Thu·May 15, 2025Thursday·May 15, 2025

1. 01*

   Effects of virtual Majorana neutrinos on charged Lepton Flavor Violation decays from a seesaw variant with radiatively induced light neutrino masses

   Enrique Ramírez🇲🇽 · Héctor Novales-Sánchez🇲🇽 · Humberto Vázquez-Castro🇲🇽 · Mónica Salinas🇲🇽

   Lepton flavor violating decays ${\ell }_{\alpha }\to {\ell }_{\beta }\gamma$, being forbidden in the Standard Model framework, provide a sensitive probe for new physics. We study these processes in a seesaw variant in which small neutrino masses are generated radiatively. By analyzing the parameter space constrained by electroweak precision data, we investigate the correlation between these decays and non-unitary effects from TeV-scale heavy neutrinos. According to our results, $\mu \to e\gamma$ is the most promising channel for new physics searches, with the bound $|{\eta }_{\mu e}|\lesssim 10^{-6}$ obtained for non-unitary effects in this radiative seesaw variant. Our estimations of $\mathcal{B}\mathcal{R}\left(\mu \to e\gamma \right)$, which depends on the mass of the heavy neutrinos, shows that both current and future experimental facilities might be sensitive to these effects.

   hep-phhep-exJ.Phys.G(2025)·3 citations
2. 02*

   Charmed Meson Structure across Crossover from SU(4) Polyakov Quark Meson Model with Isospin Asymmetry

   Abdel Magied Diab (MUTI, Cairo)🇪🇬

   The Polyakov Quark Meson (PQM) model is extended to SU(4) flavor symmetry by incorporating the charm quark and introducing a finite isospin asymmetry. This model incorporates the light, strange, and charm chiral condensates, along with the Polyakov-loop variables, to describe the confinement--deconfinement phase transition in a thermal and dense QCD medium. The inclusion of the charm quark condensate enhances the capability of the SU(4) PQM model to explore the spatial and thermal resolution of the chiral phase structure, particularly in the crossover and high-temperature regimes. We construct the QCD phase diagram ($T/T_{\chi }-{\mu }_I/m_{\pi }$) plane, indicating a decrease in the pseudo-critical temperature as the isospin chemical potential increases and explore thermodynamic quantities related to the QCD equation of state at very high temperatures. Fluctuations of quark flavors, conserved charges and baryon-charm correlations are studied across a wide temperature range. The SU(4) PQM model exhibits good qualitative agreement with lattice QCD calculations. Additionally, we calculate the meson mass spectrum at zero and finite temperature, showing that the charm sector remains thermally stable over a wide temperature range. Overall, this study highlights the capability of the SU(4) PQM model to describe key features of QCD matter at high temperatures and its relevance to heavy-ion collisions and astrophysical studies.

   hep-phhep-thCPC(2026)·1 citation
3. 03*

   Measuring the Cosmic Ray Spectrum with Next Generation Neutrino Detectors

   Stephan A. Meighen-Berger🇦🇺 · Jayden L. Newstead🇦🇺 · Louis E. Strigari🇺🇸

   We investigate the capabilities of upcoming kiloton-scale neutrino detectors, such as Hyper-Kamiokande, in determining the primary cosmic ray spectrum. These detectors provide full-sky coverage and long-term monitoring, unlike traditional satellite and balloon experiments that measure cosmic ray flux at specific altitudes and locations. By analyzing the atmospheric neutrino flux generated by cosmic ray interactions, we demonstrate that future detectors can differentiate between various cosmic ray models with high statistical significance, even when accounting for uncertainties in neutrino cross sections and hadronic interactions. We introduce a technique for reconstructing the primary cosmic ray spectrum using neutrino measurements, which reduces the flux uncertainty from approximately 20\% to about 7\%. We then show that Hyper-K has the potential to increase sensitivity to neutrino oscillation parameters, such as ${\sin }^2{\theta }_{23}$, by a factor of 2. Our results highlight the complementary role of neutrino detectors in cosmic ray physics and their critical importance for precision measurements in particle astrophysics.

