Wed·Aug 14, 2024Wednesday·August 14, 2024

1. 01*

   On the length scale of collective neutrino oscillations

   Shashank Shalgar🇩🇰

   In this paper, I present a discussion on the length scale of collective neutrino oscillations. There is a popular myth in the field that the length scale of collective neutrino oscillation is related to the strength of self-interaction potential; this is a result of confusion between the length scale and time scale. As a consequence of this myth, it is believed that the convergence of numerical simulation of quantum kinetic equations requires a spatial resolution (radial bin size) that is equal to the inverse of the self-interaction potential. I try to debunk this myth in this paper.

   hep-phastro-ph.HE5 citations
2. 02*

   Semi-automatic Calculations of Multi-loop Feynman Amplitudes with AmpRed

   Wen Chen🇨🇳

   We present a Mathematica package AmpRed for the semi-automatic calculations of multi-loop Feynman amplitudes with high efficiency and precision. AmpRed implements the methods of integration by parts and differential equations in the Feynman-parameter representation. It allows for the calculations of general parametric integrals (which may not have momentum-space correspondences). Various user-friendly tools for multi-loop calculations, such as those to construct and solve differential equations for Feynman integrals, are provided. It can also deal with tensor algebras in non-relativistic field theories. Interfaces to some packages, like QGRAF and FORM, are also provided.

   hep-phhep-thnucl-thComput.Phys.Commun.(2025)·33 citations
3. 03*

   Final multiplicity of a QED cascade in generalized Heitler model

   Y.V. Selivanov🇷🇺 · A.M. Fedotov🇷🇺

   We consider a generalized Heitler model for QED cascade. An exact formula for the final number of leptons is obtained by solving the kinetic equations. We demonstrate that in such a model the final number of leptons does not depend on photon and lepton free paths. We derive approximate formulas for the main characteristics of cascades at high energy, including the final number of leptons and the cascade depth. We show that in general the final number of leptons is asymptotically proportional to the energy of seed particle. It is also demonstrated how the original Heitler model is reproduced as a special case.

   hep-phPRD(2024)·2 citations
4. 04*

   Radiative corrections relating leptoquark-fermion couplings probed at low and high energy

   Innes Bigaran🇺🇸 · Rodolfo Capdevilla🇺🇸 · Ulrich Nierste🇩🇪

   Scalar leptoquarks (LQ) with masses between 2 TeV and 50 TeV are prime candidates to explain deviations between measurements and Standard-Model predictions in decay observables of $b$-flavored hadrons (``flavor anomalies''). Explanations of low-energy data often involve order-one LQ-quark-lepton Yukawa couplings, especially when collider bounds enforce a large LQ mass. This calls for the calculation of radiative corrections involving these couplings. Studying such corrections to LQ-mediated $b\to c\tau \nu$ and $b\to s{\ell }^{+}{\ell }^{-}$ amplitudes, we find that they can be absorbed into finite renormalizations of the LQ Yukawa couplings. If one wants to use Yukawa couplings extracted from low-energy data for the prediction of on-shell LQ decay rates, one must convert the low-energy couplings to their high-energy counterparts, which subsume the corrections to the on-shell LQ-quark-lepton vertex. We present compact formulae for these correction factors and find that in scenarios with $S_1$, $R_2$, or $S_3$ LQ the high-energy coupling is always smaller than the low-energy one, which weakens the impact of collider data on the determination of the allowed parameter spaces. For the $R_2$ scenario addressing $b\to c\tau \nu$, in which one of the two involved Yukawa coupling must be significantly larger than 1, we find this coupling reduced by 15\% at high energy. If both $S_1$ and $R_2$ are present, the high-energy coupling can also be larger and the size of the correction is unbounded, because tree contribution and vertex corrections involve different couplings. We further present the conversion formula to the $\overline{\mathrm{MS}}$ scheme for the Yukawa couplings of the $S_3$ scenario.

