Tue·Dec 24, 2024Tuesday·December 24, 2024

1. 01*

   Machine Learning Neutrino-Nucleus Cross Sections

   Daniel C. Hackett🇺🇸 · Joshua Isaacson🇺🇸 · Shirley Weishi Li🇺🇸 · Karla Tame-Narvaez🇺🇸 · Michael L. Wagman🇺🇸

   Neutrino-nucleus scattering cross sections are critical theoretical inputs for long-baseline neutrino oscillation experiments. However, robust modeling of these cross sections remains challenging. For a simple but physically motivated toy model of the DUNE experiment, we demonstrate that an accurate neural-network model of the cross section -- leveraging only Standard-Model symmetries -- can be learned from near-detector data. We perform a neutrino oscillation analysis with simulated far-detector events, finding that oscillation analysis results enabled by our data-driven cross-section model approach the theoretical limit achievable with perfect prior knowledge of the cross section. We further quantify the effects of flux shape and detector resolution uncertainties as well as systematics from cross-section mismodeling. This proof-of-principle study highlights the potential of future neutrino near-detector datasets and data-driven cross-section models.

   hep-phcs.LGhep-exnucl-thPRD(2025)·1 citation
2. 02*

   Precise determination of pomeron intercept via scaling entropy analysis

   Lucas Soster Moriggi🇧🇷 · Magno Valério Trindade Machado🇧🇷

   In this work, we confront the geometrical scaling properties of inclusive DIS cross section ($e+p\to e+X$) with the scaling entropy obtained from event multiplicity. We show that these two quantities are equivalent in the kinematic range probed by H1 Collaboration data. We propose that scaling entropy associated with partonic interactions is a more efficient way to detect scaling in experimental data. We used a combined analysis of the inclusive cross section and entropy obtained from multiplicities $P(N)$ of final-state hadrons to accurately determine the value of the Pomeron intercept. The approach could provide new constraints for future hadron collider experiments and deepen our understanding of parton saturation.

   hep-phPRD(2025)·6 citations
3. 03*

   Analytical Expressions for Neutrino Oscillation

   Adriano Cherchiglia🇧🇷 · Macello Jales🇧🇷 · Guilherme Nogueira🇧🇷 · Maressa P. Sampaio🇧🇷 · Pedro C. de Holanda🇧🇷

   Research in neutrino physics has been very active, both in experimental advances, with a new generation of detectors in operation and planning, and in theoretical discussions regarding the fundamental nature of the neutrino. This scientific dynamism has attracted many new students to the field. One of the first topics studied in neutrino physics by newcomers is the formalism of neutrino flavor oscillations and its associated phenomenology. We present this work as a compilation of this basic knowledge, through a step-by-step approach that facilitates an efficient understanding of this vast theoretical and experimental landscape.

   hep-ph0 citations
4. 04*

   NNLO phase-space integrals for semi-inclusive deep-inelastic scattering

   Taushif Ahmed🇩🇪 · Saurav Goyal🇮🇳 · Syed Mehedi Hasan🇩🇪 · Roman N. Lee🇷🇺 · Sven-Olaf Moch🇩🇪 · Vaibhav Pathak🇮🇳 · Narayan Rana🇮🇳 · Andreas Rapakoulias🇩🇪 · V. Ravindran🇮🇳

   We evaluate the phase-space integrals that arise in double real emission diagrams for semi-inclusive deep-inelastic scattering at next-to-next-to-leading order (NNLO) in QCD. Utilizing the reverse unitarity technique, we convert these integrals into loop integrals, allowing us to employ integration-by-parts identities and reduce them to a set of master integrals. The master integrals are then solved using the method of differential equations and expressed in terms of Goncharov polylogarithms. By examining the series expansion in the dimensional regulator, we discover additional relations among some of the master integrals. As an alternative approach, we solve the master integrals by decomposing them into angular and radial components. The angular parts are evaluated using Mellin-Barnes representation, while special attention is given to the singular structures of the radial integrals to handle them accurately. Here the results are provided in terms of one-fold integrals over classical polylogarithms. This approach provides a clearer understanding of the origin of soft and collinear singularities.

   hep-phPRD(2025)·13 citations
5. 05*

   Bayesian constraints on covariant density functional equations of state of compact stars with new NICER mass-radius measurements

   Jia-Jie Li🇨🇳 · Yu Tian🇺🇸 · Armen Sedrakian🇵🇱

   Recent advancements in astrophysical observations of compact stars, particularly the new and updated NICER constraints, have provided mass-radius ($M$-$R$) data for pulsars spanning masses from 1 to $2M_{\odot }$. These data offer a unique opportunity to test modern theories of dense matter using multi-messenger constraints. Covariant density functional (CDF) models of nuclear matter, which capture a broad range of nuclear and astrophysical phenomena, provide a robust theoretical framework to interpret these observations. This study applies the Bayesian framework to a class of CDF models with density-dependent meson-nucleon couplings, specifically those based on nucleonic degrees of freedom. By incorporating the latest multi-messenger constraints, we impose tighter limits on the parameter space of these models and assess their consistency with observational data. Our analysis advances previous efforts by refining the density-dependence parameterization and integrating recent $M$-$R$ ellipses. This enables more stringent evaluations of dense matter models in light of new astrophysical observations.

   hep-phnucl-thPLB(2025)·23 citations
6. 06*

   Dark photons and tachyonic instability induced by Barbero-Immirzi parameter and axion-torsion transmutation

   Zhi-Fu Gao🇨🇳 · Biaopeng Li🇨🇳 · L.C. Garcia de Andrade🇧🇷

   In this paper, we investigate Holst gravity by examining two distinct examples. The first example involves minimal coupling to torsion, while the second explores non-minimal coupling. The motivation for the first example stems from the recent work by Dombriz, which utilized a technique of imposing constraint constant coefficients to massive torsion in the model Lagrangian to determine parameters for the Einstein-Cartan-Holst gravity. We extend this methodology to investigate dark photons, where axial torsion transforms into axions.Interest in elucidating the abundance of dark photons within the framework of general relativity was sparked by Agrawal. Building on the work of Barman, who explored minimal coupling of massive torsion mediated by dark matter (DM) with light torsion on the order of 1.7 TeV, we have derived a Barbero-Immirzi (BI) parameter of approximately 0.775. This value falls within the range established by Panza et al. at TeV scales, specifically $0\le \beta \le 1.185$. This seems to our knowledge the first time BI parameter is induced by dark photons on a minimal EC gravity. Very recently, implications of findings of BI parameter in cosmological bounces has appeared in the literature. For a smaller BI parameter a higher torsion mass of 1.51 TeV is obtained. Nevertheless. this figure is still a signature of light torsion which can be compatible with light dark photon masses. Magnetic helicity instability of dark photons is investigated. Axion oscillation frequency is shown to depend on the BI parameter and the BI spectra is determined by an histogram. This study not only broadens the understanding of Holst gravity but also provides crucial insights into the interplay between torsion, dark photons, and axions in the cosmological context.