   hep-phastro-ph.HE1 citation
4. 04*

   Neutrino Fluence influenced by Memory Burdened Primordial Black Holes

   Arnab Chaudhuri🇯🇵 · Koushik Pal🇮🇳 · Rukmani Mohanta🇮🇳

   We study the impact of quantum gravitational memory burden - a backreaction effect that suppresses black hole evaporation - on neutrino signals from primordial black holes (PBHs). This suppression, modeled via a parameter k, reduces the high-energy muon neutrino fluence, particularly during the late stages of evaporation. We also consider beyond the Standard Model scenarios in which heavy neutral leptons (HNLs) are emitted by PBHs and subsequently decay, injecting secondary neutrinos that partially mitigate the suppression in the MeV-GeV range. We compute the full time-integrated neutrino spectrum and evaluate the expected IceCube event rates across the (k, mN) parameter space. We analyze both single source burst scenarios and the cumulative Galactic contribution assuming PBHs trace a realistic dark matter halo distribution. Even under optimistic proximity assumptions, the predicted event rates remain far below IceCube sensitivity, and population-level stacking within current observational bounds on the PBH abundance does not yield an observable signal in the considered mass range for PBH abundances consistent with existing observational constraints. These results demonstrate that entropy-suppressed evaporation substantially weakens neutrino detectability of light PBHs and must be consistently incorporated in future multi-messenger searches.

   hep-phNPB(2026)·11 citations
5. 05*

   Angular momentum of vacuum bubbles in a first-order phase transition

   Jan Tristram Acuña🇹🇼 · Danny Marfatia🇺🇸 · Po-Yan Tseng🇹🇼

   The formation of primordial black holes (PBHs) during a first-order phase transition (FOPT) in a dark sector has been of recent interest. A quantity that characterizes a black hole is its spin. We carry out the first step towards determining the spin of such PBHs, by calculating the spin of spherical false vacuum bubbles induced by cosmological perturbations. The angular momentum is given by the product of density and velocity perturbations. We carefully track the evolution of background quantities and calculate the transfer functions during the FOPT. We find that the dimensionless spin parameter $s=J/(G_{\mathrm{N}}{M}^2)$ of false vacuum bubbles of mass $M$ and angular momentum $J$, take a wide range of values from $\mathcal{O}(10^{-5})$ to $\mathcal{O}(10)$ for FOPTs between 10 keV and 100 GeV and a dark sector that is 0.1 to 0.4 times cooler than the visible sector. We also find a scaling relation between the root-mean-square value of the spin, the FOPT time scale, the bubble wall velocity, and the dark sector-to-visible sector temperature ratio.

   hep-phastro-ph.COhep-exJCAP(2026)·1 citation
6. 06*

   Valence quark distribution of light $\rho$ and heavy $J/\psi$ vector mesons in light-cone quark model

   Tanisha🇮🇳 · Satyajit Puhan🇮🇳 · Anurag Yadav🇮🇳 · Harleen Dahiya🇮🇳

   In this work, we have investigated the valence quark structure of light $\rho$ and heavy $J/\psi$ vector mesons using the light-cone quark model through unpolarized quark generalized parton distributions (GPDs). By solving the quark-quark correlator, we have represented the quark GPDs in the form of light-front wave function (LFWFs). The charge, magnetic, and quadrupole form factors of these particles have been derived from the unpolarized quark GPDs and compared with the available theoretical predictions and lattice simulation data. The structure functions corresponding to the Rosenbluth scattering cross section of these mesons have also been calculated and compared with the available NJL model predictions. The results of our calculations are found to follow a similar trend as the other model results. We have also calculated the parton distribution functions (PDFs) of these particles in the forward limit of GPDs. The calculated PDFs have also been evolved to 5 GeV ${}^2$ through next to next leading order Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolutions.

   hep-phPRD(2025)·9 citations
7. 07*

   Constraints On New Theories Using Rivet : CONTUR version 3 release note

   Andy Buckley🇬🇧 · Jon Butterworth🇬🇧 · Joseph Egan🇬🇧 · Christian Gutschow🇬🇧 · Sihyun Jeon🇺🇸 · Martin Habedank🇬🇧 · Tomasz Procter🇵🇱 · Peng Wang🇬🇧 · Yoran Yeh🇬🇧 · Luzhan Yue🇬🇧

