Fri·Sep 15, 2023Friday·September 15, 2023

1. 01*

   Field Theory of the Fermi Function

   Richard J. Hill🇺🇸 · Ryan Plestid🇺🇸

   The Fermi function $F(Z,E)$ accounts for QED corrections to beta decays that are enhanced at either small electron velocity $\beta$ or large nuclear charge $Z$. For precision applications, the Fermi function must be combined with other radiative corrections and with scale- and scheme-dependent hadronic matrix elements. We formulate the Fermi function as a field theory object and present a new factorization formula for QED radiative corrections to beta decays. We provide new results for the anomalous dimension of the corresponding effective operator complete through three loops, and resum perturbative logarithms and $\pi$-enhancements with renormalization group methods. Our results are important for tests of fundamental physics with precision beta decay and related processes.

   hep-phhep-thnucl-exnucl-thPRL(2024)·32 citations
2. 02*

   Signatures for tetraquark mixing from partial decay widths of the two light-meson nonets

   Hungchong Kim🇰🇷 · K.S.Kim🇰🇷

   In this talk, we present successful aspects of the tetraquark mixing model for the two light-meson nonets in the $J^{PC}=0^{++}$ channel, the light nonet [$a_0(980)$, $K_0^{\ast }(700)$, $f_0(500)$, $f_0(980)$] and the heavy nonet [$a_0(1450)$, $K_0^{\ast }(1430)$, $f_0(1370)$, $f_0(1500)$]. In particular, we focus on how their experimental partial decay widths extracted from Particle Data Group (PDG) can support this mixing model. Currently, the experimental data exhibit an unnatural tendency that partial widths of the light nonet are consistently larger than those of the heavy nonet. This unnatural tendency can be explained if the coupling into two pseudoscalar mesons is enhanced in the light nonet and suppressed in the heavy nonet as predicted by the tetraquark mixing model. Therefore, this could be strong evidence to support for the tetraquark mixing model.

   hep-phhep-exnucl-thEPJ Web Conf.(2024)·5 citations
3. 03*

   Baryon Number Violating Rate as A Function of the Proton-Proton Collision Energy

   Yu-Cheng Qiu🇨🇳 · S. -H. Henry Tye🇨🇳

   The baryon-number violation (BV) happens in the standard electroweak model. According to the Bloch-wave picture, the BV event rate shall be significantly enhanced when the proton-proton collision center of mass (COM) energy goes beyond the sphaleron barrier height $E_{\mathrm{sph}}\simeq 9.0\mathrm{TeV}$. Here we compare the BV event rates at different COM energies, using the Bloch-wave band structure and the CT18 parton distribution function data, with the phase space suppression factor included. As an example, the BV cross section at 25 TeV is 4 orders of magnitude bigger than its cross section at 13 TeV. The probability of detection is further enhanced at higher energies since an event at higher energy will produce on average more same sign charged leptons.

   hep-phPRD(2023)·0 citations
4. 04*

   Analysis of final state lepton polarization-dependent observables in $H\to {\ell }^{+}{\ell }^{-}\gamma$ in the SM at loop level

   Ishtiaq Ahmed🇵🇰 · Usman Hasan🇵🇰 · Shahin Iqbal🇵🇰 · M. Junaid🇵🇰 · Bilal Tariq🇵🇰 · A. Uzair🇵🇰

   Recently, the CMS and ATLAS collaborations have announced the results for $H\to Z[\to {\ell }^{+}{\ell }^{-}]\gamma$ with $\ell =e$ or $\mu$ \cite{CMS:2022ahq,CMS:2023mku}, where $H\to Z\gamma$ is a sub-process of $H\to {\ell }^{+}{\ell }^{-}\gamma$. This semi-leptonic Higgs decay receives loop induced resonant $H\to Z[\to {\ell }^{+}{\ell }^{-}]\gamma$ as well as non-resonant contributions. % as discussed in \cite{Kachanovich:2021pvx}. To probe further features coming from these contributions to $H\to {\ell }^{+}{\ell }^{-}\gamma$, we argue that the polarization of the final state leptons is also an important parameter. We show that the contribution from the interference of resonant and non-resonant terms plays an important role when the polarization of final state lepton is taken into account, which is negligible in the case of unpolarized leptons. For this purpose, we have calculated the polarized decay rates and the longitudinal ($P_L$), normal ($P_N$) and transverse ($P_T$) polarization asymmetries. We find that these asymmetries purely come from the loop contributions and are helpful to further investigate the resonant and non-resonant nature of $H\to Z[\to {\ell }^{+}{\ell }^{-}]\gamma$ decay. We observe that for $\ell =e,\mu$, the longitudinal decay rate is highly suppressed around $m_{\ell \ell }\approx 60$GeV when the final lepton spin is $-\frac{1}{2}$, dramatically increasing the corresponding lepton polarization asymmetries. Furthermore, we analyze another observable, the ratio of decay rates $R_{i\pm }^{\ell {\ell }^{\prime }}$, where $\ell$ and ${\ell }^{\prime }$ refer to different final state lepton generations. Precise measurements of these observables at the HL-LHC and the planned $e^{+}{e}^{-}$ can provide a fertile ground to test not only the SM but also to examine the signatures of possible NP beyond the SM.

