Fri·May 9, 2025Friday·May 9, 2025

1. 01*

   The third-generation-philic WIMP: an EFT analysis

   Georgios Demetriou🇨🇭 · Gino Isidori🇨🇭 · Gioacchino Piazza🇨🇭 · Emanuelle Pinsard🇨🇭

   We consider fermionic and scalar dark matter (DM) candidates that couple predominantly to third-generation Standard Model fermions, describing their interactions within an effective field theory framework. We show that current direct-detection constraints on these interactions are more than an order of magnitude weaker than those for flavor-universal couplings: effective scales in the few-TeV range remain allowed by existing data, leaving open the possibility of a connection between this type of new physics and a solution to the electroweak hierarchy problem. Imposing the observed relic abundance from thermal freeze-out within the same effective theory, a well-defined region for a fermionic DM candidate with mass in the 1-2 TeV range emerges. Notably, this region will be fully probed by upcoming direct-detection experiments. Finally, we show that additional parameter space for both fermion and scalar cases can be recovered by going beyond the effective theory, through the introduction of a suitable vector mediator enabling resonant DM annihilation.

   hep-phhep-thEPJC(2025)·4 citations
2. 02*

   PT2GWFinder: A Package for Cosmological First-Order Phase Transitions and Gravitational Waves

   Vedran Brdar🇺🇸 · Marco Finetti🇵🇹 · Marco Matteini🇸🇮 · António P. Morais🇵🇹 · Miha Nemevšek🇸🇮

   The detection of gravitational waves from binary black hole and neutron star mergers by ground-based interferometers, as well as the evidence for a gravitational wave background from pulsar timing array experiments, has marked a new era in astrophysics and cosmology. These experiments also have great potential for discovering new physics through gravitational wave detection. One of the most motivated sources of gravitational waves that can be realized only within a beyond-the-Standard-Model framework is first-order phase transitions. In this work we release PT2GWFinder, a Mathematica package designed to compute phase transition parameters and the gravitational wave power spectrum for an \textit{arbitrary scalar theory exhibiting a first-order phase transition, in scenarios where a single scalar acquires a vacuum expectation value. PT2GWFinder performs the phase tracing, computes the bounce profile and action using FindBounce, calculates the relevant temperatures and phase transition parameters, and finally evaluates the gravitational wave spectrum. Additionally, it offers a user-friendly interface with DRalgo, which enables the computation of the dimensionally reduced effective potential in the high-temperature regime. This work includes a user manual and two models that demonstrate the capability and performance of PT2GWFinder. As a supplement, for one of these models we obtain the bounce solution and action analytically in the thin-wall approximation and demonstrate excellent agreement with the numerical approach.

   hep-phastro-ph.COgr-qcComput.Phys.Commun.(2026)·16 citations
3. 03*

   Gravitational Wave Production and Baryogenesis in a Simple Left-Right model

   Arnab Dasgupta🇺🇸 · Matthew Knauss🇺🇸 · Marc Sher🇺🇸

   The left-right model with the simplest Higgs structure has a $SU(2{)}_L$ doublet $H_L$, a $SU(2{)}_R$ doublet $H_R$, and a singlet $\sigma$ that couples to the doublets as $\sigma (|H_L{|}^2-|H_R{|}^2)$. The left-right symmetry has $H_L\leftrightarrow H_R$ and $\sigma \leftrightarrow -\sigma$. We study gravitational wave production and baryogenesis in the electroweak phase transitions in the model. For two benchmark points, $\sigma$ first gets a vev, followed by $H_R$ and then $H_L$. An interesting feature is that the vev of $H_L$ is initially much higher than its zero temperature value, leading to a more strongly first-order transition and higher frequency gravitational waves. An unusual benchmark point has the $\sigma$ vev at zero when the electroweak symmetry breaks. This results in both $H_L$ and $H_R$ vevs being equal and in the multi-TeV range. At a lower temperature, the $\sigma$ vev turns on, breaking the left-right symmetry and $H_L$ drops to its standard model value. Since the electroweak symmetry is broken at the multi-TeV scale, the frequency of gravitational waves will be much higher than usual. Baryogenesis is also discussed.

