Fri·Jan 3, 2025Friday·January 3, 2025

1. 01*

   Forecast constraints on the axion-photon coupling from interstellar medium heating

   Makoto Amakawa🇯🇵 · Tomohiro Fujita🇯🇵 · Shinji Tsujikawa🇯🇵

   In interstellar media characterized by a nonrelativistic plasma of electrons and heavy ions, we study the effect of axion dark matter coupled to photons on the dynamics of an electric field. In particular, we assume the presence of a background magnetic field aligned in a specific direction. We show that there is an energy transfer from the oscillating axion field to photons and then to the plasma induced by forced resonance. This resonance is most prominent for the axion mass $m_{\varphi }$ equivalent to the plasma frequency ${\omega }_p$. Requiring that the heating rate of the interstellar medium caused by the energy transfer does not exceed the observed astrophysical cooling rate, we place forecast constraints on the axion-photon coupling $g$ for several different amplitudes of the background magnetic field $B_0$. By choosing a typical value $B_0=10^{-6}$ G, we find that, for the resonance mass $m_{\varphi }={\omega }_p$, the upper limit of $g$ can be stronger than those derived from other measurements in the literature. With increased values of $B_0$, it is possible to put more stringent constraints on $g$ for a wider range of the axion mass away from the resonance point.

   hep-phastro-ph.GAgr-qchep-thPLB(2025)·0 citations
2. 02*

   Searching for single production of vectorlike quarks decaying into Wb at a future muon-proton collider

   Jin-Zhong Han🇨🇳 · Yao-Bei Liu🇨🇳 · Stefano Moretti🇬🇧

   This work investigates the discovery potential for singly produced vectorlike quarks~(VLQs) $T$ ($Q=+2/3e$) and $Y$ ($Q=-4/3e$) decaying to $Wb$ at future $\mu p$ colliders with $\sqrt{s}=5.29$, 6.48, and 9.16 TeV, analyzing both leptonic and hadronic $W$ decay channels through detailed detector simulations. The hadronic channel demonstrates superior sensitivity, enabling $5\sigma$ discovery up to $m_T=3750$ GeV ($m_Y=4100$ GeV) at 9.16 TeV with 100 fb${}^{-1}$, while exclusion limits reach $m_T=4500$ GeV ($g^{\ast }\ge 0.06$) and $m_Y=4800$ GeV (${\kappa }_Y\ge 0.04$) - significantly beyond LHC capabilities. At 5.29 TeV, discovery regions cover $g^{\ast }\in [0.15,0.5]$ for $m_T\in [1500,2520]$ GeV and ${\kappa }_Y\in [0.12,0.5]$ for $m_Y\in [1700,2700]$ GeV, with exclusions extending to $m_T=2750$ GeV and $m_Y=3020$ GeV. These results, obtained within a simplified two-parameter framework ($m_{T/Y}$ and electroweak couplings $g^{\ast }$), establish $\mu p$ colliders as uniquely powerful tools for probing high-mass VLQ states, particularly in the boosted jet regime.

   hep-phPRD(2025)·9 citations
3. 03*

   $S,T,U$ Parameters in The B-LSSM

   Sheng-Kai Cui🇨🇳 · Ke-Sheng Sun🇨🇳 · Yu-Li Yan🇨🇳 · Jin-Lei Yang🇨🇳 · Tai-Fu Feng🇨🇳

   Using the pinch technique, we compute the one-loop vertices of weak interactions in the B-LSSM and incorporate their pinch contributions into the gauge boson self-energies. Compared to the definitions of the $S,T,$ and $U$ parameters in the Standard Model based on the $SU(2{)}_L\otimes U(1{)}_Y$ group, the corresponding parameters in the local B-L gauge symmetry (B-LSSM) are modified. We provide these redefined $S,T,$ and $U$ parameters and demonstrate the convergence of the results. In the framework of the low-energy effective Lagrangian for weak interactions, the $S,T,$ and $U$ parameters can be expressed as functions of certain parameters in the B-LSSM. The updated experimental and fitting results constrain the parameter space of the B-LSSM strongly.

   hep-phCPC(2026)·1 citation
4. 04*

   Studying the $B^0\to J/\psi h_1$ decays with $h_1(1170)-h_1(1415)$ mixing in the perturbative QCD approach

