmetry and new fermions and scalar doublets, charged only under $SU(2{)}_D$, that provide candidates for a multicomponent DM. Previously, we have considered in this model the asymmetric DM scenario, while in the present work, we explore the symmetric DM case. We focus on the parameter region where the dark fermion DM annihilates dominantly into the additional dark gauge bosons and the ``inert" doublet DM annihilates to SM states via the SM Higgs resonance. This particular choice of doublet mass ensures that the heavier BSM Higgs always has one decay mode open to DM leading to the possibility of detecting such particles at the LHC, in the missing energy plus dijet (${\cancel{E}}_T+2j$) final states. We also discuss the prospects for detecting DM through direct and indirect detection experiments and via Long-Lived-Particle searches. Finally, we show that, as typical of other WIMP models, for low DM mass, signals can be expected in future collider experiments, but for the higher mass range above $500$ GeV we have to rely solely on direct detection experiments. Both types of experiments will be essential to fully cover the allowed parameter space.

   hep-phJHEP(2025)·4 citations
10. 10*

    Deciphering the viscous properties and the Bjorken expansion of the QGP medium at finite angular velocity

    Shubhalaxmi Rath🇮🇷 · Nicolás A. Neill🇨🇱

    We have studied the viscous properties as well as the Bjorken expansion of a rotating QGP medium. In the noncentral events of heavy-ion collisions, the produced medium can carry a finite angular momentum with a finite range of angular velocity. This rotation can significantly affect various properties, including viscous properties and the expansion of the QGP medium. Using a novel relaxation time approximation for the collision integral in the relativistic Boltzmann transport equation at finite angular velocity, we have calculated the shear and bulk viscosities and compared them with their counterparts in the standard relaxation time approximation within the kinetic theory approach. Our results show that the angular velocity increases both shear and bulk viscosities, suggesting an enhanced momentum transfer within the medium and greater fluctuations in local pressure. This rotational effect on viscosities is more evident at lower temperatures than at higher temperatures. Our analysis also shows that, compared to the standard relaxation time approximation, the shear viscosity is lower while the bulk viscosity is higher in the novel relaxation time approximation for all temperatures. Additionally, some observables related to the flow characteristic, fluid behavior and conformal symmetry of the medium are markedly impacted due to rotation. We have also studied the hydrodynamic evolution of matter within the Bjorken boost-invariant scenario and have found that the energy density evolves faster in the presence of finite rotation than in the nonrotating case. Consequently, rapid rotation accelerates the cooling process of the QGP medium.

    hep-phhep-thnucl-thPRD(2025)·1 citation
11. 11*

    Understanding baryon stopping at the BNL Relativistic Heavy Ion Collider top energies

    Niseem Magdy🇺🇸 · Prithwish Tribedy🇺🇸 · Chun Yuen Tsang🇺🇸 · Zhangbu Xu🇺🇸

    The nucleon exhibits a rich internal structure governed by Quantum Chromodynamics (QCD), where its electric charge arises from valence quarks, while its spin and mass emerge from complex interactions among valence quarks, sea (anti-)quarks, and gluons. At the advent of QCD, an alternative hypothesis emerged suggesting, at high energies, the transport of a nucleon's baryon number could be traced by a non-perturbative configuration of gluon fields connecting its three valence quarks, forming a $Y$-shaped topology known as the gluon junction. Recent measurements by the STAR experiment are compatible with this scenario. In light of these measurements, this study aims to explore the mechanisms of baryon transport in high-energy nuclear collisions using the PYTHIA-8 framework, which incorporates a state-of-the-art hadronization model with advanced Color Flow (CF) and Color Reconnection (CR) mechanisms that mimic signatures of a baryon junction. Within this model setup, we investigate (i) the rapidity slope of the net-baryon distributions in photon-included processes ($\gamma$+p) and (ii) baryon over charge transport in the isobaric (Ru+Ru and Zr+Zr) collisions. Our study highlights the importance of the CF and CR mechanisms in PYTHIA-8, which play a crucial role in baryon transport. The results show that the CF and CR schemes significantly affect the isobaric baryon-to-charge ratio, leading to different predictions for baryon stopping and underscoring the need to account for CF and CR effects in comparisons with experimental measurements.

    hep-phnucl-exnucl-thPRC(2025)·4 citations
12. 12*

    Quantum Entanglement between gauge boson pairs at a Muon Collider

    Ran Ding🇨🇳 · Alim Ruzi🇨🇳 · Sitian Qian🇨🇳 · Andrew Levin🇨🇳 · Youpeng Wu🇨🇳 · Qiang Li🇨🇳

    Quantum entanglement is one of significant physics phenomena that can be examined at a particle collider. A muon collider can provide a stage on which we can study substantial physics phenomenon, starting from the precision measurements of the Standard Model and beyond to the undiscovered area of physics. In this work, we present a through study of quantum entanglement in ${\mu }^{+}{\mu }^{-}\to ZZ$ events at a future muon collider. By fixing the spin density matrix, observables quantifying entanglement between $Z$ boson pairs can be measured. After systematic Monte-Carlo simulation and background analysis, we measure the value of entanglement variables and perform hypothesis testing against the non-entangled hypothesis, finally observing the entanglement of the $ZZ$ system up to $2$ significance level.

    hep-ph23 citations
13. 13*

    Revisiting the deuteron mass radius via near-threshold ${\rho }^0$, $\omega$ and $\varphi$ meson photoproduction

    Xiaoxuan Lin🇨🇳 · Wei Kou🇨🇳 · Shixin Fu🇨🇳 · Rong Wang🇨🇳 · Chengdong Han🇨🇳 · Xurong Chen🇨🇳

    We present a comprehensive analysis of near-threshold photoproduction of ${\rho }^0$, $\omega$, and $\varphi$ mesons on a deuterium target, utilizing published datasets from DESY and SLAC for ${\rho }^0$ and $\omega$ production, as well as data from the LEPS and CLAS Collaborations for $\varphi$ production. In extracting the deuteron mass radius, we adopt a dipole parametrization for the scalar gravitational form factor, which effectively captures the $|t|$-dependence of the differential cross sections associated with vector meson photoproduction. In addition, results from alternative commonly used form factor parametrizations are also considered and compared. Employing the vector meson dominance (VMD) framework and invoking low-energy Quantum Chromodynamics (QCD) theorems, we extract the deuteron mass radius from near-threshold photoproduction data of ${\rho }^0$, $\omega$, and $\varphi$ mesons. The mass radii obtained from the various datasets are found to be consistent within statistical uncertainties, yielding an average value of $2.03\pm 0.13$ fm under the dipole form assumption. We also provide a detailed discussion of the sensitivity of the extracted radius to different choices of gravitational form factor models. Our result represents a significant improvement in precision compared to earlier estimates based solely on $\varphi$ meson photoproduction, offering new constraints for theoretical models of nuclear structure and deepening our understanding of the mass distribution within the deuteron.

