Wed·Mar 26, 2025Wednesday·March 26, 2025

1. 01*

   Probing Z/W Pole Physics at High-energy Muon Colliders via Vector-boson-fusion Processes

   Hao-Qiao Li🇨🇳 · Hai-Ning Yan🇨🇳 · Jiayin Gu🇨🇳 · Xiao-Ze Tan🇨🇳

   A future $e^{+}{e}^{-}$ collider could run at the Z-pole to perform important electroweak (EW) precision measurements, while such a run may not be viable for a future muon collider. This however can be compensated by the measurements of other EW processes, taking advantage of the high energy and large luminosity of the muon collider. In this paper, we consider the measurements of the vector boson fusion processes of $WW/WZ/W\gamma$ to a pair of fermions (along with a ${\nu }_{\mu }{\bar{\nu }}_{\mu }$ or ${\nu }_{\mu }{\mu }^{+}/{\bar{\nu }}_{\mu }{\mu }^{-}$ pair) at a high-energy muon collider and study their potential in probing the EW observables. We consider two run scenarios for the muon collider with center-of-mass energy of 10 TeV and 30 TeV, respectively, and focus on the processes involving $f=b,c,\tau$ and the dimension-6 operators that directly modify the corresponding fermions coupling to the $Z/W$ bosons. The invariant mass distribution of the $f\bar{f}$ pair helps to separate the events from the $Z/W$ resonance and the high-energy ones, while the polar angle of the outing fermion also provides additional information. By performing a chi-squared analysis on the binned distributions and combining the information from the $WW$ and $WZ/W\gamma$ fusion processes, all relevant Wilson coefficients can be constrained simultaneously. The precision surpasses the current EW measurement constraints and is even competitive with future $e^{+}{e}^{-}$ colliders. Our analysis can be included in a more complete framework which is needed to fully determine the potential of muon colliders in EW precision measurements.

   hep-phCPC(2025)·4 citations
2. 02*

   Quark antenna in early stage anisotropic QCD matter

   Joao Barata🇨🇭 · Carlos A. Salgado🇪🇸 · Joao M. Silva🇵🇹

   The states of matter produced in the early stage of heavy ion collisions can be highly anisotropic. If such a feature is sufficiently pronounced, one should expect the final particle distribution inside jets to reflect it in the form of non-trivial angle correlations. In this talk, we discuss a first step in exploring such correlations by studying how a $q\bar{q}$ state produced from an initial unpolarized gluon couples to the anisotropies of an underlying static QCD medium. The medium anisotropy is captured by allowing the jet quenching parameter to take different magnitudes in two orthogonal directions in the plane transverse to the jet axis. We find that the final particle distribution is sensitive to the medium anisotropy in the form of an azimuthal angle modulation, and more importantly, that this effect couples directly to the helicity/spin of the final states, offering a novel way to extract the details of the underlying matter which is not accessible with standard jet observables. We further show how such features can be extracted from the Fourier decomposition of the distribution and from final state transverse spin polarization measurements.

   hep-phnucl-thEPJ Web Conf.(2025)·1 citation
3. 03*

   Ultra-High-Energy Neutrinos from Primordial Black Holes

   Alexandra P. Klipfel🇺🇸 · David I. Kaiser🇺🇸

   The KM3NeT Collaboration recently announced the detection of a neutrino with energy 220 PeV. One possible source of such ultra-high-energy particles is the rapid emission of energetic Hawking radiation from a primordial black hole (PBH) near the end of its evaporation lifetime. The mass distribution for PBHs features a power-law tail for small masses; a small subset of PBHs would be undergoing late-stage evaporation today. We find that recent high-energy neutrino events detected by the IceCube and KM3NeT Collaborations, with energies $\mathcal{O}(1-10^2)\mathrm{PeV}$, are consistent with event-rate expectations if a significant fraction of the dark matter consists of PBHs.

   hep-phastro-ph.COastro-ph.HEPRL(2025)·50 citations
4. 04*

   A new type of lepton seesaw model in a modular $A_4$ symmetry

   Takaaki Nomura🇨🇳 · Hiroshi Okada🇨🇳

   We propose a new type of lepton seesaw model introducing a modular $A_4$ flavor symmetry in which isospin doublet vector fermions play an important role in constructing seesaw mechanisms for both the charged-lepton mass matrix and the neutrino one. The charged-lepton mass matrix is induced via the Dirac seesaw with a two-by-two block mass matrix. On the other hand, the neutrino mass matrix is generated via a seesaw with four-by-four block mass matrix where the right-handed neutral fermions are also added. Remarkably the neutral fermion mass matrix provides us a new type of seesaw formula for active neutrino mass. Through our chi square analysis, we find some tendencies about observables focusing on two fixed points $\tau =i,\omega$.