   hep-phJHEP(2024)·10 citations
5. 05*

   The muon parton distribution functions

   Stefano Frixione🇮🇹 · Giovanni Stagnitto🇨🇭

   We compute the Parton Distribution Functions (PDFs) of the unpolarised muon for the leptons, the photon, the light quarks, and the gluon. We discuss in detail the issues stemming from the necessity of evaluating the strong coupling constant at scales of the order of the typical hadron mass, and compare our novel approach with those currently available in the literature. While we restrict our phenomenological results to be leading-logarithmic accurate, we set up our formalism in a way that renders it straightforward to achieve next-to-leading logarithmic accuracy in the QED, QCD, and mixed QED$\times$QCD contributions.

   hep-phJHEP(2023)·14 citations
6. 06*

   High-energy resummation in Higgs production at the next-to-leading order

   Francesco Giovanni Celiberto🇪🇸 · Michael Fucilla🇫🇷 · Dmitry Yu. Ivanov🇷🇺 · Mohammed M.A. Mohammed🇮🇹 · Alessandro Papa🇮🇹

   We present the full next-to-leading order (NLO) result for the impact factor of a forward Higgs boson, obtained in the infinite-top-mass limit, both in the momentum representation and as superposition of the eigenfunctions of the leading-order (LO) BFKL kernel.

   hep-phPoS(2024)·17 citations
7. 07*

   Search For a Leptoquark and Vector-like Lepton in a Muon Collider

   Nivedita Ghosh🇮🇳 · Santosh Kumar Rai🇮🇳 · Tousik Samui🇮🇳

   The proposal for a high-energy muon collider offers many opportunities in the search for physics beyond the Standard Model (BSM). The collider by construction is likely to be more sensitive to the muon-philic models, primarily motivated by the BSM explanation of muon $(g-2)$ excess and quark flavor anomalies. In this work, we explore the potential of the proposed muon collider in the context of such models and focus on one such model that extends the Standard Model (SM) with a leptoquark, a vector-like lepton, and a real scalar. In this model, we propose searches for TeV scale leptoquarks in $2\mu +2b+mET$ channel. Notably, the leptoquark can be produced singly at the muon collider with a large cross-section. We have shown that a significant signal in this channel can be detected at a 3~TeV muon collider even with an integrated luminosity as low as $\sim 10$~fb${}^{-1}$

   hep-phhep-exNPB(2024)·23 citations
8. 08*

   First determination of the Jarlskog invariant of CP violation from the moduli of the CKM matrix elements

   Shu Luo🇨🇳 · Zhi-zhong Xing🇨🇳

   We find that the precision and accuracy of current experimental data on the moduli of nine Cabibbo-Kobayashi-Maskawa (CKM) quark flavor mixing matrix elements allow us to numerically determine the it correct size of the Jarlskog invariant of CP violation from four of them in eight different ways for the first time without making any special assumptions. This observation implies a remarkable self-consistency of the correlation between CP-conserving and CP-violating quantities of the CKM matrix as guaranteed by its unitarity.

   hep-phhep-exNPB(2023)·5 citations
9. 09*

   Double charmed meson production in $pp$ and $pA$ collisions at the LHC within the dipole approach in momentum representation

   G. Sampaio dos Santos🇧🇷 · G. Gil da Silveira🇧🇷 · M. V. T. Machado🇧🇷

   A study of double charmed meson production in proton-proton and proton-nucleus collisions at the LHC energies is performed. Based on the color dipole formalism developed in the transverse momentum representation and the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of $D$-mesons. The theoretical results consider the center-of-mass energy and forward rapidities associated to the measurements by the LHCb Collaboration. The results considering different unintegrated gluon distributions are presented and compared to data and predictions for proton-nucleus collisions are provided.

   hep-phhep-exEPJC(2023)·4 citations
10. 10*

    Normalized factorial moments of spatial distributions of particles in high multiplicity events: A Toy model study

    Sheetal Sharma🇮🇳 · Salman Khurshid Malik🇮🇳 · Zarina Banoo🇮🇳 · Ramni Gupta🇮🇳

    In ultra-relativistic heavy-ion collisions a strongly interacting complex system of quarks and gluons is formed. The nature of the system so created and the mechanism of multi-particle production in these collisions may be revealed by studying the normalized factorial moments ($F_{\mathrm{q}}$) as function of various parameters. The resilience of $F_{\mathrm{q}}$ moments studied using Toy model events shows that these are sensitive to the presence of dynamical fluctuations in the system and are robust against the uniform efficiencies in the data measurements. Results of this study serve as a suitable reference baseline for the experimental and simulation studies.