   hep-phgr-qcEPJC(2025)·8 citations
7. 07*

   PDFxTMDLib: A High-Performance C++ Library for Collinear and Transverse Momentum Dependent Parton Distribution Functions

   R. Kord Valeshabadi🇮🇷 · S. Rezaie🇮🇷

   Collinear parton distribution functions (cPDFs) and transverse momentum dependent distributions (TMDs) are essential for calculating cross sections in high-energy physics, particularly within collinear and kt-factorization frameworks. Currently, there exists two libraries, such as LHAPDF and TMDLib, to obtain these physical objects. However, there are limitations in both libraries, especially for TMDs, such as restricted customization and extensibility. Users are limited to the implementations provided by these libraries and cannot easily support unconventional PDFs. Moreover, no standard TMD library currently provides a consistent framework for QCD coupling evaluation or for studying uncertainties at the distribution level--features that are important for diagnostic and comparative analyses in phenomenological research. To address these shortcomings, we introduce PDFxTMDLib, a modern C++ library designed to offer a robust and flexible solution. This library supports both collinear PDFs and TMDs while allowing greater customization. It also opens the way to support higher-order distributions. In this article, we describe the structure of PDFxTMDLib. We also demonstrate its validity and performance by integrating it into the PYTHIA Monte Carlo event generator to compute Drell-Yan cross sections. Additionally, comparisons of PDFs obtained from PDFxTMDLib with those from LHAPDF and TMDLib confirm the reliability of PDFxTMDLib's results.

   hep-phEPJ RI(2026)·3 citations
8. 08*

   Updated predictions for toponium production at the LHC

   M.V. Garzelli🇩🇪 · G. Limatola🇩🇪 · S.-O. Moch🇩🇪 · M. Steinhauser🇩🇪 · O. Zenaiev🇩🇪

   We provide an update on QCD predictions for top-quark pair production close to threshold including bound state effects at the Large Hadron Collider. We compute the top-quark pair invariant mass distribution $d\sigma /d{M}_{t\bar{t}}$, including Coulomb resummation for bound-state effects, as well as threshold resummation for emissions of soft and collinear gluons. We discuss uncertainty estimates and present a proposal for the use of these predictions in experimental analyses.

   hep-phhep-exPLB(2025)·45 citations
9. 09*

   $2^{++}$ Di-gluonium from LSR at higher order

   Siyuan Li🇨🇦 · Stephan Narison🇫🇷 · Davidson Rabetiarivony🇲🇬 · Tom Steele🇨🇦

   We improve the determination of the mass and coupling of the $2^{++}$ tensor di-gluonium by using relativistic QCD Laplace sum rules (LSR). In so doing, we evaluate the next-to-leading order (NLO) corrections to the perturbative (PT) and $⟨{\alpha }_s{G}^2⟩$ condensate and the lowest order (LO) $⟨G^3⟩$ contributions to the $2^{++}$ di-gluonium two-point correlator. Within a vacuum saturation estimate ($k_G=1$) of the dimension-eight gluon condensates, we obtain: $M_T=3028(287)\text{mbox}MeV$ and the renormalization group invariant (RGI) coupling ${\hat{f}}_T=224(33)\text{mbox}MeV$. Assuming that the factorization hypothesis can be violated, we study the effect of the violation factor $k_G$ on the results and obtain: $M_T=3188(337)\text{mbox}MeV$ and ${\hat{f}}_T=245(32)\text{mbox}MeV$ for $k_G=(3\pm 2)$. Our estimation does not favour the interpretation of the observed $f_2(2010)$, $f_2(2300)$ and $f_2(2340)$ as pure glueball state.

   hep-phInt.J.Mod.Phys.A(2025)·0 citations
10. 10*

    Influence of a nontrivial Polyakov loop on the quarkonium states

    Wenqiang Liu🇨🇳 · Lihua Dong🇨🇳 · Yun Guo🇨🇳

    Using a hybrid approach based on a phenomenological heavy-quark potential model and the background field effective theory, we assess the influence of a nontrivial Polyakov loop on the in-medium properties of the heavy quarkonium states. Without resorting to any temperature-dependent parameter, the lattice simulations on the complex heavy-quark potential are well reproduced with the potential model in which the screening masses are determined by the background field effective theory. Due to the reduced screening strength near the deconfining temperature, a nontrivial Polyakov loop leads to a dramatic increase in the binding energies, together with a moderate decrease in the decay widths. In general, a more tightly bounded quarkonium state can be expected, although the increase in the dissociation temperatures is significant only for relatively large-size bounded states. Our results indicate that the background field modification on the binding and decay of the quarkonium states may have a notable impact on the density evolution of quarkonia during the expansion of the fireball, and thus on the final observed quarkonium spectra.

    hep-phPRD(2025)·3 citations
11. 11*

    Elastic Neutrino-electron Scattering at the One-loop Level in the Standard Model

    Jihong Huang🇨🇳 · Shun Zhou🇨🇳

    In this paper, we perform a complete calculation of the differential cross section for elastic neutrino-electron scattering at the one-loop level in the Standard Model (SM), by using up-to-date values of relevant input parameters in the on-shell renormalization scheme. A careful comparison with the calculation done by Sarantakos, Sirlin and Marciano more than forty years ago in the same scheme is carried out, and an excellent agreement is found if the same values of input parameters are taken. Then we apply our results to compute the event rates for the detection of reactor antineutrinos in both JUNO and TAO experiments, which are now under construction and will soon be in operation. It should be emphasized that one-loop radiative corrections in the SM must be taken into account in the first place when searching for possible new-physics effects in the coming era of precision neutrino physics.

    hep-phhep-exPRD(2025)·10 citations
12. 12*

    Prospecting bipartite Dark Matter through Gravitational Waves

    Pankaj Borah🇮🇳 · Pradipta Ghosh🇮🇳 · Abhijit Kumar Saha🇮🇳

    We explore the gravitational wave probes of a two-component dark matter framework, consisting of an $SU(2{)}_L$ triplet scalar and a Standard Model singlet fermion. The triplet scalar dark matter typically remains underabundant in the region below $\sim 1.9$ TeV, due to the strong $SU(2{)}_L$ gauge mediated interactions. We introduce a second dark matter component, an $SU(2{)}_L$ singlet vector-like Dirac fermion, to address this deficit in the dark matter relic abundance within a sub-TeV range. A key aspect of the proposed setup is the potential dark matter inter-conversion between the two components, which impacts the dark matter freeze-out dynamics and relic density of individual dark matter components. In such a scenario, we examine the properties of electroweak phase transition and identify the regions of parameter space that exhibit strong first-order phase transition. We estimate the resulting gravitational wave spectrum and its detectability, which could be probed through the conventional power-law-integrated sensitivity limits and the recently proposed peak-integrated sensitivity curves. Our analysis reveals that a novel region of the model's parameter space, compatible with dark matter observables, can generate a detectable gravitational wave spectrum, observable by upcoming space-based gravitational wave detectors such as LISA, BBO, DECIGO, and DECIGOcorr, while also offering complementary detection prospects in the dark matter and collider experiments.