   Qin Chang🇨🇳 · De-Hua Yao🇨🇳 · Xin Liu🇨🇳

   In this paper, we study the $B^0\to J/\psi h_1$ decays for the first time by using perturbative QCD approach up to the presently known next-to-leading order accuracy. The vertex corrections present significant contribution to the amplitude. In the calculation, the mixing between two light axial-vector mesons $h_1(1170)$ and $h_1(1415)$ are also studied in detail. The observables including the branching ratios, polarization fractions and $CP$ asymmetries are predicted and discussed explicitly. It is found that the $B^0\to J/\psi h_1$ decays have relatively large branching fractions, which are generally at the order of $\mathcal{O}(10^{-6}\sim 10^{-3})$, and thus are possible to be observed by the LHCb and Belle-II experiments in the near future. Moreover, they are very sensitive to the mixing angle $\theta$ and can be used to test the values of $\theta$. In addition, some ratios between the branching fractions of $B^0\to J/\psi h_1$ decays can provide much stronger constraints on $\theta$ due to their relatively small theoretical errors. The $B^0\to J/\psi h_1$ decays are generally dominated by the longitudinal polarization contributions, specifically, $f_L(B^0\to J/\psi h_1)>80\%$, except for the case that $\theta \sim 35^{\circ }$ and $-55^{\circ }$. Unfortunately, the direct $CP$ asymmetries of $B^0\to J/\psi h_1$ decays are too small to be observed soon even if the effect of $\theta$ is considered. The future precise measurements on $B^0\to J/\psi h_1$ decays are expected for testing these theoretical findings and exploring the interesting nature of $h_1(1170)$ and $h_1(1415)$.

   hep-phEPJC(2025)·2 citations
5. 05*

   A coupled-channel perspective analysis on bottom-strange molecular pentaquarks

   Qing-Fu Song🇨🇳 · Qi-Fang Lü🇨🇳 · Xiaonu Xiong🇨🇳

   At present work, we systematically study various bottom-strange molecular pentaquarks to search for possible bound states and resonances by adopting one-boson-exchange model within complex scaling method. According to our calculations, we predict several bound and resonant states for bottom baryon $Y_b({\Lambda }_b,{\Sigma }_b){\bar{K}}^{(\ast )}$ and $Y_b{K}^{(\ast )}$ systems. In particular, a bound state in the $I(J^P)=1/2(1/2^{-})$ ${\Sigma }_b\bar{K}/{\Lambda }_b{\bar{K}}^{\ast }/{\Sigma }_b{\bar{K}}^{\ast }$ system may correspond to the particle ${\Xi }_b(6227)$. Meanwhile, the predicted bound state with $6303\sim 6269\mathrm{MeV}$ in the $I(J^P)=1/2(1/2^{-}){\Sigma }_{b}K/{\Lambda }_b{K}^{\ast }/{\Sigma }_b{K}^{\ast }$ system is flavor exotic and does not appear in the spectroscopy of conventional baryons, which provides a practical way to clarify the nature of particle ${\Xi }_b(6227)$. We highly hope that our proposals can offer helpful information for the future experimental searches.

   hep-phEPJC(2025)·5 citations
6. 06*

   Gluon mass scale through the Schwinger mechanism

   M. N. Ferreira🇨🇳 · J. Papavassiliou🇪🇸

   It has long been argued that the action of the Schwinger mechanism in the gauge sector of Quantum Chromodynamics leads to the generation of a gluon mass scale. Within this scenario, the analytic structure of the fundamental vertices is modified by the creation of scalar colored excitations with vanishing mass. In the limit of zero momentum transfer, these terms act as massless poles, providing the required conditions for the infrared stabilization of the gluon propagator, and producing a characteristic displacement to the associated Ward identities. In this article we offer an extensive overview of the salient notions and techniques underlying this dynamical picture. We place particular emphasis on recent developments related to the exact renormalization of the mass, the nonlinear nature of the pole equation, and the key role played by the Fredholm alternative theorem.