   hep-phastro-ph.COPRD(2025)·3 citations
4. 04*

   Minimal length effect on meson form factors in light front AdS${}_5$/QCD

   Fidele J. Twagirayezu🇺🇸

   In this article, we investigate the impact of a minimal length scale, introduced via the Generalized Uncertainty Principle (GUP), on meson form factors within light-front holographic QCD (\(\mathrm{AdS}_5 / \mathrm{QCD}\)). By incorporating GUP through deformed operators in the QCD Lagrangian, we derive a GUP-corrected light-front wave function (LFWF) that includes contributions from all Fock states, weighted by probabilities \(a_n^2\). The resulting form factors account for transitions between Fock states via coefficients \(\mathcal{C}_{nm}\), revealing a net positive \(\beta\)-like correction driven by dominant positive coefficients (e.g., \(\mathcal{C}_{04}\), \(\mathcal{C}_{12}\)). This enhancement improves agreement with experimental pion form factor data. Our model is formulated to include all Fock states via the general summation over \( n \), but numerical evaluations truncate to \( n=0, 1, 2 \), sufficient for describing experimental data up to \( Q^2 \leq 4 \, \text{GeV}^2 \). Our findings suggest that minimal length effects amplify Fock state overlaps, offering insights into the interplay between quantum gravitational corrections and strong interaction dynamics. This generalized framework advances LFH QCD by capturing multi-parton contributions and paves the way for studying GUP effects in other hadronic systems.

   hep-ph0 citations
5. 05*

   Impact of coherent scattering on relic neutrinos boosted by cosmic rays

   Jiajie Zhang🇨🇳 · Alexander Sandrock🇩🇪 · Jiajun Liao🇨🇳 · Baobiao Yue🇩🇪

   Ultra-high-energy cosmic rays (UHECR) scattering off the cosmic relic neutrino background have recently gained renewed interest in the literature. Current data suggest that (UHECR) are predominantly made of heavy nuclei. Similar to the coherent elastic neutrino-nucleus scattering (CE$\nu$NS) observed at low-energy neutrino experiments, the cross section of heavy nucleus scattering off relic neutrinos will be coherently enhanced since the energy of relic neutrinos can reach $\sim O(10)$ MeV in the rest frame of the UHECR. We calculate the diffuse flux of relic neutrinos boosted by UHECR after taking into account the contributions from both coherent and incoherent scatterings. Using current data from IceCube and Pierre Auger Observatory, we place constraints on the overdensity of relic neutrinos down to $\sim 10^8$. Since the flux of boosted relic neutrinos peaks at an energy of $\sim 200\text{PeV}$, we also entertain the possibility to explain the recently observed KM3NeT event with boosted relic neutrinos from UHECR.

   hep-phPRD(2026)·14 citations
6. 06*

   Multiprocess imaging of nuclear modifications on parton distributions in proton-nucleus collisions

   Meng-Quan Yang🇨🇳 · Peng Ru🇨🇳 · Ben-Wei Zhang🇨🇳

   Nuclear modifications to collinear parton distribution functions are conventionally quantified by the ratios $r_i^{\text{A}}(x,Q^2)=f_i^{\text{A,proton}}(x,Q^2)/f_i^{\text{proton}}(x,Q^2)$. For a given nucleus $A$, these ratios generally depend on the parton momentum fraction $x$, the probing scale $Q^2$, and the parton species $i$. Determining these dependencies relies on a global analysis of diverse experimental data. However, in realistic observables, these dependencies are intricately intertwined, making their extraction challenging. In this paper, we propose a novel approach to effectively image the nuclear modification factors $r_i^{\text{A}}(x,Q^2)$ at the observable level in proton-nucleus collisions at the Large Hadron Collider. Specifically, through a combined study of $Z$-boson production, $Z$+jet production, and $Z+c$-jet production, we separately enhance signals arising from light-quark, gluon, and heavy-flavor (charm) distributions in nuclei. This enables us to effectively image the $r_i^{\text{A}}(x,Q^2)$ for specific parton species. The feasibility of this method is validated through perturbative calculations at next-to-leading order in the strong coupling constant, employing three sets of nuclear PDF parametrizations: EPPS21, nCTEQ15, and TUJU19. Future measurements of these observables are expected to provide more efficient constraints on nuclear PDFs and yield new insights into the detailed partonic structures of nuclei.

   hep-phnucl-thPRD(2025)·2 citations
7. 07*

   Probing Spontaneous CP-Violation through Precision Higgs Observables

   Tanmoy Mondal🇮🇳 · Kei Yagyu🇯🇵

   We investigate the implications of spontaneous CP-violation in the general two Higgs doublet model, which leads to a non-decoupling structure of the Higgs sector. All the masses of the Higgs bosons are purely determined by the vacuum expectation value of the Higgs fields, and are thus constrained to be smaller than $\mathcal{O}(500)$ GeV by the perturbative unitarity bound. Such a non-decoupling nature predicts sizable deviations from the standard model expectations in the observables of the discovered Higgs boson ($h$). We find that the magnitude of deviations in ${\mathcal{B}}_{h\to \gamma \gamma }$ (${\mathcal{B}}_{h\to Z\gamma }$) are larger than $\sim 10\%(4\%)$ in the Higgs alignment limit. Moreover, we show that a robust correlation emerges between the deviations in the one-loop corrected $hhh$ coupling and ${\mathcal{B}}_{h\to \gamma \gamma }$ to be, e.g., 200\%~(50\%) and $-10.3\%$ ($-10.8\%$), respectively, under the constraints from theoretical bounds and current experimental data. Using a few benchmark points, we highlight that flavor-violating decays of the additional Higgs bosons can be sizable due to the constrained structure of the Yukawa interactions.