    hep-phhep-exnlin.AOnucl-exNPA(2025)·2 citations
11. 11*

    Predictions of the Strange partner of $T_{cc}$ in the quark delocalization color screening model

    Xuejie Liu🇨🇳 · Dianyong Chen🇨🇳 · Hongxia Huang🇨🇳 · Jialun Ping🇨🇳

    Inspired by the detection of $T_{cc}$ tetraquark state by LHCb Collaboration, we preform a systemical investigation of the low-lying doubly heavy charm tetraquark states with strangeness in the quark delocalization color screening model in the present work. Two kinds of configurations, the meson-meson configuration and diquark-antidiquark configuration, are considered in the calculation. Our estimations indicate that the coupled channel effects play important role in the multiquark system, and a bound state with $J^P=1^{+}$ and a resonance state with $J^P=0^{+}$ have been predicted. The mass of the bound state is evaluated to be $(3971\sim 3975)$ MeV, while the mass and width of the resonance are determined to be $(4113\sim 4114)$ MeV and $(14.3\sim 16.1)$ MeV, respectively.

    hep-phhep-exPRD(2024)·3 citations
12. 12*

    An Unfamiliar Way to Generate the Hierarchy of Standard Model Fermion Masses

    S. Baek🇰🇷 · J. Kersten🇰🇷 · P. Ko🇰🇷 · L. Velasco-Sevilla🇰🇷

    While the properties of the observed Higgs boson agree with the Standard Model predictions, the hierarchy of fermion masses lacks an explanation within the model. In this work, we propose a fresh approach to this problem, involving a different Higgs doublet responsible for each quark mass. We construct a model with a gauged, non-anomalous $U(1)$ family symmetry that fixes which fermion couples to which doublet with an $\mathcal{O}(1)$ Yukawa coupling. The hierarchy of masses is generated by the hierarchy of vacuum expectation values of the Higgs fields. The model generically predicts a light, weakly coupled pseudoscalar. We verify that the model satisfies constraints from flavour changing neutral currents, Higgs phenomenology and electroweak precision tests.

    hep-phJHEP(2024)·4 citations
13. 13*

    Additional Higgs Bosons near 95 and 650 GeV in the NMSSM

    Ulrich Ellwanger🇫🇷 · Cyril Hugonie🇫🇷

    Hints for an additional Higgs boson with a mass of about 95 GeV originate from LEP and searches in the diphoton channel by CMS and ATLAS. A search for resonant production of SM plus BSM Higgs bosons in the diphoton plus bb channel by CMS showed some excess for a 650 GeV resonance decaying into the SM Higgs plus a 95 GeV Higgs boson. We investigate whether these phenomena can be interpreted simultaneously within the NMSSM subject to the latest constraints on couplings of the SM Higgs boson, on extra Higgs bosons from the LHC, and on dark matter direct detection cross sections. We find that the hints for a 95 GeV Higgs boson in the diphoton channel by CMS and ATLAS and in the diphoton plus bb channel by CMS can be fitted simultaneously within the 2 sigma level.

    hep-phEPJC(2023)·41 citations
14. 14*

    Interplay between Higgs inflation and dark matter models with dark $U(1)$ gauge symmetry

    Sarif Khan🇩🇪 · Jinsu Kim🇨🇳 · Pyungwon Ko🇰🇷

    We investigate dark matter phenomenology and Higgs inflation in a dark $U(1{)}_D$-extended model. The model features two dark matter candidates, a dark fermion and a dark vector boson. When the fermion dark matter $\psi$ is heavier than the vector dark matter $W_D$, there is an ample parameter space where $\psi$ is dominant over $W_D$. The model can then easily evade the stringent bounds from direct detection experiments, since $\psi$ has no direct coupling to the Standard Model particles. Furthermore, the model can accommodate inflation in three different ways, one along the Standard Model Higgs direction, one along the dark Higgs direction, and one along the combination of the two. Considering the running of the parameters and various observational constraints, we perform a detailed numerical analysis and identify allowed parameter spaces that explain both dark matter and Higgs inflation in a unified manner. We discuss in detail how the imposition of Higgs inflation severely constrains the dark matter parameter space. The existence of the dark Higgs field is found to play a crucial role both in dark matter phenomenology and in generalised Higgs inflation.

    hep-phastro-ph.COJHEP(2024)·13 citations
15. 15*

    Recent Progress in Low Energy Neutrino Scattering Physics and Its Implications for the Standard and Beyond the Standard Model Physics