    hep-phastro-ph.COhep-exJCAP(2025)·15 citations
13. 13*

    Towards UV-Models of Kinetic Mixing and Portal Matter VII: A Light Dark Photon in the $3_c{3}_L{1}_A{1}_B$ Model

    Thomas G. Rizzo🇺🇸

    The kinetic mixing (KM) portal, by which the Standard Model (SM) photon mixes with a light dark photon arising from a new $U(1{)}_D$ gauge group, allows for the possibility of viable scenarios of sub-GeV thermal dark matter (DM) with appropriately suppressed couplings to the SM. This KM can only occur if particles having both SM and dark quantum numbers, here termed portal matter (PM), also exist. The presence of such types of states and the strong suggestion of a need to embed $U(1{)}_D$ into a non-abelian gauge structure not too far above the TeV scale based on the RGE running of the $U(1{)}_D$ gauge coupling is potentially indicative of an enlarged group linking together the visible and dark sectors. The gauge group $G=SU(3{)}_c\times SU(3{)}_L\times U(1{)}_A\times U(1{)}_B=3_c{3}_L{1}_A{1}_B$ is perhaps the simplest setup wherein the SM and dark interactions are partially unified in a non-abelian fashion that is not a simple product group of the form $G=G_{SM}\times G_D$ encountered frequently in earlier work. The present paper describes the implications and phenomenology of this type of setup.

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

    Heavy-quark mass relation from a standard-model boson operator representation in terms of fermions

    Jaime Besprosvany🇲🇽 · Rebeca Sánchez🇩🇪

    The standard-model can be equivalently represented with its fields in a spin-extended basis, departing from fermion degrees of freedom. The common Higgs operator connects the electroweak and Yukawa sectors, restricting the top and bottom quark masses[Phys. Rev. D 99, 073001, 2019]. Using second quantization, within the heavy-particle sector, electroweak vectors, the Higgs field, and symmetry operators are expanded in terms of bilinear combinations of top and bottom quark operators, considering discrete degrees of freedom and chirality. This is interpreted as either a basis choice or as a description of composite models. The vacuum expectation value is calculated quantum mechanically, which relates to the common mass-generating scalar operator and it reproduces the vector and quark-doublet masses. This also links the corresponding scalar-vector and Yukawa vertices, and restricts the t- and b-quark masses in a hierarchy relation.

    hep-phhep-thInt.J.Mod.Phys.A(2026)·0 citations
15. 15*

    Pomeron Weights in QCD Processes at High Energy and the $S$-Matrix Unitarity Constraint

    Rami Oueslati🇧🇪

    The pomeron topological cross-section is derived for the eikonal and the $U$-matrix unitarization schemes using a generalized expansion of the unitarized elastic amplitude in an effort to examine pomeron characteristics, namely the multiplicity distribution, fluctuation, and correlation, and to reveal the impact of pomeron weights on the $pp$ multiplicity distribution. The results demonstrate that the U-matrix inherently incorporates a larger amount of diffraction production into the multi-pomeron vertices, yielding a larger pomerons' variability regardless of the energy range, while such fluctuations become significant only beyond a specific high-energy threshold in the eikonal and quasi-eikonal schemes. Most importantly, our findings indicate that within the $U$-matrix scheme, an increase in exchanged pomerons results in more pronounced higher-order pomeron correlations, which are affected by the energy and the impact parameter. Interestingly, our outcomes also highlight that the correlated pomeron exchanges within the U-matrix summation play a key role in enhancing multi-parton collisions. In light of these results, we can argue that the U-matrix is fundamentally more valid for theories with growing cross-sections with energy, such as QCD at high energies.

    hep-ph0 citations
16. 16*

    Neutrinos: Opening new doors

    Francesco Vissani🇮🇹

    In this contribution, which introduces the "Crossing the Portal" session of the NOW 2024 meeting, I discuss the value of the concepts of interdisciplinarity and innovation for neutrino physics. After some historical considerations, which provide an initial illustration of the significant role of these concepts, I review some well-known cases of neutrino science, involving both astrophysics and particle physics, which allow us to deepen the analysis. The importance of a harmonious relationship between theoretical elaborations and experiments emerges: effective collaboration between theoretical and experimental physicists played a key role in many of the successful cases and proved marginal or defective in the doubtful ones. The discussion highlights also the need to proceed armed with a patience, a virtue that Feynman himself indicated as essential to science, all the more necessary when investigating interesting but elusive particles such as neutrinos.

    hep-phhep-thPoS(2025)·1 citation
17. 17*

    Gravitational waves from a first-order phase transition of the inflaton

    Jörn Kersten🇰🇷 · Seong Chan Park🇰🇷 · Yeji Park🇰🇷 · Juhoon Son🇰🇷 · Liliana Velasco-Sevilla🇰🇷

    We explore the production of gravitational waves (GW) resulting from a first-order phase transition (FOPT) in a non-minimally coupled `Dark Higgs Inflation' model. Utilizing a dark sector scalar field as the inflaton, we demonstrate how inflationary dynamics naturally set the stage for observable FOPT. These transitions, influenced by thermal and quantum effects, generate GW spectra potentially detectable by observatories such as LISA, DECIGO, the Cosmic Explorer and the Einstein Telescope. Our study highlights the inflaton's dual role in cosmic inflation and early Universe phase transitions, presenting a unified framework to probe physics beyond the Standard Model through gravitational wave astronomy.

    hep-phastro-ph.HEgr-qcJCAP(2025)·3 citations
18. 18*

    Photonic Freeze-In

    Peter Cox🇦🇺 · Matthew J. Dolan🇦🇺 · Frederick J. Hiskens🇦🇺

    We present a new scenario of freeze-in, where the dark matter is produced exclusively via the annihilation of photons. We study fermionic and scalar dark matter models with a focus on cosmological histories with low reheat temperatures. Photonic freeze-in can be probed via direct detection, dark matter production in SN1987A, and via the production of new electromagnetically charged states at the Large Hadron Collider. We briefly discuss UV-complete models that can realise this scenario.

    hep-phPRD(2026)·4 citations
19. 19*

    Deuteron gravitational form factors, generalized parton distributions, and charge density in the framework of the soft-wall AdS/QCD model

    Shahin Mamedov🇦🇿 · Minaya Allahverdiyeva🇦🇿 · Narmin Akbarova🇦🇿

    We study the deuteron gravitational form factors (GFFs) and generalized parton distributions (GPDs) within the soft-wall AdS/QCD model, where deuteron is described by the bulk vector field with twist $\tau =6$. For the finite-temperature studies, we apply the soft-wall model, which is thermalized by introducing a thermal dilaton field. GPDs and charge density are considered in impact parameter (IP) space and at zero and finite temperatures. We plot the temperature dependence of these quantities in IP space and observe a decreasing of their peaks on temperature increasing. The gravitational root means squared radius obtained here is close to the range given by experimental data for the mass radius and has low sensitivity to the temperature.