    hep-phnucl-exnucl-thCPC(2025)·1 citation
14. 14*

    Axion-like Dark Matter Search with Space-based Gravitational Wave Detectors

    Run-Min Yao🇨🇳 · Xiao-Jun Bi🇨🇳 · Peng-Fei Yin🇨🇳 · Qing-Guo Huang🇨🇳

    We propose a novel modification to the optical benches of space-based gravitational wave detectors (SGWDs) to enable the detection of axion-like dark matter (ALDM)-induced birefringence without altering the polarization of inter-spacecraft laser links. Our design introduces an auxiliary interferometer to convert polarization modulation into measurable phase shifts. Analytical expressions for sensitivity to the ALDM-photon coupling are derived for various time-delay interferometry (TDI) combinations. Projected sensitivity curves demonstrate complementary coverage across the ALDM mass range $10^{-19}\sim 10^{-14}\mathrm{eV}$. This approach preserves the original interferometric stability while enabling new physics capabilities for SGWDs.

    hep-phastro-ph.COgr-qcJCAP(2026)·10 citations
15. 15*

    Automated next-to-leading order QCD and electroweak predictions of photon-photon processes in ultraperipheral collisions

    Hua-Sheng Shao🇫🇷 · Lukas Simon🇫🇷

    We present automated next-to-leading order QCD and/or electroweak (EW) predictions for photon-photon processes in ultraperipheral high-energy collisions of protons and ions, extending the capabilities of the MadGraph5_aMC@NLO framework together in combination with the gamma-UPC code. Key aspects of this extension are discussed. We compute QCD and/or EW quantum corrections for several phenomenologically interesting processes at LHC and FCC-hh energies.

    hep-phhep-exnucl-exnucl-thJHEP(2025)·9 citations
16. 16*

    Strong decays of singly heavy baryons

    Xiaoning Xie🇨🇳 · Juntao Tong🇨🇳 · Qi Huang🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

    More and more excited baryons have been reported experimentally, but many properties are still unclear. This work attempts to simultaneously study the masses and strong decay widths of some singly heavy baryons, in order to provide possible quantum numbers for these states. The chiral quark model and the ${}^3{P}_0$ decay model are employed to calculate the masses and decay widths of ${\Lambda }_{c(b)}$ and ${\Sigma }_{c(b)}$ baryons for all quantum numbers with $2S$, $1P$, and $2P$ waves. We considered not only two-body strong decays but also the influence of three-body decays. Our calculations show that: (i) For states with experimentally determined quantum numbers, such as ${\Lambda }_c(2595)$, ${\Lambda }_c(2625)$, ${\Lambda }_b(5912)$ and ${\Lambda }_b(5920)$, the results are consistent with experimental data and the conclusions of most theoretical studies. (ii) For states whose quantum numbers have not yet been fully determined experimentally, we provide possible interpretations. For example, our calculations tend to interpret ${\Lambda }_c(2910)$ is interpreted as a $J^P={\frac{3}{2}}^{-}$ state with 1P-wave $\rho$-mode or a $J^P={\frac{1}{2}}^{-}$ state with 2P wave $\lambda$-mode. ${\Lambda }_c(2940)$ can be interpreted as the $J^P={\frac{3}{2}}^{-}$ state with 2P-wave $\lambda$-mode. For ${\Lambda }_c(2860)$, we offer a different interpretation, proposing that its mass and width closely match those of a 2P-wave $J^P={\frac{1}{2}}^{-}$ state. It is hoped that our calculations can provide valuable information for the experimental and theoretical studies of heavy baryons.

    hep-phhep-exhep-th3 citations
17. 17*

    Multipole Moments of Double Heavy $J^P={\frac{3}{2}}^{+}$ Baryons

    T.M Aliev🇹🇷 · E. Askan🇹🇷 · A. Ozpineci🇹🇷

    In the present study, we calculate the multipole moments of spin-3/2 doubly heavy baryons within the light cone QCD sum rules. We compare our results on magnetic dipole moments with results existing in the literature. The results obtained in the present work may be useful for a deeper understanding of the properties of doubly heavy baryons as well as in the analysis of their strong and electromagnetic decays.

    hep-phEPJC(2025)·1 citation
18. 18*

    A parton shower consistent with parton densities at LO and NLO: PDF2ISR

    H. Jung🇩🇪 · L. Lönnblad🇸🇪 · M. Mendizabal🇩🇪 · S. Taheri Monfared🇩🇪

    We present a method for obtaining an initial-state parton shower model where the (backward) evolution fully consistent with the (forward) evolution of the collinear parton density used. As a proof-of-concept we use parton densities obtained with the Parton Branching (PB) approach, and modify the default initial-state shower in PYTHIA8 with this method to be consistent with them. PB is ideally suited for checking the validity of our method since, in addition to producing collinear parton densities, it also produces the corresponding transverse-dependent (TMD) ones, and these can then be directly compared to the transverse momentum distribution obtained from the parton shower. We show that TMD distributions which we in this way obtain from our modified PYTHIA8 shower using leading order (LO) parton densities and splitting functions are fully consistent with the corresponding leading order TMD densities. At next-to-leading order (NLO) it is not possible to achieve the same consistency using the built-in LO splitting functions in the shower, but we show that by introducing NLO splitting functions using a reweighting procedure, we can achieve consistency also at NLO. The method presented here, which we have named PDF2ISR, can be easily extended to any collinear parton densities, as long as the exact conditions for the evolution are known. With the PDF2ISR method we obtain an initial-state parton shower which in principle has no free parameters, and is fully consistent with collinear parton densities at LO and NLO.

    hep-phhep-exhep-thEPJC(2025)·7 citations
19. 19*

    Investigating two-zero texture in the light of gauged Type-II seesaw

    Anirban Biswas🇮🇳 · Shilpa Jangid🇰🇷 · Seong Chan Park🇰🇷

    Neutrino oscillation, discovered over two decades ago, confirmed that neutrinos have nonzero masses. Since then, two mass-squared differences have been measured with unprecedented precision, yet the absolute neutrino mass scale remains unknown. Additionally, the fundamental symmetry governing the neutrino mixing pattern is still undetermined. Among various theoretical possibilities, the two-zero texture in the neutrino mass matrix ($m_{\nu }$) stands out as an attractive framework due to its reduced number of free parameters, enabling definite predictions for the unknown parameters of the PMNS matrix. In this work, we present a comprehensive analysis of the two-zero texture, focusing on its implications for the Dirac CP phase ($\delta$), the Majorana phases ($\rho$, $\sigma$) and the effective Majorana mass ($m_{\beta \beta }$), the latter being crucial for neutrinoless double beta decay. We find that for certain two-zero textures, $m_{\beta \beta }$ reaches a few tens of meV, placing it within the sensitivity range of KamLAND-Zen. Furthermore, we demonstrate how a two-zero texture can naturally emerge in a well-motivated neutrino mass model, specifically the gauged Type-II seesaw mechanism, which requires multiple scalar triplets. Notably, some of the two-zero patterns cannot be realized in this framework, as more than two independent zeros appear in $m_{\nu }$. Finally, we discuss key phenomenological consequences of the gauged Type-II seesaw model.

    hep-phPLB(2025)·3 citations
20. 20*

    Probing the Sivers Asymmetry with Transverse Energy-Energy Correlators in the Small-$x$ Regime