    V. Pandey🇺🇸

    Neutrinos continue to provide a testing ground for the structure of the standard model of particle physics as well as hints towards the physics beyond the standard model. Neutrinos of energies spanning over several orders of magnitude, originating in many terrestrial and astrophysical processes, have been detected via various decay and interaction mechanisms. At MeV scales, there has been one elusive process, until a few years ago, known as coherent elastic neutrino-nucleus scattering (CEvNS) that was theoretically predicted over five decades ago but was never observed experimentally. The recent experimental observation of the CEvNS process by the COHERENT collaboration at a stopped pion neutrino source has inspired physicists across many subfields. This has vital implications for nuclear physics, high-energy physics, astrophysics, and beyond. CEvNS, being a low-energy process, provides a natural window to study light, weakly-coupled, new physics in the neutrino sector. In this review, we intend to provide the current status of low energy neutrino scattering physics and its implications for the standard and beyond the standard model physics. We discuss the general formalism of calculating the tree-level CEvNS cross section and present estimated theoretical uncertainties on the CEvNS cross section stemming from different sources. We also discuss the inelastic scattering of tens of MeV neutrinos that have implications for supernova detection in future neutrino experiments. We discuss how the CEvNS experiments can be used as a testing ground for the Standard Model (SM) weak physics as well as in searching for the Beyond the Standard Model (BSM) physics signals. Any deviation from the SM predicted event rate either with a change in the total event rate or with a change in the shape of the recoil spectrum, could indicate new contributions to the interaction cross-section.

    hep-phhep-exnucl-exnucl-thPPNP(2024)·23 citations
16. 16*

    Conformal little Higgs models

    Aqeel Ahmed🇩🇪 · Manfred Lindner🇩🇪 · Philipp Saake🇩🇪

    Little Higgs models address the hierarchy problem by identifying the SM Higgs doublet as pseudo-Nambu--Goldstone bosons (pNGB) arising from global symmetries with collective breakings. These models are designed to address the little hierarchy problem up to a scale of $\Lambda \sim \mathcal{O}(10)$ TeV. Consequently, these models necessitate an ultraviolet (UV) completion above this scale. On the other hand, conformal extensions of the Standard Model are intriguing because scales emerge as a consequence of dimensional transmutation. In this study, we present a unified framework in which the electroweak hierarchy problem is tackled through a conformal symmetry collectively broken around the TeV scale, offering an appealing UV completion for little Higgs models. Notably, this framework automatically ensures the presence of the required UV fixed points, eliminating the need for careful adjustments to the particle content of the theory. Moreover, this framework naturally addresses the flavor puzzles associated with composite or little Higgs models. Furthermore, we suggest that in this framework all known little Higgs models can be UV-completed through conformal dynamics above the scale $\Lambda$ up to arbitrary high scales.

    hep-phPRD(2024)·5 citations
17. 17*

    Method for measuring the charge radii of charged hyperons from the time-like region

    Yong-Hui Lin🇩🇪 · Feng-Kun Guo🇨🇳 · Ulf-G. Meißner🇩🇪

    We propose a novel method for measuring the charge radii of charged stable hadrons, with which the first measurement of the charge radii of the ${\Sigma }^{+}$ and the ${\Xi }^{-}$ is foreseen. The method explores the facts that the Dalitz decay $\psi (2S)\to Y\bar{Y}{e}^{+}{e}^{-}$ contains the hyperon form factors and the lowest measurable four-momentum transfer squared can be as low as $\sim 4m_e^2=1.05\times 10^{-6}\mathrm{Ge}{\mathrm{V}}^2$ in the time-like region. We identify a kinematic region where the hyperon form factors are essential and propose a method for subtracting the background from the data. It is estimated that the hyperon charge radii can be measured to a precision of about {0.2~fm} with the BES\Rom{3} experiment and one order of magnitude better at the future Super $\tau$-Charm Facility. Moreover, the same method can be used to measure the charge radius of the proton, which provides an independent cross-check on the extraction of proton radius from elastic $ep$ scattering or leptonic hydrogen spectroscopy.

    hep-phhep-exnucl-exnucl-thPLB(2024)·3 citations
18. 18*

    Identifying the Group-Theoretic Structure of Machine-Learned Symmetries

    Roy T. Forestano🇺🇸 · Konstantin T. Matchev🇺🇸 · Katia Matcheva🇺🇸 · Alexander Roman🇺🇸 · Eyup B. Unlu🇺🇸 · Sarunas Verner🇺🇸

    Deep learning was recently successfully used in deriving symmetry transformations that preserve important physics quantities. Being completely agnostic, these techniques postpone the identification of the discovered symmetries to a later stage. In this letter we propose methods for examining and identifying the group-theoretic structure of such machine-learned symmetries. We design loss functions which probe the subalgebra structure either during the deep learning stage of symmetry discovery or in a subsequent post-processing stage. We illustrate the new methods with examples from the U(n) Lie group family, obtaining the respective subalgebra decompositions. As an application to particle physics, we demonstrate the identification of the residual symmetries after the spontaneous breaking of non-Abelian gauge symmetries like SU(3) and SU(5) which are commonly used in model building.