    hep-phhep-thEPJC(2025)·7 citations
20. 20*

    Irreducible Three-Loop Vacuum-Polarization Correction in Muonic Bound Systems

    G. S. Adkins🇺🇸 · U. D. Jentschura🇺🇸

    Three-loop electronic vacuum-polarization corrections due to irreducible diagrams are evaluated for two-body muonic ions with nuclear charge numbers 1 <= Z <= 6. The corrections are of order alpha^3 (Zalpha)^2 m_r, where alpha is the fine-structure constant and m_r is the reduced mass. Numerically, the energy corrections are found to be of the same order-of-magnitude as the largest of the order alpha^2 (Zalpha)^6 m_r corrections, and are thus phenomenologically interesting. Our method of calculation eliminates numerical uncertainty encountered in other approaches.

    hep-phphysics.atom-phPRD(2025)·3 citations
21. 21*

    Photon Production by Chiral Magnetic Effect in the Early Stage of High-Energy Nuclear Collisions

    M. R. Jia🇨🇳

    We present an event-by-event study of photons produced by the chiral magnetic effect in the early stage of high-energy nuclear collisions. We model the early stage with an evolving, 2+1 dimensional, glasma, initialized via the McLerran-Venugopalan model. The photons are produced from the interplay of the chiral anomaly of quantum chromodynamics and the strong magnetic fields generated by the colliding nuclei. In particular, we focus on the spectrum and the elliptic flow of the produced photons. We find that the chiral magnetic effect has a minor impact on the photon spectrum compared to other production mechanisms as well as to experimental data. However, the photons produced by the present early stage mechanism can exhibit a significant elliptic flow.

    hep-phPRD(2025)·3 citations
22. 22*

    Neutrinos as background and signal in searches using the Migdal effect

    Tarak Nath Maity🇦🇺

    Ionization or excitation resulting from the noninstantaneous response of the electron cloud to nuclear recoil is known as the Migdal effect. Dark matter searches utilizing this process set the most stringent bounds on the spin-independent dark matter-nucleon scattering cross section over a large region of the sub-GeV dark matter parameter space, underscoring its significance in dark matter detection. In this paper, we quantify the regions of dark matter parameter space that are challenging to probe via the Migdal effect due to the presence of dominant solar neutrino backgrounds for both liquid noble and semiconductor targets. Our findings reveal that there is no hard floor in the dark matter parameter space. Instead, we map the so-called neutrino fog. In mapping the neutrino fog, we identify the importance of incorporating the Migdal effect induced by neutrinos, as well as neutrino-electron scattering and dominant coherent neutrino-nucleus scattering, particularly for semiconductor targets. Furthermore, we demonstrate that a large portion of the relic density allowed parameter space lies within the neutrino fog. Finally, we estimate the exposure required to detect neutrino-induced Migdal events in direct detection experiments.

    hep-phastro-ph.COastro-ph.SRhep-exPRD(2025)·15 citations
23. 23*

    hep-aid: A Python Library for Sample Efficient Parameter Scans in Beyond the Standard Model Phenomenology

    Mauricio A. Diaz🇬🇧 · Srinandan Dasmahapatra🇬🇧 · Stefano Moretti🇬🇧

    This paper presents hep-aid, a modular Python library conceived for utilising, implementing, and developing parameter scan algorithms. Originally devised for sample-efficient, multi-objective active search approaches in computationally expensive Beyond Standard Model (BSM) phenomenology, the library currently integrates three Machine Learning (ML)-based approaches: a Constraint Active Search (CAS) algorithm, a multi-objective Active Search (AS) method (called b-CASTOR), and a self-exploration method named Machine Learning Scan (MLScan). These approaches address the challenge of multi-objective optimisation in high-dimensional BSM scenarios by employing surrogate models and strategically exploring parameter spaces to identify regions that satisfy complex objectives with fewer evaluations. Additionally, a Markov-Chain Monte Carlo method using the Metropolis-Hastings algorithm (MCMC-MH) is implemented for method comparison. The library also includes a High Energy Physics (HEP) module based on SPheno as the spectrum calculator. However, the library modules and functionalities are designed to be easily extended and used also with other external software for phenomenology. This manual provides an introduction on how to use the main functionalities of hep-aid and describes the design and structure of the library. Demonstrations based on the aforementioned parameter scan methods show that hep-aid methodologies enhance the efficiency of BSM studies, offering a versatile toolset for complex, multi-objective searches for new physics in HEP contexts exploiting advanced ML-based approaches.

    hep-ph10 citations
24. 24*

    Confronting the seesaw mechanism with neutrino oscillations: a general and explicit analytical bridge

    Zhi-zhong Xing🇨🇳 · Jing-yu Zhu🇨🇳

    With the help of a full Euler-like block parametrization of the flavor structure for the canonical seesaw mechanism, we present the first general and explicit analytical calculations of the two neutrino mass-squared differences, three flavor mixing angles and the effective Dirac CP-violating phase responsible for the primary behaviors of neutrino oscillations. Such model-independent results will pave the way for testing the seesaw mechanism at low energies.

    hep-phhep-exNPB(2025)·9 citations
25. 25*

    On the Coulomb corrections in nuclear beta decay

    Edoardo Alviani🇫🇷 · Adam Falkowski🇫🇷

    We propose a Lorentz invariant and little group covariant description of beta decay amplitudes relying on on-shell amplitude methods and the spinor variables for massive particles. The framework is employed to calculate Coulomb corrections to the decay amplitude and their contribution to T -odd correlation coefficients, including the D parameter. In the SM limit we recover the known results for the Coulomb contributions to D and update their numerical values. We also calculate new subleading contributions to D in the presence of non-standard scalar and tensor interactions. We also point out that two other T -odd correlation coefficients are generated in the SM at the same order as the D parameter, and provide their numerical values for selected transitions.

    hep-phJHEP(2025)·1 citation
26. 26*

    Revisiting the Inert Scalar Dark Matter with Vector-like Quarks

    Prasanta Kumar Das🇮🇳 · Shyamashish Dey🇮🇳 · Saumyen Kundu🇮🇳 · Santosh Kumar Rai🇮🇳

    The inert doublet model (IDM), a minimal extension of the Standard Model (SM), provides a scalar dark matter (DM) candidate that belongs to the additional Higgs doublet. The model faces challenges in achieving the correct relic abundance for compressed spectra and DM masses in the high-mass range. In this work we introduce a $Z_2$-odd singlet vector-like quark (VLQ) into the IDM framework that helps us alleviate these issues and provide new channels of contributions to the relic abundance. The VLQ not only enhances the DM relic abundance for masses above $550$ GeV but also eases constraints from direct detection experiments by enabling smaller couplings between the inert scalars and the SM Higgs. We analyze the impact of the VLQ on DM phenomenology, including relic density, direct and indirect detection constraints. The results demonstrate that the extended IDM framework not only resolves existing limitations in the compressed spectrum but also offers exciting prospects for detection in current and future collider experiments.