   hep-phPRD(2025)·1 citation
8. 08*

   Unraveling New Physics Effects in $b\to s{\ell }_1{\ell }_2$ Transitions with a Model-Independent Perspective

   Aishwarya Bhatta🇮🇳 · Dhiren Panda🇮🇳 · Rukmani Mohanta🇮🇳

   Motivated by recent anomalies in observables associated with flavor-changing neutral current (FCNC) transitions, specifically $b\to s{\ell }^{+}{\ell }^{-}$ processes, we present a comprehensive analysis of lepton flavor-violating (LFV) decay modes mediated by $b\to s{\ell }_1{\ell }_2$ transitions with ${\ell }_1\ne {\ell }_2$. While such LFV processes are forbidden within the Standard Model (SM), they naturally arise in several of its extensions, including models featuring additional vector-like fermions and extra $Z^{\prime }$ bosons. Employing the most general effective Hamiltonian for $b\to s{\ell }_1{\ell }_2$ transitions, we derive the angular distributions of the relevant decay modes. Adopting a model-independent framework, we systematically study the LFV decays $B\to K^{\ast }{\ell }_1{\ell }_2$, $B_s\to \varphi {\ell }_1{\ell }_2$, $B\to K_2^{\ast }{\ell }_1{\ell }_2$, and ${\Lambda }_b\to \Lambda {\ell }_1{\ell }_2$. Although LFV mesonic decays have been widely explored, the corresponding baryonic decays remain comparatively under-investigated. We provide bounds on branching ratio ($\mathcal{B}$), forward-backward asymmetry (${\mathcal{A}}_{FB}$), and longitudinal lepton polarization fraction (${\mathcal{F}}_L$). Furthermore, considering the projected sensitivities of the LHCb upgrade and Belle II experiments, we estimate upper limits for these observables, offering promising avenues for probing new physics in these LFV channels.

   hep-phPRD(2025)·0 citations
9. 09*

   A new method for estimating unknown one-order higher QCD corrections to the perturbative series using the linear regression through the origin

   Zhi-Fei Wu🇨🇳 · Xing-Gang Wu🇨🇳 · Jiang Yan🇨🇳 · Xu-Dong Huang🇨🇳 · Jian-Ming Shen🇨🇳

   It is generally believed that the QCD theory is the fundamental theory for strong interactions. Due to the asymptotic freedom at the short distances, after proper factorization, one can predict the value of high-energy physical observable by using the perturbative QCD (pQCD). It has been demonstrated that by recursively using of renormalization group equation with the help of Principle of Maximum Conformality (PMC), one can eliminate conventional renormalization scheme-and-scale ambiguities existed in the initial fixed-order pQCD series. To extend the predictive power of pQCD, we are still facing the problem of how to reliably estimate the contributions from the unknown higher-order (UHO) terms. In this paper, using the PMC scheme-and-scale invariant series as the starting point, we suggest a novel method of using linear regression through the origin (LRTO) to fix the asymptotic form of the pQCD series, which subsequently predicts the reasonable magnitude of the one-order higher UHO-terms. As an explicit example, we apply the method to deal with the ratio $R_{\tau }$, which has been calculated up to four-loop QCD corrections. Our results show that the LRTO method works well, demonstrating its reliability and significant predictive power for estimating the UHO-terms. Especially, we show that the scale-invariant and more convergent PMC series exhibits a much better predictive power with stability and reliability than the initial scale-dependent pQCD series.

   hep-phEPJC(2026)·3 citations
10. 10*

    Probing the Collision Geometry via Two-Photon Processes in Heavy-Ion Collisions

    Jiaxuan Luo🇨🇳 · Xinbai Li🇨🇳 · Zebo Tang🇨🇳 · Xin Wu🇨🇳 · Shuai Yang🇨🇳 · Wangmei Zha🇨🇳 · Zhan Zhang🇨🇳

    The initial collision geometry, including the reaction plane, is crucial for interpreting collective phenomena in relativistic heavy-ion collisions, yet it remains experimentally inaccessible through conventional measurements. Recent studies propose utilizing photon-induced processes as a direct probe, leveraging the complete linear polarization of emitted photons whose orientation strongly correlates with the collision geometry. In this work, we employ a QED-based approach to systematically investigate dilepton production via two-photon processes in heavy-ion collisions at RHIC and LHC energies and detector acceptances. Our calculations reveal that dilepton emission exhibits significant sensitivity to the initial collision geometry through both the azimuthal angles of their emission (defined by the relative momentum vector of the two leptons) and the overall momentum orientation of the dilepton pairs. These findings highlight the potential of two-photon-generated dileptons as a novel, polarization-driven probe to quantify the initial collision geometry and reduce uncertainties in characterizing quark-gluon plasma properties.