    hep-phcs.LGhep-thmath-ph+2PLB(2023)·6 citations
19. 19*

    Single-soft emissions for amplitudes with two colored particles at three loops

    Franz Herzog🇬🇧 · Yao Ma🇨🇭 · Bernhard Mistlberger🇺🇸 · Adi Suresh🇺🇸

    We compute the three-loop correction to the universal single-soft emission current for the case of scattering amplitudes with two additional color-charged partons. We present results valid for QCD and $\mathcal{N}=4$ super-symmetric Yang-Mills theory. To achieve our results we develop a new integrand expansion technique for scattering amplitudes in the presence of soft emissions. Furthermore, we obtain contributions from single final-state parton matrix elements to the Higgs boson and Drell-Yan production cross section at next-to-next-to-next-to-next-to leading order (N${}^4$LO) in perturbative QCD in the threshold limit.

    hep-phhep-thJHEP(2023)·23 citations
20. 20*

    Covariant form factors for spin-1 particles

    J. P. B. C. de Melo (Laboratório de Física Teórica e Computacional - LFTC, Universidade Cruzeiro do Sul and Universidade Cidade de São Paulo (UNICID), São Paulo, Brazil)🇧🇷

    Spin-1 particles, is a fundamental bound state for the two quarks, and play a crucial role in elucidating the electromagnetic properties within the realm of hadronic physics. Their intrinsic relativistic nature mandates a quantum field theory (QFT) framework for a comprehensive analysis. In this investigation, we employ both the instant form of QFT and light-front quantum field theory (LFQFT) as our theoretical tools. While conventional LFQFT approaches predominantly focus on the plus component of the electromagnetic current to extract the properties of spin-1 vector particles, our study extends this analysis by systematically incorporating the minus component as well. Our findings demonstrate that achieving a rigorous equivalence between these distinct current components necessitates the inclusion of nonvalence terms within the electromagnetic current operator. This crucial inclusion serves to restore manifest covariance and ensures a robust consistency with the results independently derived from the more conventional instant form of quantum field theory.

    hep-phhep-thnucl-thPRD(2026)·1 citation
21. 21*

    Pseudoscalar current and covariance with the light-front approach

    Jurandi Leãoo (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo, and Instituto Federal de São Paulo, Avenida Bahia, Caraguatatuba, 11665-071 São Paulo, Brazil)🇧🇷 · J. P. B. C. de Melo (Laboratório de Física Teórica e Computacional-LFTC, Universidade Cruzeiro do Sul / Universidade Cidade de São Paulo, 015060-000, São Paulo, SP, Brazil)🇧🇷

    Quantum Field Theory (QFT) is used to describe the physics of particles in terms of their fundamental constituents. The Light-Front Field Theory~(LFFT), introduced by Paul Dirac in 1949, is an alternative approach to solve some of the problems that arise in quantum field theory. The LFFT is similar to the Equal Time Quantum Field Theory~(EQT), however, some particularities are not, such as the loss of covariance in the light-front. Pion electromagnetic form factor is studied in this work at lower and higher momentum transfer regions to explore the constituent quark models and the differences among these and other models. The electromagnetic current is calculated with both the ``plus'' and ``minus'' components in the light-front approach. The results are compared with other models, as well as with experimental data.

    hep-phnucl-thRev.Mex.Fis.(2023)·2 citations
22. 22*

    Dark Matter Direct Detection in $t$-channel mediator models

    Giorgio Arcadi🇮🇹 · David Cabo-Almeida🇮🇹 · Federico Mescia🇪🇸 · Javier Virto🇪🇸

    We perform a comprehensive study of the Direct Detection phenomenology of singlet Dark Matter $t$-channel portal models. For that purpose, we present a complete one-loop matching onto a Heavy Dark-Matter Effective Field Theory, leading to a complete computation of the loop induced direct detection cross-section for both scalar and fermionic Dark Matter candidates. The results are compared with current and future bounds from Direct Detection experiments, as well as with the requirement of the correct Dark Matter relic density.

    hep-phJCAP(2024)·12 citations
23. 23*

    Non-standard axion electrodynamics and the dual Witten effect

    Ben Heidenreich🇺🇸 · Jacob McNamara🇺🇸 · Matthew Reece🇺🇸

    Standard axion electrodynamics has two closely related features. First, the coupling of a massless axion field to photons is quantized, in units proportional to the electric gauge coupling squared. Second, the equations of motion tell us that a time-dependent axion field in a background magnetic field sources an effective electric current, but a time-dependent axion field in a background electric field has no effect. These properties, which manifestly violate electric-magnetic duality, play a crucial role in experimental searches for axions. Recently, electric-magnetic duality has been used to motivate the possible existence of non-standard axion couplings, which can both violate the usual quantization rule and exchange the roles of electric and magnetic fields in axion electrodynamics. We show that these non-standard couplings can be derived from SL(2,Z) duality, but that they come at a substantial cost: in non-standard axion electrodynamics, all electrically charged particles become dyons when the axion traverses its field range, in a dual form of the standard Witten effect monodromy. This implies that there are dyons near the weak scale, leads to a large axion mass induced by Standard Model fermion loops, and dramatically alters Higgs physics. We conclude that non-standard axion electrodynamics, although interesting to consider in abstract quantum field theory, is not phenomenologically viable.