   The CONTUR toolkit exploits RIVET and its library of more than a thousand energy-frontier differential cross-section measurements from the Large Hadron Collider to allow rapid limit-setting and consistency checks for new physics models. In this note we summarise the main changes in the new CONTUR 3 major release series. These include additional statistical treatments, efficiency improvements, new plotting utilities and many new measurements and Standard Model predictions.

   hep-phhep-ex7 citations
8. 08*

   Quantum Entanglement Theory and Its Generic Searches in High Energy Physics

   Junle Pei🇨🇳 · Yaquan Fang🇨🇳 · Lina Wu🇨🇳 · Da Xu🇨🇳 · Mustapha Biyabi🇨🇳 · Tianjun Li🇨🇳

   We propose a new formalism for quantum entanglement (QE), and study its generic searches at the colliders. For a general quantum system with $N$ particles, we show that the quantum space (the total spin polarization parameter space) is complex projective space, and the classical space (the spin polarization parameter space for classical theory) is the cartesian product of the complex projective spaces. Thus, the quantum entanglement space is the difference of these two spaces. For the $ff$, $AA$, $Af$, $fff$, and $ffA$ systems, we propose their discriminants ${\Delta }_i$. The corresponding classical spaces are the discriminant locus $\Delta =0$ for $ff$ system, and intersections of the discriminant loci ${\Delta }_i=0$ for $AA$, $Af$, $fff$, and $ffA$ systems in the quantum space. In particular, for two fermion $ff$ system, we prove that our discriminant criterion is equivalent to the original Peres-Horodecki criterion and the CHSH criterion. And thus our quantum entanglement space is indeed Bell non-local. With the collider searches, we can reconstruct the discriminants from various measurements, and probe the quantum entanglement spaces via a fundamental approach at exact level. In addition, for the specific approach, we present a comprehensive framework to detect quantum entanglement in high-energy multi-particle systems, spanning fermion pairs ($t\bar{t}$, ${\tau }^{+}{\tau }^{-}$), bosonic pairs ($W^{-}{W}^{+}$), and hybrid or three-body systems ($W^{-}t$, $ttt$, $t\bar{t}{W}^{-}$), by diverse observables through angular correlations in decay products. These results establish model-independent methodologies for probing QE across collider experiments, bridging quantum information principles with high-energy phenomenology, while offering novel pathways to explore exotic particles and quantum properties in multi-particle systems.

   hep-phhep-th9 citations
9. 09*

   Eddington-inspired Born-Infeld gravity: Constraints from the generalized parton distributions (GPDs)

   The MMGPDs Collaboration · Muhammad Goharipour · Anoushiravan Moradi · K. Azizi

   The Eddington-inspired Born-Infeld (EiBI) theory of gravity modifies general relativity in high-density regimes. It offers an alternative framework that avoids cosmological singularities and remodels gravitational dynamics within compact objects. An important feature of EiBI gravity is its additional parameter, $\kappa$, which governs deviations from standard gravitational behavior. In this study, we investigate constraints on $\kappa$ using the internal pressure distribution of the proton, derived from gravitational form factor (GFF) $D(t)$ obtained through a QCD analysis of generalized parton distributions (GPDs). By comparing pressure profiles extracted from skewness-dependent GPDs with previous determinations based on deeply virtual Compton scattering (DVCS) data, we establish updated bounds on $\kappa$. Our results show that the choice of proton pressure model significantly impacts the constraints, with the strongest limits ($|\kappa |\le 0.10\text{–}0.3{\text{m}}^5{\text{kg}}^{-1}{\text{s}}^{-2}$). We further demonstrate that constraints obtained based on the first and second moments of the pressure distribution yield competitive bounds compared to those derived from peak pressures or those derived from just the first moment. These findings highlight the importance of precise experimental and theoretical determinations of the proton's mechanical properties in testing alternative theories of gravity. The present study motivates future improvements in GPD reconstructions for stronger constraints on EiBI gravity and related modifications.