   hep-phJHEP(2025)·4 citations
5. 05*

   3-loop Feynman Integral Extrapolations for the Baseball Diagram

   E de Doncker🇺🇸 · F Yuasa🇯🇵 · T Ishikawa🇯🇵 · K Kato🇯🇵

   We focus on numerical techniques for expanding 3-loop Feynman integrals with respect to the dimensional regularization parameter $\epsilon ,$ which is related to the space-time dimension as $\nu =4-2\epsilon ,$ and describes underlying UV singularities located at the boundaries of the integration domain. As a function of the squared momentum $s,$ the expansion coefficients exhibit thresholds that generally delineate regions for their computational techniques. For the problem at hand, a sequence of integrations with a linear extrapolation as $\epsilon \to 0$ may be performed to determine leading coefficients of the $\epsilon$-expansion numerically. For the "baseball" Feynman diagram, we have used extrapolation with respect to an additional parameter to improve the accuracy of the $\epsilon$-expansion coefficients in case of singularities internal to the domain.

   hep-ph0 citations
6. 06*

   Resonant Forbidden CP Asymmetry from Soft Leptons

   Shinya Kanemura🇯🇵 · Shao-Ping Li🇯🇵

   To explain the baryon asymmetry in the early universe via leptogenesis, quantum corrections to new particles are commonly invoked to generate the necessary CP asymmetry. We demonstrate, however, that a large CP asymmetry can already arise from Standard Model leptons. The mechanism relies on resummation of soft leptons at finite temperatures. The CP asymmetry, which is kinematically forbidden in vacuum, can be resonantly enhanced from thermally resummed leptons by seven orders of magnitude. Contrary to the resonance from exotic particles, we show that the resonant enhancement from soft leptons is protected by controlled widths under finite-temperature perturbation theory. We quantify such CP asymmetries in leptogenesis with secluded flavor effects and comment on the significance and application. The mechanism exploits the maximal role of leptons themselves, featuring low-scale leptogenesis, minimal model buildings and dark matter cogenesis.

   hep-phhep-thPRL(2025)·4 citations
7. 07*

   Spin Alignment of Vector Mesons Induced by Local Spin Density Fluctuations

   Kun Xu🇨🇳 · Mei Huang🇨🇳

   We propose a novel mechanism that the spin alignment of vector meson $\varphi$ and $K^{\ast 0}$ in most central heavy ion collisions is induced by intrinsic QCD dynamics without external vortical/ magnetic fields. The local spin density fluctuation of quarks due to the axial-vector and tensor interactions between quarks can induce the spin alignments of vector meson. It is found that axial-vector interaction results in ${\rho }_{00}<1/3$ for the spin alignment of $\varphi$ meson, while tensor interaction results in ${\rho }_{00}>1/3$. We argue that the spin alignment of $K^{\ast 0}$ due to the spin density fluctuation from flavor-mixing would be a signature or hint of instanton.

   hep-phPRD(2024)·8 citations
8. 08*

   Search for QCD Axions in light of String Theory

   Qiaoli Yang🇨🇳 · Runchao Huang🇨🇳

   The QCD axion stands as one of the most promising candidates for resolving the strong CP problem. However, the value of the axion's decay constant $f_a$ and, by extension, its mass $m_a$, remain uncertain within the framework of effective field theory, posing a challenge for experimental detection. Fortunately, fields such as cosmology and astrophysics can offer crucial clues about potential mass ranges. Additionally, string theory and the more recent swampland principles might shed some light on the subject. The most straightforward string theory compactifications suggest that $f_a$ is around the GUT scale, leading to a quantum abundance of dark matter. We found that this range can be detected through hydrogen atomic transitions. The recent concept of the dark dimension scenario introduces an alternative possibility. If axions are confined to the four-dimensional Standard Model brane, their decay constant $f_a$ would be on the order of $10^{10}$ GeV. In this scenario, where axions constitute only a minor portion of dark matter, we show that a laser-interferometry setup would be an effective detection method.

   hep-phhep-thphysics.atom-phphysics.optics2 citations
9. 09*

   Proton gluonic distributions in a light front spectator model

   Poonam Choudhary🇮🇳 · Dipankar Chakrabarti🇮🇳 · Bheemsehan Gurjar🇮🇳 · Tanmay Maji🇮🇳 · Chandan Mondal🇨🇳 · Asmita Mukherjee🇮🇳

   We investigate the leading-twist gluonic distribution functions within the proton by formulating a light-front spectator model. The proton light-front wave functions (LFWFs) are adopted from the soft-wall AdS/QCD predictions, and the model parameters are determined using the gluon unpolarized parton distribution function from the NNPDF3.0nlo dataset. Furthermore, we demonstrated the model calculations for gluon transverse momentum distributions (TMDs) and generalized parton distributions (GPDs). We also predicted the gluon spin and orbital angular momentum (OAM) contributions to the total proton spin.

