Wed·Mar 12, 2025Wednesday·March 12, 2025

1. 01*

   Neutrino masses and mixing: Entering the era of subpercent precision

   Francesco Capozzi🇮🇹 · William Giarè🇬🇧 · Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹 · Alessandro Melchiorri🇮🇹 · Antonio Palazzo🇮🇹

   We perform an updated global analysis of the known and unknown parameters of the standard $3\nu$ framework as of 2025. The known oscillation parameters include three mixing angles $({\theta }_{12},{\theta }_{23},{\theta }_{13})$ and two squared mass gaps, chosen as $\delta m^2=m_2^2-m_1^2>0$ and $\Delta m^2=m_3^2-\frac{1}{2}(m_1^2+m_2^2)$, where $\alpha =\mathrm{sign}(\Delta m^2)$ distinguishes normal ordering (NO, $\alpha =+1$) from inverted ordering (IO, $\alpha =-1$). With respect to our previous 2021 update, the combination of oscillation data leads to appreciably reduced uncertainties for ${\theta }_{23}$, ${\theta }_{13}$ and $|\Delta m^2|$. In particular, $|\Delta m^2|$ is the first $3\nu$ parameter to enter the domain of subpercent precision (0.8\% at $1\sigma$). We underline some issues about systematics, that might affect this error estimate. Concerning oscillation unknowns, we find a relatively weak preference for NO versus IO (at $2.2\sigma$), for CP violation versus conservation in NO (1.3$\sigma$) and for the first ${\theta }_{23}$ octant versus the second in NO ($1.1\sigma$). We discuss the status and qualitative prospects of the mass ordering hint in the plane $(\delta m^2,\Delta m_{ee}^2)$, where $\Delta m_{ee}^2=|\Delta m^2|+\frac{1}{2}\alpha ({\cos }^2{\theta }_{12}-{\sin }^2{\theta }_{12})\delta m^2$, to be measured by the JUNO experiment with subpercent precision. We also discuss upper bounds on nonoscillation observables. We report $m_{\beta }<0.50$~eV and $m_{\beta \beta }<0.086$~eV ($2\sigma$). Concerning the sum of neutrino masses $\Sigma$, we discuss representative combinations of data, with or without augmenting the $\Lambda$CDM model with extra parameters accounting for possible systematics or new physics. The resulting $2\sigma$ upper limits are roughly spread around the bound $\Sigma <0.2$~eV within a factor of three. [Abridged]

   hep-phastro-ph.COhep-exnucl-exPRD(2025)·93 citations
2. 02*

   Explaining the KM3-230213A Detection without Gamma-Ray Emission: Cosmic-Ray Dark Radiation

   Yuma Narita🇯🇵 · Wen Yin🇯🇵

   Recently, a high-energy neutrino event, designated KM3-230213A, was observed by the KM3NeT/ARCA detector in the Mediterranean Sea. This event is characterized by a reconstructed muon energy of approximately 120 PeV, corresponding to a median neutrino energy of roughly 220 PeV. To understand the origin, it is essential to investigate consistency with multi-messenger observations--particularly gamma-ray constraints--in various theoretical scenarios within and beyond the Standard Model. Motivated by this, we explore the possibility that the detected event does not originate from conventional neutrinos but rather from right-handed neutrinos (sterile neutrinos) mixing with active neutrinos, leading to the observed muon signal. Such cosmic-ray dark radiation may have originated either in the early Universe or through dark matter decay in the present epoch. We show that in both cases, while satisfying existing general constraints on light sterile neutrinos, the stringent multi-messenger gamma-ray limits can be significantly alleviated. A distinct prediction of this scenario is that such events can arrive from directions through Earth that would typically attenuate conventional neutrinos. A related scenario involving cosmic-ray boosted WIMP dark matter is also discussed.

   hep-phastro-ph.COastro-ph.HEJCAP(2026)·28 citations
3. 03*

   A Brief History of Mass

   Scott Willenbrock🇺🇸

   It has been known since the 1950's that an unstable particle is associated with a complex pole in the propagator. This had to be rediscovered twice: in the early 1970's in the context of hadronic resonances, and in the early 1990's in the context of the $Z$ boson. The physical mass of the particle is the real part of the pole in the complex energy plane. In hadronic physics, this replaced the ``Breit-Wigner mass,'' which was found to depend on the parameterization of the ``energy-dependent width.'' In $Z$ physics, it replaced the ``on-shell'' mass, which was found to be gauge dependent. Although the mass defined from the complex pole position has been widely discussed in the literature, it has not yet made its way into quantum field theory textbooks.