    hep-phastro-ph.COJHEP(2025)·4 citations
27. 27*

    Dark gauge-mediated supersymmetry breaking with a massless dark photon

    Brian Batell🇺🇸 · Yechan Kim🇰🇷 · Hye-Sung Lee🇰🇷 · Jiheon Lee🇰🇷

    We study dark gauge-mediated supersymmetry breaking (dark GMSB) in a theory with a new unbroken $U(1{)}_D$ local symmetry and massless dark photon. Messenger fields charged under both Standard Model and dark gauge symmetries produce new soft supersymmetry-breaking terms due to gauge kinetic mixing between $U(1{)}_Y$ hypercharge and $U(1{)}_D$. We show that large kinetic mixing induces significant distortions to the superpartner spectra relative to conventional GMSB. Notably, shifts in the Higgs soft masses impact the conditions for electroweak symmetry breaking, lowering the $\mu$ parameter and yielding a relatively light Higgsino that may be accessible at the LHC. Furthermore, for very simple messenger representations, a very light bino-dark photino mixed state is present in the spectrum, which may be probed through exotic Higgs boson decays at future Higgs factories. We also examine the cosmological and phenomenological consequences of the messengers, the lightest of which is absolutely stable and carries fractional electric charge.

    hep-phastro-ph.COJHEP(2025)·1 citation
28. 28*

    Encoding off-shell effects in top pair production in Direct Diffusion networks

    Mathias Kuschick🇩🇪

    To meet the precision targets of upcoming LHC runs in the simulation of top pair production events it is essential to also consider off-shell effects. Due to their great computational cost I propose to encode them in neural networks. For that I use a combination of neural networks that take events with approximate off-shell effects and transform them into events that match those obtained with full off-shell calculations. This was shown to work reliably and efficiently at leading order. Here I discuss first steps extending this method to include higher order effects.

    hep-phSciPost Phys.Proc.(2026)·0 citations
29. 29*

    Feebly-Interacting Peccei-Quinn Model

    Wen Yin🇯🇵

    The QCD axion is widely studied as a dark matter (DM) candidate and as a solution to the strong CP problem of the Standard Model. In conventional field-theoretic models, a much larger mass scale than the electroweak (EW) scale is typically introduced to spontaneously break Peccei-Quinn (PQ) symmetry with a large enough axion decay constant, $f_a$, thereby avoiding constraints from star cooling. In this paper, I propose an alternative approach to achieving the large decay constant: a PQ scalar field with a large wave function renormalization constant, analogous to a feebly coupled gauge theory. Other dimensionless parameters are $O(1)$ in the unit of the EW scale for the naturalness. This framework predicts a light PQ Higgs boson with a mass $\sim (\mathrm{EW}\mathrm{scale}{)}^2/f_a$. Exotic particles associated with the PQ anomaly are expected to have masses around the EW scale. The proposed model alleviates both the PQ quality and EW scale fine-tuning problems and introduces interesting axion-PQ Higgs cosmologies, encompassing: slim axion DM from a fat string network, heavy axion DM from PQ Higgs condensate fragmentation, PQ Higgs DM, and axion-PQ Higgs co-DM scenarios. Potential experimental signatures are explored, including fifth-force tests, DM detections, accelerator searches, and gravitational wave observations by employing lattice simulation. Possible extensions of the scenario are also discussed.

    hep-phastro-ph.COhep-exJHEP(2025)·10 citations
30. 30*

    Spin identification of the mono-Z${}^{\prime }$ resonance in muon-pair production at the ILC with simulated electron-positron collisions at $\sqrt{s}$ = 500 GeV

    S. Elgammal🇪🇬

    In this analysis, we examine the angular distribution of low-mass dimuon pairs produced in simulated electron-positron collisions at the proposed International Linear Collider (ILC), which operates at a center-of-mass energy of 500 GeV and has an integrated luminosity of 4 ab\(^{-1}\). Our focus is on the cos\(\theta_{\text{CS}}\) variable, which is defined in the Collins-Soper frame. In the Standard Model, the production of low-mass dimuon pairs is primarily driven by the Drell-Yan process, which exhibits a notable forward-backward asymmetry. However, many scenarios beyond the Standard Model predict different shapes for the cos\(\theta_{\text{CS}}\) distribution. This angular distribution can be valuable for distinguishing between these models, especially in the event of observing excesses beyond the Standard Model expectations. We utilized the mono-Z\(^{\prime}\) model to interpret the simulated data. In the absence of any discoveries of new physics, we establish upper limits at the 95\% confidence level on the masses of various particles in the model, which includes the spin-1 \(Z^{\prime}\) boson and fermionic dark matter.

    hep-phPTEP·1 citation
31. 31*

    Catalogues of Cosmologically Self-Consistent Hadronic QCD Axion Models

    Luca Di Luzio🇮🇹 · Sebastian Hoof🇮🇹 · Coenraad Marinissen🇳🇱 · Vaisakh Plakkot🇳🇱

    We extend the catalogue of "phenomenologically preferred" hadronic axion models to include heavy fermion representations associated with higher-dimensional decay operators. The latter have recently been shown to self-consistently trigger a period of early matter domination, making the underlying axion models cosmologically viable. After identifying all possible representations up to decay operator dimension $d\le 9$, we update the hadronic axion band for the axion-photon coupling. The central regions of the axion band are similar to those found previously and approximately independent of the axion decay constant $f_a$, suggesting that they are robust predictions and targets for future axion searches. Moreover, we find that $d=6$ and $d=7$ operators can lead to two new viable "model islands" around $f_a\sim 10^{12}$ GeV and $f_a\sim 10^{14}$ GeV, i.e., beyond the standard post-inflationary mass region.

    hep-phJCAP(2025)·13 citations
32. 32*

    Monte Carlo Study of TeV-Scale String Resonances in Photon-Jet Scattering

    Kyle Drury🇨🇦

    STRINGS is a Monte Carlo (MC) event generator for simulating the production and decay of first and second string resonances in proton-proton collisions. STRINGS can also interface with other programs such as Pythia using the Les Houches Accord to produce more accurate data. In this paper, we validate STRINGS for the simulation of 2-parton $\to$ $\gamma$-parton scattering events by comparing to previous literature. After validation, we produce MC samples of resonances using $M_s$ = {5.0,5.5,6.0,6.5,7.0} TeV at $\sqrt{s}$ = {13,13.6} TeV with STRINGS and Pythia and analyze the kinematic data. To accurately reproduce previous results close to resonance, it is necessary to introduce a scaling factor of $\approx$ 0.53. With this correction, the resonance structure is as expected.

    hep-phhep-th0 citations
33. 33*

    Analysis of NOvA and MicroBooNE charged-current inclusive neutrino measurements within the SuSAv2 framework