    Shohini Bhattacharya🇺🇸 · Zhong-Bo Kang🇺🇸 · Diego Padilla🇺🇸 · Jani Penttala🇺🇸

    We investigate transverse energy-energy correlators (TEECs) for both polarized and unpolarized targets in the small-$x$ regime at the Electron-Ion Collider (EIC). Focusing on the approximately back-to-back electroproduction of a hadron-electron pair, we apply transverse-momentum-dependent (TMD) factorization formulas that incorporate TMD evolution for both event-shape observables and expand them in terms of the small-$x$ dipole amplitude. This allows us to write the TEEC off the transversely polarized proton in terms of a C-odd interaction, corresponding to an odderon exchange. Due to the charge-conjugation-odd nature of the small-$x$ quark Sivers function, we restrict the sum over final hadronic states to positively and negatively charged hadrons separately. We present numerical predictions for the TEEC Sivers asymmetry at the EIC and find the magnitude of the asymmetry to be on the $0.01\%$ level. This channel offers a promising avenue for benchmarking the still largely unconstrained odderon amplitude.

    hep-phhep-exnucl-th17 citations
21. 21*

    Probing Long-Range Forces in Neutrino Oscillations at the ESSnuSB Experiment

    ESSnuSB: J. Aguilar🇪🇸 · M. Anastasopoulos🇸🇪 · D. Barčot🇭🇷 · E. Baussan🇫🇷 · A. K. Bhattacharyya🇸🇪 · A. Bignami🇸🇪 · M. Blennow🇸🇪 · M. Bogomilov🇧🇬 · B. Bolling🇸🇪 · E. Bouquerel🇫🇷 · F. Bramati🇮🇹 · A. Branca🇮🇹 and 86 other authors

    Neutrino oscillations constitute an excellent tool to probe physics beyond the Standard Model. In this paper, we investigate the potential of the ESSnuSB experiment to constrain the effects of flavour-dependent long-range forces (LRFs) in neutrino oscillations, which may arise due to the extension of the Standard Model gauge group by introducing new $U(1)$ symmetries. Focusing on three specific $U(1)$ symmetries -- $L_e-L_{\mu }$, $L_e-L_{\tau }$, and $L_{\mu }-L_{\tau }$, we demonstrate that ESSnuSB offers a favourable environment to search for LRF effects. Our analyses reveal that ESSnuSB can set $90\%$ confidence level bounds of $V_{e\mu }<2.99\times 10^{-14}\text{eV}$, $V_{e\tau }<2.05\times 10^{-14}\text{eV}$, and $V_{\mu \tau }<1.81\times 10^{-14}\text{eV}$, which are competitive to the upcoming Deep Underground Neutrino Experiment (DUNE). It is also observed that reducing the systematic uncertainties from $5\%$ to $2\%$ improves the ESSnuSB limits on $V_{\alpha \beta }$. Interestingly, we find limited correlations between LRF parameters and the less constrained lepton mixing parameters ${\theta }_{23}$ and ${\delta }_{\text{CP}}$, preserving the robustness of ESSnuSB's sensitivity to CP violation. Even under extreme LRF potentials ($V_{\alpha \beta }\gg 10^{-13}\text{eV}$), the CP-violation sensitivity and ${\delta }_{\text{CP}}$ precision remain largely unaffected. These results establish ESSnuSB as a competitive experimental setup for probing LRF effects, complementing constraints from other neutrino sources and offering critical insights into the physics of long-range forces.

    hep-phhep-exJHEP(2025)·6 citations
22. 22*

    Independent connection in ACTion during inflation

    Alberto Salvio🇮🇹

    The Atacama Cosmology Telescope (ACT) has recently released new measurements and constraints on inflationary observables. In this paper it is shown that a component of a dynamical affine connection, which is independent of the metric, can easily drive inflation in agreement with these observations. Such geometrical explanation of inflation is analysed in detail here in the minimal model, including the predictions for the scalar spectral index $n_s$ and its running ${\alpha }_s$, the amplitude of the scalar perturbations and the tensor-to-scalar ratio $r$. Furthermore, this minimal model is shown to provide an inflationary attractor: arbitrary initial values of the kinetic energy density are dynamically attracted down to negligible values compared to the potential energy density in homogeneous and isotropic metrics. Also, the role of the Higgs boson during and after inflation is briefly discussed.

    hep-phastro-ph.COgr-qchep-thPRD(2025)·68 citations
23. 23*

    Exploring the effects of $\alpha$-clustered structure of ${}^{16}O$ nuclei in anisotropic flow fluctuations in ${}^{16}O$-${}^{16}O$ collisions at the LHC within a CGC+Hydro framework

    Suraj Prasad🇮🇳 · Neelkamal Mallick🇮🇳 · Raghunath Sahoo🇮🇳 · Gergely Gabor Barnafoldi🇭🇺

    In this paper, we explore the effects of the presence of clustered nuclear structure of ${}^{16}O$ in the final state elliptic flow fluctuations through ${}^{16}O$-${}^{16}O$ collisions at $\sqrt{s_{\mathrm{NN}}}=7$ TeV within a hybrid model, IPGlasma+MUSIC+iSS+ UrQMD. We compare the results of elliptic flow fluctuations using $\alpha$-clustered nuclear structure to the Woods-Saxon nuclear profile having no clustered structure. We observe a significant difference in the elliptic flow fluctuations, which arise due to the consideration of a clustered nuclear structure of ${}^{16}O$.

    hep-phhep-exnucl-exnucl-thJ.Subatomic Part.Cosmol.(2026)·0 citations
24. 24*

    Beyond Poincaré Stresses: A Modern Quantum Field Theory Take on Hydrogen's Electromagnetic Mass

    Qasem Exirifard🇨🇦 · Alessio D'Errico🇨🇦 · Ebrahim Karimi🇨🇦

    We revisit the longstanding electromagnetic mass problem from a modern quantum field theory perspective. Focusing on a system of two widely separated hydrogen atoms, one in an excited $nS$ state and the other in the ground $1S$ state, we isolate the electromagnetic contribution to the electron's total linear momentum by comparing the full energy-momentum tensor with the predictions of a point-like bound state model. Our analysis reveals that the leading perturbative correction introduces a factor $4/3$, which, along with subsequent corrections, indicates that the effective electromagnetic mass deviates from the conventional relation $E/c^2$. This discrepancy is attributed to the intrinsic nonlocality of the electromagnetic field, rather than to additional compensating mechanisms such as Poincaré stresses. We further contrast our quantum field theory results with the highly accurate predictions of the Schrödinger equation, which, despite neglecting higher-order terms, achieves an average error on the order of $10^{-5}\%$. Attempts to improve this accuracy via perturbative inclusion of the self-interaction of the electron's wave function instead increase the error, prompting a re-examination of the underlying perturbative assumptions. Our findings suggest that a non-perturbative treatment of the tree-level action may be required to fully capture the dynamics of bound states in quantum field theory.

    hep-phhep-thnucl-thquant-ph0 citations
25. 25*

    RVV$\times$V: Interference contributions to inclusive Higgs boson and Drell-Yan production at N${}^4$LO in QCD

    Bernhard Mistlberger🇺🇸 · Adi Suresh🇺🇸

    We present partonic contributions to the inclusive gluon-fusion Higgs boson and Drell-Yan production cross sections at Hadron colliders at next-to-next-to-next-to-next-to leading order (N${}^4$LO). Specifically, we compute contributions due to the interference of one-loop amplitudes with two-loop amplitudes with three QCD partons and the Higgs boson or a virtual photon. Our result is in the form of a Laurent expansion in the dimensional regulator $ϵ$, the coefficients of which are analytic functions in the ratio of the Higgs boson or virtual photon mass to the partonic center of mass energy. Furthermore, we introduce and deploy a new package implemented in Mathematica, CIFAR ("Color Invariant Feynman Amplitude Reducer"), to express color factors in terms of general Casimir invariants of simple compact Lie algebras.