   hep-phhep-exEur.Phys.J.Plus(2025)·6 citations
4. 04*

   The Pierre Auger Observatory and Physics Beyond the Standard Mode

   R. Aloisio (for the Pierre Auger Collaboration)🇮🇹

   The Pierre Auger Observatory, the world's largest cosmic ray detector, plays a pivotal role in exploring the frontiers of physics beyond the standard model of particle physics. By the observation of ultra-high energy cosmic rays, Auger provides critical insights into two major scenarios: super heavy dark matter and Lorentz invariance violation. Super heavy dark matter, hypothesized to originate in the early universe, offers a compelling explanation for the dark matter problem and is constrained by Auger through searches for photons and neutrinos resulting from its decay. Lorentz invariance violations, motivated by quantum gravity theories implying deviations from fundamental symmetries, are probed by Auger through alterations of the particle dispersion relation and the energy thresholds of their interactions with astrophysical photons backgrounds.

   hep-phastro-ph.HEhep-exPoS(2025)·1 citation
5. 05*

   Discriminative versus Generative Approaches to Simulation-based Inference

   Benjamin Sluijter🇳🇱 · Sascha Diefenbacher🇺🇸 · Wahid Bhimji🇺🇸 · Benjamin Nachman🇺🇸

   Most of the fundamental, emergent, and phenomenological parameters of particle and nuclear physics are determined through parametric template fits. Simulations are used to populate histograms which are then matched to data. This approach is inherently lossy, since histograms are binned and low-dimensional. Deep learning has enabled unbinned and high-dimensional parameter estimation through neural likelihiood(-ratio) estimation. We compare two approaches for neural simulation-based inference (NSBI): one based on discriminative learning (classification) and one based on generative modeling. These two approaches are directly evaluated on the same datasets, with a similar level of hyperparameter optimization in both cases. In addition to a Gaussian dataset, we study NSBI using a Higgs boson dataset from the FAIR Universe Challenge. We find that both the direct likelihood and likelihood ratio estimation are able to effectively extract parameters with reasonable uncertainties. For the numerical examples and within the set of hyperparameters studied, we found that the likelihood ratio method is more accurate and/or precise. Both methods have a significant spread from the network training and would require ensembling or other mitigation strategies in practice.

   hep-phcs.LGhep-exMach.Learn.Sci.Tech.(2025)·3 citations
6. 06*

   Constraints on new vector boson mediated electron-nucleus interactions from spectroscopy of polar diatomic molecules

   Konstantin Gaul🇩🇪 · Lei Cong🇩🇪 · Dmitry Budker🇩🇪

   A measurement of parity violation in the hyperfine structure of ${}^{138}$Ba${}^{19}$F [E. Altuntaş et al. Phys. Rev. Lett. 120, 142501 (2018)] is reinterpreted with electronic structure calculations in terms of beyond Standard Model vector boson mediated electron-nucleus interactions. Our results set constraints on previously unexplored, new boson mediated axial vector-vector nucleus-electron interactions. Similar bounds are obtained by analyzing the atomic parity violation experiment with ${}^{133}$Cs. Moreover, we show that future experiments with cold heavy diatomic molecules like ${}^{225}$RaF can improve the present sensitivity to axial vector-vector nucleus-electron and nucleon-nucleus interactions by up to five orders of magnitudes.

   hep-phphysics.atom-phphysics.chem-phPRL(2026)·7 citations
7. 07*

   Neutrino Mass Matrix with broken Scaling in light of LMA and Dark-LMA Solutions

   Ajay Kumar🇮🇳 · Dikshit Gautam🇮🇳 · Surender Verma🇮🇳

   In the present work we have investigated some patterns of broken ``scaling" ansatz of the neutrino mass matrix. The scaling neutrino mass matrix is disallowed by the current neutrino oscillation data as, among others, it predicts vanishing reactor angle (${\theta }_{13}=0$). We study its possible breaking scenarios in light of the large mixing angle (LMA) and Dark-LMA solutions suggested by current neutrino oscillation data. The normal hierarchical neutrino mass spectrum is ruled out in all three possible breaking patterns. Also, one of the interesting features of these breaking scenarios is the interplay between ${\theta }_{23}$-octant and possible CP violation. We find that the model allows maximal CP violation for ${\theta }_{23}$ above $6\%$ of its maximal value which, interestingly, is close to its current best-fit value for inverted hierarchical neutrino masses. We have, also, investigated the implications for effective Majorana neutrino mass parameter $|M_{ee}|$ for allowed breaking patterns. The correlation behavior of Majorana CP phases, which can be probed in $0\nu \beta \beta$ decay experiments, is found to have the capability of distinguishing LMA and Dark-LMA solutions.