   hep-phPoS(2025)·0 citations
10. 10*

    Renormalization-group consistent treatment of color superconductivity in the NJL model

    Hosein Gholami🇩🇪 · Marco Hofmann🇩🇪 · Michael Buballa🇩🇪

    The Nambu-Jona-Lasinio (NJL) model and specifically its extension to color superconductivity (CSC) is a popular effective model for investigating dense quark matter. However, the reliability of its results is challenged by cutoff artifacts, which emerge if temperature or chemical potential are of the order of the cutoff energy scales. In this work, we generalize an idea from [Braun et al. SciPost Phys., 6:056, 2019], which is based on the requirement of renormalization-group (RG) consistency and has successfully been applied to the two-flavor Quark-Meson-Diquark model, to the NJL model for electrically and color-neutral three-flavor color-superconducting quark matter. To this end, we analyze the medium divergences of the model and eliminate them by appropriate counterterms, introducing three different schemes. We show that the RG-consistent treatment removes the cutoff artifacts of the conventional regularization and enables the investigation of CSC matter at higher densities by the model. Our studies reveal the emergence of a so-called d-quark superconducting (dSC) phase within the melting pattern of the Color-Flavor Locked (CFL) phase at high chemical potentials, consistent with earlier Ginzburg-Landau analyses.

    hep-phhep-thnucl-thPRD(2025)·47 citations
11. 11*

    Dispersive analysis of excited glueball states

    Hsiang-nan Li🇹🇼

    Motivated by the determination for the spin-parity quantum numbers of the $X(2370)$ meson at BESIII, we extend our dispersive analysis on hadronic ground states to excited states. The idea is to start with the dispersion relation which a correlation function obeys, and subtract the known ground-state contribution from the involved spectral density. Solving the resultant dispersion relation as an inverse problem with available operator-product-expansion inputs, we extract excited-state masses from the subtracted spectral density. This formalism is verified by means of the application to the series of $\rho$ resonances, which establishes the $\rho (770)$, $\rho (1450)$ and $\rho (1700)$ mesons one by one under the sequential subtraction procedure. Our previous study has suggested the admixture of the $f_0(1370)$, $f_0(1500)$ and $f_0(1710)$ mesons (the $\eta (1760)$ meson) to be the lightest scalar (pseudoscalar) glueball. The present work predicts that the $f_0(2200)$ ($X(2370)$) meson is the first excited scalar (pseudoscalar) glueball.

    hep-phChin.Phys.Lett.(2024)·10 citations
12. 12*

    Charmonium: Conventional and $XYZ$ States in a Relativistic Screened Potential Model

    Chaitanya Anil Bokade🇮🇳 · Bhaghyesh🇮🇳

    In this work a comprehensive analysis of the mass spectrum and decay properties of charmonium states within a relativistic framework is carried out. The present experimental status of charmonium states is reviewed. Utilizing a screened potential model, we compute the spectra and various decay widths for $c\bar{c}$ bound system, comparing our results with experimental data and existing theoretical models. We calculate the decay constants, $E1$ and $M1$ transitions, and annihilation decay widths, confirming the consistency of our model with experimental observations for well-established charmonium states. The interpretation of charmonium-like states, $X(4140)$, $X(4274)$, and $X(4500)$ as $P$ wave charmonium states and $\psi (4040)$, $\psi (3770)$, $\psi (4160)$, $\psi (4230)$, $\psi (4360)$, $\psi (4415)$, $Y(4500)$ and $Y(4360)$ as $S-D$ mixed charmonium states are carried out.

    hep-phPRD(2025)·17 citations
13. 13*

    QCD corrections at subleading power for inclusive nonleptonic $b\to c\bar{u}d$ decays

    Thomas Mannel🇩🇪 · Daniel Moreno🇨🇭 · Alexei A. Pivovarov🇩🇪

    In this paper we compute the NLO QCD corrections for the inclusive nonleptonic decay rates of $B$-hadrons at subleading power of the heavy quark expansion. In particular, we discuss the coefficient of the chromomagnetic moment parameter ${\mu }_G$ which has a large uncertainty at leading order due to its dependence on the renormalization scale. We find that the renormalization-scale dependence of this coefficient is significantly reduced, thereby reducing the theoretical uncertainty of the coefficient and consequently of the rates. The sign of the coefficient becomes stable, and we estimate that the NLO corrections will increase the decay rates by around $2\%$.