   hep-phPTEP(2025)·9 citations
5. 05*

   $Z_c(3900)$ in a hadronic molecule and a triangle singularity approach at finite temperature

   Ying Zhang🇨🇳 · Atsushi Hosaka🇯🇵 · Qian Wang🇨🇳 · Shigehiro Yasui🇯🇵

   Studying exotic hadrons is a challenge against the conventional quark model, providing us with a good platform to deepen our understanding of the strong interaction. An inclusive study of the exotic hadrons in vacuum and at finite temperature is an intriguing approach to shed light on their nature. As a first step, we study the $Z_c(3900)$ in both the $D{\bar{D}}^{\ast }$ hadronic molecular and the triangle singularity pictures, and discuss the behaviors of $Z_c(3900)$ at finite temperature in these two different pictures. As a result, we show the properties that its mass becomes smaller and its width becomes larger when the temperature increases, which are seen commonly in the hadronic molecular picture and in the triangle singularity picture. The enhanced widths in hot medium indicate that the $Z_c(3900)$ will be dissociated at a sufficiently high temperature. This feature is also reflected by a decrease of the effective couplings in the hadronic molecular picture. It is concluded that, not only in vacuum but also in hot medium, the behaviors of $Z_c(3900)$ are similar in the two different interpretations of $Z_c(3900)$.

   hep-phPRD(2025)·7 citations
6. 06*

   Two-photon Transition Form Factor of ${\eta }_{c,b}(nS)$ and ${\chi }_{c0,b0}(nP)$ via Relativized Mock Meson States

   Tian-Cheng Ding🇨🇳 · Jian Huang🇨🇳 · Muyang Chen🇨🇳

   We construct relativized mock meson states for heavy quarkonium, where the Dirac spinors import kinetic relativistic correction and the dynamic wave functions are the same as those solved from Schrödinger equation. We find that the kinetic relativistic correction imported by Dirac spinors is crucial to study the two-photon transition form factors. Using relativized mock meson states, we give credible predictions for the two-photon transition form factors and decay widths of ${\eta }_{c,b}(n^1{S}_0)$ and ${\chi }_{c,b}(n^3{P}_0)$ ($n=1,2,3$).

   hep-phPRD(2025)·2 citations
7. 07*

   Theoretical Uncertainties in First-Order Electroweak Phase Transitions

   Yongzhao Zhu🇨🇳 · Jie Liu🇨🇳 · Renhui Qin🇨🇳 · Ligong Bian🇨🇳

   We systematically investigate theoretical uncertainties in perturbative analyses of first-order electroweak phase transitions (EWPT). Utilizing the Standard Model Effective Field Theory (SMEFT) framework, we quantify the gauge dependence, renormalization scheme, and scale dependences in predicting phase-transition parameters across both zero and finite chemical potential regimes. Our key findings reveal that: 1) the gauge-parameter dependence and the chemical potential are subdominants, and 2) Baryon number preservation criteria and phase transition observables exhibit pronounced sensitivity to the renormalization scale in the $\overline{\mathrm{MS}}$ scheme. Comparative analyses with the on-shell scheme demonstrate that within strongly first-order EWPT parameter spaces, the $\overline{\mathrm{MS}}$ scheme predicts enhanced phase transition strengths and prolonged transition durations.

   hep-phastro-ph.COhep-thPRD(2025)·14 citations
8. 08*

   Strongly Interacting Dark Matter admixed Neutron Stars

   Yannick Dengler🇦🇹 · Suchita Kulkarni🇦🇹 · Axel Maas🇦🇹 · Kevin Radl🇦🇹

   Dark matter may accumulate in neutron stars given its gravitational interaction and abundance. We investigate the influence of strongly-interacting dark matter, described by a QCD-like one-flavor $G_2$ gauge theory, on neutron stars. This choice allows to test, for the first time, a first-principles-determined non-Abelian dark matter equation of state, which supports composite fermionic dark matter and thus a Fermi-pressure-stabilized dark matter component. The ordinary matter part of the mixed star is described by available model-agnostic equations of state that interpolate between the low-density regime and high-density regime. We find that strongly-interacting dark matter has a similar impact on neutron stars as other model equation of states and confirm that strongly-interacting dark matter can be accommodated by constraints from neutron star observations within our uncertainties.

   hep-phastro-ph.HEnucl-thSciPost Phys.Core(2026)·7 citations
9. 09*

   Exploring Efimov states in $D^{\ast }{D}^{\ast }{D}^{\ast }$ and $D{D}^{\ast }{D}^{\ast }$ three-body systems

   Hai-Long Fu🇨🇳 · Yong-Hui Lin🇩🇪 · Feng-Kun Guo🇨🇳 · Hans-Werner Hammer🇩🇪 · Ulf-G. Meißner🇩🇪 · Akaki Rusetsky🇩🇪 · Xu Zhang🇨🇳