   hep-phgr-qchep-thPLB(2025)·1 citation
10. 10*

    Flavour Non-Singlet Splitting Functions at Four Loops in QCD -- The Fermionic Contributions

    B.A. Kniehl🇩🇪 · S. Moch🇩🇪 · V.N. Velizhanin (U. Hamburg)🇩🇪 · A. Vogt (Liverpool U., Dept. Math.)🇬🇧

    We have determined the fourth-order $n_f$ contributions to the two splitting functions governing the evolution of all flavor differences of quark distributions of hadrons in perturbative quantum chromodynamics with $n_f$ light flavors. The analytic forms of these functions are presented in both Mellin $N$-space and momentum-fraction $x$-space for a general gauge group. In the small-$x$ limit double logarithms occur, but the small-$x$ rise of both splitting functions is confined to extremely small $x$-values, $x\lesssim 10^{-6}$. The large-$x$ limit includes the $n_f$-part of the four-loop quark virtual anomalous dimension. Using this result we obtain also the $n_f$ contributions to the corresponding gluonic quantity and the complete threshold-enhanced logarithms from soft-gluon emission for a large class of inclusive observables, including Higgs boson production in gluon-gluon fusion.

    hep-phPRL(2025)·24 citations
11. 11*

    Pion in the Bethe-Salpeter approach with separable kernel

    S. Bondarenko (1,2)🇷🇺 · M. Slautin (1,2) ((1) Joint Institute for Nuclear Research, Dubna, Russia, (2) Dubna State University, Dubna, Russia)🇷🇺

    In the paper, the static and dynamic properties of the pion in the Bethe-Salpeter approach are considered. The rank-one separable kernel of the quark-antiquark interaction is used to solve the equation analytically. Multidimensional integrals describing pion properties are calculated by several numerical methods and compared with previous papers. An error in the calculation of the interaction part of the elastic pion form factor is found. Using the corrected results, the kernel parameters are refitted. The calculated static properties as well as transition and elastic form factors are presented in comparison with the recent experimental data.

    hep-phnucl-thPhys.Part.Nucl.Lett.(2025)·2 citations
12. 12*

    Benchmarking a fading window: electroweak baryogenesis in the C2HDM, LHC constraints after Run 2 and prospects for LISA

    Thomas Biekötter🇪🇸 · María Olalla Olea-Romacho🇬🇧

    The origin of the baryon asymmetry of the universe remains one of the most pressing open questions in particle physics and cosmology. Electroweak baryogenesis offers an experimentally testable explanation, requiring new sources of CP violation and a strong first-order electroweak phase transition. The Two Higgs doublet model (2HDM) is the simplest scalar extension of the Standard Model that can accommodate both ingredients. We critically assess the viability of the complex 2HDM (C2HDM) (a 2HDM with a softly broken ${\mathbb{Z}}_2$ symmetry and a single source of explicit CP violation in the Higgs sector) as a framework for electroweak baryogenesis, incorporating for the first time a comprehensive set of LHC Run 2 results at 13 TeV. By defining CP-violating benchmark planes tailored for a strong first-order electroweak phase transition, we identify regions of parameter space motivated by electroweak baryogenesis that will be testable at the LHC, and at future space-based gravitational wave experiments. The benchmark planes are intended to guide ongoing efforts in defining representative scenarios for the exploration of CP-violation in extended scalar sectors at the LHC Run 3 and beyond, while also assessing the emerging synergy between the LHC and future gravitational wave observatories such as LISA. We also quantify the current tension between the realisation of electroweak baryogenesis and the non-observation of the electron electric dipole moment (EDM), finding that the predicted electron EDMs typically exceed the experimental limits by at least an order of magnitude.