    hep-phPRD(2024)·10 citations
14. 14*

    Loop induced $H^{\pm }{W}^{\mp }Z$ vertices in the general two Higgs doublet model with CP violation

    Shinya Kanemura🇯🇵 · Yushi Mura🇯🇵

    Understanding symmetry of extended Higgs models helps to construct the theory beyond the standard model and gives important insights for testing these models by experiments. The custodial symmetry plays an important role as a leading principle to construct non-minimal Higgs sectors. On the other hand, new sources of CP violation in the Higgs sector are essentially important to explain the baryon asymmetry of the Universe. In the two Higgs doublet model, it has been known that the CP violation and the custodial symmetry are not compatible, and thus the CP violating Higgs potential in general violates the custodial symmetry in the Higgs sector. In this paper, we discuss the loop-induced $H^{\pm }{W}^{\mp }Z$ vertices in the two Higgs doublet model, which are induced due to the custodial symmetry violation of the sector of the particles in the loop, and study how the vertices are affected by the CP violation. We calculate the $H^{\pm }{W}^{\mp }Z$ vertices in the most general two Higgs doublet model with the CP violation at the one-loop level and evaluate the decay modes $H^{\pm }\to W^{\pm }Z$ caused by these vertices. We obtain new contributions to the $H^{\pm }{W}^{\mp }Z$ vertices from the CP violating part of the model, in addition to the known contributions from the CP conserving part. Moreover, we find that an asymmetry between the decays $H^{+}\to W^{+}Z$ and $H^{-}\to W^{-}Z$ is caused by the CP violating phases in the model, some of which are important for the electroweak baryogenesis. We also briefly mention testability of these vertices at future collider experiments.

    hep-phJHEP(2024)·10 citations
15. 15*

    Pion to photon transition form factor: Beyond valence quarks

    Xiaoyi Wu🇨🇳 · Zhimin Zhu🇨🇳 · Ziyang Lin🇨🇳 · Chandan Mondal🇨🇳 · Jiangshan Lan🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸

    We investigate the singly virtual transition form factor (TFF) for the ${\pi }^0\to {\gamma }^{\ast }\gamma$ process in the space-like region using the hard-scattering formalism within the Basis Light-Front Quantization (BLFQ) framework. This form factor is expressed in terms of the perturbatively calculable hard-scattering amplitudes (HSAs) and the light-front wave functions (LFWFs) of the pion. We obtain the pion LFWFs by diagonalizing the light-front QCD Hamiltonian, which is determined for its constituent quark-antiquark and quark-antiquark-gluon Fock sectors with a three-dimensional confinement. We employ the HSAs up to next-to-leading order (NLO) in the quark-antiquark Fock sector and leading order (LO) in the quark-antiquark-gluon Fock sector. The NLO correction to the TFF in the quark-antiquark Fock sector is of the same order as the LO contribution to the TFF in the quark-antiquark-gluon Fock sector. We find that while the quark-antiquark-gluon Fock sector has minimal effect in the large momentum transfer ($Q^2$) region, it has a noteworthy impact in the low-$Q^2$ region. Our results show that, after accounting for both Fock sectors, the TFF within the BLFQ framework aligns well with existing experimental data, particularly in the low $Q^2$ region.

    hep-phnucl-thPRD(2025)·4 citations
16. 16*

    Challenges for analytic calculations of the massive three-loop form factors

    J Blümlein🇩🇪 · A. De Freitas🇦🇹 · P. Marquard🇩🇪 · C. Schneider🇦🇹

    The calculation of massive three-loop QCD form factors using in particular the large moments method has been successfully applied to quarkonic contributions in [1]. We give a brief review of the different steps of the calculation and report on improvements of our methods that enabled us to push forward the calculations of the gluonic contributions to the form factors.

    hep-phcs.SCPoS(2024)·2 citations
17. 17*

    xFitter Updates: Probing Z Boson Couplings with Forward-Backward Asymmetry

    Oleksandr Zenaiev (Hamburg University, on behalf of the xFitter developers team)🇩🇪

    We present recent updates in the xFitter software framework for global fits of parton distribution functions in high-energy physics. Our focus is on investigating the sensitivity to Z boson couplings using the forward-backward asymmetry in Drell-Yan production. By utilizing an effective approach and simulated data, we assess the accuracy of these couplings, specifically considering the full LHC data sample. Furthermore, we compare our results with predictions for future colliders, providing insights into their potential impact on understanding Z boson interactions.

