Wed·Dec 11, 2024Wednesday·December 11, 2024

1. 01*

   Do we owe our existence to a Gravitational Anomaly?

   Nick E. Mavromatos🇬🇷

   I review a mechanism for a potential explanation of the dominance of matter over antimatter in the Universe (``our existence''), based on a (3+1)-dimensional string-inspired cosmological model, characterised by (uncancelled) gravitational Chern-Simons (gCS) anomalies in the premordial epochs. The model is consistent with general covariance but entails spontaneous Lorentz (LV) and CPT Violation (CPTV), due to appropriate backgrounds of axion fields, which couple to the anomaly terms. Upon condensation of the gCS terms, due to primordial gravitational waves, these axions acquire a linear potential, which drives inflation of a Running-Vacuum-Model (RVM) type, while the effective action is also characterised by imaginary parts as well, which imply metastability of this RVM inflation. The axion backgrounds remain undiluted until the exit from inflation, and are responsible for yielding unconventional LV and CPTV Leptogenesis, which is then communicated to the baryon sector (Baryogenesis) via sphaleron processes. The model provides a phenomenologically consistent cosmological evolution from inflation till the modern era.

   hep-phgr-qchep-thJ.Phys.Conf.Ser.(2025)·2 citations
2. 02*

   A first computation of three-loop master integrals for the production of two off-shell vector bosons with different masses

   Dhimiter Canko🇮🇹 · Mattia Pozzoli🇮🇹

   We present analytic results on physical kinematics for four integral families that are relevant to the production of two off-shell vector bosons with different masses. Our study consists of a ladder-box, a tennis-court, and two reducible ladder-box-like families. The results for the master integrals of these families are expressed up to order six in the dimensional regulator in terms of real-valued multiple polylogarithms. Furthermore, a semi-numeric solution is provided, employing generalized power series expansions using the package DiffExp.

   hep-phhep-thJHEP(2025)·9 citations
3. 03*

   Product Manifold Machine Learning for Physics

   Nathaniel S. Woodward🇺🇸 · Sang Eon Park🇺🇸 · Gaia Grosso🇺🇸 · Jeffrey Krupa🇺🇸 · Philip Harris🇺🇸

   Physical data are representations of the fundamental laws governing the Universe, hiding complex compositional structures often well captured by hierarchical graphs. Hyperbolic spaces are endowed with a non-Euclidean geometry that naturally embeds those structures. To leverage the benefits of non-Euclidean geometries in representing natural data we develop machine learning on $\mathcal{P}\mathcal{M}$ spaces, Cartesian products of constant curvature Riemannian manifolds. As a use case we consider the classification of "jets", sprays of hadrons and other subatomic particles produced by the hadronization of quarks and gluons in collider experiments. We compare the performance of $\mathcal{P}\mathcal{M}$-MLP and $\mathcal{P}\mathcal{M}$-Transformer models across several possible representations. Our experiments show that $\mathcal{P}\mathcal{M}$ representations generally perform equal or better to fully Euclidean models of similar size, with the most significant gains found for highly hierarchical jets and small models. We discover significant correlation between the degree of hierarchical structure at a per-jet level and classification performance with the $\mathcal{P}\mathcal{M}$-Transformer in top tagging benchmarks. This is a promising result highlighting a potential direction for further improving machine learning model performance through tailoring geometric representation at a per-sample level in hierarchical datasets. These results reinforce the view of geometric representation as a key parameter in maximizing both performance and efficiency of machine learning on natural data.

   hep-ph4 citations
4. 04*

   High-Energy Neutrino Flavor State Transition Probabilities

   John Harrison🇺🇸 · Richard Anantua🇺🇸

   We analytically determine neutrino transitional probabilities and abundance ratios at various distances from the source of creation in several astrophysical contexts, including the Sun, supernovae and cosmic rays. In doing so, we determine the probability of a higher-order transition state from ${\nu }_{\tau }\to {\nu }_{\lambda }$, where ${\nu }_{\lambda }$ represents a more massive generation than Standard Model neutrinos. We first calculate an approximate cross section for high-energy neutrinos which allows us to formulate comparisons for the oscillation distances of solar, supernova and higher-energy cosmic ray neutrinos. The flavor distributions of the resulting neutrino populations from each source detected at Earth are then compared via fractional density charts.

   hep-phhep-thAppl.Sciences(2024)·0 citations
5. 05*

   Single production of singlet vector-like leptons at the ILC

   Chong-Xing Yue🇨🇳 · Yue-Qi Wang🇨🇳 · Xiao-Chen Sun🇨🇳 · Xin-Yang Li🇨🇳

   Vector-like leptons (VLLs) as one kind of interesting new particles can produce rich phenomenology at low- and high-energy experiments. In the framework of the singlet vector-like leptons with scalar (VLS) model, we investigate the discovery potential of VLL via its single production at the International Linear Collider (ILC) with the center of mass energy $\sqrt{s}=$ 1 TeV and the integrated luminosity $\mathcal{L}$ = 1 ab${}^{-1}$, taking into account the appropriate polarization. For the signal and standard model (SM) background analysis, we have considered two kinds of decay channels for the W boson, i.e. pure leptonic and fully hadronic decay channels. Our analytic results show that the parameter space $M_F\in$ [300, 675] GeV and $\kappa \in$ [0.0294, 0.1] might be detected by the proposed ILC for pure leptonic decay channel. For fully hadronic decay channel, larger detection region of the parameter space are derived as $M_F\in$ [300, 700] GeV and $\kappa \in$ [0.0264, 0.0941].