    hep-phJHEP(2025)·13 citations
13. 13*

    Illuminating Very Heavy Dark Matter in the Earth with Tau Neutrinos

    Tianyi Ding🇺🇸 · Ali Kheirandish🇺🇸 · Qinrui Liu🇨🇦

    Dark matter accumulates in the center of the Earth as the planet plows through the dark matter halo in the Milky Way. Possible annihilation of dark matter to Standard Model particles can be probed in indirect dark matter searches. Among possible messengers, neutrinos are uniquely ideal as they can escape dense regions. Therefore, neutrino telescopes, with their large volume and broad energy exposures, offer new opportunities to search for dark matter signals from the center of the Earth. However, such studies have been restricted to dark matter masses below $\sim$ PeV as the Earth becomes opaque to very-high-energy neutrinos. In this study, we demonstrate that neutrino telescopes operating at TeV-PeV energies can probe very heavy dark matter particles if they annihilate to tau neutrinos or tau leptons. Here, we report upper limits on the spin-independent dark matter-nucleon cross section for masses between $10^5$ GeV and $10^{10}$ GeV by using 7.5 years of IceCube high-energy starting event observations. Our results motivate detailed analyses in IceCube and other upcoming neutrino telescopes in the Northern Hemisphere.

    hep-phastro-ph.HEJCAP(2026)·2 citations
14. 14*

    Towards testing $(g-2{)}_{\tau }$ in $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$: radiative corrections and projections for Belle II

    Joël Gogniat🇨🇭 · Martin Hoferichter🇨🇭 · Yannick Ulrich🇬🇧

    The arguably most promising avenue towards testing physics beyond the Standard Model in the anomalous magnetic moment of the $\tau$ proceeds via suitably constructed asymmetries in $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$ in the presence of a polarized electron beam. Such a program, as could be realized at Belle II assuming a polarization upgrade of the SuperKEKB $e^{+}{e}^{-}$ collider, crucially relies on a careful consideration of radiative corrections. In this work, we present the complete one-loop result for the fully polarized $e^{+}{e}^{-}\to {\tau }^{+}{\tau }^{-}$ process and its implementation in the Monte-Carlo integrator McMule. As an application, we discuss projections relevant for measurements at Belle II, both with and without electron polarization, and outline the necessary steps for a generalization to next-to-next-to-leading order.

    hep-phhep-exnucl-thJHEP(2025)·16 citations
15. 15*

    Neutrino-less double beta decay in the $\nu$ Standard Model

    Vincenzo Cirigliano🇺🇸 · Wouter Dekens🇺🇸 · Sebastián Urrutia Quiroga🇺🇸

    We perform a comprehensive study of the $3+3$ Type-I seesaw model for a broad range of right-handed mass scales (from keV to 10 TeV). We take into account and, in some cases, update the constraints from a large number of high- and low-energy experiments and study the implications on neutrino-less double beta ($0\nu \beta \beta$) decay experiments. We illustrate our findings through profile likelihood plots for the half-life $T_{1/2}^{0\nu }$ and two-dimensional plots correlating $T_{1/2}^{0\nu }$ to neutrino masses. We find that in this simple class of models for Majorana neutrino masses, current and next-generation $0\nu \beta \beta$ decay experiments have a broad discovery potential in both the normal and inverted orderings of the spectrum of light active neutrinos.

    hep-phnucl-exnucl-th1 citation
16. 16*

    Precise Standard-Model predictions for polarised Z-boson pair production and decay at the LHC

    Costanza Carrivale🇮🇹 · Roberto Covarelli🇮🇹 · Ansgar Denner🇩🇪 · Dongshuo Du🇨🇳 · Christoph Haitz🇩🇪 · Mareen Hoppe🇩🇪 · Martina Javurkova🇺🇸 · Duc Ninh Le🇻🇳 · Jakob Linder🇩🇪 · Rafael Coelho Lopes de Sa🇺🇸 · Olivier Mattelaer🇧🇪 · Susmita Mondal🇺🇸 and 10 other authors

    Providing accurate theoretical predictions in the Standard Model for processes with polarised electroweak bosons is crucial to understand more in-depth the electroweak-symmetry breaking mechanism and to enhance the sensitivity to potential new-physics effects. Motivated by the rapidly increasing number of polarisation analyses of di-boson processes with LHC data, we carry out a comprehensive study of the inclusive production of two polarised Z bosons in the decay channel with four charged leptons. We perform a detailed comparison of fixed-order predictions obtained with various Monte Carlo programs which rely on different signal-definition strategies, assessing non-resonant and interference effects by contrasting polarised results with unpolarised and full off-shell ones. For the first time, we accomplish the combination of NNLO QCD and NLO EW corrections, setting the new state-of-the-art perturbative accuracy for polarised Z-boson pairs at the LHC. The impact of parton-shower matching and multi-jet merging is investigated by scrutinising calculations obtained with event generators that are typically used in experimental analyses. Integrated and differential results are discussed in a realistic fiducial setup and compared to publicly available ATLAS results.