    hep-phNucl.Sci.Tech.(2026)·2 citations
11. 11*

    Non-invertible symmetry as an axion-less solution to the strong CP problem

    Qiuyue Liang🇯🇵 · Tsutomu T. Yanagida🇯🇵

    We use a non-invertible symmetry to construct a three-zero texture for the down-type quark mass matrix, which can resolve the strong CP problem without invoking the axion, in four-dimensional spacetime with three quark families in QCD. We assume CP invariance at the fundamental high-energy scale.

    hep-phhep-thPLB(2025)·40 citations
12. 12*

    Directed flow from parton spin-orbit coupling in $pp$ and $pA$ collisions

    Sanjin Benić🇭🇷 · Yoshitaka Hatta🇺🇸

    We point out a novel mechanism to generate $\cos \varphi$ two-particle azimuthal correlation (`directed flow') in unpolarized proton-proton and proton-nucleus collisions in the forward rapidity region of the projectile proton. This is a direct consequence of the recently discovered strong spin-orbit coupling in gluons at small-$x$. The observable simultaneously serves as a unique probe into the double helicity parton distribution functions of the proton.

    hep-phhep-exnucl-exnucl-thPLB(2025)·3 citations
13. 13*

    Computing singlet scalar freeze-out with plasmon and plasmino states

    S. Biondini🇩🇪 · M. Eriksson🇨🇭 · M. Laine🇨🇭

    The final-state particles from cosmological dark matter co-annihilation are expected to equilibrate. As dictated by Hard Thermal Loop resummation, the spectrum of equilibrated quasiparticles is richer than in vacuum, with a massless gauge field possessing three independent polarization states (``plasmons''), and a massless fermion developing a novel branch (``plasmino''). Furthermore, once the Higgs phenomenon sets in, vacuum and thermal mass corrections interfere. We collect together the corresponding poles and residues for the Standard Model around its crossover temperature. Choosing its singlet scalar extension for illustration, we subsequently demonstrate, both numerically and via power counting, and in accordance with general theoretical expectations, how in the freeze-out of TeV-scale dark matter, these effects remain well hidden in the inclusive annihilation cross section. In particular, the dominant (longitudinal) gauge channel is shown to be practically temperature-independent. Cosmological constraints on TeV-scale singlet scalars are reconfirmed.

    hep-phJHEP(2025)·6 citations
14. 14*

    Effective ALP-Photon Coupling in External Magnetic Fields

    Ozan Semin🇩🇪

    We presented a complete calculation of the one-loop fermionic correction to the effective coupling between axion-like particles (ALPs) and photons within a constant, homogeneous magnetic field of arbitrary strength. This interaction, responsible for the Primakoff effect, is central to detecting axion-like particles in astrophysical settings and terrestrial experiments like helioscopes and haloscopes. Accurately predicting the interaction rate requires accounting for quantum corrections. Our work tackles this by employing magnetically field-dressed fermion propagators derived using Schwinger's proper time method and a systematic Lorentz decomposition using the Ritus basis. We evaluate the triangle loop diagram exactly, and compare it to approximations on field strength under specific assumptions.

    hep-phhep-thJHEP(2026)·0 citations
15. 15*

    Vacuum Stability Conditions for New $SU(2)$ Multiplets

    André Milagre🇵🇹 · Darius Jurčiukonis🇱🇹 · Luís Lavoura🇵🇹

    We consider the addition to the Standard Model of a scalar $SU(2)$ multiplet ${\Delta }_n$ with dimension $n$ going from $1$ to $6$. The multiplet ${\Delta }_n$ is assumed to have null vacuum expectation value and an arbitrary (free) hypercharge. We determine the shape of the phase space for the new terms that appear in the scalar potential (SP); we observe in particular that, in the case of a 6-plet, the phase space is slightly concave along one of its boundaries. We determine the bounded-from-below and vacuum stability conditions on the SP for each value of $n$.

    hep-phhep-thPTEP(2025)·3 citations
16. 16*

    Constituent-quark-model based coupled-channels calculation of the $\mathbf{bb}\bar{\mathbf{c}}\bar{\mathbf{c}}$ and $\mathbf{bc}\bar{\mathbf{b}}\bar{\mathbf{c}}$ tetraquark systems

    Pablo G. Ortega🇪🇸 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸 · Jorge Segovia🇪🇸