   hep-phJ.Phys.G(2025)·7 citations
6. 06*

   Truncation orders, external constraints, and the determination of $|V_{cb}|$

   Eric Persson🇩🇪 · Florian Bernlochner🇩🇪

   We present a model selection framework for the extraction of the CKM matrix element $|V_{cb}|$ from exclusive $B\to D^{\ast }l\nu$ decays. By framing the truncation of the Boyd-Grinstein-Lebed (BGL) parameterization as a model selection task, we apply the Akaike Information Criterion (AIC) to choose the optimal truncation order. We demonstrate the performance of our approach through a comprehensive toy study, comparing it to the Nested Hypothesis Test (NHT) method used in previous analyses. Our results show that the AIC-based approach produces unbiased estimates of $|V_{cb}|$, albeit with some issues of undercoverage. We further investigate the impact of unitarity constraints and explore model averaging using the Global AIC (gAIC) approach, which produced unbiased results with correct coverage properties. Our findings suggest that model selection techniques based on information criteria and model averaging offer a promising path towards more reliable $|V_{cb}|$ determinations.

   hep-phhep-exPoS(2025)·0 citations
7. 07*

   Scale Separation, Strong Coupling UV Phases, and the Identification of the Edge of the Conformal Window

   Anja Alfano🇬🇧 · Nick Evans🇬🇧

   We use a simple holographic model to discuss approaching the edge of the conformal window in strongly coupled gauge theories to draw lessons for lattice studies. Walking gauge theories have a gap between the scale where they enter the strong coupling regime and the scale of chiral symmetry breaking. We highlight that there can also be a gap between the scale where the critical value of the quark anti-quark operator's anomalous dimension is passed and the scale of the condensate. This potentially makes identifying the edge of the conformal window in a lattice simulation with UV bare coupling below the fixed point value on a finite lattice difficult. A resolution is to study the theory with a coupling above the fixed point value at the UV cut off. Here we show that an ``artefact" phase with chiral symmetry breaking triggered at the UV cut off exists and lies arbitrarily close to the fixed point at the edge of the conformal window. We quantify the chance of a misidentification of a chiral symmetry breaking theory as IR conformal. We also quantify where the artefact phase lies, tuned to the fixed point value. We use the latest lattice results for SU(3) gauge theory with ten quark flavours in [Hasenfratz:2023wbr] as a test case; we conclude their identification that the theory is in the conformal window is reliable.

   hep-phhep-lathep-thPRD(2025)·1 citation
8. 08*

   Investigation of the FCNC couplings between the top quark and the photon in $\gamma \gamma$ and ${\gamma }^{\ast }{\gamma }^{\ast }$ collisions at the CLIC

   Eda Alici🇹🇷

   The investigation of flavour-changing neutral current transitions(FCNC) involving the top quark are only possible with new theoretical frameworks that extend the Standard Model(SM), given that these transitions are almost entirely suppressed within the SM. In this regard, examining these transitions with extended theories beyond the SM may provide significant insights into future experiments. To this end, we present a phenomological study about the anomalous FCNC transitions via $tq\gamma$ couplings with effective field theory. Here, $\gamma \gamma \to \text{l}{\nu }_{\text{l}}b\bar{q}$ , $e^{+}{e}^{-}\to e^{+}{\gamma }^{}{\gamma }^{}\to e^{+}\text{l}{\nu }_{\text{ l}}b\bar{q}{e}^{-}$, $\gamma \gamma \to j\bar{j}b\bar{q}$ and $e^{+}{e}^{-}\to e^{+}{\gamma }^{}{\gamma }^{}{e}^{-}\to e^{+}j\bar{j}b\bar{q}{e}^{-}$ processes are investigated for the CLIC at $\sqrt{s}=1.5$TeV and 3 TeV. Thus, we have calculated the constraints at $95\%$ confidence level on the $BR(t\to q\gamma )$. As a result, the obtained constraints are at least one order of magnitude better than the available experimental ones.

   hep-phInt.J.Theor.Phys.(2022)·1 citation
9. 09*

   Orthogonal color bases for exotic representations

   Malin Sjodahl🇸🇪

   A complication in the treatment of any strongly charged particle is the SU(3) color structure. For the standard model quarks antiquarks and gluons there are various well-known strategies for dealing with the color structure, including orthogonal multiplet bases. For exotic representations, beyond triplets, antitriplets and octets, non-orthogonal bases have been systematically worked out only recently. In this letter we demonstrate how to construct orthogonal multiplet bases also for processes including exotic representations.