   hep-phhep-lathep-thnucl-thPPNP(2025)·23 citations
7. 07*

   Impact of QCD sum rules coupling constants on neutron stars structure

   F. Moradi Jangal🇮🇷 · H. R. Moshfegh🇮🇷 · K. Azizi🇮🇷

   We present a detailed investigation on the structure of neutron stars, incorporating the presence of hyperons within a relativistic model under the mean-field approximation. Employing coupling constants derived from QCD sum rules, we explore the particle fraction in beta equilibrium and establish the mass-radius relationship for neutron stars with hyperonic matter. Additionally, we compute the stellar Love number (${\mathcal{K}}_2$) and the tidal deformability parameter ($\Lambda$), providing valuable insights into the dynamical properties of these celestial objects. Through comparison with theoretical predictions and observational data, our results exhibit good agreement, affirming the validity of our approach. These findings contribute significantly to refining the understanding of neutron star physics, particularly in environments containing hyperons, and offer essential constraints on the equation of state governing such extreme astrophysical conditions.

   hep-phastro-ph.HEnucl-thEPJC(2025)·5 citations
8. 08*

   Di-${\pi }^0$ Production and Generalized Distribution Amplitudes at Future Electron-Ion Colliders

   Bing'ang Guo🇨🇳 · Jing Han🇨🇳 · Ya-Ping Xie🇨🇳 · Xurong Chen🇨🇳

   Generalized distribution amplitudes (GDAs) offer valuable insights into the three-dimensional structure of hadrons, delineating the amplitudes associated with the transition from a quark-antiquark pair to a hadron pair. Currently, hadron GDAs can be probed in electron-positron collisions, with experimental feasibility demonstrated at facilities such as Belle and BESIII. In this study, we put forth the proposition that hadron GDAs can also be investigated in electron-hadron collisions at forthcoming Electron-Ion Colliders (EICs), specifically through the subprocess ${\gamma }^{\ast }\gamma \to h_1{h}_2$. In this framework, a quasi-real photon, emitted by the ion, exhibits a photon flux proportional to the square of the ion's electric charge. Consequently, we anticipate that the cross sections in EICs will be substantially larger than those in electron-positron collisions. We present numerical calculations pertaining to di-${\pi }^0$ production employing the equivalent photon approximation (EPA). Our findings suggest that, within the same kinematic region, electron-proton ($e$-$p$) collisions at the EIC could yield an event rate comparable to that of Belle II, while electron-gold ($e$-Au) collisions are expected to generate an even greater number of events. This enhanced event rate facilitates a high-precision examination of di-${\pi }^0$ GDAs at the EIC.

   hep-phEPJC(2025)·2 citations
9. 09*

   Gravitational waves from color restoration in a leptoquark model of radiative neutrino masses

   Mårten Bertenstam🇸🇪 · Marco Finetti🇵🇹 · António P. Morais🇵🇹 · Roman Pasechnik🇸🇪 · Johan Rathsman🇸🇪

   We study the first-order phase transitions and the emerging stochastic gravitational wave spectrum in a minimal leptoquark extension of the Standard Model that explains active neutrino oscillation data while satisfying current flavor physics constraints. This model exhibits diverse phase transition patterns, including color symmetry-breaking scenarios in the early Universe. Strong correlations between model parameters and gravitational-wave signals yield testable predictions for future experiments such as LISA, BBO, and DECIGO. Specifically, a detectable signal in the mHz$–$0.1~Hz frequency range features color-restoration and leptoquark masses near $1.5\mathrm{TeV}$. With this article, we also present the first application in the literature of \texttt{Dratopi}. This is a soon-to-be-released tool for phase transition analysis using the dimensional reduction formalism, that interfaces the \texttt{DRalgo} package with \texttt{Python} and a slightly modified version of \texttt{CosmoTransitions}.

   hep-phastro-ph.COJCAP(2025)·6 citations
10. 10*

    Two-loop dimension Six Effective Action: Integrating Out Heavy Scalar

    Nilabhra Adhikary🇮🇳 · Jaydeb Das🇮🇳 · Debmalya Dey🇮🇳

    For the first time, we present the model-independent two-loop effective action up to dimension six after integrating out heavy scalar(s) employing the Heat-Kernel method. We compute the effective operators that emerge at two-loop for two example models: heavy electroweak complex Triplet and Doublet scalars. We present our results on the SILH basis. We also capture the effect in the fermion sector. For these two scenarios, we compute all the fermionic effective operators up to dimension six.