   hep-phInt.J.Theor.Phys.(2025)·1 citation
8. 08*

   Suppressed Drell-Yan process by an external magnetic field

   Shile Chen🇨🇳 · Jiaxing Zhao🇩🇪 · Pengfei Zhuang🇨🇳

   The strongest electromagnetic fields in nature are created in high energy nuclear collisions and expected to change the dynamic scattering processes in the early stage. The magnetic field effect on the Drell-Yan process is investigated in this work. The single photon decay into quark pairs and lepton pairs in an external magnetic field leads to a significant Drell-Yan suppression in low and intermediate invariant mass region. The calculation up to the Landau level $n-1$ is complete in the energy region $s<2/3n(eB)$, and the enlarged phase space at higher landau levels may enhance the dilepton spectrum in the high mass region.

   hep-phnucl-thPLB(2025)·1 citation
9. 09*

   Relativistic spin hydrodynamics from novel relaxation time approximation

   Samapan Bhadury🇵🇱

   With the help of a semi-classical kinetic theory, a new collision kernel is proposed, which simultaneously conserves the energy-momentum tensor and the spin tensor of a relativistic fluid of spin-1/2 particles irrespective of the frame and matching conditions, even when relaxation time is momentum dependent. The relativistic Boltzmann's equation is solved using this new collision kernel to obtain the expressions of the transport coefficients with general definitions for the frame and matching conditions. The results indicate the expected existence of Barnett-like effect and the non-existence of Einstein--de-Haas-like effects.

   hep-phhep-thnucl-thPRC(2025)·7 citations
10. 10*

    Superkick Effect in Vortex Particle Scattering

    Shiyi Liu🇨🇳 · Bei Liu🇨🇳 · Igor P. Ivanov🇨🇳 · Liangliang Ji🇨🇳

    Vortex states of photons or electrons are a novel and promising experimental tool across atomic, nuclear, and particle physics. Various experimental schemes to generate high-energy vortex particles have been proposed. However, diagnosing the characteristics of vortex states at high energies remains a significant challenge, as traditional low-energy detection schemes become impractical for high-energy vortex particles due to their extremely short de Broglie wavelength. We recently proposed a novel experimental detection scheme based on a mechanism called "superkick" that is free from many drawbacks of the traditional methods and can reveal the vortex phase characteristics. In this paper, we present a complete theoretical framework for calculating the superkick effect in elastic electron scattering and systematically investigate the impact of various factors on its visibility. In particular, we argue that the vortex phase can be identified either by detecting the two scattered electrons in coincidence or by analyzing the characteristic azimuthal asymmetry in individual final particles.

    hep-phquant-phPRA(2025)·4 citations
11. 11*

    Testing the dark origin of neutrino masses with oscillation experiments

    Andrew Cheek🇨🇳 · Luca Visinelli🇮🇹 · Hong-Yi Zhang🇨🇳

    The origin of neutrino masses remains unknown to date. One popular idea involves interactions between neutrinos and ultralight dark matter, described as fields or particles with masses $m_{\varphi }\ll 10\mathrm{eV}$. Due to the large phase-space number density, this type of dark matter exists in coherent states and can be effectively described by an oscillating classical field. As a result, neutrino mass-squared differences undergo field-induced interference in spacetime, potentially generating detectable effects in oscillation experiments. We demonstrate that if $m_{\varphi }\gg 10^{-14}\mathrm{eV}$, the mechanism becomes sensitive to dark matter density fluctuations, which suppresses the oscillatory behavior of flavor-changing probabilities as a function of neutrino propagation distance in a model-independent way, thereby ruling out this regime. Furthermore, by analyzing data from the Kamioka Liquid Scintillator Antineutrino Detector (KamLAND), a benchmark long-baseline reactor experiment, we show that the hypothesis of a dark origin for the neutrino masses is disfavored for $m_{\varphi }\ll 10^{-14}\mathrm{eV}$, compared to the case of constant mass values in vacuum. This result holds at more than the 4$\sigma$ level across different datasets and parameter choices. The mass range $10^{-17}\mathrm{eV}\lesssim m_{\varphi }\lesssim 10^{-14}\mathrm{eV}$ can be further tested in current and future oscillation experiments by searching for time variations (rather than periodicity) in oscillation parameters.

    hep-phastro-ph.COhep-thPRL(2025)·9 citations
12. 12*

    Strong decays of $P_{\psi }^N(4440{)}^{+}$ and $P_{\psi }^N(4457{)}^{+}$ within the Bethe-Salpeter framework