    hep-phPoS(2025)·0 citations
18. 18*

    DarkMatters: A powerful tool for WIMPy analysis

    Michael Sarkis🇿🇦 · Geoff Beck🇿🇦

    We introduce a new software package, DarkMatters, which has been designed to facilitate the calculation of all aspects of indirect dark matter detection of WIMPs in astrophysical settings. Two primary features of this code are the improvement in performance compared to existing tools, and higher levels of accuracy when determining radio synchrotron emission associated with WIMP annihilations, both of which are enabled by the employment of a set of modern and novel numerical techniques. The code also includes functionality for a multi-wavelength set of output products including gamma-ray, radio and neutrino fluxes which can be saved in common formats used by the astronomical community, such as the FITS data file format. The calculations may be tailored to work with a wide range of astrophysical target structures, from dwarf galaxies to galaxy clusters, and the configuration of the underlying calculations is managed by a set of key-value dictionary entries that are easy to understand and use. The code base is publicly accessible through an online repository with a permissive MIT source code licence.

    hep-phastro-ph.COastro-ph.HEphysics.comp-phPhys.Dark Univ.(2025)·6 citations
19. 19*

    Are in-medium quark-gluon showers strongly coupled? Results in the large-$N_f$ limit

    Peter Arnold🇺🇸 · Omar Elgedawy🇺🇸 · Shahin Iqbal🇵🇰

    Inside a medium, showers originating from a very high energy particle develop via medium-induced splitting processes such as bremsstrahlung and pair production. During shower development, two consecutive splittings sometimes overlap quantum mechanically, so that they cannot be treated independently. Some of these effects can be absorbed into an effective value of a medium parameter known as $\hat{q}$. Previous calculations (with certain simplifying assumptions) have found that, after adjusting the value of $\hat{q}$, the leftover effect of overlapping splittings is quite small for purely gluonic large-$N_c$ showers but is very much larger for large-$N_f$ QED showers, at comparable values of $N\alpha$. Here, by investigating the same problem for QCD with *quarks* in the large-$N_f$ limit of many quark flavors, we make a first study of whether the small effect in purely gluonic showers (i) was merely an accident or (ii) is more broadly characteristic of such overlap effects in QCD. We also offer a qualitative explanation for the large size of the effect in QED vs. QCD.

    hep-phnucl-thJHEP(2025)·13 citations
20. 20*

    Search for baryon junctions in e+A collisions at the Electron Ion Collider

    Niseem Magdy🇺🇸 · Abhay Deshpande🇺🇸 · Roy Lacey🇺🇸 · Wenliang Li🇺🇸 · Prithwish Tribedy🇺🇸 · Zhangbu Xu🇺🇸

    Constituent quarks in a nucleon are the essential elements in the standard ``quark model" associated with the electric charge, spin, mass, and baryon number of a nucleon. Quantum Chromodynamics (QCD) describes nucleon as a composite object containing current quarks (valence quarks and sea (anti-)quarks) and gluons. These subatomic elements and their interactions are known to contribute in complex ways to the overall nucleon spin and mass. In the early development of QCD theory in the 1970s, an alternative hypothesis postulated that the baryon number might manifest itself through a non-perturbative configuration of gluon fields forming a Y-shaped topology known as the gluon junction. In this work, we propose to test such hypothesis by measuring (i) the Regge intercept of the net-baryon distributions for $e$+($p$)Au collisions, (ii) baryon and charge transport in the isobaric ratio between $e$+Ru and $e$+Zr collisions, and (iii) target flavor dependence of proton and antiproton yields at large rapidity, transported from the hydrogen and deuterium targets in $e+p$(d) collisions. Our study indicates that these measurements at the EIC can help determine what carries the baryon number.

    hep-phhep-exnucl-exnucl-thEPJC(2024)·3 citations
21. 21*

    Interpreting Pulsar Timing Array data of Gravitational Waves with Ekpyrosis-Bouncing Cosmology

    Taotao Qiu🇨🇳 · Mian Zhu🇵🇱

    Recent pulsar timing array (PTA) experiments have reported strong evidence of the stochastic gravitational wave background (SGWB). If interpreted as primordial Gravitational Waves (pGWs), the signal favors a strongly blue-tilted spectrum. On the other hand, the Ekpyrosis-bouncing cosmology with a strongly blue-tilted GW spectrum, i.e., $n_T\simeq 2$, offers a potential explanation for the observed SGWB signal. In this paper, we construct a concrete Ekpyrosis-bouncing model, and show its capacity to intepret the PTA result without pathologies. Both tensor and scalar perturbations are analysed with constraints from the current observations.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2025)·14 citations
22. 22*