    hep-phhep-thNPB(2026)·4 citations
11. 11*

    Sub-MHz Radio Background from Ultralight Dark Photon Dark Matter

    Javier F. Acevedo🇺🇸 · Amit Bhoonah🇺🇸 · Kun Cheng🇺🇸

    Dark photons are a well-motivated candidate for dark matter, but their detection becomes challenging for ultralight masses with both experimental and astrophysical probes. In this work, we propose a new approach to explore this regime through the dark inverse Compton scattering of ultralight dark photons with cosmic ray electrons and positrons. We show this process generates a potentially observable background radiation that is most prominent at frequencies below MHz. We compute this effect using the latest cosmic ray models and radio absorption maps. Comparing it to observations of the Milky Way's radio spectrum from Explorer 43, Radio Astronomy Explorer 2, and the Parker Solar Probe, we place leading constraints on the kinetic mixing of dark photon dark matter for masses $\lesssim 2\times 10^{-17}\mathrm{eV}$.

    hep-phastro-ph.GAastro-ph.HE2 citations
12. 12*

    Gravitational Waves of GUT Phase Transition during Inflation

    Xi-He Hu🇨🇳 · Ye-Ling Zhou🇨🇳

    Grand unified theory (GUT) phase transition is generally considered unobservable due to its ultrahigh energy scale, and the monopole problem associated with GUT phase transition is one motivation of inflation. We propose that if a first-order GUT phase transition happens during inflation, the induced gravitational waves (GWs) are redshifted and deformed, and might be observed today in GW observatories. We review the formalism of inflated GWs and derive the general deformation function between inflated and uninflated GW spectra in the instant-source or transitory-source application. It is valid for any e-folding number of instant or transitory source. Applying the formalism to GUT phase transition, we find that the e-folding number at 15 or 25 can shift the GWs to 10 Hz or mHz hands, respectively, which might be tested in the future ground-based or space-based interferometers. We further generalise the discussion to inflated GWs via phase transition below the GUT scale. It is worth mentioning that, due to the deformation of the spectrum, the peak of inflated GWs is not simply a redshift of the peak of uninflated GWs.

    hep-phastro-ph.COPRD(2025)·12 citations
13. 13*

    Open Questions and Future Directions in Titan Science

    Conor A. Nixon · Natalie Carrasco · Christophe Sotin

    In this chapter we attempt to distill the very large number of possible future inquiries of Titan into a relatively concise list of twenty high level questions - each of which of would necessarily entail a multitude of more specific investigations and studies. While this list does not encompass all possible open questions, and is divided into topics according to our preference and not in any way uniquely, we believe that it does however span a wide range of the most intriguing topics about Titan, and may form some sort of guide especially for those embarking into Titan studies for the first time. At the end of this chapter we return to explore how these four techniques may be used to answer the large, high-level open questions in Titan science.

    ↳ astro-ph.EPastro-ph.IMhep-phChapter 15 of book: "Titan after Cassini-…·0 citations
14. 14*

    The Role of Electric Dominance for Particle Injection in Relativistic Reconnection

    Sanya Gupta🇩🇪 · Navin Sridhar🇺🇸 · Lorenzo Sironi🇺🇸

    Magnetic reconnection in relativistic plasmas -- where the magnetization $\sigma \gg 1$ -- is regarded as an efficient particle accelerator, capable of explaining the most dramatic astrophysical flares. We employ two-dimensional (2D) particle-in-cell simulations of relativistic pair-plasma reconnection with vanishing guide field and outflow boundaries to quantify the impact of the energy gain occurring in regions of electric dominance ($E>B$) for the early stages of particle acceleration (i.e., the ``injection'' stage). We calculate the mean fractional contribution $\zeta ({ϵ}^{\ast },{ϵ}_{\mathrm{T}}$) by $E>B$ fields to particle energization up to the injection threshold energy, ${ϵ}^{\ast }=\sigma /4$; here, ${ϵ}_{\mathrm{T}}$ is the particle energy at time $T$. We find that $\zeta$ monotonically increases with $\sigma$ and ${ϵ}_{\mathrm{T}}$; for $\sigma \gtrsim 50$ and ${ϵ}_{\mathrm{T}}/\sigma \gtrsim 8$, we find that $\gtrsim 80\%$ of the energy gain obtained before reaching ${ϵ}^{\ast }=\sigma /4$ occurs in $E>B$ regions. We find that $\zeta$ is independent of simulation box size $L_x$, as long as ${ϵ}_{\mathrm{T}}$ is normalized to the maximum particle energy, which scales as ${ϵ}_{\max }\propto L_{\mathrm{x}}^{1/2}$ in 2D. The distribution of energy gains ${ϵ}_{\chi }$ acquired in $E>B$ regions can be modeled as $dN/d{ϵ}_{\chi }\propto {ϵ}_{\chi }^{-0.35}\exp [-({ϵ}_{\chi }/0.06\sigma {)}^{0.5}]$. Our results help assess the role of electric dominance in relativistic reconnection with vanishing guide fields, which may be realized in the magnetospheres of black holes and neutron stars.