    Qiang Li🇨🇳 · Chao-Hsi Chang🇨🇳 · Xin Tong🇨🇳 · Xiao-Ze Tan🇨🇳 · Tianhong Wang🇨🇳 · Guo-Li Wang🇨🇳

    By combining the effective Lagrangian and Bethe-Salpeter framework, we studied the mass spectra, wave functions, and strong decay widths of the two pentaquark states $P_{\psi }^N(4440{)}^{+}$ and $P_{\psi }^N(4457{)}^{+}$ reported by LHCb in 2019. Taking into account both the mass ordering and the decay widths, our results favor the interpretation of $P_{\psi }^N(4440{)}^{+}$ and $P_{\psi }^N(4457{)}^{+}$ as the isospin-$\frac{1}{2}$ $[{\bar{D}}^{\ast }{\Sigma }_c]$ molecular states with $J^P$ configuration $(\frac{3}{2}{)}^{-}$ and $(\frac{1}{2}{)}^{-}$, respectively. We first calculate the one-boson-exchange interaction kernel of $[{\bar{D}}^{\ast }{\Sigma }_c]$ in the isospin-$\frac{1}{2}$ configuration. Then we present the Bethe-Salpeter equation (BSE) and wave functions for the bound states of a vector meson and a $\frac{1}{2}$ baryon with $J^P={\frac{1}{2}}^{-}$ and ${\frac{3}{2}}^{-}$. The obtained mass results for the $(\frac{3}{2}{)}^{-}$ and $(\frac{1}{2}{)}^{-}$ are $4.442$ and $4.457$ GeV, respectively. Combining the effective Lagrangians and the BS wave functions, we further calculate the strong decay channels ${\bar{D}}^{(\ast )0}{\Lambda }_c^{+}$, $J/\psi ({\eta }_c)p$, and $\bar{D}{\Sigma }_c^{(\ast )}$ for the two $P_{\psi }^N$ states. In the favored ${\frac{3}{2}}^{-}$ and ${\frac{1}{2}}^{-}$ configuration, the obtained total widths are $21.8$ MeV and $13.0$ MeV, respectively, which are substantially consistent with the LHCb data. Our results suggest that ${\bar{D}}^0{\Lambda }_c^{+}$ and ${\bar{D}}^{(\ast )0}{\Lambda }_c^{+}$ are the dominant decay channels to detect $P_{\psi }^N(4440{)}^{+}$ and $P_{\psi }^N(4457{)}^{+}$, respectively.

    hep-phhep-exhep-latJHEP(2025)·8 citations
13. 13*

    Investigating the broadening phenomenon in two-particle correlations induced by gluon saturation

    Kiera Cassar🇺🇸 · Zhen Wang🇨🇳 · Xiaoxuan Chu🇺🇸 · Elke-Caroline Aschenauer🇺🇸

    It has been found that the gluon density inside the proton grows rapidly at small momentum fractions. Quantum Chromodynamics (QCD) predicts that this growth can be regulated by nonlinear effects, ultimately leading to gluon saturation. Within the color glass condensate framework, nonlinear QCD effects are predicted to suppress and broaden back-to-back angular correlations in collisions involving heavy nuclei. While suppression has been observed in various experiments in $d/p$$+$A collisions compared to $p$$+$$p$ collisions, the predicted broadening remains unobserved. This study investigates the contributions of intrinsic transverse momentum ($k_T$), which is associated with saturation physics, as well as parton showers and transverse motion from fragmentation ($p_T^{\mathrm{frag}}$), which are not saturation dependent, to the width of the correlation function. Our findings show that the non-saturation dependent effects, especially the initial-state parton shower and $p_T^{\mathrm{frag}}$, which occur independently of the collision system, smear the back-to-back correlation more than gluon saturation does, making the broadening phenomenon difficult to observe.

    hep-phnucl-exnucl-thPRD(2025)·6 citations
14. 14*

    Light-by-Light scattering in ultraperipheral heavy ion collisions: Estimating inelastic contributions