   hep-phPLB(2025)·2 citations
10. 10*

    Toward a Direct Measurement of Partial Restoration of Chiral Symmetry at J-PARC E16 via Density-induced Chiral Mixing

    Ren Ejima🇯🇵 · Philipp Gubler🇯🇵 · Chihiro Sasaki🇵🇱 · Kenta Shigaki🇯🇵

    The degeneracy of chiral partners is an ideal signal for measuring the restoration of the spontaneously broken chiral symmetry in QCD. In this work, we investigate the observability of the $\varphi$ - $f_1(1420)$ degeneracy in the J-PARC E16 experiment, which measures di-electrons emitted from 30 GeV pA collisions. We for this purpose make use of an effective Lagrangian approach, which naturally incorporates the broken charge-conjugation symmetry in nuclear matter and the ensuing anomaly-induced mixing between vector and axial-vector mesons, to compute the spectral function relevant for the experimental measurement. The real-time dynamics of the pA collision is obtained from a transport simulation. Including experimental background and resolution effects on top of that, we find that a signal of the $\varphi$ - $f_1(1420)$ mixing can be observed around 2.5 $\sigma$ with the Run2 statistics planned for the J-PARC E16 experiment with an ideal mixing strength.

    hep-phnucl-thPRC(2025)·6 citations
11. 11*

    Confronting the broken phase N2HDM with Higgs Data

    Maien Binjonaid🇸🇦

    The broken phase of the Next-to two-Higgs-doublet model (N2HDM) constitutes an archetype of extended Higgs sectors. In the presence of a softly-broken ${\mathrm{Z}}_2$ symmetry throughout the scalar and Yukawa sectors, as the additional gauge singlet field does not interact with fermions, the model admits four variants of Yukawa interactions between the doublets and Standard Model fermions. We confront each type with experimental Higgs data, especially from CMS and ATLAS detectors at the LHC. Interfacing the models with the the state-of-the-art package $\mathtt{HiggsTools}$, we perform a statistical ${\chi }^2$ analysis to determine the best-fit points and exclusion limits at the $95\%$ and $68\%$ C.L., and identify SM-like Higgs measurements that affect each type the most. We further analyze the exclusion bounds on the additional Higgs bosons at the $95\%$ C.L., paying special attention to searches of hypothetical non-SM Higgs resonances decaying into a pair of bosons or fermions. We show regions where the additional Higgs bosons do not satisfy the narrow-width approximation utilized in most experimental searches.

    hep-phhep-exParticles(2025)·2 citations
12. 12*

    Implementation and investigation of electron-nucleus scattering in the \textsc{NEUT} neutrino event generator

    Seisho Abe🇯🇵

    Understanding nuclear effects is essential for improving the sensitivity of neutrino oscillation measurements. Validating nuclear models solely through neutrino scattering data is challenging due to limited statistics and the broad energy spectrum of neutrinos. In contrast, electron scattering experiments provide abundant high-precision data with various monochromatic energies and angles. Since both neutrinos and electrons interact via electroweak interactions, the same nuclear models can be applied to simulate both interactions. Thus, high-precision electron scattering data is essential for validating the nuclear models used in neutrino experiments. To enable this, the author has introduced a new electron scattering framework in the \textsc{NEUT} neutrino event generator, covering two interaction modes: quasielastic (QE) and single pion production. \textsc{NEUT} predictions of QE agree well with numerical calculations, supporting the validity of this implementation. From comparisons with \textsc{NEUT} predictions and inclusive electron scattering data, the momentum-dependent removal energy correction is derived, addressing effects beyond the plane wave impulse approximation. This correction is applied to neutrino interactions, observing significant changes in charged lepton kinematics. Notably, the reconstructed neutrino energy distribution shows a peak shift of approximately 20--30\,MeV, which is crucial for accurately measuring neutrino oscillation parameters.

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

    The magic of top quarks

    Chris D. White🇬🇧 · Martin J. White🇦🇺

    In recent years, there has been increasing collaboration between the fields of quantum computing and high energy physics, including using LHC processes such as top (anti-)quark pair production to perform high energy tests of quantum entanglement. In this proceeding, I will review another interesting property from quantum computing ("magic"), that is needed to make quantum computers with genuine computational advantage over their classical counterparts. How to make and enhance magic in general quantum systems is an open question, such that new insights are always useful. To this end, I will show that the LHC naturally produces magic top quarks, providing a novel playground for further study in this area.

    hep-phhep-thquant-phSciPost Phys.Proc.(2026)·5 citations
14. 14*

    Electroweak double-box integrals for Moller scattering

    Niklas Schwanemann🇩🇪 · Stefan Weinzierl🇩🇪

    We present for Moller scattering planar and non-planar two-loop double-box integrals where three electroweak gauge bosons are exchanged between the fermion lines, among which at least one is a photon. These integrals are relevant for the NNLO electroweak corrections to Moller scattering.