    J. Gonzalez-Rosa🇪🇸 · G. D. Megias🇪🇸 · J. A. Caballero🇪🇸 · M. B. Barbaro🇮🇹

    In this work we compare the SuSAv2 model, based on the superscaling phenomenon and the relativistic mean field theory, with charged-current inclusive neutrino cross sections from the NOvA and MicroBooNE experiments, whose targets are composed primarily by 12 C and 40 Ar, respectively. The neutrino energy in these experiments covers a kinematic range from tens of MeV to roughly 20 GeV. Thus, we consider the different reaction mechanisms that contribute significantly to these kinematics, namely quasielastic, two-particle two-hole meson exchange currents, resonances and deep inelastic scattering contributions.

    hep-phnucl-thPRD(2025)·6 citations
34. 34*

    Spectroscopy of light atoms and bounds on physics beyond the standard model

    R M Potvliege🇬🇧

    Newly calculated bounds on the strength of the coupling of an electron to a proton or a neutron by a fifth force are presented. These results are derived from the high precision spectroscopic data currently available for hydrogen, deuterium, helium-3 and helium-4. They do not depend on specific assumptions on how the interaction would couple to a deuteron compared to a proton or would couple to an $\alpha$ particle compared to a helion. They depend on its coupling to a muon, but not in a significant way for carrier masses below 100~keV if one assumes that the strength of the interaction with a muon would be of a similar order of magnitude as the strength of the interaction with an electron in that mass region.

    ↳ physics.atom-phhep-phNew J.Phys.(2025)·9 citations
35. 35*

    A complete analysis of inflation with piecewise quadratic potential

    Xinpeng Wang🇨🇳 · Xiao-Han Ma🇨🇳 · Misao Sasaki🇯🇵

    We conduct a thorough study of the comoving curvature perturbation $\mathcal{R}$ in single-field inflation with two stages, represented by a piecewise quadratic potential, where both the first and second derivatives are allowed to be discontinuous at the transition point. We calculate the evolution of $\mathcal{R}$ by combining the perturbative and non-perturbative methods consistently, and obtain the power spectrum and the non-Gaussian features in the probability distribution function. We find that both the spectrum and the statistics of $\mathcal{R}$ depend significantly on the second derivatives of the potential at both the first and second stages. Furthermore, we find a new parameter constructed from the potential parameters, which we call $\alpha$, plays a decisive role in determining various features in the spectrum such as the amplitude, the slope, and the existence of a dip. In particular, we recover the typical $k^4$ growth of the spectrum in most cases, but the maximum growth rate of $k^5(\log k{)}^2$ can be obtained by fine-tuning the parameters. Then, using the $\delta N$ formalism valid on superhorizon scales, we give fully nonlinear formulas for $\mathcal{R}$ in terms of the scalar field perturbation $\delta \varphi$ and its time derivative. In passing, we point out the importance of the nonlinear evolution of $\delta \varphi$ on superhorizon scales. Finally, using the Press-Schechter formalism for simplicity, we discuss the effect of the non-Gaussian tails of the probability distribution function on the primordial black hole formation.

    ↳ astro-ph.COgr-qchep-ph12 citations
36. 36*

    Conformal geometry as a gauge theory of gravity: covariant equations of motion & conservation laws

    C. Condeescu🇷🇴 · D. M. Ghilencea🇷🇴 · A. Micu🇷🇴

    We study Weyl conformal geometry as a general gauge theory of the Weyl group (of Poincaré and dilatations symmetries) in a manifestly Weyl gauge covariant formalism in which this geometry is automatically metric and physically relevant. This gives a realistic (quadratic) gauge theory of gravity, with Einstein-Hilbert gravity recovered in its spontaneously broken phase, motivating our interest in this geometry. For the most general action we compute the manifestly Weyl gauge covariant equations of motion and present the conservation laws for the energy-momentum tensor and Weyl gauge current. These laws are valid both in Weyl conformal geometry (with respect to the Weyl gauge covariant derivative) but also in the Riemannian geometry equivalent picture (with respect to its associated covariant derivative). This interesting result is a consequence of gauged diffeomorphism invariance of the former versus usual diffeomorphism invariance of the latter. These results are first derived in $d=4$ dimensions. We then successfully derive the conservation laws and equations of motion in Weyl conformal geometry in arbitrary $d$ dimensions, while maintaining manifest Weyl gauge invariance/covariance. The results are useful in physical applications with this symmetry.

    ↳ hep-thgr-qchep-phAnnals Phys.(2025)·11 citations
37. 37*

    Returning Back to Mukhanov Parametrization of Inflationary Equation of State

    Barun Kumar Pal🇮🇳

    We have re-examined Mukhanov parametrization for inflationary equation of state, $1+\omega =\frac{\beta }{(N+1{)}^{\alpha }}$, in the light of Planck 2018 results and latest bound of tensor-to-scalar ratio employing Hamilton-Jacobi formalism. We have found that the current observational values of scalar spectral index and tensor-to-scalar ratio can be used efficiently to constrain the model parameters. The recent bound of $r<0.032$ has been used to put an upper bound on one of the model parameter. Whereas 1-$\sigma$ bound of the scalar spectral index $0.9607\le n_{{}_S}\le 0.9691$ along with the upper bound of tensor-to-scalar ratio provided restriction on the other model parameter $1.50<\alpha \le 2.20$. These bounds however depend on the number of e-foldings still left before the end of inflation and whenever $1.50<\alpha \le 2.20$ we can find appropriate values of the other model parameter $\beta$ so that the observational predictions are in tune with the latest available inflationary observables. We have further utilized the predictions from forthcoming CMB missions in the likes of CMB-S4 and LiteBIRD in order to obtain bounds on the model parameters. We find that detection of gravity waves would help us constrain the model parameters further. But in the absence of detection of primordial gravity wave signal by these CMB missions may rule out Mukhanov parametrization.

    ↳ gr-qcastro-ph.COhep-phEPJC(2025)·0 citations
38. 38*

    Extracting the Epoch of Reionization Signal with 3D U-Net Neural Networks Using Data-driven Systematic Effect Model

    Li-Yang Gao🇨🇳 · Léon V. E. Koopmans🇳🇱 · Florent G. Mertens · Satyapan Munshi · Yichao Li🇺🇸 · Stefanie A. Brackenhoff · Emilio Ceccotti · J. Kariuki Chege · Anshuman Acharya · Raghunath Ghara · Sambit K. Giri · Ilian T. Iliev · Garrelt Mellema · Xin Zhang🇺🇸

    Neutral hydrogen (HI) serves as a crucial probe for the Cosmic Dawn and the Epoch of Reionization (EoR). Actual observations of the 21-cm signal often encounter challenges such as thermal noise and various systematic effects. To overcome these challenges, we simulate SKA-Low-depth images in South Celestial Pole (SCP) field and process them with a deep learning method. We utilized foreground residuals acquired by LOFAR during actual North Celestial Pole (NCP) field observations, thermal and excess variances calculated via Gaussian process regression (GPR), and 21-cm signals generated with 21cmFAST for signal extraction tests. Our approach to overcome these foreground, thermal noise, and excess variance components employs a 3D U-Net neural network architecture for image analysis. When considering thermal noise corresponding to 1752 hours of integration time, U-Net provides reliable 2D power spectrum predictions, and robustness tests ensure that we get realistic EoR signals. Adding foreground residuals, however, causes inconsistencies below the horizon delay-line. Lastly, evaluating both thermal noise and excess variances with observations up to 4380 hours and 13140 hours ensures reliable power spectrum estimations within the EoR window and across nearly all scales, respectively. The incoherence of excess variances in the frequency direction can greatly affect deep learning to extract 21-cm signals.