    hep-phhep-thJHEP(2024)·24 citations
24. 24*

    CDF W mass anomaly revisited

    Shou-hua Zhu (Peking University)🇨🇳

    The CDF, ATLAS and LHCb have released the measurements on the W boson mass $m_W$ at $\sqrt{S}=1.96,7,13TeV$, respectively. The measured values show the declining tendency, namely $m_W$ decreases with the increment of the collider energy. If the declining tendency is confirmed, it might be the signal of metric field at high energy colliders. In this paper, we propose a model to account for such tendency and explore the properties of the model.

    hep-phhep-exAAPPS Bull.(2023)·2 citations
25. 25*

    Towards quantitative precision for QCD at large densities

    Friederike Ihssen🇩🇪 · Jan M. Pawlowski🇩🇪 · Franz R. Sattler🇩🇪 · Nicolas Wink🇩🇪

    QCD at large density reveals a rich phase structure, ranging from a potential critical end point and inhomogeneous phases or moat regimes to color superconducting ones with competing order effects. Resolving this region in the phase diagram of QCD with functional approaches requires a great deal of quantitative reliability, already for a qualitative access. In the present work, we systematically extend the functional renormalisation group approach to low energy QCD by setting up a fully self-consistent approximation scheme in a low energy effective quark-meson theory. In this approximation, all pointlike multi-scattering events of the mesonic pion and the sigma mode are taken into account in terms of an effective potential as well as all higher quark-antiquark-mesonic scattering orders. As a first application we compute the phase structure of QCD including its low temperature - large chemical potential part. The quantitative reliability of the approximation and systematic extensions are also discussed.

    ↳ hep-thhep-phPRD(2025)·28 citations
26. 26*

    Finite-time Cosmological Singularities and the Possible Fate of the Universe

    Jaume de Haro🇪🇸 · Shin'ichi Nojiri🇯🇵 · S. D. Odintsov🇪🇸 · V. K. Oikonomou🇬🇷 · Supriya Pan🇮🇳

    Singularities in any physical theory are either remarkable indicators of the unknown underlying fundamental theory, or indicate a change in the description of the physical reality. In General Relativity there are three fundamental kinds of singularities that might occur, firstly the black hole spacelike crushing singularities, e.g. in the Schwarzschild case and two cosmological spacelike singularities appearing in finite-time, namely, the Big Bang singularity and the Big Rip singularity. In the case of black hole and Big Bang singularity, the singularity indicates that the physics is no longer described by the classical gravity theory but some quantum version of gravity is probably needed. The Big Rip is a future singularity which appears in the context of General Relativity due to a phantom scalar field needed to describe the dark energy era. Apart from the Big Rip singularity, a variety of finite-time future singularities, such as, sudden singularity, Big Freeze singularity, generalized sudden singularity, $w$-singularity and so on, are allowed in various class of cosmological models irrespective of their origin. The occurrence of these finite-time singularities has been intensively investigated in the context of a variety of dark energy, modified gravity, and other alternative cosmological theories. These singularities suggest that the current cosmological scenario is probably an approximate version of a fundamental theory yet to be discovered. In this review we provide a concrete overview of the cosmological theories constructed in the context of Einstein's General Relativity and modified gravity theories that may lead to finite-time cosmological singularities. We also discuss various approaches suggested in the literature that could potentially prevent or mitigate finite-time singularities within the cosmological scenarios.

    ↳ gr-qcastro-ph.COhep-phhep-th+2Phys.Rept.(2023)·98 citations
27. 27*

    Feynman integrals, geometries and differential equations

    Sebastian Pögel🇩🇪 · Xing Wang🇩🇪 · Stefan Weinzierl🇩🇪

    In this talk we discuss the construction of a basis of master integrals for the family of the $l$-loop equal-mass banana integrals, such that the differential equation is in an $\epsilon$-factorised form. As the $l$-loop banana integral is related to a Calabi-Yau $(l-1)$-fold, this extends the examples where an $\epsilon$-factorised form has been found from Feynman integrals related to curves (of genus zero and one) to Feynman integrals related to higher-dimensional varieties.

    ↳ hep-thhep-phmath-phmath.MPPoS(2024)·3 citations
28. 28*

    Unraveling the bounce: a real time perspective on tunneling

    Kfir Blum🇮🇱 · Omri Rosner🇮🇱

    We study tunneling in one-dimensional quantum mechanics using the path integral in real time, where solutions of the classical equation of motion live in the complex plane. Analyzing solutions with small (complex) energy, relevant for constructing the wave function after a long time, we unravel the analytic structure of the action, and show explicitly how the imaginary time bounce arises as a parameterization of the lowest order term in the energy expansion. The real time calculation naturally extends to describe the wave function in the free region of the potential, reproducing the usual WKB approximation. The extension of our analysis to the semiclassical correction due to fluctuations on the saddle is left for future work.