    Mariola Klusek-Gawenda🇵🇱 · Victor P. Goncalves🇧🇷 · Antoni Szczurek🇵🇱

    The current state-of-the-art theoretical estimations lead to cross-sections for $AA\to \gamma \gamma AA$ which are somewhat smaller than the measured ones by the ATLAS and CMS Collaborations, which motivates the searching and calculation of subleading corrections disregarded in these previous studies. In this paper, we estimate for the first time the contribution of inelastic channels to the Light-by-Light (LbL) scattering in ultraperipheral collisions of heavy ions (UPHICs), in which one or both of the incident nuclei dissociate ($AA\to \gamma \gamma XY$ where $X,Y=A,A^{\prime }$) due to the photon emission. These new mechanisms are related to extra emissions that are rather difficult to identify at the LHC and may be misinterpreted as enhanced $\gamma \gamma \to \gamma \gamma$ scattering compared to the Standard Model result. We include processes of coupling of photons to individual nucleons (protons and neutrons) in addition to coherent coupling to the whole nuclei (called standard approach here). Both elastic (nucleon in the ground state) and inelastic (nucleon in an excited state) in the couplings of photons to nucleons are taken into account. The inelastic nucleon fluxes are calculated using CT18qed photon in nucleon PDFs. The inelastic photon fluxes are shown and compared to standard photon fluxes in the nucleus. In addition, we show the ratio of the inelastic corrections to the standard contribution as a function of diphoton invariant mass and photon rapidity difference. We find that for the ATLAS acceptance region the inelastic corrections grow with $M_{\gamma \gamma }$ and rapidity difference. Our results indicate that the inelastic contributions can be of the order of 20-40 \% of the traditional (no nuclear excitation) predictions. Uncertainties due to factorization scale choice are quantified.

    hep-phnucl-thPLB(2025)·7 citations
15. 15*

    Hydrogenlike molecules composed of $D_1{D}_1$, $D_1{D}_2^{\ast }$ and $D_2^{\ast }{D}_2^{\ast }$

    Hu-Hua He🇨🇳 · Mao-Jun Yan🇨🇳 · Chun-Sheng An🇨🇳 · Cheng-Rong Deng🇨🇳

    We systematically explore the S-wave $D_1{D}_1$, $D_1{D}_2^{\ast }$ and $D_2^{\ast }{D}_2^{\ast }$ states with various isospin-spin-orbit ($ISL$) configurations in the quark model. We propose nine stable dimeson states with the $ISL$ configurations, $ISL=001$, $010$, $012$, $100$, $102$, $110$, $112$, $120$, and $122$, against dissociation into their constituent mesons. Those bound states are hydrogenlike molecular states, where the two subclusters are moderately overlapped and the QCD covalent bond is formed due to the delocalization of light quarks. The QCD covalent bond serves as the primary binding mechanism in the bound states with $I=1$. However, the exchange of $\pi$ and $\sigma$-meson plays a pivotal role in the bound states with $I=0$. The coupled-channel effect is essential in the formation of the bound states with $ISL=001$, $010$, $012$, $100$, and $102$.

    hep-phPRD(2025)·1 citation
16. 16*

    On new physics off the Z peak in $H\to {\ell }^{+}{\ell }^{-}\gamma$

    Aliaksei Kachanovich🇧🇪 · Jean Kimus🇧🇪 · Steven Lowette🇧🇪 · Michel H.G. Tytgat🇧🇪

    Motivated by a small but intriguing excess observed in the decay mode $H\to {\ell }^{+}{\ell }^{-}\gamma$ reported by both the ATLAS and CMS collaborations, we explore the possibility that new physics contributes directly to the effective $H\ell \overline{\ell }\gamma$ coupling rather than modifying the $Z$ peak. Concretely, we consider a dimension-8 operator that could arise from new particles via box diagrams. Such non-resonant contribution may provide an alternative origin for current or future excesses. We examine how experimental cuts may distinguish between possible modifications of the $Z$ peak and non-resonant contributions. The currently measured excess requires that the new physics scale is relatively low $({\Lambda }_R\sim v$). However, we show that it may remain within current experimental bounds. In particular, we illustrate this using a simplified model, motivated by the dark matter problem, and discuss its other experimental constraints.

    hep-phhep-exJHEP(2025)·6 citations
17. 17*

    Long-lived Light Mediators in a Higgs Portal Model at the FCC-ee

    Biplob Bhattacherjee🇮🇳 · Camellia Bose🇮🇳 · Herbi K. Dreiner🇩🇪 · Nivedita Ghosh🇯🇵 · Shigeki Matsumoto🇯🇵 · Rhitaja Sengupta🇩🇪