    hep-phSciPost Phys.(2025)·11 citations
15. 15*

    Electromagnetic form factors of hyperons in the timelike region: A short review

    Ling-Yun Dai🇨🇳 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪

    We review recent experimental and theoretical results for the electromagnetic form factors of hyperons (Y) in the timelike region, accessible in the reactions $e^{+}{e}^{-}\to \bar{Y}Y$. Specifically, we focus on the final states $\bar{\Lambda }\Lambda$, $\bar{\Lambda }{\Sigma }^0$/${\bar{\Sigma }}^0\Lambda$, $\bar{\Sigma }\Sigma$, $\bar{\Xi }\Xi$, and $\bar{\Omega }\Omega$. The ${\bar{\Lambda }}_c{\Lambda }_c$ system is also discussed.

    hep-phhep-exnucl-thChin.Phys.Lett.(2025)·10 citations
16. 16*

    On the quantum numbers of the $X(1880)$

    Qin-He Yang🇨🇳 · Ling-Yun Dai🇨🇳 · Ulf-G. Meißner🇩🇪

    We study the properties of the $X(1880)$, the structure around the $\bar{p}p$ threshold that appears in the $3({\pi }^{+}{\pi }^{-})$ invariant mass spectrum in the decay process of $J/\psi \to \gamma 3({\pi }^{+}{\pi }^{-})$. Nucleon-antinucleon rescattering is taken into account in our analysis, and the decay amplitude of $J/\psi \to \gamma 3({\pi }^{+}{\pi }^{-})$ can be obtained by the distorted wave Born approximation. With these amplitudes, we analyze the contributions to the $X(1880)$ from different partial waves. Our analysis suggests that the $X(1880)$ should be isoscalar $0^{-+}$, and it is generated by the threshold behavior.

    hep-phnucl-thPRD(2026)·4 citations
17. 17*

    New LCSR predictions for hadronic form factors

    Y. Monceaux🇫🇷

    We present an overview of a novel approach to the QCD Light-Cone Sum Rule method, employing $B$-meson Light-Cone Distribution Amplitudes. This method circumvents the semi-global quark-hadron duality (QHD) approximation, which can introduce an unknown and potentially significant systematic error in form factor predictions. Instead, our approach is more dependent on higher-order contributions in perturbation theory and higher-twist contributions. Unlike the systematic errors from semi-global QHD, truncation errors can be evaluated and systematically improved, allowing for robust form factor predictions.

    hep-ph0 citations
18. 18*

    Natural solution of SUSY $\mu$ problem from modulus stabilization in modular flavor model

    Hong Jie Fan🇨🇳 · Fei Wang🇨🇳 · Ying Kai Zhang🇨🇳

    We propose a solution to the SUSY $\mu$-problem within the framework of modular flavor symmetry. The explicit $\mu$-term is prohibited by modular symmetry, and an effective $\mu$-term is regenerated following the stabilization of the modulus field. We examine the stabilization mechanism of a single modulus field with the presence of SUSY breaking contributions described by the non-linear SUSY realization scheme involving a nilpotent Goldstino ${\text{X}}_{nl}$ superfield. A natural small ${\mu }_{eff}$, significantly smaller than the SUSY scale, can result from either the expansion of typical modular forms using a small deviation parameter near the fixed point $\omega$, or from the combined effects of suppression by powers of $q^{1/24}$ [or $(2\Im \tau {)}^{-1}$] along with the asymptotic suppression behavior of typical modular forms away from the fixed point $i\infty$, taking the form of appropriate power of the tiny deviation parameter. A natural small ${\mu }_{eff}$ can also be achieved by a weighton-like mechanism for $H_u{H}_d$ bilinear.

    hep-phhep-thPRD(2025)·3 citations
19. 19*

    An EWPD SMEFT likelihood for the LHC -- and how to improve it with measurements of W and Z boson properties

    Hannes Mildner🇩🇪

    This paper presents a computer code for analyzing electroweak precision data (EWPD) in the framework of the Standard Model Effective Field Theory (SMEFT), highlights the importance of recent ATLAS and CMS precision measurements, and introduces a novel analysis of the forward-backward asymmetry at the LHC. The computer code provides the likelihood of SMEFT Wilson coefficients based on precision measurements of $W$ and $Z$ pole observables, interpolation formulas for Standard Model predictions, and modular SMEFT parametrizations. SMEFT predictions including next-to-leading-order (NLO) effects in perturbative and SMEFT expansion are available and five alternative electroweak input parameter schemes are supported. The likelihood addresses shortcomings of previous formulations in the treatment of parametric uncertainties and can be straightforwardly included in SMEFT fits of LHC data. The input parameter scheme dependence and role of NLO corrections is studied for the EWPD fit in the SMEFT. Furthermore, the impact of recent ATLAS and CMS measurements - of the $W$ boson mass and width, of the lepton flavour universality (LFU) of $W$ branching fractions, and the effective leptonic weak mixing angle - is analyzed. A test of LFU that surpasses the precision of existing measurements is proposed based on the weak mixing angle measurement. Finally, an ATLAS Drell-Yan triple-differential cross-section measurement is reinterpreted in the SMEFT and combined with the EWPD likelihood. This analysis demonstrates the feasibility of the LFU precision test, improves constraints on muon couplings with respect to the world average, and determines a combination of the quark-coupling asymmetry parameters $A_u$ and $A_d$ with a precision comparable to that of the heavy flavour parameters $A_c$ and $A_b$.