    ↳ astro-ph.IMastro-ph.COgr-qchep-phApJ(2025)·6 citations
39. 39*

    A diversity-enhanced genetic algorithm for efficient exploration of parameter spaces

    Jonas Wessén · Eliel Camargo-Molina🇸🇪

    We present a Python package together with a practical guide for the implementation of a lightweight diversity-enhanced genetic algorithm (GA) approach for the exploration of multi-dimensional parameter spaces. Searching a parameter space for regions with desirable properties, e.g. compatibility with experimental data, poses a type of optimization problem wherein the focus lies on pinpointing all "good enough" solutions, rather than a single "best solution". Our approach dramatically outperforms random scans and other GA-based implementations in this aspect. We validate the effectiveness of our approach by applying it to a particle physics problem, showcasing its ability to identify promising parameter points in isolated, viable regions meeting experimental constraints. The companion Python package is applicable to optimization problems beyond those considered in this work, including scanning over discrete parameters (categories). A detailed guide for its usage is provided.

    ↳ cs.NEhep-ph3 citations
40. 40*

    Radiative Energy Loss in a Temperature-Evolving QGP with Dynamical Constituents

    Bithika Karmakar🇵🇱 · Magdalena Djordjevic🇷🇸

    We present a theoretical formalism for calculating first-order-in-opacity radiative energy loss that incorporates the spatial and temporal temperature evolution of the quark-gluon plasma (QGP) in a finite-size QCD medium with dynamical (i.e., moving) constituents. The derived expressions allow for arbitrary temperature profiles, enabling detailed evaluations of radiative energy loss across different medium-evolution scenarios. Importantly, the resulting kernel applies to both single partons (R = 0) and jets (R > 0) via an out-of-cone selection, providing a unified starting point for precision QGP tomography.

    ↳ nucl-thhep-phPRC(2026)·2 citations
41. 41*

    Potential Surge Preheating: enhanced resonance from potential features

    Pankaj Saha🇯🇵 · Yuko Urakawa🇯🇵

    We investigate the effects of local features in the inflationary potential on the preheating dynamics after inflation. We show that a small feature in the potential can enhance the resonance and bring the radiation-like state equation during preheating despite the inflationary potential being a quadratic one. Such localized features may naturally arise due to various physical effects without altering the large-scale predictions of the original model for cosmic microwave background (CMB) observables. We demonstrate that these features effectively introduce localized higher-power terms in the potential, significantly influencing the preheating dynamics $–$ a phenomenon we term potential surge preheating. We outline the resulting modifications in energy distribution among different components. We further show that these small-scale features leave detectable imprints in the form of gravitational wave signals. These signals influence CMB measurements of the effective number of relativistic species, $N_{\mathrm{eff}}$, offering a way to reconstruct the shape of the inflaton potential at small scales. Finally, we argue that these modifications to the scalar potential provide a framework to explore preheating dynamics and the fragmentation of scalar fields using simple scalar potentials.

    ↳ astro-ph.COgr-qchep-phJCAP(2025)·5 citations
42. 42*

    Form factors for semileptonic B(s) -> D*(s) l nu_l decays

    Anastasia Boushmelev🇩🇪 · Matthew Black🇩🇪 · Oliver Witzel🇩🇪

    Semileptonic $B_{(s)}$ decays are of great phenomenological interest because they allow to extract CKM matrix elements or test lepton flavour universality. Taking advantage of existing data, we explore extracting form factors for vector final states using the narrow width approximation. Based on RBC/UKQCD's set of 2+1 flavour gauge field ensembles with Shamir domain-wall fermion and Iwasaki gauge field action, we study semileptonic $B_{(s)}$ decays using domain-wall fermions for light, strange and charm quarks, whereas bottom quarks are simulated with the relativistic heavy quark (RHQ) action. Exploratory results for $B_s\to D_s^{\ast }\ell {\nu }_{\ell }$ are presented.

    ↳ hep-lathep-phPoS(2025)·2 citations
43. 43*

    Spectral analysis for nucleon-pion and nucleon-pion-pion states in both parity sectors using distillation with domain-wall fermions

    Andreas Hackl🇩🇪 · Christoph Lehner🇩🇪

    We present a study using the distillation method to analyze the spectra of nucleon, nucleon-pion, and nucleon-pion-pion states in the positive-parity sector, as well as nucleon and nucleon-pion states in the negative-parity sector. The study uses seven domain-wall fermion ensembles with varying pion masses ($m_{\pi }=139-279\text{MeV}$), lattice spacings ($a^{-1}=1.730\text{GeV}$ and $a^{-1}=2.359\text{GeV}$) and volumes ($m_{\pi }L=3.8-7.5$). To address the large number of contractions in this project, we implemented an algorithm to automate the contraction of nucleon-pion correlation functions that contain an arbitrary number of pions. In the positive parity sector, we extrapolate the nucleon mass to the physical point. This study demonstrates the effectiveness of the distillation method for baryonic quantities with a focus on multi-hadronic states and establishes a foundation for future work.

    ↳ hep-lathep-phnucl-thPRD(2026)·8 citations
44. 44*

    Finite Temperature Quarkonia Spectral Functions in the Pseudoscalar Channel

    Dibyendu Bala🇩🇪 · Sajid Ali🇩🇪 · Olaf Kaczmarek🇩🇪 · Pavan🇩🇪

    Quarkonia, the bound states of heavy quark-antiquark pairs, are important tools for studying the quark-gluon plasma (QGP). In this study, we examine the behavior of in-medium quarkonium bound states in the QGP by analyzing their spectral functions at two temperatures, $T=220\text{MeV}$ and $T=293\text{MeV}$. We use physics-motivated information to reconstruct the spectral function from the Euclidean lattice correlator. Near the threshold, the spectral function is estimated through a complex potential, determined non-perturbatively from Wilson line correlators. Our results show that the real part of the potential undergoes color screening above $T_{pc}$, while the imaginary part grows rapidly with increasing distance and temperature. For the ultraviolet (UV) part of the spectral function, we use the perturbative vacuum spectral function, as the temperature effects are suppressed in this region. In the absence of a transport peak in the pseudoscalar channel, we find that this combination effectively describes the pseudoscalar correlator on the lattice, calculated using relativistic quark fields. Our results show that pseudoscalar charmonium (${\eta }_c$) experiences significant thermal effects, as indicated by the broadening of the ${\eta }_c(1S)$ state. In contrast, the ${\eta }_b(1S)$ state remains intact, with a sharp bound state peak.