    hep-phhep-exEPJC(2025)·20 citations
17. 17*

    Dark Matter-Independent Orbital Decay Bounds on Ultralight Bosons from OJ287

    Qianhang Ding🇰🇷 · Minxi He🇰🇷 · Volodymyr Takhistov🇯🇵 · Hui-Yu Zhu🇰🇷

    Ultralight bosons, predicted in scenarios beyond the Standard Model and viable dark matter (DM) candidates, can form superradiant clouds around spinning black holes influencing their dynamics. Using century-long monitored OJ287 supermassive black hole binary we set first DM-independent, dynamical constraints on their masses $\mu =(8.5-22)\times 10^{-22}$ eV. These dynamical constraints, driven by boson cloud friction, are robust against DM-model uncertainties and offer a novel ultralight boson probe. We show that analogous superradiant dynamics across the cosmic population of supermassive black hole systems could help resolve final-parsec evolution stalling problem and imprint a detectable suppression and break in the gravitational wave background.

    hep-phastro-ph.COastro-ph.HEgr-qcPRD(2025)·10 citations
18. 18*

    Early Universe production of $W$ bosons in neutrino decays

    Amalia Dariana Fodor🇷🇴 · Andru Mihai Buga🇷🇴 · Cosmin Crucean🇷🇴

    In this paper we study, via perturbative methods, the rates of production of $W$ bosons emitted in neutrino decays during the early stages of the Universe. We compute the transition amplitude corresponding to the first order of de Sitter electroweak perturbation theory and study its various limiting cases. The transition rates are derived using minimal subtraction and dimensional regularization. In the end we attempt to obtain the density number of $W$ bosons produced in perturbative transitions in de Sitter spacetime, using the rates obtained in this paper and in previous ones, and analyze the density number with respect to the particle momenta and renormalisation mass $\mu$.

    hep-phhep-th0 citations
19. 19*

    Black hole mimickers: from theory to observation

    Cosimo Bambi🇨🇳 · Ramy Brustein🇮🇱 · Vitor Cardoso🇩🇰 · Andrew Chael🇺🇸 · Ulf Danielsson🇸🇪 · Suvendu Giri🇸🇪 · Anuradha Gupta🇺🇸 · Pierre Heidmann🇺🇸 · Luis Lehner🇨🇦 · Steven Liebling🇺🇸 · Andrea Maselli🇮🇹 · Elisa Maggio🇩🇪 and 7 other authors

    The black hole paradigm, while remarkably successful, raises fundamental questions-both classical and quantum-about the nature of spacetime, horizons, and singularities. Black hole mimickers, horizonless ultra-compact objects, have emerged as potential alternatives that seek to resolve some of these puzzles while remaining consistent with current observational constraints. Recent breakthroughs in gravitational-wave astronomy and horizon-scale electromagnetic imaging have opened new avenues to test this paradigm-making this an opportune moment to systematically investigate such alternatives. This vision document presents a snapshot of the field as discussed at the Black Hole Mimickers: From Theory to Observation workshop, where experts from gravitational wave astronomy, very long baseline interferometry, numerical and mathematical relativity, and high-energy physics converged to assess the current frontiers. By highlighting key open questions and proposing concrete pathways forward, this document aims to guide future efforts to probe the nature of compact objects. As the field stands at the crossroads of theoretical innovation and observational breakthroughs, we outline strategies to harness upcoming observational capabilities to fundamentally test the black hole paradigm.