    In the search for beyond the Standard Model (SM) physics, long-lived particles (LLPs) have emerged as potential candidates and are being explored in various ongoing experiments. Future lepton colliders, such as the FCC-ee, shall provide an excellent opportunity to probe LLPs, owing to their clean environment and improved particle identification. This study investigates the potential of the proposed \textbf{I}nnovative \textbf{D}etector for an \textbf{E}lectron-Positron \textbf{A}ccelerator (IDEA) detector at FCC-ee in the detection of LLPs produced from $B$-meson and Higgs boson decays. We explore benchmark scenarios for different final states resulting from LLP decays, including a detailed analysis of the SM long-lived hadronic background. Additionally, we propose dedicated LLP detectors with different configurations, dimensions, and locations with respect to the IDEA detector. DELIGHT B, originally proposed as a dedicated LLP detector for the FCC-hh, stands out as the detector with the maximum efficiency for detecting LLPs produced at FCC-ee. We find that cylindrical detector configurations, if feasible to construct around the IDEA detector, would also enhance sensitivity for LLPs mostly decaying outside it.

    hep-phhep-exPRD(2026)·9 citations
18. 18*

    Exotic $h\to Za$ Higgs decays into $\tau$ leptons

    M. Cepeda🇪🇸 · J.M. No🇪🇸 · C. Ramos🇧🇷 · R.M. Sandá Seoane🇪🇸 · J. Zurita🇪🇸

    Exotic Higgs decays are among the most promising areas to be explored at the High-Luminosity LHC, given the unprecedentedly large amount $(\sim 3\times 10^8)$ of 125 GeV Higgs bosons that will be produced. In this context, we propose a new search channel for which the Higgs boson decays to a (leptonically decaying) $Z$ boson and a light BSM pseudoscalar $a$, which subsequently decays to a pair of $\tau$-leptons ($h\to Za\to \ell \ell \tau \tau$). After performing a validation of existing ATLAS and CMS exotic Higgs decay searches in related channels, we analyze the HL-LHC projected sensitivity of our $a\to \tau \tau$ search, targeting the kinematic region where the exotic Higgs decay is two-body. We are able to probe pseudoscalar masses $m_a\in [5,33]$ GeV by leveraging both leptonic and hadronic $\tau$ decays, and establish model-independent 95\% C.L. sensitivity projections on the branching fraction $\mathrm{BR}(h\to Za)\times \mathrm{BR}(a\to \tau \tau )$. These $a\to \tau \tau$ projections yield a competitive probe of light pseudoscalars, which depending on the model can become significantly more sensitive than projections from existing experimental searches in $a\to \mu \mu$ and $a\to \gamma \gamma$ final states. Finally, we explore the potential of our search to probe an Axion-Like-Particle (ALP) solution to the muon $(g-2)$ anomaly (when taken face-value), finding that our proposed $h\to Za$, $a\to \tau \tau$ search can provide valuable constraints on such ALP scenario, in complementarity with existing $h\to Za$, $a\to \gamma \gamma$ experimental searches.

    hep-phJHEP(2025)·2 citations
19. 19*

    Exploring the gluon Sivers function in photon + jet production

    Deepesh Bhamre🇧🇷 · Aman Gupta🇮🇳 · Anuradha Misra🇮🇳 · Siddhesh Padval🇮🇳

    We study transverse single spin asymmetries (TSSAs) in back-to-back photon plus jet production in the scattering of unpolarized beams of protons off a transversely polarized proton target as probes of Gluon Sivers Function (GSF). We provide estimates within the region where the imbalance ${\vec{q}}_{\perp }\equiv {\vec{p}}_{\gamma \perp }+{\vec{p}}_{J\perp }$ between the transverse momenta of the photon and the jet is much smaller than the average of the transverse momenta ${\vec{p}}_{\perp }\equiv |{\vec{p}}_{\gamma \perp }-{\vec{p}}_{J\perp }|/2$ i.e. the back-to-back region. The presence of these two scales in the process makes it particularly suitable for applying transverse momentum dependent (TMD) factorization, in contrast to single-scale processes that rely on the generalized parton model approach. We present our preliminary results of the transverse single spin asymmetry for this process at $\sqrt{s}$ = 200 GeV.

    hep-phSpringer Proc.Phys.(2026)·0 citations
20. 20*

    Effects of the Cosmic Neutrino Background Capture on Astrophysical Objects

    Beatriz Hernandez-Molinero🇪🇸 · Raul Jimenez🇪🇸 · Carlos Peña Garay🇪🇸

    Low-energy neutrinos from the cosmic background are captured by objects in the sky that contain material susceptible of single beta decay. Neutrons, which compose most of a neutron star, capture low-energy neutrinos from the cosmic neutrino background and release a high-energy electron in the MeV range. Also, planets contain unstable isotopes that capture the cosmic neutrinos. We show that this process is feasible and results in a non-negligible flux of electrons in the MeV range in neutron stars. We present a novel observable, the redshift evolution of the temperature of neutron stars due to neutrino capture, that could provide a route for detection of the cosmic neutrino background from future gravitational waves observatories. For planets the flux is significantly smaller and a measurement is not possible with currently envisioned technology. While the signature from neutron stars is small and challenging, it could result in a novel way to detect the cosmic neutrino background.