    hep-phJHEP(2025)·9 citations
20. 20*

    In Search of an Invisible $Z^{\prime }$

    Joe Davighi🇨🇭

    We consider extending the Standard Model by an anomaly-free and possibly flavour non-universal $U(1{)}_X$ gauge symmetry, whose breaking gives a $Z^{\prime }$ boson that does not affect electroweak precision observables at tree-level or via 1-loop renormalisation group (RG) running. Provided it does not also couple to electrons, such a $Z^{\prime }$ boson would be largely invisible to an electroweak precision machine like FCC-ee or CEPC (up to small finite 1-loop matching contributions that we quantify). We show that, while this class of $Z^{\prime }$ models can also evade tests of quark flavour violation, the constraint of anomaly-cancellation implies that valence quarks, muons, and taus are all charged under $U(1{)}_X$, with the up quark charge being necessarily large. The conclusion holds even if one augments the SM by three right-handed neutrinos to try and absorb anomalies. This means such $Z^{\prime }$ bosons cannot simultaneously hide below the TeV scale from $pp\to \ell \ell$ Drell--Yan measurements at the LHC and, even if we entertain esoteric models in which the lepton charges are numerically very small, we cannot escape dijet searches at the LHC. For equitable quark and lepton charges, $pp\to \ell \ell$ already excludes such a $Z^{\prime }$ up to $M/g\gtrsim$ 10 TeV, with a reach of 20 TeV expected by the end of the High-Luminosity LHC. The dijet bounds currently sit around 5 TeV, while sensitivity up to 10 TeV could be achieved at HL-LHC. We thus find an excellent complementarity between FCC-ee and HL-LHC in covering all anomaly-free $Z^{\prime }$ bosons up to several TeV.

    hep-phJHEP(2025)·8 citations
21. 21*

    Phenomenological Aspects of Models with Low Scale Seesaw

    Juan Marchant González

    Various phenomenological consequences of seesaw theories for the generation of the fermion mass hierarchy of the Standard Model have been analyzed, with an emphasis on models in which the light-active neutrino masses are derived from low-scale seesaw mechanisms. In particular, fermion masses and lepton flavor-violating decay processes, the flavor-changing neutral current, have been studied, and the implications of these theories for the observed dark matter relic density in the Universe have been determined. From the analysis of these phenomenological aspects, it was possible to determine the allowed parameter spaces of these theories and to obtain a parameter fit consistent with the currently measured experimental values. In this way, correlations between the different observables of the fermionic sector could be obtained, where all values were within the experimental ranges at $3\sigma$. Predictions for new physics consistent with cosmological limits were also obtained.

    hep-ph0 citations
22. 22*

    New calculation of the geo-neutrino energy spectrum and its implication

    Yu-Feng Li🇨🇳 · Zhao Xin🇨🇳

    The energy spectrum of geo-neutrinos plays a vital role in the experimental measurement of geo-neutrinos that have profound implications for both particle physics and earth sciences. In this letter, we present a state-of-the-art calculation of the energy spectrum of geo-neutrinos originating from the beta decay of Uranium-238 and Thorium-232. Our calculation is underpinned by the latest updates in the nuclear database, accounts for previously overlooked forbidden transitions, and incorporates advanced corrections for the beta decay. This brand new geo-neutrino flux model, compared to the widely-used estimates from Enomoto, reveals notable distinction in the energy spectrum shape because of our comprehensive approach. When considering the inverse beta decay (IBD) detection process, our findings show a significant deviation in the predicted IBD yield of around 4% for Uranium-238 and 9% for Thorium-232 decay chains. The implications of using the new geo-neutrino flux model for the experimental analysis are substantial, potentially affecting the analysis results of geo-neutrino measurements of KamLAND and Borexino by around 10% to 20%. Our study represents a significant advancement in geo-neutrino research, establishing a new benchmark for accuracy and reliability in the field.

    hep-phnucl-exphysics.geo-ph0 citations
23. 23*

    Probing nonperturbative transverse momentum dependent PDFs with chiral perturbation theory: the $\bar{d}-\bar{u}$ asymmetry