    ↳ gr-qcastro-ph.HEastro-ph.IMhep-ph+149 citations
20. 20*

    Signatures of asymmetry: Gravitational wave memory and the parity violation

    Indranil Chakraborty🇮🇳 · Susmita Jana🇮🇳 · S. Shankaranarayanan (IIT Bombay)🇮🇳

    Einstein's equivalence principle suggests a deep connection between matter and spacetime, prompting the question: if matter violates parity, must gravity? This letter explores the detection of parity violation in gravity using gravitational wave (GW) memory. Gravitational parity violation could be observable through GW amplitude birefringence and large-scale structure correlations. With improved sensitivity, next-generation GW detectors offer unprecedented opportunities to probe these effects. We propose that the integrated cosmological memory (ICM) of GWs, amplified over cosmological distances, can enhance faint parity-violating signatures. Specifically, if GWs from astrophysical events have differing polarization amplitudes, as in Chern-Simons gravity, ICM significantly amplifies this disparity. ICM uniquely and independently allows us to test fundamental symmetries, constrain gravity parameters, and gain insights into the interplay of particle physics, cosmology and gravity.

    ↳ gr-qchep-phhep-thPRD(2025)·5 citations
21. 21*

    Non-equilibrium scalar fields at finite temperature and density

    Sebastian Mendizabal🇨🇱

    We study propagators in bosonic field theories at finite temperature and chemical potential using the Schwinger-Keldysh real-time formalism. The system is considered in contact with a thermal reservoir, allowing for a consistent treatment of both equilibrium and non-equilibrium situations. The chemical potential, associated with conserved charges, modifies the structure of the propagators and introduces features that require detailed analysis. We focus on how a finite chemical potential affects the analytic structure of the bosonic propagators, including changes in the position of poles and the structure of branch cuts. In our setup, the chemical potential enters the theory as a constant background field, which alters both the dynamics and the boundary conditions. This work provides a basis for understanding the behavior of bosonic fields in thermal and dense environments.

    ↳ hep-thhep-phAnnals Phys.(2026)·2 citations
22. 22*

    The Possibility of Formation of Compact Boson Stars via Cosmological Evolution of a Background Scalar Field

    Yu Miyauchi🇯🇵 · Takahiro Tanaka🇯🇵

    Boson stars, hypothetical astrophysical objects bound by the self-gravity of a scalar field, have been widely studied as a type of exotic compact object that is horizonless and provides a testing ground for physics beyond the Standard Model. In particular, many previous works have demonstrated methods for distinguishing compact boson stars from black holes in general relativity through gravitational wave observations. However, the formation scenario of compact boson stars within the age of the universe remains unclear. In this paper, we explore a possible scenario for the formation of compact boson stars. The model we consider requires two coupled scalar fields: a complex scalar field that forms a boson star and a spatially homogeneous background field, as formation of a compact boson star cannot be achieved in a single filed model. Using the adiabatic approximation, we show that non-relativistic boson clouds can evolve into compact boson stars through the cosmological time-evolution of the background field. In our model the background field evolves to increase the effective mass of the scalar field, and as a result compact boson stars can form within the cosmological timescale, if the variation of the background field is as large as the Planck scale. However, further investigation is required because the required initial states are not the configurations that can be described by the well-studied Schrödinger-Poisson system.

    ↳ gr-qcastro-ph.COhep-phJCAP(2025)·0 citations
23. 23*

    Probing Self-Interacting Dark Matter via Gravitational-Wave Background from Eccentric Supermassive Black Hole Mergers

    Mu-Chun Chen🇨🇳 · Yong Tang🇨🇳

    The nature of dark matter is still mysterious despite various astronomical evidence. As a possible candidate, self-interacting dark matter (SIDM) can potentially resolve some issues appearing in cold dark matter paradigm. Here we investigate how SIDM around supermassive black holes (SMBH) in galaxy centers may form a density spike and imprint in the spectrum shape of stochastic gravitational-wave background from SMBH binaries (SMBHBs). Employing a refined dynamical friction formula and consistently evolving the orbital dynamics, we demonstrate that current pulsar timing arrays (PTAs) data is sensitive to the cross section of SIDM with $\sigma (v)/m_{\chi }\lesssim 0.66{\mathrm{cm}}^2/\mathrm{g}$, comparable to other astrophysical probes. We also highlight the importance of including the eccentricity of SMBHBs in the parameter inference, which would affect the results significantly. Our findings reveal the promising potential of PTAs observations in probing the nature of dark matter.