    ↳ astro-ph.COastro-ph.EPastro-ph.HEastro-ph.SR+1JCAP(2026)·3 citations
21. 21*

    Feynman integrals at large loop order and the $\log$-$\Gamma$ distribution

    Michael Borinsky🇨🇦 · Andrea Favorito🇨🇭

    We find empirically that the value of Feynman integrals follows a $\log$-$\Gamma$ distribution at large loop order. This result opens up a new avenue towards the large-order behavior in perturbative quantum field theory. Our study of the primitive contribution to the scalar ${\varphi }^4$ beta function in four dimensions up to 17 loops provides accompanying evidence. Guided by instanton considerations, we discuss the extrapolation of this contribution to all loop orders.

    ↳ hep-thhep-phmath-phmath.MPJHEP(2025)·6 citations
22. 22*

    Oscillations of the black hole photon ring as a probe of ultralight dilaton fields

    Chunlong Li🇨🇳 · Chao Chen🇨🇳 · Xiao Yan Chew🇨🇳

    Advancements of very long baseline interferometry (VLBI) have facilitated unprecedented probing of superradiant phenomena in the vicinities of supermassive black holes (SMBHs), establishing an ideal laboratory to detect ultralight bosons beyond the Standard Model. In this study, we delve into how ultralight dilaton clouds, formed via SMBH superradiance, impact the black hole photon rings. Our focus is on the dilaton-electromagnetic coupling term of the form $f(\varphi )F_{\mu \nu }{F}^{\mu \nu }$. By integrating geometric optics with plasma refractive effects in accretion environments, we demonstrate that the dilaton cloud dynamically alters the plasma frequency. Through systematic ray-tracing simulations covering a range of photon frequencies and dilaton coupling strengths, we reveal a photon ring oscillation that follows the period of that of the dilaton field. As the dilaton mass increases, this oscillation becomes suppressed due to the washout effect of the dilaton-induced correction term over the light path integration. We further evaluated the observability of such dilaton-induced photon ring oscillations with current radio interferometric capabilities. Our estimates indicate that this effect could potentially constrain the dilaton-photon coupling to $g_{\varphi \gamma }\lesssim 10^{-11}{\text{GeV}}^{-1}$ for dilaton masses $\mu \lesssim 10^{-18}\mathrm{eV}$.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-ph2 citations
23. 23*

    Interference between Meson Exchange and One-Body Currents in Quasielastic Electron Scattering

    P.R. Casale🇪🇸 · J.E. Amaro🇪🇸 · V. Belocchi🇮🇹 · M.B Barbaro🇮🇹 · A De Pace🇮🇹 · Marco Martini🇫🇷

    In this work, we present a detailed analysis of the interference between meson exchange currents (MEC) and one-body currents in quasielastic electron scattering, with a focus on the sign of this interference in the transverse response for one-particle emission. We prove that the interference of both the Delta and pion-in-flight currents with the one-body current is negative, leading to a partial cancellation with the seagull current. This is mathematically demonstrated within the framework of the Fermi gas model. By comparing these interferences across various independent particle models, both relativistic and non-relativistic, our results indicate that all studied models display the same behavior. This consistency suggests that the interference is negative in models that do not incorporate tensor correlations in the nuclear wave function.

    ↳ nucl-thhep-phPRC(2025)·9 citations
24. 24*

    Density matrices in quantum field theory: Non-Markovianity, path integrals and master equations

    Christian Käding🇦🇹 · Mario Pitschmann🇦🇹

    Density matrices are powerful mathematical tools for the description of closed and open quantum systems. Recently, methods for the direct computation of density matrix elements in scalar quantum field theory were developed based on thermo field dynamics (TFD) and the Schwinger-Keldysh formalism. In this article, we provide a more detailed discussion of these methods and derive expressions for density matrix elements of closed and open systems. At first, we look at closed systems by discussing general solutions to the Schrödinger-like form of the quantum Liouville equations in TFD, showing that the dynamical map is indeed divisible, deriving a path integral-based expression for the density matrix elements in Fock space, and explaining why perturbation theory enables us to use the last even in situations where all initial states in Fock space are occupied. Subsequently, we discuss open systems in the same manner after tracing out environmental degrees of freedom from the solutions for closed systems. We find that, even in a general basis, the dynamical map is not divisible, which renders the dynamics of open systems non-Markovian. Finally, we show how the resulting expressions for open systems can be used to obtain quantum master equations, and comment on the artificiality of time integrals over density matrices that usually appear in many other master equations in the literature but are absent in ours.