   The Efimov effect is an intriguing three-body quantum phenomenon. Searching for Efimov states within the realms of nuclear and hadronic physics presents a challenge due to the inherent inability of natural physical systems to exhibit adjustable two-body scattering lengths. In this study, we examine the potential existence of Efimov states in the $D^{\ast }{D}^{\ast }{D}^{\ast }$ and $D{D}^{\ast }{D}^{\ast }$ three-hadron systems. Utilizing a pionless effective field theory framework, we determine that the presence of Efimov states in the spectrum of the $D^{\ast }{D}^{\ast }{D}^{\ast }$ system is contingent upon the existence of an $(I,J)=(1,2)$ $D^{\ast }{D}^{\ast }$ two-body bound system. If only the $T_{cc}^{+}$ and its heavy quark spin partner $T_{cc}^{\ast +}$ exist while there is no near-threshold pole in all other $S$-wave $D^{(\ast )}{D}^{\ast }$ scattering amplitudes, no Efimov effect is expected in the $D^{(\ast )}{D}^{\ast }{D}^{\ast }$ systems.

   hep-phnucl-thJHEP(2025)·10 citations
10. 10*

    Phase Transitions in the Early Universe: Impacts on BBN and CMB Observables

    Rui Xu🇨🇳 · Jiachen Lu🇨🇳 · Shihao Deng🇨🇳 · Ligong Bian🇨🇳

    We explore the effects of low-scale cosmological first-order phase transitions on Big Bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB) anisotropy and distortion. We examine two scenarios: the distribution of the phase-transition energy in the cosmic background and the phase transition as an additional source of energy injection. Our analysis reveals that the CMB spectrum from the Planck 2018 dataset imposes stringent constraints on sub-MeV-scale phase transitions, while keV-scale phase transitions can induce significant CMB distortions. Consequently, BBN and CMB observables serve as complementary tools to constrain phase-transition parameters, alongside gravitational wave detections.

    hep-phastro-ph.COPRD(2025)·4 citations
11. 11*

    The role of chiral symmetry and the non-ordinary $\kappa /K_0^{\ast }(700)$ nature in ${\pi }^{\pm }{K}_S$ femtoscopic correlations

    Miguel Albaladejo🇪🇸 · Alejandro Canoa🇪🇸 · Juan Nieves🇪🇸 · Jose Ramón Peláez🇪🇸 · Enrique Ruiz-Arriola🇪🇸 · Jacobo Ruiz de Elvira🇪🇸

    We show that the use of realistic $\pi K$ interactions, obtained from a dispersive analysis of scattering data, as well as relativistic corrections, are essential to describe recently observed ${\pi }^{\pm }{K}_S$ femtoscopic correlations. We demonstrate that the spontaneous chiral symmetry breaking dynamics and the non-ordinary features of the $\kappa /K_0^{\ast }(700)$ resonance, together with large cancellations between isospin channels, produce a large suppression of ${\pi }^{\pm }{K}_S$ femtoscopic correlations compared to widely used models. Within an improved version of the standard on-shell factorization formalism, we illustrate that compensating for this interaction suppression leads to source radii smaller than 1 fm, contrary to usual expectations, as well as larger correlation strengths. The relation between these two parameters cannot be accommodated within naive models describing the nature of the resonances. This may raise concerns about the applicability of popular but too simple approaches for systems with light mesons. However, the correlation-suppression effects we demonstrate here will be relevant in any formalism, and substantial corrections may be expected for other femtoscopic systems involving light mesons.

    hep-phhep-exnucl-thPLB(2025)·13 citations
12. 12*

    Homotopy approach for scattering amplitude for running QCD coupling

    Carlos Contreras🇨🇱 · José Garrido🇨🇱 · Eugene Levin🇮🇱

    In this paper we proposed the homotopy approach for solving the nonlinear Balitsky-Kovchegov (BK) evolution equation with running QCD coupling. The approach consists of two steps. First, is the analytic solution to the nonlinear evolution equation for the simplified, leading twist kernel. Second, is the iteration procedure that allow us to calculate corrections analytically or semi-numerically. For the leading twist kernel it is shown that the first iteration leads to $\le 1\%$ accuracy. The $\zeta =-\frac{4N_c}{b_0}Y\ln \text{Lb}\text{bas}(1/Q_s^2(Y))/\text{bas}\text{Lb}{r}^2\text{Rb}\text{Rb}$ ($r$ is the dipole size, $Q_s$ is the saturation scale) and geometric scaling behaviour of the scattering amplitude are discussed as well as the dependence on the value of the infrared cutoff.

    hep-phnucl-thPRD(2025)·3 citations
13. 13*

    Chiral extrapolation of the doubly charmed baryons magnetic properties

    Jiong-Jiong Liu🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiu-Lei Ren🇩🇪 · Yu Zhuge🇨🇳