    ↳ astro-ph.GAastro-ph.COgr-qchep-phPRD(2025)·9 citations
24. 24*

    The Dual Primordial Black Hole Formation Scenario

    Xinpeng Wang🇨🇳 · Misao Sasaki🇯🇵 · Ying-li Zhang🇨🇳

    We report a novel mechanism where two families of primordial black holes (PBHs) may form at nearly the same comoving scales but at two different epochs. It is realized in two-stage inflation where a non-inflationary stage is sandwiched by the two inflationary stages. In this case, smaller PBHs form when the comoving scale of interest re-enters the horizon during the break period, and larger PBHs form when the scale re-enters the horizon after inflation. This mechanism may realize both reheating of the universe through the evaporation of ultralight PBHs formed during the break stage and the dark matter by those formed after inflation. We show that this scenario may give rise to a distinctive signature in the stochastic gravitational wave background that can be tested by the near-future gravitational wave observatories such as LISA and DECIGO. Our work thus provides a unified observational window into the physics of inflation, reheating, and dark matter.

    ↳ astro-ph.COgr-qchep-phPRD(2026)·12 citations
25. 25*

    Photonuclear Tomography in Ultraperipheral Heavy-Ion Collisions

    J.D. Baker🇺🇸 · C.A. Bertulani🇺🇸 · Victor P. Goncalves🇧🇷

    We present a theoretical investigation of photonuclear tomography as a novel technique for probing the internal structure of nuclei. In this approach, ultraperipheral heavy-ion collisions (UPCs) serve as a source of intense fluxes of virtual photons, which induce coherent production of vector mesons. By analyzing the probabilities and cross sections of these photon-induced processes, we propose a methodology for reconstructing the spatial distribution of nucleons within the nucleus. Our framework provides a systematic way to access information on the nuclear geometry probed in UPCs, offering new opportunities for studies of nuclear structure using particle production as a probe. Numerical calculations for selected examples illustrate the feasibility and potential of this method.

    ↳ nucl-thhep-phnucl-exPRC(2025)·1 citation
26. 26*

    Quantum simulation of bubble nucleation across a quantum phase transition

    De Luo🇺🇸 · Federica Maria Surace🇺🇸 · Arinjoy De🇺🇸 · Alessio Lerose🇬🇧 · Elizabeth R. Bennewitz🇺🇸 · Brayden Ware🇺🇸 · Alexander Schuckert🇺🇸 · Zohreh Davoudi🇺🇸 · Alexey V. Gorshkov🇺🇸 · Or Katz🇺🇸 · Christopher Monroe🇺🇸

    The liquid-vapor transition is a classic example of a discontinuous (first-order) phase transition. Such transitions underlie many phenomena in cosmology, nuclear and particle physics, and condensed-matter physics. They give rise to long-lived metastable states, whose decay can be driven by either thermal or quantum fluctuations. Yet, direct experimental observations of how these states collapse into a stable phase remain elusive in the quantum regime. Here, we use a trapped-ion quantum simulator to observe the real-time dynamics of ``bubble nucleation'' induced by quantum fluctuations. Bubbles are localized domains of the stable phase which spontaneously form, or nucleate, and expand as the system is driven across a discontinuous quantum phase transition. Implementing a mixed-field Ising spin model with tunable and time-dependent interactions, we track the microscopic evolution of the metastable state as the Hamiltonian parameters are varied in time with various speeds, bringing the system out of equilibrium. Site-resolved measurements reveal the emergence and evolution of finite-size quantum bubbles, providing direct insight into the mechanism by which the metastable phase decays. We also identify nonequilibrium scaling behavior near the transition, consistent with a generalized Kibble-Zurek mechanism. Our results demonstrate the power of quantum simulators to probe out-of-equilibrium many-body physics, including quantum bubble nucleation, a key feature of discontinuous quantum phase transitions, with application to studies of matter formation in the early universe.

    ↳ quant-phcond-mat.quant-gashep-lathep-ph36 citations

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