    The triton lifetime from nuclear lattice effective field theory

    Serdar Elhatisari🇹🇷 · Fabian Hildenbrand🇩🇪 · Ulf-G. Meißner🇩🇪

    In this work, we present a calculation of the triton $\beta$-decay lifetime using Nuclear Lattice Effective Field Theory (NLEFT) at next-to-next-to-next-to-leading order in the chiral expansion. By incorporating a non-perturbative treatment of the higher-order corrections, we achieve consistent predictions for the Fermi and Gamow-Teller matrix elements, which are crucial for determining the triton lifetime. Our results are consistent with earlier theoretical calculations, confirming the robustness of our approach. This study marks a significant advancement in the systematic application of NLEFT to nuclear $\beta$-decay processes, paving the way for future high-precision calculations in more complex nuclear systems. Additionally, we discuss potential improvements to our approach, including the explicit inclusion of two-pion exchange mechanisms and the refinement of three-nucleon forces. These developments are essential for extending the applicability of NLEFT to a broader range of nuclear phenomena, including neutrinoless double-$\beta$ decay.

    ↳ nucl-thhep-lathep-phnucl-exPLB(2024)·10 citations
23. 23*

    Search for ${\eta }_c(2S)\to \omega \omega$ and $\omega \varphi$ decays and measurements of ${\chi }_{cJ}\to \omega \omega$ and $\omega \varphi$ in $\psi (2S)$ radiative processes

    BESIII Collaboration: M. Ablikim · M. N. Achasov · P. Adlarson · O. Afedulidis · X. C. Ai · R. Aliberti · A. Amoroso · Q. An · Y. Bai · O. Bakina · I. Balossino · Y. Ban and 655 other authors

    Using $(2712\pm 14)$ $\times$ 10${}^6$ $\psi (2S)$ events collected with the BESIII detector at the BEPCII collider, we search for the decays ${\eta }_c(2S)\to \omega \omega$ and ${\eta }_c(2S)\to \omega \varphi$ via the process $\psi (2S)\to \gamma {\eta }_c(2S)$. Evidence of ${\eta }_c(2S)\to \omega \omega$ is found with a statistical significance of $3.2\sigma$. The branching fraction is measured to be $\mathcal{B}({\eta }_c(2S)\to \omega \omega )=(5.65\pm 3.77(stat.)\pm 5.32(syst.))\times 10^{-4}$. No statistically significant signal is observed for the decay ${\eta }_c(2S)\to \omega \varphi$. The upper limit of the branching fraction at the 90\% confidence level is determined to be $\mathcal{B}(\psi (2S)\to \gamma {\eta }_c(2S),{\eta }_c(2S)\to \omega \varphi )<2.24\times 10^{-7}$. We also update the branching fractions of ${\chi }_{cJ}\to \omega \omega$ and ${\chi }_{cJ}\to \omega \varphi$ decays via the $\psi (2S)\to \gamma {\chi }_{cJ}$ transition. The branching fractions are determined to be $\mathcal{B}({\chi }_{c0}\to \omega \omega )=(10.63\pm 0.11\pm 0.46)\times 10^{-4}$, $\mathcal{B}({\chi }_{c1}\to \omega \omega )=(6.39\pm 0.07\pm 0.29)\times 10^{-4}$, $\mathcal{B}({\chi }_{c2}\to \omega \omega )=(8.50\pm 0.08\pm 0.38)\times 10^{-4}$, $\mathcal{B}({\chi }_{c0}\to \omega \varphi )=(1.18\pm 0.03\pm 0.05)\times 10^{-4}$, $\mathcal{B}({\chi }_{c1}\to \omega \varphi )=(2.03\pm 0.15\pm 0.12)\times 10^{-5}$, and $\mathcal{B}({\chi }_{c2}\to \omega \varphi )=(9.37\pm 1.07\pm 0.59)\times 10^{-6}$, where the first uncertainties are statistical and the second are systematic.