    The magnetic moments, magnetic form factors, and transition magnetic form factors of doubly charmed baryons are studied within heavy baryon chiral perturbation theory. We regulate the loop integrals using the finite-range regularization. The contributions of vector mesons are taken into account to investigate the dependence of form factors on the transferred momentum. The finite volume and lattice spacing effects are considered to analyze the lattice QCD simulations which can be understood well in our framework.

    hep-phhep-latPRD(2025)·0 citations
14. 14*

    Master integrals for semi-inclusive cuts of massless four-loop propagators

    Vitaly Magerya🇨🇭 · Levente Fekésházy🇩🇪

    We present the analytic calculation of all master integrals for 3-, 4-, and 5-particle semi-inclusive cuts of four-loop massless propagators by means of differential equations. We fix the integration constants by reducing the semi-inclusive integrals to their fully inclusive counterparts with the Integration-By-Parts (IBP) method. We validate our results by calculating the next-to-next-to-next-to-leading order (N3LO) semi-inclusive $e^{+}{e}^{-}\to X$ cross-section and integrating directly over the differential variable. We provide the results in a machine-readable form. The presented integrals are essential for the direct calculation of NNLO time-like splitting functions and N3LO coefficient functions, which play a crucial role in precision QCD calculations.

    hep-ph2 citations
15. 15*

    Distorting the Top Resonance with Effective Interactions

    Felix Egle🇩🇪 · Christoph Englert🇬🇧 · Margarete Mühlleitner🇩🇪 · Michael Spannowsky🇬🇧

    Interference effects in effective field theory (EFT) analyses can significantly distort sensitivity expectations, leaving subtle yet distinct signatures in the reconstruction of final states crucial for limit setting around Standard Model predictions. Using the specific example of four-fermion operators in top-quark pair production at the LHC, we provide a detailed quantitative assessment of these resonance distortions. We explore how continuum four-fermion interactions affect the resonance shapes, creating potential tensions between the high-statistics resonance regions and rare, high momentum-transfer continuum excesses. Our findings indicate that although four-fermion interactions do modify the on-shell region comparably to continuum enhancements, current experimental strategies at the High-Luminosity LHC are unlikely to capture these subtle interference-induced distortions. Nonetheless, such effects could become critical for precision analyses at future lepton colliders, such as the FCC-ee. Our work underscores the importance of resonance-shape measurements as complementary probes in global EFT approaches, guiding robust and self-consistent experimental strategies in ongoing and future high-energy physics programmes.

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

    A natural MSSM from a novel $\mathsf{SO}(10)$, Yukawa unification, light sparticles, and SUSY implications at LHC

    Jinzheng Li🇺🇸 · Pran Nath🇺🇸 · Raza M. Syed🇺🇸

    The $\mathsf{SO}(10)$ model with a heavy Higgs spectrum consisting of $560+\overline{560}$ and a light Higgs spectrum consisting of $2\times 10+320$ plet representations of $\mathsf{SO}(10)$ is unique among $\mathsf{SO}(10)$ models.,It has the remarkable property that VEVs of $560$ and $\overline{560}$ can simultaneously reduce the rank of the gauge group and further reduce the remaining symmetry down to the standard model gauge group. Additionally, on mixing with the light fields all the Higgs fields become heavy except for one pair of light Higgs doublets just as in MSSM. This model has not been fully explored thus far because of the technical difficulty of computing the couplings of the heavy and the light Higgs sectors, specifically the interaction $(560\times 560)\cdot 320$ involving the coupling of tensor-spinors with a third rank ~mixed tensor $320$. An explicit analysis of such couplings is given in this paper. Spontaneous symmetry breaking of the $\mathsf{SO}(10)$ symmetry is carried out reducing the gauge group to ${\mathsf{SU}(3)}_c\times {\mathsf{SU}(2)}_L\times {\mathsf{U}(1)}_Y$ with just one just pair of light Higgs. Thus a natural deduction of MSSM arises from the $\mathsf{SO}(10)$ model with no fine tuning needed. Further, it is shown that the light Higgs doublet of the model is a linear combination of the Higgs doublet fields of the $2\times 10$ and the $320$ Higgs fields. It is shown that in this class of $\mathsf{SO}(10)$ models $b-t-\tau$ unification can be achieved with $\tan \beta$ as low as 5-10. An analysis of the sparticle spectrum within $\tilde{g}$SUGRA renormalization group evolution is given which leads to a bi-modal sparticle spectrum consisting of a compressed low mass spectrum for sleptons and weakinos and a high mass spectrum of gluino, squarks, and heavy Higgs.LHC.

    hep-phhep-exJHEP(2025)·4 citations
17. 17*

    Signatures of quasi-Dirac neutrinos in diffuse high-energy astrophysical neutrino data