    hep-phhep-thJHEP(2025)·4 citations
26. 26*

    Cosmogenic neutrinos as probes of new physics

    Luighi P. S. Leal🇧🇷 · Daniel Naredo-Tuero🇪🇸 · Renata Zukanovich Funchal🇧🇷

    The scattering of extremely energetic cosmic rays with both cosmic microwave background and extragalactic background light, can produce $\mathcal{O}(10^{18}\mathrm{eV})$ neutrinos, known as cosmogenic neutrinos. These neutrinos are the only messengers from the extreme cosmic accelerators that can reveal the origin of the most energetic cosmic rays. Consequently, much effort is being devoted to achieving their detection. In particular, the GRAND project aims to observe the ${\nu }_{\tau }$ and ${\bar{\nu }}_{\tau }$ components of the cosmogenic neutrino flux in the near future using radio antennas. In this work, we investigate how the detection of cosmogenic neutrinos by GRAND can be used to probe beyond the Standard Model physics. We identify three well-motivated scenarios which induce distinct features in the cosmogenic neutrino spectrum at Earth: neutrino self-interactions mediated by a light scalar ($\nu$SI), pseudo-Dirac neutrinos (PD$\nu$) and neutrinos scattering on ultra-light Dark Matter ($\nu$DM). We show these scenarios can be tested by GRAND, using 10 years of cosmogenic neutrino data, in a region of parameter space complementary to current experiments. For the $\nu$SI model,, we find that GRAND can constrain the coupling to ${\nu }_{\tau }$ in the range [$10^{-2},10^{-1}$] for a scalar with mass in the range 0.1 to 1 GeV. For PD$\nu$, we find that GRAND is sensitive to sterile-active mass squared splitting in the range [$10^{-15},10^{-13}$] ${\mathrm{eV}}^2$. Finally, for the $\nu$DM model, assuming a heavy mediator, GRAND can do substantially better than the current limits from other available data. These results rely on the fact that the actual cosmogenic flux is around the corner, not far from the current IceCube limit.

    hep-phastro-ph.HEJHEP(2025)·10 citations
27. 27*

    Hadronic light-by-light scattering in the anomalous magnetic moments of electron and $\tau$

    Martin Hoferichter🇨🇭 · Peter Stoffer🇨🇭 · Maximilian Zillinger🇨🇭

    In Refs. [1,2] we provided a complete dispersive evaluation of the hadronic light-by-light (HLbL) contribution to the anomalous magnetic moment of the muon. While the evaluation strategy was developed for the kinematic situation determined by the muon mass, a similar approach also applies to the HLbL corrections to the anomalous magnetic moments of the electron and $\tau$ lepton, shifting the sensitivity in the loop integrals to smaller and larger momenta, respectively. In this Letter, we propagate the corresponding uncertainties of the various contributions, obtaining $a_e^{\text{HLbL}}=3.51(23)\times 10^{-14}$ and $a_{\tau }^{\text{HLbL}}=3.77(29)\times 10^{-8}$.

    hep-phhep-exhep-latnucl-thPLB(2025)·19 citations
28. 28*

    Dark matter phase-in: producing feebly-interacting particles after a first-order phase transition

    Cristina Benso🇩🇪 · Felix Kahlhoefer🇩🇪 · Henda Mansour🇩🇪

    The freeze-in mechanism describes the out-of-equilibrium production of dark matter (DM) particles via feeble couplings or non-renormalisable interactions with large suppression scales. In the latter case, predictions suffer from a strong sensitivity to the initial conditions of the universe, such as the details of reheating. In this work, we investigate how this sensitivity is altered in the presence of a cosmological first-order phase transition. We show that freeze-in via non-renormalisable interactions is not always dominated by the highest temperatures of the Standard Model (SM) thermal bath, but instead may be governed by the period immediately after the phase transition, during which the decaying scalar field transfers its energy density to the SM radiation. We refer to this alternative production regime as DM $\text{phase-in}$. Using numerical and approximate analytical solutions of the relevant Boltzmann equations, we determine the conditions that under which phase-in or conventional freeze-in production dominates the final DM abundance in terms of the type of interaction between the DM and SM particles, the amount of supercooling before and the evolution of the scalar field after the phase transition. In the phase-in regime, the DM abundance is correlated with the peak frequency of the gravitational wave signal associated with the phase transition, opening up new observational possibilities.

    hep-phastro-ph.COJHEP(2025)·9 citations
29. 29*

    t-channel dark matter at the LHC -- a whitepaper

    Chiara Arina · Benjamin Fuks · Luca Panizzi · Michael J. Baker · Alan S. Cornell · Jan Heisig · Benedikt Maier · Rute Pedro · Dominique Trischuk · Diyar Agin · Alexandre Arbey · Giorgio Arcadi and 58 other authors

    This report, summarising work achieved in the context of the LHC Dark Matter Working Group, investigates the phenomenology of $t$-channel dark matter models, spanning minimal setups with a single dark matter candidate and mediator to more complex constructions closer to UV-complete models. For each considered class of models, we examine collider, cosmological and astrophysical implications. In addition, we explore scenarios with either promptly decaying or long-lived particles, as well as featuring diverse dark matter production mechanisms in the early universe. By providing a unified analysis framework, numerical tools and guidelines, this work aims to support future experimental and theoretical efforts in exploring $t$-channel dark matter models at colliders and in cosmology.

    hep-phastro-ph.COhep-exEPJC(2025)·19 citations
30. 30*

    [C II]-deficit caused by self-absorption in an ionized carbon-filled bubble in RCW79

    Eduard Keilmann🇩🇪 · Simon Dannhauer🇩🇪 · Slawa Kabanovic🇩🇪 · Nicola Schneider🇩🇪 · Volker Ossenkopf-Okada🇩🇪 · Robert Simon🇩🇪 · Lars Bonne🇺🇸 · Paul F. Goldsmith🇺🇸 · Rolf Güsten🇩🇪 · Annie Zavagno🇫🇷 · Jürgen Stutzki🇩🇪 · Dominik Riechers🇩🇪 and 3 other authors

    Recent spectroscopic observations of the [C II] 158$\mu \mathrm{m}$ fine-structure line of ionized carbon (C${}^{+}$), using the Stratospheric Observatory for Infrared Astronomy (SOFIA), have revealed expanding [C II] shells in Galactic H II regions. We report the discovery of a bubble-shaped source (S144 in RCW79), associated with a compact H II region, excited by a single O7.5--9.5V/III star, which is consistent with a scenario that the bubble is still mostly ``filled'' with C${}^{+}$. This indicates most likely a very early evolutionary state, in which the stellar wind has not yet blown material away, as it is the case for more evolved H II regions. Using the SimLine non-LTE radiative transfer code, the [C II] emission can be modeled to originate from three regions. First, a central H II region with little C${}^{+}$ in the fully ionized phase, followed by two layers with gas density around $2500\mathrm{c}{\mathrm{m}}^{-3}$ of partially photo-dissociated gas. The second layer is a slowly expanding [C II] shell with an expansion velocity of $\sim$$2.6\mathrm{km}{\mathrm{s}}^{-1}$. The outermost layer exhibits a temperature and velocity gradient that produces the observed self-absorption features in the optically thick [C II] line ($\tau \sim 4$) leading to an apparent deficit in [C II] emission and a low ratio of [C II] to total far-infrared (FIR) emission. We developed a procedure to approximate the missing [C II] flux and find a linear correlation between [C II] and FIR without a [C II]-deficit. This demonstrates that at least some of the [C II]-deficit found in Galactic H II bubbles can be attributed to self-absorption.