    ↳ quant-phhep-phhep-th10 citations
29. 29*

    $\text{ChisholmD.wl}$- Automated rational approximant for bi-variate series

    Souvik Bera🇮🇳 · Tanay Pathak🇮🇳

    The Chisholm rational approximant is a natural generalization to two variables of the well-known single variable Padé approximant, and has the advantage of reducing to the latter when one of the variables is set equals to 0. We present, to our knowledge, the first automated Mathematica package to evaluate diagonal Chisholm approximants of two variable series. For the moment, the package can only be used to evaluate diagonal approximants i.e. the maximum powers of both the variables, in both the numerator and the denominator, is equal to some integer $M$. We further modify the original method so as to allow us to evaluate the approximants around some general point $(x,y)$ not necessarily $(0,0)$. Using the approximants around general point $(x,y)$, allows us to get a better estimate of the result when the point of evaluation is far from $(0,0)$. Several examples of the elementary functions have been studied which shows that the approximants can be useful for analytic continuation and convergence acceleration purposes. We continue our study using various examples of two variable hypergeometric series, ${\mathrm{Li}}_{2,2}(x,y)$ etc that arise in particle physics and in the study of critical phenomena in condensed matter physics. The demonstration of the package is discussed in detail and the Mathematica package is provided as an ancillary file.

    ↳ cs.MScs.NAhep-phmath-ph+2Eur.Phys.J.ST(2026)·2 citations
30. 30*

    Cosmological Correlators Through the Looking Glass: Reality, Parity, and Factorisation

    David Stefanyszyn🇬🇧 · Xi Tong🇨🇳 · Yuhang Zhu🇨🇳

    We consider the evolution of quantum fields during inflation, and show that the total-energy singularities appearing in the perturbative expansion of the late-time Wavefunction of the Universe are purely real when the external states are massless scalars and massless gravitons. Our proof relies on the tree-level approximation, Bunch-Davies initial conditions, and exact scale invariance (IR-convergence), but without any assumptions on invariance under de Sitter boosts. We consider all $n$-point functions and allow for the exchange of additional states of any mass and integer spin. Our proof makes use of a decomposition of the inflationary bulk-bulk propagator of massive spinning fields which preserves UV-convergence and ensures that the time-ordered contributions are purely real after we rotate to Euclidean time. We use this reality property to show that the maximally-connected parts of wavefunction coefficients, from which total-energy singularities originate, are purely real. In a theory where all states are in the complementary series, this reality extends to the full wavefunction coefficient. We then use our reality theorem to show that parity-odd correlators (correlators that are mirror asymmetric) are factorised and do not diverge when the total-energy is conserved. We pay special attention to the parity-odd four-point function (trispectrum) of inflationary curvature perturbations and use our reality/factorisation theorems to show that this observable is factorised into a product of cubic diagrams thereby enabling us to derive exact shapes. We present examples of couplings between the inflaton and massive spin-1 and spin-2 fields, with the parity-violation in the trispectrum driven by Chern-Simons corrections to the spinning field two-point function, or from parity-violating cubic interactions which we build within the Effective Field Theory of Inflation.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2024)·62 citations
31. 31*

    $\epsilon$-forms for non-planar triangles with elliptic curves at two loops

    Xuhang Jiang · Xing Wang · Li Lin Yang · Jingbang Zhao

    In this talk, we discuss how to generalize ideas developed for Banana integrals to two two-loop non-planar triangle Feynman integrals involving elliptic curves, which have non-trivial sub-sectors and whose Picard-Fuchs operators share less symmetry than Banana integrals, to obtain the canonical differential equations and to solve them with suitable boundary conditions.

    ↳ hep-thhep-phPoS(2024)·0 citations
32. 32*

    Complete analysis of the background and anisotropies of scalar-induced gravitational waves: primordial non-Gaussianity $f_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$ considered