    Kiara Carloni🇺🇸 · Yago Porto🇧🇷 · Carlos A. Argüelles🇺🇸 · P. S. Bhupal Dev🇺🇸 · Sudip Jana🇮🇳

    Although the sources of astrophysical neutrinos are still unknown, they are believed to be produced by a population of sources in the distant universe. Measurements of the diffuse, all-sky astrophysical flux can thus be sensitive to flavor and energy-dependent propagation effects, such as very long baseline oscillations. These oscillations are present in certain neutrino mass models, such as when neutrinos are quasi-Dirac. Assuming generic models for the source flux, we find that these oscillations can still be resolved even when integrated over wide distributions in source redshift. We use two sets of IceCube all-sky flux measurements, made with muon and all-flavor neutrino samples, to set constraints at the $3\sigma$ level on quasi-Dirac mass-splittings between $(5\times 10^{-19},8\times 10^{-19}){\text{eV}}^2$. We also consider systematic uncertainties on the source population and find that our results are robust under alternate spectral hypotheses or physical redshift distributions. Our analysis shows that spectral features in the all-sky neutrino measurements provide strong constraints on massive neutrino scenarios and are sensitive to uncharted parameter space.

    hep-phastro-ph.HEhep-thPRD(2026)·17 citations
18. 18*

    Drell-Yan production in universal theories beyond dimension-six SMEFT

    Tyler Corbett🇦🇹 · Jay Desai🇺🇸 · O. J. P. Eboli🇧🇷 · M. C. Gonzalez-Garcia🇺🇸 · Matheus Martines🇧🇷 · Peter Reimitz🇧🇷

    We study Drell-Yan production in universal theories consistently including effects beyond dimension six in the SMEFT. Within universal SMEFT and with $C$ and $P$ conservation we find that eleven dimension-eight operators contribute in addition to the six contributing at dimension-six. We first work in an operator basis in which operators with higher derivatives of the bosonic fields have been rotated by equations of motion in favor of combinations of operators involving SM fermion currents. We derive the general form of the amplitudes consistently in the expansion to $\mathcal{O}({\Lambda }^{-4})$ and identify eight combinations of the 17 Wilson coefficients which are physically distinguishable by studying the invariant mass distribution of the lepton pairs produced. We then introduce an extension of the parametrization of universal effects in terms of oblique parameters obtained by linearly expanding the self-energies of the electroweak gauge-bosons to $\mathcal{O}(q^6)$. It contains eleven oblique parameters of which only eight are generated within SMEFT at dimension-eight: $\hat{S}$, $\hat{T}$, $W$, $Y$, $\hat{U}$, $X$, plus two additional which we label $W^{\prime }$ and $Y^{\prime }$ and show how they match at linear order with the eight identified combinations of operator coefficients. We then perform a combined analysis of a variety of LHC data on the neutral- and charged-current Drell-Yan processes with the aim of constraining the eight combinations. We compare and combine the LHC bounds with those from electroweak precision $W$ and $Z$ pole observables which can only provide constraints in four directions of the eight-parameter space. We present the results in terms of limits on the eight effective Wilson coefficients as well as on the eight oblique parameters. In each case, we study the dependence of the derived constraints on the order of the expansion considered.

    hep-phPRD(2025)·6 citations
19. 19*

    Phenomenological implications of a class of non-invertible selection rules

    Motoo Suzuki🇮🇹 · Ling-Xiao Xu🇮🇹

    We demonstrate that non-invertible fusion algebras give rise to a class of selection rules with genuine organizing power in particle physics models, which we call non-invertible selection rules (NISRs). We identify the algebraic structures that distinguish NISRs from ordinary group-based selection rules and from their generic explicit breaking. As a minimal example, we study a singlet-scalar extension of the Standard Model and show that the NISR based on Fibonacci fusion rules leads to distinctive scattering patterns. We further apply the Ising fusion rules to a supersymmetric flipped $SU(5)$ model, addressing the doublet-triplet splitting problem. In this construction, the NISR plays a crucial role in forbidding the $\mu$-term, thereby evading a no-go result for ordinary Abelian symmetries. We anticipate that this class of selection rules can be applied to a wide range of models beyond the Standard Model. To facilitate such applications, we provide a pedagogical review of radiative violation of NISRs in the appendices, with a dark matter model also being discussed.

    hep-phhep-exhep-th35 citations
20. 20*

    Entanglement witnesses mediated via axionLike particles

    Pablo Guillermo Carmona Rufo🇪🇸 · Ayush Kumar🇮🇳 · Carlos Sabín🇪🇸 · Anupam Mazumdar🇳🇱

    Entanglement is solely a quantum property and it can be extremely helpful to test the physics beyond the Standard Model in tabletop experiments with the advent of future quantum technologies. In this work, we provide an entanglement-based partial positive transpose witness for Yukawa-type potentials in the infrared regime between pairs of neutral/charged particles in a spatial quantum superposition. The entanglement is created by the interaction beyond the Standard Model such as axionlike particle or physics motivated by string theory such as extra dimensions in the context of gravity. We will study the constrained couplings in a few different models along with the decoherence rate to show what parameters can be searched for in near-future entanglement-driven experiments for the search of new physics.