    ↳ astro-ph.GAastro-ph.HEastro-ph.IMhep-phAstron.Astrophys.(2025)·0 citations
31. 31*

    Comparison of dark energy models using late-universe observations

    Peng-Ju Wu🇨🇳

    In the framework of general relativity, dark energy was proposed to explain the cosmic acceleration. A pivotal inquiry in cosmology is to determine whether dark energy is the cosmological constant, and if not, the challenge lies in constraining how it evolves with time. In this paper, we utilize the latest observational data to constrain some typical dark energy models, and make a comparison for them according to their capabilities of fitting the current data. Our study is confined to late-universe observations, including the baryon acoustic oscillation, type Ia supernova, cosmic chronometer, and strong gravitational lensing time delay data. We employ the Akaike information criterion (AIC), deviance information criterion (DIC), and Bayesian information criterion (BIC) to assess the worth of models. The AIC and DIC analyses indicate that all dark energy models outperform the $\Lambda$CDM model. However, the BIC analysis leaves room for $\Lambda$CDM due to its heavier penalty on the model complexity. Compared to $\Lambda$CDM, most dark energy models are robustly supported by AIC and DIC while being explicitly disfavored by BIC. The models that are robustly favored by AIC and DIC and not explicitly disfavored by BIC include the $w$CDM, interacting dark energy, and Ricci dark energy models. Furthermore, we observe that an alternative modified gravity model exhibits superior performance when compared with $\Lambda$CDM across all information criteria.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·36 citations
32. 32*

    Quasinormal modes of spherically symmetric black hole with cosmological constant and global monopole in bumblebee gravity

    Yenshembam Priyobarta Singh🇮🇳 · Irengbam Roshila Devi🇮🇳 · Telem Ibungochouba Singh🇮🇳

    This paper studies the scalar, electromagnetic field and Dirac field perturbations of spherically symmetric black hole within the framework of Einstein-bumblebee gravity model with global monopole and cosmological constant. We investigate the effective potentials, greybody factors and quasinormal modes (QNMs) by applying the Klein-Gordon equation, electromagnetic field equation and Dirac equation expressed in Newman-Penrose (NP) formalism. Using the general method of rigorous bound, the greybody factors of scalar, electromagnetic and Dirac field are derived. Applying the sixth order WKB approximation and Padé approximation, the QNM frequencies are derived. We also discuss the impact of global monopole $\eta$, cosmological constant $\Lambda$ and Lorentz violation parameter $L$ to the effective potential, greybody factor and QNMs. Increasing the parameter $\eta$ prevents the rise of effective potential for both Schwarzschild-de Sitter (SdS)-like and Schwarzschild-Anti de Sitter (SAdS)-like black holes with global monopole and consequently increases the greybody factors. However, decreasing the parameter $L$ reduces the rise of effective potential for the SAdS-like black hole with global monopole and it increases the greybody factor but increasing the parameter $L$ has an opposite effect for SdS-like black hole with global monopole. It is also shown that the shadow radius increases with increasing the parameter $\eta$ for both dS and AdS cases. Increasing the value of $L$ tends to increase the shadow radius for dS black hole but it has an opposite effect in AdS case. A careful studying is being carried out to investigate how the absorption cross-section gets affected when the parameter $L$ appears into the picture.

    ↳ gr-qchep-phNPB(2025)·15 citations
33. 33*

    Glueball mass spectrum at finite temperature revisited: Constant contribution in glueball correlators in the deconfinement phase

    Toshizo Arikawa🇯🇵 · Keita Sakai🇯🇵 · Shoichi Sasaki🇯🇵

    We study the glueball properties at finite temperature from the temporal correlation in $SU(3)$ Yang-Mills theory using anisotropic lattice QCD. Although the existence of a constant contribution to the meson correlation function appearing in the deconfinement phase is known, its effect on the glueball correlation function at finite temperature has not been considered in previous studies. The present study reveals that the constant contribution to the glueball correlation function actually occurs in the three lowest-lying glueball states, corresponding to the $0^{++}$, $2^{++}$, and $0^{-+}$ glueballs, from near the critical temperature of the deconfinement phase transition $T_C$ to the high temperature side. If the existence of constant terms is taken into account in the standard pole-mass analysis, it is observed that the pole-mass of the glueball ground state remains unchanged below $T_c$ and then increases with temperature above $T_C$. The result indicates that the true temperature dependence of the glueball mass above $T_C$ is opposite to the results of the previous studies.

    ↳ hep-lathep-phPRD(2025)·6 citations
34. 34*

    Constraints on the simultaneous variation of the fine structure constant and electron mass in light of DESI BAO data

    Yo Toda🇯🇵 · Osamu Seto🇯🇵

    We study the cosmological constraints of the time variation of the electron mass $m_e$ and the fine-structure constant $\alpha$, using data of cosmic microwave background, supernovae light curve and baryon acoustic oscillation (BAO) data including the recent DESI BAO DR2 measurements. The results are slightly depending on the BAO data set included in the analysis. The latest DESI BAO DR2 data strongly indicates that $m_e$ or $\alpha$ is slightly larger than the previous data from 6DF+SDSS and DESI BAO DR1. We also compare the varying $m_e$ model, the varying $\alpha$ model, and the simultaneous variation of $m_e$ and $\alpha$. When considering the Hubble tension, a larger electron mass is the most promising option and the variation of the fine-structure constants does not alleviate the tension.

    ↳ astro-ph.COgr-qchep-phPhys.Dark Univ.(2025)·13 citations
35. 35*

    A prototype differential atom interferometer for fundamental physics

    C. F. A. Baynham · R. Hobson · O. Buchmueller · D. Evans · L. Hawkins · L. Iannizzotto-Venezze · A. Josset · D. Lee · E. Pasatembou · B. E. Sauer · M. R. Tarbutt · T. Walker and 80 other authors

    Gravitational waves and ultralight dark matter are among the most compelling frontiers in fundamental physics, motivating proposals for Very Long-Baseline Atom Interferometers (VLBAIs) such as AION, MAGIS, AICE and AEDGE that aim to detect frequencies at which ground-based and space-borne laser interferometers lose sensitivity. VLBAIs look for signals by comparing the quantum phase evolution of widely separated atomic ensembles interrogated by a common laser. However, their performance depends critically on suppressing noise sources, particularly laser phase noise. Experimental validation of such noise rejection remains an important challenge. Here we demonstrate a prototype differential atom interferometer based on the single-photon clock transition of fermionic 87Sr, realising for the first time a gradiometer configuration with a species intrinsically suited to kilometre-scale and space-baseline operation. The instrument operates at the Standard Quantum Limit with no excess noise beyond atom shot noise, and the differential configuration maintains quantum-limited sensitivity in the presence of several radians of artificially injected laser phase noise per shot, emulating the conditions expected in a VLBAI. We further demonstrate recovery of coherent oscillatory signals across a broad frequency range under fully phase-randomised conditions, a capability that is inaccessible to a single interferometer operating in the same regime. These results provide an experimental validation of the noise-immune measurement principle underlying VLBAIs and mark an important step towards next-generation quantum sensors for gravitational-wave detection and searches for ultralight dark matter.