    We perform a coupled-channels study of the $bb\bar{c}\bar{c}$ and $bc\bar{b}\bar{c}$ tetraquark systems in a molecular approach using a constituent quark model which has been widely used to satisfactorily describe a broad range of properties of heavy quark hadron systems, either conventional or exotic. Within a molecular framework, the interaction in the heavy quark sector is governed by gluon exchange or confinement forces that are inherently color-dependent. While the $B_c{B}_c$ system contains two identical quarks, enabling stronger interactions via exchange diagrams, the forces in the $B_c{\bar{B}}_c$ and $(c\bar{c})-(b\bar{b})$ systems are expected to be significantly weaker. Consequently, the theoretical and experimental analysis of $B_c^{(\ast )}{B}_c^{(\ast )}$, $B_c^{(\ast )}{\bar{B}}_c^{(\ast )}$, and charmonium-bottomonium bound structures could play a crucial role in clarifying the dominant mechanisms responsible for the formation of fully-heavy tetraquarks. For the $bb\bar{c}\bar{c}$ tetraquark sector, we find several resonance states with different spin-parity quantum numbers. These resonances are characterized by their proximity, but not too close, to the $B_c^{(\ast )}{B}_c^{(\ast )}$ thresholds and their large total decay widths, indicating strong decay channels. In contrast, our analysis of the $bc\bar{b}\bar{c}$ tetraquark sector reveals no bound states, virtual states, or resonances; suggesting that tetraquark states of the $(c\bar{c})-(b\bar{b})$ or $B_c^{(\ast )}{\bar{B}}_c^{(\ast )}$ molecular type are unlikely to be formed, within our model assumptions.

    hep-phPRD(2025)·2 citations
17. 17*

    Prospects for Probing Sub-GeV Leptophilic Dark Matter with the Future VLAST

    Tian-Peng Tang🇨🇳 · Meiwen Yang🇨🇳 · Kai-Kai Duan🇨🇳 · Yue-Lin Sming Tsai🇨🇳 · Yi-Zhong Fan🇨🇳

    The proposed Very Large Area Space Telescope (VLAST), with its expected unprecedented sensitivity in the MeV-GeV range, can also address the longstanding "MeV Gap" in gamma-ray observations. We explore the capability of VLAST to detect sub-GeV leptophilic dark matter (DM) annihilation, focusing on scalar and vector mediators and emphasizing the resonance region where the mediator mass is approximately twice the DM mass. While $s$-wave annihilation is tightly constrained by relic density and cosmic microwave background observations, $p$-wave and mixed $(s+p)$-wave scenarios remain viable, particularly near resonance. Additionally, direct detection experiments, especially those probing DM-electron scattering, significantly constrain nonresonance parameter space but are less effective in the resonance regime. VLAST can uniquely probe this surviving region, outperforming existing and planned instruments, and establishing itself as a crucial tool for indirect detection of thermal relic DM.

    hep-phastro-ph.HEJCAP(2025)·7 citations
18. 18*

    Testing an unstable cosmic neutrino background

    Pasquale Di Bari🇬🇧

    I discuss how different cosmological observations can test the possibility that neutrinos might be unstable on cosmological times, resulting into an unstable cosmic neutrino background. I also discuss out how actually there are different independent anomalies intriguingly hint to such a possibility that would clearly point to new physics. I first focus on how the new DESI results place an upper bound on the sum of neutrino masses that starts to be in tension with the lower bound from neutrino oscillation experiments and how this tension could be easily solved assuming unstable relic neutrinos. Then I show how 21 cm cosmology allows to test radiative relic neutrino decays and how these could explain the controversial EDGES anomaly. I also discuss how the excess radio background and in particular the ARCADE 2 data can also be nicely explained by relic neutrino radiative decays. Finally, I point out the difficulties in building a model that does not clash with the upper limits on the effective magnetic moment coming from neutrino-electron scattering experiments and globular cluster stars.

    hep-phPoS(2025)·0 citations
19. 19*

    Primordial black-hole formation and heavy r-process element synthesis from the cosmological QCD transition. Two aspects of an inhomogeneous early Universe

    M. Gonin🇩🇪 · G. Hasinger🇩🇪 · D. Blaschke🇵🇱 · O. Ivanytskyi🇵🇱 · G. Röpke🇩🇪

    We review the role of primordial black holes (PBHs) for illuminating the dark ages of the cosmological evolution and as dark matter candidates. We elucidate the role of phase transitions for primordial black hole formation in the early Universe and focus our attention to the cosmological QCD phase transition within a recent microscopical model. We explore the impact of physics beyond the Standard Model on the cosmic equation of state and the probability distribution for the formation of primordial black holes which serve as dark matter (DM) candidates. We argue that besides primordial black holes also droplet-like quark-gluon plasma inhomogeneities may become gravitationally stabilized for a sufficiently long epoch to distill baryon number and form nuclear matter droplets which upon their evaporation may enrich the cosmos locally with heavy $r$-process elements already in the early Universe.