    ↳ quant-phhep-phPRD(2026)·6 citations
21. 21*

    Reconstructing hadronically decaying tau leptons with a jet foundation model

    Laurits Tani🇪🇪 · Joosep Pata🇪🇪 · Joschka Birk🇩🇪

    The limited availability and accuracy of simulated data has motivated the use of foundation models in high energy physics, with the idea to first train a task-agnostic model on large and potentially unlabeled datasets. This enables the subsequent fine-tuning of the learned representation for specific downstream tasks, potentially requiring much smaller dataset sizes to reach the performance of models trained from scratch. We study how OmniJet-$\alpha$, one of the proposed foundation models for particle jets, can be used on a new set of tasks, and in a new dataset, in order to reconstruct hadronically decaying $\tau$ leptons. We show that the pretraining can successfully be utilized for this multi-task problem, improving the resolution of momentum reconstruction by about 50\% when the pretrained weights are fine-tuned, compared to training the model from scratch. While much work remains ahead to develop generic foundation models for high-energy physics, this early result of generalizing an existing model to a new dataset and to previously unconsidered tasks highlights the importance of testing the approaches on a diverse set of datasets and tasks.

    ↳ hep-exhep-phSciPost Phys.Core(2025)·5 citations
22. 22*

    Solar System Constraints on Light Propagation from Higher Derivative Corrections to General Relativity and Implications for Fundamental Physics

    Mark P. Hertzberg🇺🇸 · Rachel Nathan🇺🇸 · Suzanna E. Semaan🇺🇸

    While the two derivative action of gravitation is specified uniquely, higher derivative operators are also allowed with coefficients that are not specified uniquely by effective field theory. We focus on a four derivative operator in which the Riemann tensor couples directly to the electromagnetic field $a{R}_{\mu \nu \alpha \beta }{F}^{\mu \nu }{F}^{\alpha \beta }$. We compute the corresponding corrections to the Shapiro time delay in the solar system and compare this to data from the Cassini probe. We place an observational upper bound on the coefficient $a$ at 95\% confidence $|a|<26(1000\text{mbox}km{)}^2$. By way of motivation, we also compare this to a weak gravity conjecture (WGC) prediction of a bound on the coefficients $a,b$ of four derivative operators involving the graviton and the photon; this includes the above term $a{R}_{\mu \nu \alpha \beta }{F}^{\mu \nu }{F}^{\alpha \beta }$ as well as $b{F}^4$. We show that by using the observed value of the $b$ coefficient from measurements of light by light scattering, which arises in the Standard Model from integrating out the electron, the WGC predicted bound for $a$ is $a\lesssim 7.8(1000\text{mbox}km{)}^2$. This is consistent with the above observational bound, but is intriguingly close and can be further probed in other observations.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2025)·5 citations
23. 23*

    Direct Collapse Supermassive Black Holes from Ultralight Dark Matter

    Hao Jiao🇨🇦 · Robert Brandenberger🇨🇦 · Vahid Kamali🇨🇦

    We study the possibility that parametric resonant excitation of photons in an ultralight dark matter halo could generate the required flux of Lyman-Werner photons to allow the direct collapse formation of supermassive black hole seeds.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1PRD(2025)·12 citations
24. 24*

    S-dual Quintessence, the Swampland, and the DESI DR2 Results

    Luis A. Anchordoqui🇺🇸 · Ignatios Antoniadis🇹🇭 · Dieter Lust🇩🇪

    We propose a dark energy model in which a quintessence field $\varphi$ rolls near the vicinity of a local maximum of its potential characterized by the simplest $S$ self-dual form $V(\varphi )=\Lambda \mathrm{sech}(\sqrt{2}\varphi /M_p)$, where $M_p$ is the reduced Planck mass and $\Lambda \sim 10^{-120}{M}_p^4$ is the cosmological constant. We confront the model with Swampland ideas and show that the $S$-dual potential is consistent with the distance conjecture, the de Sitter conjecture, and the trans-Planckian censorship conjecture. We also examine the compatibility of this phenomenological model with the intriguing DESI DR2 results and show that the shape of the $S$-dual potential is almost indistinguishable from the axion-like potential, $V(\varphi )=m_a^2{f}_a^2[1+\cos (\varphi /f_a)]$, with $m_a$ and $f_a$ parameters fitted by the DESI Collaboration to accommodate the DR2 data. The self-dual potential has the advantage that one starts at the self-dual point and this is a theoretical motivation, because as the universe cools off the ${\mathbb{Z}}_2$ symmetry gets broken leading to a natural rolling away from the symmetric point.