    ↳ hep-exastro-ph.IMgr-qchep-ph+1Nature(2026)·22 citations
36. 36*

    Analogue of Chern-Simons invariant in non-metricity gravity and axion cosmology

    Shin'ichi Nojiri🇯🇵 · Sergei D. Odintsov🇪🇸

    We propose a pseudo-scalar quantity, which is an analogue of the Chern-Simons invariant, in the framework of non-metricity gravity. By considering the coupling between the pseudo-scalar quantity and the axion, we give scenarios which may solve the problems of the axion misalignment, the $S_8$ problem, and the beginning of inflation. When the phase transition associated with the spontaneous breaking of the gauge symmetry of the electroweak theory or grand unified theories (GUTs) occurs, the pseudo-scalar quantity has a non-trivial value, which induces the misalignment of the axion field and axion particles are produced. If the gradient of the potential is small, the $S_8$ problem might be solved. We also propose a mechanism which induces inflation by the misalignment of the axion field generated by the phase transition of the GUTs.

    ↳ gr-qcastro-ph.COhep-phhep-thPhys.Dark Univ.(2025)·3 citations
37. 37*

    Event-shape dependence of symmetry plane correlations using the Gaussian estimator in Pb-Pb collisions at the LHC using a multiphase transport model

    Sarthak Tripathy🇮🇳 · Suraj Prasad🇮🇳 · Raghunath Sahoo🇮🇳

    The study of symmetry plane correlations (SPCs) can be useful in characterizing the direction of the anisotropic emission of produced particles in the final state. The study of SPCs provides an independent method to understand the transport properties of the system formed in heavy-ion collisions. Similar to anisotropic flow coefficients, which are largely influenced by the initial spatial anisotropy, SPCs also depend upon the participant plane correlations measured using the participating nucleons of the collision overlap region. In this paper, SPCs have been studied in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV using the event generator AMPT. In addition to their behaviour with the changing centrality of the collision, their event shape dependence has also been studied for the first time, using the event shape classifier transverse spherocity. The Gaussian estimator has been used to evaluate the correlations, and these have been compared to the participant plane correlations defined in an analogous way to the symmetry plane correlations, and a qualitative match has been found between them. These event-shape differentiated symmetry plane correlations can be used to deduce the presence of higher-order anisotropies in the initial energy distribution, thus giving insight into the initial geometry of the colliding system, among other applications like model development and model testing using Bayesian analyses.

    ↳ nucl-exhep-exhep-phhep-th+1PRD(2025)·7 citations
38. 38*

    Black holes with electroweak hair -- the detailed derivation

    Romain Gervalle🇫🇷 · Mikhail S. Volkov🇫🇷

    We present a very detailed derivation of solutions describing hairy black holes within the gravity-coupled Weinberg-Salam theory, which were previously reported in \href{https://doi.org/10.1103/PhysRevLett.133.171402}{Phys.Rev.Lett. 133 (2024) 171402}. These black holes support a strong magnetic field that polarizes the electroweak vacuum and creates a condensate of massive fields carrying superconducting currents along the black hole horizon. The currents, in turn, generate a ``corona'' of magnetic vortex segments attached to the horizon at both ends. The condensate and corona together constitute the black hole hair. The extremal solutions approach, in the far field, the magnetic Reissner-Nordström configuration, with a total mass that is {\it lower} than the total charge, $M<|Q|$, due to the negative Zeeman energy of the condensate. This makes the removal of the hair energetically unfavorable. The maximally hairy black holes exhibit masses comparable to terrestrial values, with approximately 11\% of their total mass stored in the hair. Given that these solutions arise within a well-tested theoretical framework, they are likely to have physical relevance.

    ↳ hep-thastro-ph.HEgr-qchep-phPRD(2025)·5 citations
39. 39*

    Non-perturbative renormalization group for pseudo-hermitian scalar fields in 4D

    André LeClair🇺🇸

    We define a model of 2 coupled SU(2) doublets of scalar fields in $4$ spacetime dimensions which have a rich structure of renormalization group (RG) flows to 1-loop when the SU(2) is broken to U(1). The model is pseudo-hermitian, $H^{†}=\mathcal{K}H{\mathcal{K}}^{†}$ with ${\mathcal{K}}^{†}\mathcal{K}={\mathcal{K}}^2=1$, which makes it non-unitary, however in a very specific manner with some desirable properties. We compute the beta functions to 3 loops from the operator product expansion and show that the 1-loop structure of flows persists to higher orders. For $SU(2)$ broken to $U(1)$, we conjecture a beta function to all orders. The flows can be extended to large coupling using a strong-weak coupling symmetry $g\to 1/g$ of the beta functions. One finds a line of fixed points which are non-unitary conformal field theories in 4 spacetime dimensions that were previously unknown. We also find massless flows between 2 non-trivial fixed points, and a regime with a cyclic RG flow, which is allowed since the model is non-unitary. For the flows between fixed points on the critical line, we compute the anomalous dimensions of the perturbations in the UV and IR, and identify some special points where anomalous dimensions are rational numbers.

    ↳ hep-thhep-phJ.Phys.A(2026)·2 citations
40. 40*

    Revisiting the Longitudinal Development of Electromagnetic Air Showers: Analytical Improvements to the Greisen Formalism with Zenith Angle Dependence

    Sebastián Mendizabal🇨🇱 · Nicolás Viaux M.🇨🇱 · Sebastián Tapia🇨🇱 · Raquel Pezoa R.🇨🇱 · Barbara Gutiérrez🇨🇱 · Constanza Valdivieso🇨🇱

    We present a new analytical approach to the longitudinal development of electromagnetic air showers, offering improvements to the classical Greisen formalism. We introduce a novel profile for the slope function ${\lambda }_1(s)$ that achieves an agreement less than $0.75\%$ with the original ${\lambda }_1$ for shower age parameter $s$ between $0.3<s<1.4$, where $s$ represents the stage of shower development. Our new formalism provides an improved representation of shower evolution, particularly near and beyond the shower maximum. In addition, we derive a complete expression for the number of particles $N(t)$. Our implementation includes the zenithal angle dependence on the number of particles at the detector level at high altitudes, making it particularly useful for high-altitude observatories. This expression is suitable for implementing air shower simulation tool fitting procedures over a wide range of energies and geometries. Our analysis suggests that the proposed new formalism may provide better agreement with the expected evolution of particle numbers compared to the traditional Greisen formulation.