    hep-phastro-ph.COnucl-thEPJA(2025)·11 citations
20. 20*

    Unbinned inclusive cross-section measurements with machine-learned systematic uncertainties

    Lisa Benato🇦🇹 · Cristina Giordano🇦🇹 · Claudius Krause🇦🇹 · Ang Li🇦🇹 · Robert Schöfbeck🇦🇹 · Dennis Schwarz🇦🇹 · Maryam Shooshtari🇦🇹 · Daohan Wang🇦🇹

    We introduce a novel methodology for addressing systematic uncertainties in unbinned inclusive cross-section measurements and related collider-based inference problems. Our approach incorporates known analytic dependencies on parameters of interest, including signal strengths and nuisance parameters. When these dependencies are unknown, as is frequently the case for systematic uncertainties, dedicated neural network parametrizations provide an approximation that is trained on simulated data. The resulting machine-learned surrogate captures the complete parameter dependence of the likelihood ratio, providing a near-optimal test statistic. As a case study, we perform a first-principles inclusive cross-section measurement of $\text{H}\to \tau \tau$ in the single-lepton channel, utilizing simulated data from the FAIR Universe Higgs Uncertainty Challenge. Results in Asimov data, from large-scale toy studies, and using the Fisher information demonstrate significant improvements over traditional binned methods. Our computer code ``Guaranteed Optimal Log-Likelihood-based Unbinned Method'' (GOLLUM) for machine-learning and inference is publicly available.

    hep-phhep-exphysics.data-anPRD(2025)·20 citations
21. 21*

    Discriminating Tauphilic Leptoquark Explanations of the $B$ Anomalies via $K\to \pi \nu \bar{\nu }$ and $B\to K\nu \bar{\nu }$

    Andreas Crivellin🇨🇭 · Syuhei Iguro🇯🇵 · Teppei Kitahara🇯🇵

    Leptoquark models are prime candidates for new physics (NP) explanations of the long-standing anomalies in semi-leptonic $B$ decays; $b\to c\tau \bar{\nu }$ (encoded in $R(D^{(\ast )})$) and $b\to s\ell \bar{\ell }(\ell =e,\mu )$ transitions. Furthermore, Belle II and NA62 reported weaker-than-expected limits on $B^{+}\to K^{+}\nu \bar{\nu }$ and $K^{+}\to {\pi }^{+}\nu \bar{\nu }$, respectively. While the $R(D^{(\ast )})$ and $b\to s\ell \bar{\ell }$ measurements can be explained with NP contributions at the $O(10\%)$ level, the neutrino channels suggest that the NP effect could be comparable in size to the Standard Model one. In this context, we consider the two types of leptoquark models with minimal sets of the couplings that can best describe the semi-leptonic $B$ anomalies and lead at the same time to effects in the neutrino modes, the singlet-triplet scalar leptoquark model ($S_1+S_3$) and the singlet vector leptoquark model ($U_1$). More specifically, the neutrino channels pose non-trivial constraints on the parameter space, and we find that large effects (i.e., accounting for the current central value) in $B\to K^{(\ast )}\nu \bar{\nu }$ are only possible in the $S_1+S_3$ setup, while both models can account for the central value of $K^{+}\to {\pi }^{+}\nu \bar{\nu }$.

    hep-phhep-exPRD(2025)·14 citations
22. 22*

    Tidal effects on primordial black hole capture in neutron stars

    Ian Holst🇺🇸 · Yoann Génolini🇫🇷 · Pasquale Dario Serpico🇫🇷

    We revisit the problem of the capture of a primordial black hole (PBH) by a neutron star, accounting for the tidal perturbation from a nearby star or planet. For asteroid-mass PBHs, which could constitute all of the dark matter in the universe, a weakly bound post-capture orbit could be tidally disturbed to the point of preventing the PBH from settling in the neutron star and consuming it within a cosmologically short timescale. We show how this effect depends on environmental parameters and can weaken the proposed constraints based on observations of old neutron stars in high-density dark matter environments for PBH masses $\lesssim 10^{22}$g. We also provide approximate analytical formulae for the capture rates.