    ↳ hep-exhep-phPRD(2025)·0 citations
24. 24*

    Global Bases for Nonplanar Loop Integrands, Generalized Unitarity, and the Double Copy to All Loop Orders

    Zvi Bern🇺🇸 · Enrico Herrmann🇺🇸 · Radu Roiban🇺🇸 · Michael S. Ruf🇺🇸 · Mao Zeng🇬🇧

    We introduce a constructive method for defining a global loop-integrand basis for scattering amplitudes, encompassing both planar and nonplanar contributions. Our approach utilizes a graph-based framework to establish a well-defined, non-redundant basis of integrands. This basis, constructed from a chosen set of non-redundant graphs together with a selection of irreducible scalar products, provides clear insights into various physical properties of scattering amplitudes and proves useful in multiple contexts, such as on-shell Ward identities and manifesting gauge-choice independence. A key advantage of our integrand basis is its ability to streamline the generalized unitarity method. Specifically, we can directly read off the coefficients of basis elements without resorting to ansatze or solving linear equations. This novel approach allows us to lift generalized unitarity cuts -- expressed as products of tree amplitudes -- to loop-level integrands, facilitating the use of the tree-level double copy to generate complete gravitational integrands at any loop order. This method circumvents the difficulties in identifying complete higher-loop-order gauge-theory integrands that adhere to the color-kinematics duality. Additionally, our cut-based organization is well-suited for expansion in hard or soft limits, aiding in the exploration of ultraviolet or classical limits of scattering amplitudes.

    ↳ hep-thhep-phJHEP(2025)·28 citations
25. 25*

    Thermodynamics from the S-matrix reloaded, with applications to QCD and the confining Flux Tube

    Pietro Baratella🇸🇮 · Joan Elias Miro🇮🇹 · Emanuele Gendy🇩🇪

    Over the past decade and more, S-matrix-based calculational methods have experienced a resurgence, proving to be both an elegant and powerful tool for extracting physical quantities without the need for an underlying Lagrangian formulation. In this work, we critically review and further develop the formalism introduced by Dashen, Ma, and Bernstein, which connects the thermodynamics of relativistic systems to the information contained in their scattering amplitudes. As a demonstration, we revisit the computation of the QCD equation of state to leading order in the strong coupling, showcasing the advantages of this method over traditional Thermal Field Theory techniques. Additionally, we apply these tools to the effective theory of a long confining Flux Tube in D dimensions, analyzing thermal effects up to and including NNLO contributions. Our results are compared with those obtained using the Thermodynamic Bethe Ansatz method. We also discuss how these techniques enable the inclusion of non-universal effects in the study of Flux Tubes, while relying solely on the S-matrix as input.

    ↳ hep-thhep-lathep-phJHEP(2024)·8 citations
26. 26*

    Nonexponential decay law of the 2P-1S transition of the H-atom

    Francesco Giacosa🇵🇱 · Krzysztof Kyzioł🇵🇱

    We evaluate numerically the survival probability $P(t)$ for the unstable 2P excited state of the hydrogen atom, which decays into the ground-state 1S emitting one photon ($\tau \sim 1.595$ ns), thus extending the analytic study of Facchi and Pascazio, Physics Letters A 241 (1998). To this end, we first determine the analytic expression of the spectral function of the unstable state, which allows for an accurate evaluation of $P(t)$. As expected, for short and long times $P(t)$ shows deviations from the exponential law: a `Zeno' region occurs at extremely short times (up to $\sim 0.3$ attosec, followed by a longer `anti-Zeno' domain (up to $\sim 50$ attosec); at long times above $125\tau$, the decay law scales as $t^{-4}$.

    ↳ quant-phhep-phActa Phys.Polon.A(2024)·2 citations
27. 27*

    Cosmological collider non-Gaussianity from multiple scalars and $R^2$ gravity

    Shuntaro Aoki🇰🇷 · Anish Ghoshal🇵🇱 · Alessandro Strumia🇮🇹

    Cosmological collider signals of primordial non-Gaussianity arise at tree level when an extra scalar has Hubble mass during inflation. We critically review the formalism finding that a large class of inflationary theories, based on Planck-scale physics, predict a scalar bi-spectrum around the gravitational floor level. This mild signal arises for example in $R^2$ gravity, in the regime where its gravitational scalar has Hubble-scale mass. Signals much above the gravitational floor arise in theories where scalars undergo multiple turns during inflation, thanks to sub-Planckian physics.

    ↳ astro-ph.COhep-phhep-thJHEP(2024)·17 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.