    ↳ astro-ph.HEhep-phhep-thAstropart.Phys.(2026)·2 citations
41. 41*

    Spectroscopy of Strange Mesons and First Observation of a Strange Crypto-Exotic State with $J^P=0^{-}$

    G. D. Alexeev · M. G. Alexeev · C. Alice · A. Amoroso · V. Andrieux · V. Anosov · K. Augsten · W. Augustyniak · C. D. R. Azevedo · B. Badelek · R. Beck · J. Beckers and 152 other authors

    We measured the strange-meson spectrum in the scattering reaction $K^{-}+p\to K^{-}{\pi }^{-}{\pi }^{-}+p$ with the COMPASS spectrometer at CERN. Using the world's largest sample of this reaction, we performed a comprehensive partial-wave analysis of the mesonic final state. It substantially extends the strange-meson spectrum covering twelve states with masses up to 2.4 GeV/$c^2$. We observe the first candidate for a crypto-exotic strange meson with $J^P=0^{-}$ and find $K_3$ and $K_4$ states consistent with predictions for the ground states.

    ↳ hep-exhep-ph10 citations
42. 42*

    Tropical sampling from Feynman measures

    Michael Borinsky🇨🇦 · Mathijs Fraaije🇨🇭

    We introduce an algorithm that samples a set of loop momenta distributed as a given Feynman integrand. The algorithm uses the tropical sampling method and can be applied to evaluate phase-space-type integrals efficiently. We provide an implementation, momtrop, and apply it to a series of relevant integrals from the loop-tree duality framework. Compared to naive sampling methods, we observe convergence speedups by factors of more than $10^6$.

    ↳ hep-thhep-phmath-phmath.MPComput.Phys.Commun.(2025)·3 citations
43. 43*

    Constraints on the lepton asymmetry from DESI DR2 BAO data

    Zhi-Chao Zhao🇨🇳 · Dong-Mei Xia🇨🇳 · Sai Wang🇨🇳

    It is important to explore the potential existence of lepton asymmetry in the neutrino sector. Conducting a joint analysis of DESI DR2 BAO data and \emph{Planck} 2018 CMB data, we obtain the upper limits on the neutrino degeneracy parameter, i.e., $\xi <0.56$ for the normal mass hierarchy while $\xi <0.62$ for the inverted mass hierarchy, at 95\% confidence level. Considering the influence of the dynamical dark energy, we find that these upper limits remain to be robust. This work may provide helpful implications for model buildings of the matter-antimatter asymmetry in the universe.

    ↳ astro-ph.COgr-qchep-phPRD(2025)·3 citations
44. 44*

    Coupling Selection Rules in Heterotic Calabi-Yau Compactifications

    Jun Dong🇯🇵 · Tatsuo Kobayashi🇯🇵 · Ryusei Nishida🇯🇵 · Satsuki Nishimura🇯🇵 · Hajime Otsuka🇯🇵

    We study coupling selection rules of chiral matter fields in heterotic string theory with standard embedding. These selection rules are determined by topological properties of Calabi-Yau threefolds. We classify coupling selection rules on complete intersection Calabi-Yau threefolds for $h^{1,1}\le 5$. It is found that all of these selection rules for $h^{1,1}\le 5$ are understood by combinations of only five types of fusion rules.

    ↳ hep-thhep-phJHEP(2025)·18 citations
45. 45*

    Axion Mixing in the String Axiverse

    Hai-Jun Li🇨🇳 · Yu-Feng Zhou🇨🇳

    String axiverse provides a fascinating and complex landscape for axion physics. The requirement in type IIB string axiverse models necessitates at least two axions to ensure the presence of both a QCD axion candidate and an additional axion-like particle (ALP). In this work, we study axion mass mixing and adopt a bottom-up perspective to investigate what conditions an axion model must satisfy in order to exhibit maximal mixing -- the scenario where the degree of effective mixing is maximized. We find that maximal mixing occurs when the masses of all ALPs are smaller than the zero-temperature mass of the QCD axion, with no two ALP masses being equal, and when the decay constants of all ALPs are uniformly either smaller or larger than the decay constant of the QCD axion. Additionally, the transfer of axion energy density ultimately takes place only between the two axions with the closest masses. These findings provide critical insights into axion dynamics not only within type IIB string axiverse models but also in broader multi-axion mixing frameworks. The potential cosmological implications of axion mass mixing are also addressed at the end.

    ↳ hep-thhep-phNPB(2026)·8 citations
46. 46*

    Essay: A path for the construction of a Muon Collider

    Diktys Stratakis🇺🇸

    Muons are elementary particles and provide cleaner collision events that can explore higher energies compared to composite particles like protons. Muons are also far heavier than their electron cousins, meaning that they emit less synchrotron radiation that effectively limits the energies of circular electron-positron colliders. These characteristics open up the possibility for a Muon Collider to surpass the direct energy reach of the Large Hadron Collider while achieving unprecedented precision measurements of Standard Model processes. In this Essay, after briefly summarizing the progress achieved so far, I identify important missing R&D steps and envision a compelling plan to bring a Muon Collider to reality in the next two decades. A Muon Collider could allow for the exploration of physics that is not available with current technologies. For example, it may provide a way to study the Higgs boson directly or probe new particles, including those related to dark matter or other phenomena beyond the Standard Model.

    ↳ hep-exhep-phPRL(2025)·7 citations
47. 47*

    Dynamical systems approach to Cold and Warm Inflation within slow-roll and beyond

    Sandip Biswas🇮🇳 · Saddam Hussain🇨🇳 · Kaushik Bhattacharya🇮🇳

    In this work, we systematically present a new dynamical systems approach to standard inflationary processes and their variants as constant-roll inflation. Using the techniques presented in our work one can in general investigate the attractor nature of the inflationary models in the phase space. We have compactified the phase space coordinates, wherever necessary, and regulated the nonlinear differential equations, constituting the autonomous system of equations defining the dynamical system, at the cost of a new redefined time variable which is a monotonic increasing function of the standard time coordinate. We have shown that in most of the relevant cases the program is executable although the two time coordinates may show different durations of cosmological events. If one wishes one can revert back to the cosmological time via an inverse transformation. The present work establishes a standard norm for studying dynamical as well as stability issues in any new inflationary system.

    ↳ gr-qchep-ph1 citation
48. 48*

    False and genuine decoherence in the early universe: a local observer and time-averaged observables

    Fumiya Sano🇯🇵 · Junsei Tokuda🇨🇦

    We study quantum decoherence of curvature perturbations at superhorizon scales caused by the gravitational nonlinearities. We show that cubic gravitational couplings, constrained by the spatial diffeomorphism invariance, lead to infrared (IR) and ultraviolet (UV) divergences in the decoherence rate at one loop. These divergences arise from fluctuations of deep IR modes which look like a background mode for a local observer and violent zero-point fluctuations in the deep UV, respectively. We argue that these divergences are unobservable, as they vanish when considering proper observables. We consider correlators defined using the geodesic distance for IR divergences and time-averaged correlators for UV divergences. To account for these observer's perspectives, we propose to consider an effective quantum state, defined in terms of actual observables, as a more appropriate probe of the quantum coherence of the system measured by an observer. We then evaluate the finite decoherence rate induced by superhorizon environment during inflation and at late universe.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2025)·14 citations
49. 49*