    ↳ astro-ph.HEhep-phJCAP(2025)·3 citations
23. 23*

    Three-dimensional femtoscopy for proton pairs in heavy-ion collisions

    Adam Kisiel🇵🇱

    Femtoscopy, a technique of measuring the size and the dynamics of the system created in heavy-ion collisions is used extensively in experiments at RHIC, LHC, SPS, and the FAIR/GSI. Analysis for pairs of pions is most common, due to their large abundance in the collisions, as well as well-understood theoretical formalism and advanced experimental methodology. It is usually performed in three dimensions in longitudinally co-moving reference frame of the pair, to maximize the amount of information obtained about the source. Similar three-dimensional analysis has also been performed for charged and neutral kaons. In contrast analyses for all other pair types -- either for pairs of identical protons, or for pairs of non-identical particles are only one-dimensional. The abundance of heavier particles is lower than for pions, while the theoretical formalism for such correlations, as well as practical experimental methodology is limited to one-dimensional case up to now. This work identifies specific challenges arising in the analysis of three-dimensional proton-proton femtoscopy and proposes a theoretical formalism to analyze them, as well as specific experimental methods to extract and fit correlations. A test and validation of these methods is performed on correlations simulated in the LHyquid+Therminator2 model, and demonstrates the feasibility of such analysis. The caveats in the theoretical interpretation of the results are discussed, by comparing the fitted values of femtscopic radii with the true characteristics of the source extracted directly from the model.

    ↳ hep-exhep-phnucl-th2 citations
24. 24*

    Late-blooming magnetars: awakening as long period transients after a dormant cooling epoch

    Arthur G. Suvorov🇪🇸 · Clara Dehman🇪🇸 · José A. Pons🇪🇸

    Long-period transients are an elusive class of compact objects uncovered by radio surveys. While magnetars are a leading candidate for those sources that appear isolated, several observational properties challenge the established evolutionary framework: (i) low quiescent X-ray luminosities, (ii) $\sim$hour-long rotational periods, and (iii) highly-variable radio flux. It is shown via magnetothermal modelling that, if electric currents thread the fluid core at the time of crust freezing, the neutron star remains multiband silent for an initial period of approximately 0.1 Myr while cooling passively. Once the crust becomes cold enough, the Hall effect begins to dominate the magnetic evolution, triggering crustal failures that inject magnetospheric twist that initiates radio pulsing while depleting rotational kinetic energy from an already-slow star. Depending on where electric currents circulate, such 'late-blooming' magnetars manifesting as long-period transients may thus form a distinct branch from soft gamma repeaters and anomalous X-ray pulsars.

    ↳ astro-ph.HEhep-phhep-thApJ(2026)·5 citations
25. 25*

    Manifest Gauge Invariance for Structure Dependent Radiative Corrections to Processes Involving Atoms and Nuclei

    Ryan Plestid🇺🇸 · Mark B. Wise🇺🇸

    Radiative corrections to reactions involving atoms or nuclei can become sensitive to the structure of the bound state. Generically, one encounters correlation functions of multiple currents which must satisfy Ward identities. At intermediate steps, however the Ward identities are obscured, and often violated by physically motivated approximation schemes. In this paper we outline a method to construct a representation of the aforementioned correlators that manifests gauge invariance in the limit of a heavy target (i.e., when recoil energy can be neglected). This representation then enables manifestly gauge invariant approximation schemes. Furthermore, the proposed representation naturally separates the largest contributions that dominate scattering amplitudes in the limit of a heavy constituent (e.g., proton) mass. We analyze elastic electron scattering from nuclei in detail, and also discuss radiative corrections to processes mediated by the weak interaction.

    ↳ nucl-thhep-phnucl-ex4 citations
26. 26*

    Screened Axio-dilaton Cosmology: Novel Forms of Early Dark Energy

    Adam Smith🇬🇧 · Philippe Brax🇫🇷 · Carsten van de Bruck🇬🇧 · C.P. Burgess🇨🇦 · Anne-Christine Davis🇬🇧

    We study the cosmology of multi-field Dark Energy, using a well-motivated axio-dilaton model that contains the minimal number of fields to have the 2-derivative sigma-model interactions that power-counting arguments show naturally compete with General Relativity at low energies. Our analysis differs from earlier, related, studies by treating the case where the dilaton's couplings to matter are large enough to require screening to avoid unacceptable dilaton-mediated forces in the solar system. We use a recently proposed screening mechanism that exploits the interplay between stronger-than-gravitational axion-matter couplings with the 2-derivative axion-dilaton interactions to suppress the couplings of the dilaton to bulk matter. The required axion-matter couplings also modify cosmology, with the axion's background energy density turning out to resemble early dark energy. We compute the properties of the axion fluid describing the rapid oscillations of the axion field around the time-dependent minimum of its matter-dependent effective potential, extending the usual formalism to include nontrivial kinetic sigma-model interactions. We explore the implications of these models for the Cosmic Microwave Background and the growth of structure and find that for dilaton potentials of the Albrecht-Skordis form (itself well-motivated by UV physics), successful screening can be consistent with the early dark energy temporarily comprising as much as 10% of the total density in the past. We find that increasing the dilaton-matter coupling decreases the growth of structure due to enhanced Hubble friction, an effect that dominates the usual fifth-force effects that amplify structure growth.