    Marston Copeland🇺🇸 · Thomas Mehen🇺🇸

    We use chiral perturbation theory to study the long distance regime of transverse momentum dependent parton distribution functions (TMD PDFs). Chiral corrections to the TMD PDFs are computed from proton to pion/baryon splittings. For consistent power counting, we find that the fraction of the proton's momentum that a pion may carry must be kept small. We make predictions for a $\bar{d}-\bar{u}$ asymmetry in the proton's TMD PDFs and find that the effective theory gives a natural exponential suppression of the TMD PDF at long distances. We then explore the effects that additional nonperturbative physics may have on the TMD $\bar{d}-\bar{u}$ asymmetry.

    hep-phnucl-th4 citations
24. 24*

    Isgur-Wise functions for ${\mathbf{\Lambda }}_{\mathbf{b}}\to {\mathbf{\Lambda }}_{\mathbf{c}}\left({\frac{1}{2}}^{\pm }\right)$ transitions in the Bakamjian-Thomas Relativistic Quark Model

    V. Morénas🇫🇷 · A. Le Yaouanc🇫🇷 · L. Oliver🇫🇷

    We study the transitions ${\Lambda }_b\to {\Lambda }_c\left({\frac{1}{2}}^{\pm }\right)$ in the Bakamjian-Thomas (BT) relativistic quark model formalism, which describes hadrons with a fixed number of constituents. In the heavy quark limit, the BT model yields covariant form factors and Isgur-Wise (IW) scaling, regardless of the spectroscopic model used to describe the bound states. It has been extensively applied to heavy mesons where subtle properties of the IW limit of QCD, including the Bjorken-Uraltsev sum rules, have been shown to be satisfied. The present paper, where the BT construction is applied to baryons, is unavoidably technical because one is dealing with a three-body problem. The complications originate from the natural choice of the Jacobi coordinates $\vec{\rho }$ (relative space coordinate between the two light spectator quarks) and $\vec{\lambda }$ (relative space coordinate between the center-of-mass of the two light quarks and the heavy quark). The corresponding orbital angular momenta are denoted by ${\vec{\ell }}_{\rho }$ and ${\vec{\ell }}_{\lambda }$, with ${\vec{\ell }}_{\rho }+{\vec{\ell }}_{\lambda }=\vec{L}$. For the transitions ${\Lambda }_b\to {\Lambda }_c\left({\frac{1}{2}}^{\pm }\right)$, i.e. $L=0\to L=0$ or $L=0\to L=1$, one can see that the moduli ${\ell }_{\rho }$ and ${\ell }_{\lambda }$ can take an infinite number of values. For $L=0\to L=0$ one has the constraint ${\ell }_{\lambda }={\ell }_{\rho }$ and for $L=0\to L=1$ the constraint is ${\ell }_{\lambda }={\ell }_{\rho }\pm 1$. We compute explicitly the IW function ${\xi }_{\Lambda }(w)$ in the elastic case ${\Lambda }_b\left({\frac{1}{2}}^{+}\right)\to {\Lambda }_c\left({\frac{1}{2}}^{+}\right)$ and the much more involved IW function ${\sigma }_{\Lambda }(w)$ in the inelastic case ${\Lambda }_b\left({\frac{1}{2}}^{+}\right)\to {\Lambda }_c\left({\frac{1}{2}}^{-}\right)$. These functions exhibit the expected properties of covariance and IW scaling.

    hep-ph0 citations
25. 25*

    Positively Identifying HEFT or SMEFT

    Grant N. Remmen🇺🇸 · Nicholas L. Rodd🇺🇸

    We establish the bounds on Wilson coefficients of the Higgs effective field theory (HEFT) mandated by unitarity and analyticity. These positivity constraints can be projected into the space of the standard model effective field theory (SMEFT) as HEFT$\supset$SMEFT. Doing so reveals a subspace allowed by the HEFT but forbidden by SMEFT positivity, thereby identifying a region that could herald the use of the wrong EFT rather than a pathological UV. Restricting to custodial symmetric dimension-eight Higgs operators, there is a unique pair within the SMEFT where this concept can be sharply realized and is already being probed at colliders.

    hep-phhep-thPRD(2026)·19 citations
26. 26*

    Symbolic regression for precision LHC physics

    Manuel Morales-Alvarado🇮🇹 · Daniel Conde🇪🇸 · Josh Bendavid🇺🇸 · Veronica Sanz🇪🇸 · Maria Ubiali🇬🇧

    We study the potential of symbolic regression (SR) to derive compact and precise analytic expressions that can improve the accuracy and simplicity of phenomenological analyses at the Large Hadron Collider (LHC). As a benchmark, we apply SR to equation recovery in quantum electrodynamics (QED), where established analytical results from quantum field theory provide a reliable framework for evaluation. This benchmark serves to validate the performance and reliability of SR before extending its application to structure functions in the Drell-Yan process mediated by virtual photons, which lack analytic representations from first principles. By combining the simplicity of analytic expressions with the predictive power of machine learning techniques, SR offers a useful tool for facilitating phenomenological analyses in high energy physics.