    Jun-Peng Li🇨🇳 · Sai Wang🇨🇳 · Zhi-Chao Zhao🇨🇳 · Kazunori Kohri🇯🇵

    Investigation of primordial non-Gaussianity holds immense importance in testing the inflation paradigm and shedding light on the physics of the early Universe. In this study, we conduct the complete analysis of scalar-induced gravitational waves (SIGWs) by incorporating the local-type non-Gaussianity $f_{\mathrm{NL}}$ and $g_{\mathrm{NL}}$. We develop Feynman-like diagrammatic technique and derive semi-analytic formulas for both the energy-density fraction spectrum and the angular power spectrum. For the energy-density fraction spectrum, we analyze all the relevant Feynman-like diagrams, determining their contributions to the spectrum in an order-by-order fashion. As for the angular power spectrum, our focus lies on the initial inhomogeneities, giving rise to anisotropies in SIGWs, that arise from the coupling between short- and long-wavelength modes due to primordial non-Gaussianity. Our analysis reveals that this spectrum exhibits a typical multipole dependence, characterized by ${\tilde{C}}_{\ell }\propto [\ell (\ell +1){]}^{-1}$, which plays a crucial role in distinguishing between different sources of gravitational waves. Depending on model parameters, significant anisotropies can be achieved. We also show that the degeneracies in model parameters can be broken. The findings of our study underscore the angular power spectrum as a robust probe for investigating primordial non-Gaussianity and the physics of the early Universe. Moreover, our theoretical predictions can be tested using space-borne gravitational-wave detectors and pulsar timing arrays.

    ↳ astro-ph.COgr-qchep-phJCAP(2024)·78 citations
33. 33*

    Diffeomorphism on-shell breaking from radion stabilization

    Haiying Cai🇰🇷

    We present for the first time the nonlinear diffeomorphism in the Randall Sundrum model that can keep the effective Lagrangian invariant in any order of expansion. We will show that the off-shell diffeomorphism shapes the interaction structure. However the radion mass is in fact protected by an on-shell diffeomorphism, which can be spontaneously broken by the Goldberger-Wise mechanism. The nonlinear property of diffeomorphism also ensures a unique radion field even in the extension of RS model with intermediate branes.

    ↳ hep-thgr-qchep-ph2 citations
34. 34*

    Gravitational Wave Measurement in the Mid-Band with Atom Interferometers

    Sebastian Baum🇺🇸 · Zachary Bogorad🇺🇸 · Peter W. Graham🇺🇸

    Gravitational Waves (GWs) have been detected in the $\sim$100 Hz and nHz bands, but most of the gravitational spectrum remains unobserved. A variety of detector concepts have been proposed to expand the range of observable frequencies. In this work, we study the capability of GW detectors in the ``mid-band'', the $\sim$30 mHz -- 10 Hz range between LISA and LIGO, to measure the signals from and constrain the properties of $\sim$1 -- 100 $M_{\odot }$ compact binaries. We focus on atom-interferometer-based detectors. We describe a Fisher matrix code, AIMforGW, which we created to evaluate their capabilities, and present numerical results for two benchmarks: terrestrial km-scale detectors, and satellite-borne detectors in medium Earth orbit. Mid-band GW detectors are particularly well-suited to pinpointing the location of GW sources on the sky. We demonstrate that a satellite-borne detector could achieve sub-degree sky localization for any detectable source with chirp mass ${\mathcal{M}}_c\lesssim 50M_{\odot }$. We also compare different detector configurations, including different locations of terrestrial detectors and various choices of the orbit of a satellite-borne detector. As we show, a network of only two terrestrial single-baseline detectors or one single-baseline satellite-borne detector would each provide close-to-uniform sky-coverage, with signal-to-noise ratios varying by less than a factor of two across the entire sky. We hope that this work contributes to the efforts of the GW community to assess the merits of different detector proposals.

    ↳ gr-qcastro-ph.COastro-ph.IMhep-ph+1JCAP(2024)·11 citations
35. 35*

    Simulation-based inference for stochastic gravitational wave background data analysis

    James Alvey🇳🇱 · Uddipta Bhardwaj🇳🇱 · Valerie Domcke🇨🇭 · Mauro Pieroni🇨🇭 · Christoph Weniger🇳🇱

    The next generation of space- and ground-based facilities promise to reveal an entirely new picture of the gravitational wave sky: thousands of galactic and extragalactic binary signals, as well as stochastic gravitational wave backgrounds (SGWBs) of unresolved astrophysical and possibly cosmological signals. These will need to be disentangled to achieve the scientific goals of experiments such as LISA, Einstein Telescope, or Cosmic Explorer. We focus on one particular aspect of this challenge: reconstructing an SGWB from (mock) LISA data. We demonstrate that simulation-based inference (SBI) - specifically truncated marginal neural ratio estimation (TMNRE) - is a promising avenue to overcome some of the technical difficulties and compromises necessary when applying more traditional methods such as Monte Carlo Markov Chains (MCMC). To highlight this, we show that we can reproduce results from traditional methods both for a template-based and agnostic search for an SGWB. Moreover, as a demonstration of the rich potential of SBI, we consider the injection of a population of low signal-to-noise ratio supermassive black hole transient signals into the data. TMNRE can implicitly marginalize over this complicated parameter space, enabling us to directly and accurately reconstruct the stochastic (and instrumental noise) contributions. We publicly release our TMNRE implementation in the form of the code saqqara.

    ↳ gr-qcastro-ph.COastro-ph.IMhep-phPRD(2024)·41 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.