    Vector induced Gravitational Waves sourced by Primordial Magnetic Fields

    Arko Bhaumik🇮🇳 · Theodoros Papanikolaou🇮🇹 · Anish Ghoshal🇵🇱

    In this work, we develop a generic formalism for the study of tensor perturbations induced at second order by first-order vector metric perturbations, dubbing these induced tensor modes $\text{vector-induced gravitational waves}$ (VIGWs). Notably, considering an inflation-inspired power-law type magnetic field power spectrum of the form $P_B(k)\propto k^{n_{\mathrm{B}}}$ (where $n_{\mathrm{B}}$ is the magnetic spectral index), we show that the VIGW signal is enhanced for stiff post-inflationary EoS, with the maximum enhancement happening for $w=1$. We explicitly demonstrate this contribution is dominant over the first-order magnetically-sourced GWs. The VIGW spectrum exhibits a maximum at around the scale crossing the cosmological horizon at the end of reheating, $k_{\mathrm{reh}}$, with its present day peak amplitude scaling as ${\Omega }_{\mathrm{GW}}(k_{\mathrm{reh}},{\eta }_0)\propto \Delta N_{\mathrm{reh}}\times (H_{\inf }/M_{\mathrm{Pl}}{)}^8$, where $H_{\inf }$ is the Hubble parameter at the end of inflation and $\Delta N_{\mathrm{reh}}$ the duration of the post-inflationary era in $e$-folds. For $w=1$ (kination) and $n_{\mathrm{B}}>-3/2$, one further obtains a nearly $n_{\mathrm{B}}$-independent frequency scaling of the GW spectrum of the form ${\Omega }_{\mathrm{GW}}(f,{\eta }_0)\propto {\left(\frac{f}{f_{\mathrm{reh}}}\right)}^{-2.8}$ for $f>f_{\mathrm{reh}}\equiv k_{\mathrm{reh}}/(2\pi )$. Finally, we highlight that the VIGW signal can be well within the detection bands of several next-generation interferometric GW missions at small scales. Indicatively, for $H_{\inf }\sim O(10^7)\mathrm{GeV}$ and $O(10^{14})\mathrm{GeV}$, and $\Delta N_{\mathrm{reh}}\sim 15$ and $10$, the VIGW signal is expected to be detectable by LISA and ET respectively.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·16 citations
50. 50*

    Confining Quantum Chromodynamics Model for 3-Quark Baryons, New Mass Source, `Proton Spin Crisis' Solution and Idealized Quark-Lepton Mass Symmetry

    Jong-Ping Hsu🇺🇸 · Leonardo Hsu🇺🇸

    We discuss a model for the relativistic bound states of 3-quark baryons based on confining quantum chromoynamics (QCD) with general Yang-Mills symmetry. The model postulates that 3-quark states are formed by consecutive 2-body collisions. For a proton, d and u quarks get together first, and then they capture another u quark so that the d quark is at the core to form a stable proton state with intergral electric charge. The two u quarks form a quantum spheric shell and move in a confining potential $C(r)=Q^{\prime }r$ of the core d quark. The confining potential $C(r)$ is a static solution of new `phase' fields satisfying the fourth-order equation based on general Yang-Mills symmetry. The two u quarks with the confining linear potentials $C(r)$ in the spherical shell can produce an effective quark Hooke potential $V_{qH}(r)=Q{r}^2+V_o$ for the d quark at the core, where Q and $Q^{\prime }$ are not independent. The proton mass is assumed to be approximately given by $E(d)+2E(u)$, which can be obtained analytically from Dirac Hamiltonians involving $V_{qH}(r)$ and $C(r)$ for d and two u quarks respectively. The model gives a reasonable understanding of roughly 120 baryon masses based on two different coupling constants and one free parameter $V_o$ for sub-spectra specfied by $J^P$. These results are roughly within 20\% in percent deviation, which appears to be independent of the assumption of color charges. The confining QCD model also gives the neutron-proton mass difference $\approx 0.6MeV$. We propose an experimental test of the proton structure.

    ↳ physics.gen-phhep-ph0 citations
51. 51*

    Probing Primordial Power Spectrum and Non-Gaussianities With Fast Radio Bursts

    Zhiyao Lu🇨🇳 · Lian-Tao Wang🇺🇸 · Huangyu Xiao🇺🇸

    We use the precision measurements of the arrival time differences of the same fast radio burst (FRB) source along multiple sightlines to measure the primordial power spectrum and Non-Gaussianities. The anticipated experiment requires a sightline separation of 100 AU, achieved by sending three or more radio telescopes to the outer solar system. The Shapiro time delays, measured relatively between different telescopes, are sensitive to the gradient field of the gravitational potential between different sightlines. Since the arrival time difference is independent of when the transient signal is emitted from the source, every measurement of the detected FRB source can be correlated. With enough FRB sources discovered, we can map the gravitational potential across the sky. We further calculate the two-point and three-point correlation function of the arrival time difference between telescopes for different FRB sources in the sky. If $10^4$ FRBs were to be detected, our results suggest that this technique can test the inflationary scale-invariant power spectrum down to $\sim 10^3\mathrm{Mp}{\mathrm{c}}^{-1}$ and primordial Non-Gaussianities at a level of $f_{\mathrm{NL}}\sim 1$.

    ↳ astro-ph.COhep-phJCAP(2026)·1 citation
52. 52*

    Sakai-Sugimoto Model in an Off-Shell: Chiral Lagrangian to All Orders

    Michael Lublinsky🇮🇱 · Timofey Solomko🇮🇱

    The Sakai-Sugimoto holographic model is famous for implementing the approximate chiral symmetry of QCD and reproducing the Chiral Lagrangian in a top-down approach. In this manuscript, we revisit the model in a formalism that is somewhat different from the original work by Sakai and Sugimoto: We start by identifying boundary degrees of freedom and splitting the bulk equations of motion into dynamical ones and constraints. The former are then solved to all orders in derivatives of the boundary fields. The constraints are left unsolved, leaving the dynamical degrees of freedom off-shell. This approach enables us to systematically derive the effective action of the boundary theory. The derived effective action is very rich in physics: it contains an $U(N_f)$ multiplet of massless pseudoscalars interacting (via trilinear and higher terms) with towers of massive (axial-)vector mesons. In contrast to the previous studies, our effective action is non-local. The original Chiral Lagrangian is recovered as its local expansion in small $\pi$-meson momenta (derivative expansion). We particularly zoom in on the values of four derivative terms couplings, the low energy constants, and compare those with the ones reported in the literature.

    ↳ hep-thhep-phnucl-thJHEP(2025)·0 citations
53. 53*

    A $\nu$ look at the Sun: Probing the conditions of the solar core using ${}^8$B neutrinos

    Melanie A. Zaidel🇺🇸 · John F. Beacom🇺🇸

    In the coming age of precision neutrino physics, neutrinos from the Sun become robust probes of the conditions of the solar core. Here, we focus on ${}^8$B neutrinos, for which there are already high precision measurements by the Sudbury Neutrino Observatory and Super-Kamiokande. Using only basic physical principles and straightforward statistical tools, we estimate projected constraints on the temperature and density of the ${}^8$B neutrino production zone compared to a reference solar model. We outline how to better understand the astrophysics of the solar interior using forthcoming neutrino data and solar models. Finally, we note that detailed forward modeling will be needed to develop the full potential of this approach.

    ↳ astro-ph.SRastro-ph.HEhep-phnucl-thPRC(2025)·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.