    hep-ph11 citations
27. 27*

    Gravity-Mediated Dark Matter at a low reheating temperature

    Hyun Min Lee🇰🇷 · Myeonghun Park🇰🇷 · Veronica Sanz🇪🇸

    We present a new study on the Gravity-Mediated Dark Matter (GMDM) scenario, where interactions between dark matter (DM) and the Standard Model are mediated by spin-two particles. Expanding on this established framework, we explore a novel regime characterized by a low reheating temperature that offers an alternative to the conventional thermal relic paradigm. This approach opens new possibilities for understanding the dynamics of the dark sector, encompassing both the dark matter particles (fermion, scalar and vector) and the spin-two mediators. Our analysis examines the constraints imposed by the relic abundance of DM, collider experiments, and direct detection searches, spanning a wide mass range for the dark sector, from very light to extremely heavy states. This work opens new possibilities for the phenomenology of GMDM.

    hep-phJHEP(2025)·23 citations
28. 28*

    Exploring the circumstellar environment of Tycho's supernova remnant. II. Impact on the broadband non-thermal emission

    Ryosuke Kobashi · Shiu-Hang Lee · Takaaki Tanaka · Keiichi Maeda

    While the environment around Tycho's supernova remnant (SNR) has long been believed to be close to homogeneous, the latest analysis of Chandra data has identified a substantial deceleration of the forward shock which poses a major challenges to this picture. arXiv:2310.14841 showed that the existence of dense molecular cloud (MC) surrounding a rarefied wind-like circumstellar matter (CSM) can explain this observational finding in term of the shock-expansion dynamics, supporting the so-called single-degenerate scenario for the progenitor system. We here extend this work to study the non-thermal emission processes and investigate whether such an environment is consistent with the observed multi-wavelength spectrum. While the simulated broadband spectrum based on the wind-MC environment is largely consistent with observations, we find that such an environment predicts a harder gamma-ray spectrum than observed due to the relatively low CSM density in the cavity interior of the MC. This difference can be at least partially attributed to the present one-dimensional setup of the model which does not account for the clumpy and multi-dimensional structure of the CSM. Our model provides predictions for the long-term evolution of the broadband spectrum which can be used to further probe Tycho's surrounding environment in the future, a key to resolving the long-standing issue of type Ia supernova progenitor channels.

    ↳ astro-ph.HEhep-phApJ(2025)·1 citation
29. 29*

    Investigation of $\pi N$ contributions to nucleon matrix elements

    Constantia Alexandrou🇨🇾 · Giannis Koutsou🇨🇾 · Yan Li🇨🇾 · Marcus Petschlies🇩🇪 · Ferenc Pittler🇨🇾

    We investigate an improved method to extract nucleon matrix elements from lattice 3-point functions using a generalized eigenvalue problem (GEVP) with nucleon and pion-nucleon interpolating fields. Our method avoids the computation of the costly three-point functions that have pion-nucleon interpolators at both source and sink. We demonstrate that excited state contamination from $N\pi$ is minimized in nucleon matrix elements of the scalar, vector, pseudoscalar, axial, and tensor currents and discuss our results based on a physical-point ensemble with a pion mass value of 131 MeV. We find that the GEVP is most significant for the isovector pseudoscalar and axial currents.

    ↳ hep-lathep-phnucl-thPoS(2025)·2 citations
30. 30*

    Kick it like DESI: PNGB quintessence with a dynamically generated initial velocity

    Maximilian Berbig🇪🇸

    Motivated by the hint for time-dependent dynamical dark energy from an analysis of the DESI Baryon Accoustic Oscillation (BAO) data together with information from the Cosmic Microwave Background (CMB) and Supernovae (SN), we relax the assumption of a vanishing initial velocity for a quintessence field. In particular we focus on pseudo-Nambu-Goldstone-Boson (PNGB) quintessence in the form of an axion like particle, that can arise as the phase of a complex scalar and could possess derivative couplings to fermions or topological couplings to abelian gauge fields, without upsetting the necessary flatness of its potential. We discuss mechanisms from the aforementioned interactions for sourcing an initial axion field velocity $\dot{{\theta }_i}$ at redshifts $3\le z\le 10$, that will "kick" it into motion. Driven by this initial velocity the axion will first roll up in its potential, similar to "freezing" dark energy. After it has reached the pinnacle of its trajectory, it will start to roll down, and behave as "thawing" quintessence. As a proof of concept we undertake a combined fit to BAO, SN and CMB data at the background level. We find that a scenario with $\dot{{\theta }_i}=\mathcal{O}(1)m_a$, where $m_a$ is the axion mass, is slightly preferred over both $\Lambda$CDM and the conventional "thawing" quintessence with $\dot{{\theta }_i}=0$. The best fit points for this case exhibit transplanckian decay constants and very flat potentials, which both are in tension with conjectures from string theory.