    ↳ hep-thastro-ph.COhep-phPLB(2025)·46 citations
25. 25*

    Searches for Heavy Neutral Leptons at FCC-ee in final states including a muon

    L Bellagamba🇮🇹 · G Polesello🇮🇹 · N. Valle🇮🇹

    The sensitivity of the CERN FCC-ee collider to the production of heavy neutral leptons (HNL) is investigated. The study focuses on a simplified model with a single low-mass HNL mixing with a muon, and addresses the fully leptonic and semileptonic decay modes of the HNL. Complete Monte Carlo analyses of signal and background based on a parametrised detector simulation are performed for the FCC-ee run at the $Z$-pole, resulting in an estimate of the intervals of the mixing parameter for which the FCC-ee will have a 95% CL sensitivity as a function of the HNL mass.

    ↳ hep-exhep-phEPJC(2025)·15 citations
26. 26*

    Energy-Momentum Tensor and D-term of Baryons in Top-down Holographic QCD

    Shigeki Sugimoto🇯🇵 · Taichi Tsukamoto🇯🇵

    We study the energy-momentum tensor of a baryon in a top-down holographic QCD. In holographic QCD, the baryons are represented as solitons in a 5-dimensional gauge theory. We obtain the soliton solution by solving the equations of motion numerically. Using this result, the energy-momentum tensor and related quantities such as the mass, mean square radii, and the D-term (druck term) are computed. The evaluated D-term is about -2.05, whose absolute value is significantly larger than that in the previous work arXiv:2206.06578.

    ↳ hep-thhep-phPTEP(2025)·18 citations
27. 27*

    Singular instantons with finite action

    Misao Sasaki🇯🇵 · Vicharit Yingcharoenrat🇯🇵 · Ying-li Zhang🇨🇳

    Recently, it was shown that in the absence of gravity there exist non-$O(4)$-symmetric instanton solutions with finite action beyond Coleman's instantons. In this paper, focusing on the false-vacuum decay in a single scalar field in flat Euclidean space, we provide a general discussion on $O(4)$-symmetric instantons that are singular at the true-vacuum bubble. We find that, for the action to remain finite without introducing a UV cutoff, the potential must be unbounded from below, thereby evading Coleman's theorem. We then consider two explicit examples of such instantons and perturbatively analyze the dynamics of small deformations around them. We find that one of them does not allow regular deformations, which indicates that the $O(4)$ symmetric solution still gives the minimum action, while the other one is found to allow regular deformations that cost no additional action at second order in perturbation. The latter example opens up the possibility of the existence of non-linear non-$O(4)$-symmetric solutions with lower action if we allow singular instantons with finite action.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2025)·3 citations
28. 28*

    Dip and non-linearity in the curvature perturbation from inflation with a transient non-slow-roll stage

    Tomohiro Fujita🇯🇵 · Ryodai Kawaguchi🇯🇵 · Misao Sasaki🇯🇵 · Yuichiro Tada🇯🇵

    We consider models of inflation that contain a transient non-slow-roll stage and investigate the conditions under which a dip appears in the power spectrum of the curvature perturbation. Using the $\delta N$ formalism, we derive a general relation between the comoving curvature perturbation $\mathcal{R}$ and the scalar field perturbation $\delta \phi$ and its velocity perturbation $\delta \pi$. Compared with the result obtained in linear perturbation theory, it turns out that properly taking account of the $\delta \pi$ contribution is essential to reproduce the dip in the power spectrum. Namely, the curvature perturbation is proportional to a specific linear combination of $\delta \phi$ and $\delta \pi$ at the linear order. We also investigate the non-linearity at the dip scale and find that models with a bump or an upward step exhibit much larger non-linearity than ultra-slow-roll and Starobinsky's linear potential models. Finally, we demonstrate the importance of non-linearity by computing the probability density functions (PDFs) for the above-mentioned models and show that highly asymmetric PDFs are realised for models with a bump or a step.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2025)·10 citations
29. 29*

    The role of natural language in understanding the universe: a teaching-learning sequence for high school students

    Matteo Tuveri🇮🇹 · Viviana Fanti

    Introducing gravitational physics at high school provides educational means for bridging the gap between the image of science held by students and science itself. Natural language is fundamental in this learning. It engages students in constructing an understanding of a concept or a notion, establishing new relations between previous and new elements of knowledge. We present a teaching/learning sequence (TLS) aimed to contextualize gravitational physics along the lines of the Einstein Telescope educational program in Sardinia devoted to upper secondary school students. We focused on the role of debates and controversy in the evolution of science, proposing science-reflexive meta discourses to present physics as a unified knowledge textbook. We discuss our design and present results by analyzing students' semiotic registers to recap their learning during the activity. Finally, we discuss the potentiality of our TLS in orientating students towards STEM.