    ↳ hep-thhep-phquant-ph22 citations
25. 25*

    Cosmic topology. Part IIIb. Eigenmodes and correlation matrices of spin-2 perturbations in orientable Euclidean manifolds

    Amirhossein Samandar🇺🇸 · Javier Carrón Duque🇪🇸 · Craig J. Copi🇺🇸 · Mikel Martin Barandiaran🇪🇸 · Deyan P. Mihaylov🇺🇸 · Glenn D. Starkman🇺🇸 · Yashar Akrami🇪🇸 · Stefano Anselmi🇮🇹 · Fernando Cornet-Gomez🇺🇸 · Johannes R. Eskilt🇳🇴 · Andrew H. Jaffe🇬🇧 · Arthur Kosowsky🇺🇸 and 4 other authors

    We study the eigenmodes of the spin-2 Laplacian in orientable Euclidean manifolds and their implications for the tensor-induced part of the cosmic microwave background (CMB) temperature and polarization anisotropies. We provide analytic expressions for the correlation matrices of Fourier-mode amplitudes and of spherical harmonic coefficients. We demonstrate that non-trivial spatial topology alters the statistical properties of CMB tensor anisotropies, inducing correlations between harmonic coefficients of differing $\ell$ and $m$ and across every possible pair of temperature and $E$- and $B$-modes of polarization. This includes normally forbidden $TB$ and $EB$ correlations. We compute the Kullback-Leibler (KL) divergence between the pure tensor-induced CMB fluctuations in the usual infinite covering space and those in each of the non-trivial manifolds under consideration, varying both the size of the manifolds and the location of the observer. We find that the amount of information about the topology of the Universe contained in tensor-induced anisotropies does not saturate as fast as its scalar counterpart; indeed, the KL divergence continues to grow with the inclusion of higher multipoles up to the largest $\ell$ we have computed. Our results suggest that CMB polarization measurements from upcoming experiments can provide new avenues for detecting signatures of cosmic topology, motivating a full analysis where scalar and tensor perturbations are combined and noise is included.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·10 citations
26. 26*

    Exact Results in Chiral Gauge Theories with Flavor

    Jacob M. Leedom🇨🇿 · Hitoshi Murayama🇺🇸 · Gup Singh🇺🇸 · Bethany Suter🇺🇸 · Jason Wong🇺🇸

    We present exact results in softly-broken supersymmetric $\text{SU}(N_C)$ chiral gauge theories with charged fermions in one antisymmetric, $N_F$ fundamental, and $N_C+N_F-4$ anti-fundamental representations. We achieve this by considering the supersymmetric version of these theories and utilizing anomaly mediated supersymmetry breaking at a scale $m\ll \Lambda$ to generate a vacuum. The connection to non-supersymmetric theories is then conjectured in the limit $m\to \infty$. For odd $N_C$, we determine the massless fermions and unbroken global symmetries in the infrared. For even $N_C$, we find global symmetries are non-anomalous and no massless fermions. In all cases, the symmetry breaking patterns differ from what the tumbling hypothesis would suggest.

    ↳ hep-thhep-phPRD(2025)·8 citations
27. 27*

    Echoes of Self-Interacting Dark Matter from Binary Black Hole Mergers

    Amitayus Banik🇰🇷 · Jeong Han Kim🇰🇷 · Jun Seung Pi🇰🇷 · Yuhsin Tsai🇺🇸

    Dark matter (DM) environments around black holes (BHs) can influence their mergers through dynamical friction, causing gravitational wave (GW) dephasing during the inspiral phase. While this effect is well studied for collisionless dark matter (CDM), it remains unexplored for self-interacting dark matter (SIDM) due to the typically low DM density in SIDM halo cores. In this work, by considering BH mergers within SIDM spikes, which can arise from models with a massive force mediator, we show that the GWs emitted are dephased in a distinct manner. To incorporate the feedback of the BH orbital motion that can significantly modify the DM profiles, we use $N$-body simulations to analyze GW dephasing in binary BH inspirals within CDM and SIDM spikes. By tracking the binary's motion in different DM environments, we show that the Laser Interferometer Space Antenna (LISA) can observe GW dephasing arising from SIDM spikes in particular scenarios. Our results indicate that these observations offer a possibility of distinguishing between binary-BH inspirals in different DM environments.

    ↳ astro-ph.COhep-phPRD(2026)·5 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.