    ↳ astro-ph.COhep-phhep-thJCAP(2025)·30 citations
31. 31*

    Scalar-induced gravitational wave from domain wall perturbation

    Bo-Qiang Lu🇨🇳

    Domain walls represent two-dimensional topological defects that emerge from the spontaneous breaking of discrete symmetries in various new physics models. In this study, we undertake the first calculation of gravitational waves produced by scalar perturbations generated from the gravitational wave network. Our findings indicate that the gravitational wave spectrum is notably distinct from that of other sources. This opens up a promising avenue for future gravitational wave experiments aimed at exploring the role of domain walls in the early universe.

    ↳ gr-qcastro-ph.COhep-phhep-thJHEP(2025)·7 citations
32. 32*

    Fastest spinning millisecond pulsars: indicators for quark matter in neutron stars?

    Christoph Gärtlein🇵🇹 · Violetta Sagun🇵🇹 · Oleksii Ivanytskyi🇵🇱 · David Blaschke🇵🇱 · Ilidio Lopes🇵🇹

    We study rotating hybrid stars, with a particular emphasis on the effect of a deconfinement phase transition on their properties at high spin. Our analysis is based on a hybrid equation of state (EoS) with a phase transition from hypernuclear matter to color-superconducting quark matter, where both phases are described within a relativistic density functional approach. By varying the vector meson and diquark couplings in the quark matter phase, we obtain different hybrid star sequences with varying extension of the quark matter core, ensuring consistency with astrophysical constraints from mass, radius and tidal deformability measurements. As a result, we demonstrate the impact of an increasing rotational frequency on the maximum gravitational mass, the central energy density of compact stars, the appearance of the quasi-radial oscillations and non-axisymmetric instabilities. We demonstrate that for the most favorable parameter sets with a strong vector coupling, hybrid star configurations with color superconducting quark matter core can describe the fastest spinning and heaviest galactic neutron star (NS) J0952-0607, while it is out of reach for the purely hadronic hypernuclear star configuration. We also revise the previously proposed empirical relation between the Kepler frequency, gravitational mass, and radius of non-rotating NSs, obtained based on the assumption that all NSs, up to the heaviest, are hadronic. We show how the phase transition to quark matter alters this relation and, consequently, the constraints on the dense matter EoS. Our findings reveal that incorporating the hybrid EoS has significant implications for the constraints on the properties of strongly interacting matter and NSs, placing the upper limit on $R_{1.4}\le 14.90$ km and $R_{0.7}<11.49$ km (considering 716 Hz frequency limit from J1748+2446ad) and $R_{1.4}\le$11.90~km (for 1000 Hz).

    ↳ nucl-thastro-ph.HEhep-phPRD(2025)·17 citations
33. 33*

    Accretion onto a Charged Black Hole in Consistent 4D Einstein-Gauss-Bonnet Gravity

    Kourosh Nozari🇮🇷 · Sara Saghafi🇮🇷 · Mohammad Hassani🇮🇷

    In astrophysics, accretion is the process by which a massive object acquires matter. The infall leads to the extraction of gravitational energy. Accretion onto dark compact objects such as black holes, neutron stars, and white dwarfs is a crucial process in astrophysics as it turns gravitational energy into radiation. The accretion process is an effective technique to investigate the properties of other theories of gravity by examining the behavior of their solutions with compact objects. In this paper, we investigate the behavior of test particles around a charged four dimensional Einstein Gauss Bonnet black hole in order to understand their innermost stable circular orbit (ISCO) and energy flux, differential luminosity, and temperature of the accretion disk. Then, we examine particle oscillations around a central object via applying restoring forces to treat perturbations. Next, we explore the accretion of perfect fluid onto a charged 4D EGB black hole. We develop analytical formulas for four-velocity and proper energy density of the accreting fluid. The EGB parameter and the charge affect properties of the test particles by decreasing their ISCO radius and also decreasing their energy flux. Increasing the EGB parameter and the charge, near the central source reduces both the energy density and the radial component of the infalling fluid's four-velocity.

    ↳ gr-qchep-phJHEAp(2025)·12 citations
34. 34*

    Massive Inflationary Amplitudes: Differential Equations and Complete Solutions for General Trees

    Haoyuan Liu🇨🇳 · Zhong-Zhi Xianyu🇨🇳

    We construct and solve a complete system of differential equations for general tree-level inflation correlators with an arbitrary number of massive scalar exchanges and time-dependent couplings. Any massive tree correlators can be uniquely fixed by solving this system of equations with appropriate boundary conditions. We take a hybrid approach to solve this system, using the differential equation to get the inhomogeneous solution and the bulk time integrals to determine the homogeneous solution. Altogether, we obtain analytical results for all tree-level massive inflation correlators with generic kinematics, expressed as multivariate hypergeometric series of energy ratios. The result can be neatly organized as a sum of the completely inhomogeneous solution, which we call the massive family tree, and all of its cuts. As simple applications, we provide full analytical expressions for tree correlators with one, two, and three massive exchanges.

    ↳ hep-thastro-ph.COhep-phJHEP(2025)·31 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.