    ↳ physics.ed-phastro-ph.COgr-qchep-phNuovo Cim.C(2025)·0 citations
30. 30*

    Early Career Researcher Input to the European Strategy for Particle Physics Update: White Paper

    Jan-Hendrik Arling (1)🇩🇪 · Alexander Burgman (2)🇸🇪 · Christina Dimitriadi (3)🇸🇪 · Ulrich Einhaus (4)🇩🇪 · Axel Gallén (5)🇸🇪 · Abdelhamid Haddad (6)🇫🇷 · Laura Huhta (7)🇫🇮 · Armin Ilg (8)🇨🇭 · Jan Klamka (9)🇵🇱 · Elizabeth Long (10)🇨🇿 · Thomas Madlener (1)🇩🇪 · Arnau Morancho Tardà (11)🇩🇰 and 33 other authors

    This document, written by early career researchers (ECRs) in particle physics, aims to represent the perspectives of the European ECR community and serves as input for the 2025--2026 update of the European Strategy for Particle Physics. With input from a community-wide survey, it highlights key challenges faced by ECRs -- career stability, funding access and long-term research opportunities -- while proposing policy recommendations and targeted initiatives. It underscores the importance of practices fostering diverse, equitable, inclusive and healthy workplaces, as well as of stronger ECR communities, and highlights how effective communication and interdisciplinary collaborations reinforce the societal relevance of particle physics and promote continued support for large-scale and long-term projects. Finally, the future of both collider and beyond-collider experiments is addressed, emphasising the critical role of ECRs in shaping future projects. The ECR contribution is formed of two parts: the ten-page executive summary submitted as input to the European Strategy for Particle Physics Update and, as backup document, this extended white paper providing additional context.

    ↳ hep-exhep-phhep-thphysics.acc-ph+16 citations
31. 31*

    How Much NEC Breaking Can the Universe Endure?

    Elly Moghtaderi🇨🇦 · Brayden R. Hull🇨🇦 · Jerome Quintin🇨🇦 · Ghazal Geshnizjani🇨🇦

    Quantum fields can notoriously violate the null energy condition (NEC). In a cosmological context, NEC violation can lead to, e.g., dark energy at late times with an equation-of-state parameter smaller than $-1$ and nonsingular bounces at early times. However, it is expected that there should still be a limit in semiclasssical gravity to how much `negative energy' can accumulate over time and in space as a result of quantum effects. In the course of formulating quantum-motivated energy conditions, the smeared null energy condition has emerged as a recent proposal. This condition conjectures the existence of a semilocal bound on negative energy along null geodesics, which is expected to hold in semiclassical gravity. In this work, we show how the smeared null energy condition translates into theoretical constraints on NEC-violating cosmologies. Specifically, we derive the implied bounds on dark energy equation-of-state parameters and an inequality between the duration of a bouncing phase and the growth rate of the Hubble parameter at the bounce. In the case of dark energy, we identify the parameter space over which the smeared null energy condition is consistent with the recent constraints from the Dark Energy Spectroscopic Instrument (DESI).

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2025)·21 citations
32. 32*

    Spotting Stasis in Cosmological Perturbations

    Keith R. Dienes🇺🇸 · Lucien Heurtier🇬🇧 · Daniel Hoover🇺🇸 · Fei Huang🇮🇱 · Anna Paulsen🇺🇸 · Brooks Thomas🇺🇸

    As discussed in a number of recent papers, cosmological stasis is a phenomenon wherein the abundances of multiple cosmological energy components with different equations of state remain constant for an extended period despite the expansion of the universe. One of the most intriguing aspects of the stasis phenomenon is that it can give rise to cosmological epochs in which the effective equation-of-state parameter $⟨w⟩$ for the universe is constant, but differs from the canonical values associated with matter, radiation, vacuum energy, etc. Indeed, during such a stasis epoch, the spatial average of the energy density of the universe evolves in precisely the same manner as it would have evolved if the universe were instead dominated by a perfect fluid with an equation-of-state parameter equal to $⟨w⟩$. However, as we shall demonstrate, this equivalence is broken at the level of the perturbations of the energy density. To illustrate this point, we consider a stasis epoch involving matter and radiation and demonstrate that within this stasis background the density perturbations associated with a spectator matter component with exceedingly small energy density exhibit a power-law growth that persists across the entire duration of the stasis epoch. This growth can potentially lead to significant enhancements of structure at small scales. Such enhancements are not only interesting in their own right, but may also provide a way of observationally distinguishing between a stasis epoch and an epoch of perfect-fluid domination -- even if the universe has the same equation of state in both cases.

    ↳ 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.