    ↳ hep-lathep-phnucl-exJ.Subatomic Part.Cosmol.(2025)·3 citations
45. 45*

    Effects of a first-order QCD phase transition on light nucleus production

    He Liu🇨🇳 · Kai-Jia Sun🇨🇳 · Peng-Cheng Chu🇨🇳

    Using an extended Polyakov-looped Nambu--Jona-Lasinio (PNJL) model to describe the baryon density fluctuations of quark matter along the isentropic trajectories corresponding to different $s/{\rho }_B$ values extracted from Au+Au collisions at energies $\sqrt{s_{NN}}=7.7-200$ GeV, we investigate the effects of the first-order phase transition on the light nucleus yield ratio $N_t\times N_p/N_d^2$. The results indicate that the second-order scaled density moment $y_2$, used to quantify density fluctuations, rapidly increases to form a peak when the isentropic trajectories pass through the phase coexistence region. We extract the yield ratios $N_t\times N_p/N_d^2$ at chemical freeze-out from the isentropic trajectories at different collision energies and found significant enhancements at 19.6 GeV and 27 GeV. This is similar to the trends observed by the STAR experiment, suggesting that the enhancements in the yield ratios $N_t\times N_p/N_d^2$ observed in the STAR experiment could be explained by the density fluctuations generated in the first-order phase transition region.

    ↳ nucl-thhep-ph1 citation
46. 46*

    Axion effects on quark matter and quark-matter cores in massive hybrid stars

    He Liu🇨🇳 · Yu-Heng Liu🇨🇳 · Yong-Hang Yang🇨🇳 · Min Ju🇨🇳 · Xu-Hao Wu🇨🇳 · Hong-Ming Liu🇨🇳 · Peng-Cheng Chu🇨🇳

    Using a three-flavor Nambu--Jona-Lasinio model to describe the charge-parity violating effects through axion field, we investigate the axion effects on quark matter and quark-matter cores in massive hybrid stars. The properties of quark matter vary with the scaled axion field $a/f_a$ in a periodic manner, with a period of $2\pi$. Within the range from 0 to $\pi$, axion field decrease the baryon chemical potential of the first-order phase transition, leading to an increase in normalized pressure and stiffening of the quark matter equation of state. The effect of axions on hybrid star matter that includes the hadron-quark phase transition is contrary to expectations. The axion field shifts the onset of the hadron-quark mixed phase to lower densities but slightly softens the equation of state of the mixed phase matter, which also results in a slight decrease in the maximum mass and corresponding radius of the hybrid stars. However, we also find that the lowering of the onset of the mixed phase significantly increases the radius and mass of the quark-matter core in the hybrid star. Therefore, our results indicate with axion effects, a sizable quark-matter core can appear in $2M_{\odot }$ massive neutron stars.

    ↳ nucl-thastro-ph.HEhep-phPRD(2025)·6 citations
47. 47*

    Symmetry-breaking inflation in non-minimal metric-affine gravity

    Ioannis D. Gialamas🇪🇪 · Antonio Racioppi🇪🇪

    We study symmetry-breaking inflation within the framework of metric-affine gravity. By introducing a non-minimal coupling, $\beta (\varphi )\tilde{\mathcal{R}}$, between the Holst invariant and the inflaton, both small-field and large-field inflationary predictions can be brought into agreement with the latest observational constraints. Remarkably, even for sub-Planckian vacuum expectation values, appropriately chosen values of $\beta (\varphi )$ enable viable inflation, a scenario previously considered unattainable.

    ↳ gr-qcastro-ph.COhep-phJCAP(2025)·20 citations
48. 48*

    High-Energy Fixed-Angle Meson Scattering and the Constituent Counting Rule in Holographic QCD

    Adi Armoni🇬🇧 · Bartosz Pyszkowski🇯🇵 · Shigeki Sugimoto🇯🇵 · Dorin Weissman🇰🇷

    We investigate the high-energy fixed-angle scattering of pions and $\rho$-mesons in a bottom-up holographic QCD model. To this end, we generalise the approach of Polchinski and Strassler arXiv:hep-th/0109174 to write an ansatz for meson scattering amplitudes based on superstring scattering amplitudes in asymptotically AdS space. We demonstrate that our generalisation of the Polchinski--Strassler proposal is necessary to describe $\rho$-meson scattering consistently with the Nambu--Goldstone boson equivalence theorem. Our results for pion and $\rho$-meson scattering amplitudes are in agreement with the constituent counting rule found in QCD. Moreover, our proposal for 2-to-2 scattering amplitudes provides a method for computing scattering angle dependence.

    ↳ hep-thhep-phJHEP(2025)·3 citations
49. 49*

    Classical (and Quantum) Heuristics for Gravitational Wave Detection

    Raffaele Tito D'Agnolo🇫🇷 · Sebastian A. R. Ellis🇨🇭

    We derive a lower bound on the sensitivity of generic mechanical and electromagnetic gravitational wave detectors. We consider both classical and quantum detection schemes, although we focus on the former. Our results allow for a simple reproduction of the sensitivities of a variety of experiments, including optical interferometers, resonant bars, optomechanical sensors, and electromagnetic conversion experiments. In the high-frequency regime, all detection schemes we consider can be characterised by their stored electromagnetic energy and the signal transfer function, which we provide. We discuss why high-frequency gravitational wave searches are especially difficult and primordial gravitational wave backgrounds might not be detectable above the sensitivity window of existing interferometers.

    ↳ gr-qchep-exhep-phJHEP(2025)·21 citations
50. 50*

    Analytic bootstrap bounds on masses and spins in gravitational and non-gravitational scalar theories

    Justin Berman🇺🇸 · Nicholas Geiser🇺🇸

    We derive analytic constraints on the weakly-coupled spectrum of theories with a massless scalar under the standard assumptions of the S-matrix bootstrap program. These bootstrap bounds apply to any theory (with or without gravity) with fully crossing symmetric (i.e. $stu$-symmetric) four-point amplitudes and generalize results for color- or flavor-ordered (i.e. $su$-symmetric) planar amplitudes recently proved by one of the authors. We assume that the theory is weakly-coupled below some cut-off, that the four-point massless scalar amplitude is polynomially-bounded in the Regge limit, and that this amplitude exchanges states with a discrete set of masses and a finite set of spins at each mass level. The spins and masses must then satisfy ``Sequential Spin Constraints" (SSC) and ``Sequential Mass Constraints" (SMC). The SSC requires the lightest spin-$j$ state to be lighter than the lightest spin-$(j+1)$ state (in the $su$-symmetric case) or the lightest spin-$(j+2)$ state (in the $stu$-symmetric case). The SMC requires the mass of the lightest spin-$j$ state to be smaller than some non-linear function of the masses of lower-spin states. Our results also apply to super-gluon and super-graviton amplitudes stripped of their polarization dependence. In particular, the open and closed superstring spectra saturate the SSC with maximum spins $J_{n,\text{open}}=n+1$ and $J_{n,\text{closed}}=2n+2$, respectively, at the $n^{\text{th}}$ mass level.

    ↳ hep-thhep-phJHEP(2025)·21 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.