    ↳ hep-thastro-ph.COgr-qchep-phEPJC(2025)·33 citations
27. 27*

    Comparison of integral equations used to study $T_{cc}^{+}$ for a stable $D^{\ast }$

    Sebastian M. Dawid🇺🇸 · Fernando Romero-López🇨🇭 · Stephen R. Sharpe🇺🇸

    We perform a detailed comparison between three formalisms used in recent studies of $D{D}^{\ast }$ scattering, which aim to understand the properties of the doubly-charmed tetraquark, $T_{cc}^{+}(3875)$. These methods are the three-particle relativistic field theory (RFT) formalism, the two-body Lippmann-Schwinger (LS) equation with chiral effective field theory potentials, and the two-particle relativistic framework proposed by Baiao Raposo and Hansen (BRH approach). In a simplified single-channel setting, we derive the conditions under which the infinite-volume integral equations from the RFT and BRH approaches reduce to the LS form. We present numerical examples showing that differences between these methods can be largely removed by adjusting short-range couplings. We also address a number of technical issues in the RFT approach.

    ↳ nucl-thhep-lathep-phJHEP(2025)·12 citations
28. 28*

    Di-nucleons do not form bound states at heavy pion mass

    John Bulava🇩🇪 · M.A. Clark🇺🇸 · Arjun S. Gambhir🇺🇸 · Andrew D. Hanlon🇺🇸 · Ben Hörz🇩🇪 · Bálint Joó🇺🇸 · Christopher Körber🇩🇪 · Ken McElvain🇺🇸 · Aaron S. Meyer🇺🇸 · Henry Monge-Camacho🇺🇸 · Colin Morningstar🇺🇸 · Joseph Moscoso🇺🇸 and 7 other authors

    We perform a high-statistics lattice QCD calculation of the low-energy two-nucleon scattering amplitudes. In order to address discrepancies in the literature, the calculation is performed at a heavy pion mass in the limit that the light quark masses are equal to the physical strange quark mass, $m_{\pi }=m_K\simeq 714$ MeV. Using a state-of-the-art momentum space method, we rule out the presence of a bound di-nucleon in both the isospin 0 (deuteron) and 1 (di-neutron) channels, in contrast with many previous results that made use of compact hexaquark creation operators. In order to diagnose the discrepancy, we add such hexaquark interpolating operators to our basis and find that they do not affect the determination of the two-nucleon finite volume spectrum, and thus they do not couple to deeply bound di-nucleons that are missed by the momentum-space operators. Further, we perform a high-statistics calculation of the HAL QCD potential on the same gauge ensembles and find qualitative agreement with our main results. We conclude that di-nucleons do not form bound states at heavy pion masses and that previous identification of deeply bound di-nucleons must have arisen from a misidentification of the spectrum from off-diagonal elements of a correlation function.

    ↳ hep-lathep-phnucl-thPRC(2026)·26 citations
29. 29*

    Multipositivity Bounds for Scattering Amplitudes

    Clifford Cheung🇺🇸 · Grant N. Remmen🇺🇸

    Lorentz invariance, unitarity, and causality enforce powerful constraints on the theory space of physical scattering amplitudes. However, virtually all efforts in this direction have centered on the very simplest case of four-point scattering. In this work, we derive an infinite web of "multipositivity bounds" that nonlinearly constrain all tree-level higher-point scattering amplitudes under similarly minimal assumptions. Our construction rules out several deformations of the string and implies mixed-multiplicity bounds on the Wilson coefficients of planar effective field theories. Curiously, an infinite class of multipositivity bounds is exactly saturated by the amplitudes of the open string.

    ↳ hep-thhep-phPRD(2025)·32 citations
30. 30*

    Casimir Forces Across Magnetic Plasmas at Nuclear Separations

    S. K. Panja🇵🇱 · L. Inacio🇵🇱 · S. Pal🇨🇦 · M. Boström🇵🇱

    A theory and numerical findings are presented on the magnetic Casimir interaction that arises from vacuum fluctuations of the quantized field and its effects at the nuclear scale. We investigate how the zero-temperature Casimir effect at nuclear scales can generate the black-body temperatures required to induce a magnetic electron-positron plasma. The magnetic permeability of the plasma and any magnetic fields present influence the screened Casimir-Yukawa potentials between perfect conducting surfaces. We discuss implications for the magnetic Casimir-Yukawa potential, its screening length, and a magnetic permeability-dependent quantity that resembles the meson mass.

    ↳ quant-phhep-phhep-thAnnals Phys.(2025)·2 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.