    ↳ astro-ph.HEhep-phMNRAS(2025)·5 citations
15. 15*

    Thermodynamics of charmed hadrons across chiral crossover from lattice QCD

    Sipaz Sharma🇩🇪 · Frithjof Karsch🇩🇪 · Peter Petreczky🇺🇸

    We use up to fourth-order charm fluctuations and their correlations with net baryon number, electric charge, and strangeness fluctuations, calculated within the framework of lattice QCD, to study the continuum partial pressure contributions of charmed baryons and mesons. We show that, at and below the chiral crossover temperature, these partial pressures receive enhanced contributions from experimentally unobserved charmed hadrons predicted by the Quark Model. Additionally, we demonstrate that at the chiral crossover, the Hadron Resonance Gas description breaks down, signaling the modification of open charm hadrons and thereby implying the onset of charm deconfinement. We present evidence for the survival of low-lying non-radial $1S$ and $1P$ hadron-like excitations above the chiral crossover, which hints at the sequential melting of charmed hadrons. Finally, we investigate the continuum partial pressure contribution of charm quark-like excitation that emerges at the chiral crossover and calculate its temperature-dependent in-medium mass.

    ↳ hep-lathep-exhep-phhep-thJ.Subatomic Part.Cosmol.(2025)·7 citations
16. 16*

    Multi-Observatory Study of Young Stellar Energetic Flares (MORYSEF): No Evidence For Abnormally Strong Stellar Magnetic Fields After Powerful X-ray Flares

    Konstantin V. Getman (1)🇺🇸 · Oleg Kochukhov (2) · Joe P. Ninan (3) · Eric D. Feigelson (1)🇺🇸 · Vladimir S. Airapetian (4)🇺🇸 · Abygail R. Waggoner (5) · L. Ilsedore Cleeves (5) · Jan Forbrich (6) · Sergio A. Dzib (7) · Charles J. Law (5) · Christian Rab (8) · Daniel M. Krolikowski (9) ((1) Pennsylvania State University, (2) Uppsala University, (3) Tata Institute of Fundamental Research, (4) NASA/GSFC/SEEC, (5) University of Virginia, (6) University of Hertfordshire, (7) Max-Planck-Institut fur Radioastronomie, (8) Max-Planck-Institut fur Extraterrestrische Physik, (9) University of Arizona)

    We explore the empirical power-law relationship between X-ray luminosity (Lx) and total surface magnetic flux (Phi), established across solar magnetic elements, time- and disk-averaged emission from the Sun, older active stars, and pre-main-sequence (PMS) stars. Previous models of large PMS X-ray flares, lacking direct magnetic field measurements, showed discrepancies from this baseline law, which MHD simulations attribute to unusually strong magnetic fields during flares. To test this, we used nearly simultaneous Chandra X-ray and HET-HPF near-infrared observations of four young Orion stars, measuring surface magnetic fields during or just after powerful PMS X-ray flares. We also modeled these PMS X-ray flares, incorporating their measured magnetic field strengths. Our findings reveal magnetic field strengths at the stellar surface typical of non-flaring PMS stars, ruling out the need for abnormally strong fields during flares. Both PMS and solar flares deviate from the Lx-Phi law, with PMS flares exhibiting a more pronounced deviation, primarily due to their much larger active regions on the surface and larger flaring loop volumes above the surface compared to their solar counterparts. These deviations likely stem from the fact that powerful flares are driven by magnetic reconnection, while baseline X-ray emission may involve less efficient mechanisms like Alfven wave heating. Our results also indicate a preference for dipolar magnetic loops in PMS flares, consistent with Zeeman-Doppler imaging of fully convective stars. This requirement for giant dipolar loops aligns with MHD predictions of strong dipoles supported by polar magnetic surface active regions in fast-rotating, fully convective stars.

    ↳ astro-ph.SRastro-ph.HEhep-phApJ(2025)·1 citation

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