HEP Phenomenology·hep-ph

Thu·Oct 19, 2023Thursday·October 19, 2023

17 papers—8 primary·9 cross-listed·reconstructed*

01*
The mechanical radius of the proton
V.D. Burkert🇺🇸 · L. Elouadrhiri🇺🇸 · F.X. Girod🇺🇸
We present the first determination of the proton mechanical radius. The result was obtained by employing a novel theoretical approach that connects experimental data of deeply virtual Compton scattering with the spin = 2 interaction that is characteristic of gravity coupling with matter. We find that the proton mechanical radius is significantly smaller than its charge radius, consistent with the latest Lattice QCD computation.
hep-phhep-latnucl-exnucl-th20 citations
02*
Three-loop matching of heavy flavor-changing (axial-)tensor currents
Wei Tao🇨🇳 · Zhen-Jun Xiao🇨🇳
We present the three-loop calculations of the nonrelativistic QCD (NRQCD) current renormalization constants and corresponding anomalous dimensions, and the matching coefficients for the spatial-temporal tensor and spatial-spatial axial-tensor currents with two different heavy quark masses. We obtain the convergent decay constant ratio up to the next-to-next-to-next-to-leading order (N $^{3}$ LO) for the $S$ -wave vector meson $B_{c}^{*}$ involving the tensor and axial-tensor currents. We obtain the three-loop finite ( $ϵ^{0}$ ) term in the ratio of the QCD heavy flavor-changing tensor current renormalization constant in the on-shell ( $OS$ ) scheme to that in the modified-minimal-subtraction ( $MS$ ) scheme, which is helpful to obtain the three-loop matching coefficients for all heavy flavor-changing (axial-)tensor currents.
hep-phJHEP(2023)·3 citations
03*
Quark propagator and di-lepton production rate in a hot, dense and very strongly magnetized rotating Quark-Gluon Plasma
Aritra Das🇮🇳
In this paper, a theoretical calculation of thermal di-lepton production rate (DPR) is reported from a hot and dense, unbounded rotating quark gluon plasma in the presence of very strong uniform background magnetic field typically generated at heavy-ion collision experiments. In this extreme magnetic field, the quarks as well as anti-quarks are approximated to be confined in the lowest Landau level (LLL). Firstly, I have converted the expression of the quark propagator in LLL approximation to the momentum space representation. After that, using the derived quark propagator, the di-lepton production rate is calculated from the photon polarization tensor (PPT) with the help of the framework of thermal field theory. The system is first confined in a cylinder of radius $R_{⊥}$ and then $R_{⊥}$ is taken to be very large in order to consider the situation of unbounded system. Depending on the charge of participating quarks, the role of rotation is to alter the chemical potential. The DPR is suppressed prominently for low invariant mass with respect to the LLL-approximated non-rotating case that was reported earlier.
hep-ph3 citations
04*
Analytical calculations of the tenth order QED radiative corrections to lepton anomalies within the Mellin-Barnes representation
O.P. Solovtsova🇷🇺 · V.I. Lashkevich🇧🇾 · L.P. Kaptari🇷🇺
We investigate the radiative quantum electrodynamic (QED) corrections to the lepton ( $L = e, μ$ and $τ$ ) anomalous magnetic moment due to the contributions of diagrams with insertions of the photon vacuum polarisation operator consisting solely of four closed lepton ( $l = e, μ$ and $τ$ ) loops. Moreover, we focus on specific operators with two loops formed by leptons $L$ of the same type as the external one, the other two formed by leptons $ℓ$ different from $L$ . The approach is essentially based on the employment of the Mellin-Barnes representation of the $x$ -parametrization of the corresponding Feynman diagrams. This allows one to obtain, for the first time, exact analytical expressions for the radiative corrections of the tenth order w.r.t. the electromagnetic coupling constant $e$ . Analytically, the radiative corrections are expressed in terms of the ratio $r = m_{ℓ} / m_{L}$ of the internal to external lepton masses. The dependence on $r$ is investigated numerically in the whole interval of $r$ , $0 < r < \infty$ . To make comparisons with earlier published results possible, our exact analytical expressions are expanded about $r = 0$ and $r \to \infty$ and compared with the corresponding asymptotic expansions known in the literature.
hep-phhep-thJ.Phys.G(2024)·2 citations
05*
Scotogenic $U (1)_{L_{μ} - L_{τ}}$ origin of $(g - 2)_{μ}$ , W-mass anomaly and 95 GeV excess
Debasish Borah🇮🇳 · Satyabrata Mahapatra🇰🇷 · Partha Kumar Paul🇮🇳 · Narendra Sahu🇮🇳
We study a scotogenic extension of the minimal gauged $L_{μ} - L_{τ}$ model, including three right-handed singlet fermions and a scalar doublet all odd under an in-built $Z_{2}$ symmetry to explain the anomalous magnetic moments of the muon, CDF-II W-mass anomaly, and the 95 GeV excess reported by the CMS collaboration. While the minimal model can successfully explain the muon $(g - 2)$ and CDF-II W-mass anomalies, the required diphoton signal strength for the 95 GeV scalar, together with that of the SM Higgs, can not be obtained in the minimal model. The same can, however, be explained by incorporating one additional scalar doublet whose only role is to contribute radiatively to diphoton decay modes of the light, neutral scalars. Due to the scotogenic extension, the model remains consistent with the observed properties of light neutrinos and dark matter in the Universe.
hep-phPRD(2024)·47 citations
06*
Gravitational Waves from Particle Decays during Reheating
Shinya Kanemura🇯🇵 · Kunio Kaneta🇯🇵
Gravitational waves have become an irreplaceable tool for exploring the post-inflationary universe. Their cosmological and astrophysical origins have been attracting numerous attention. In this Letter, we point out a novel source of ultra-high frequency gravitational waves: the decay of particles produced during the reheating era. We highlight the decay of the Higgs boson as a representative case, showing how it yields a testable gravitational wave spectrum by future observations.
hep-phastro-ph.COgr-qcPLB(2024)·43 citations
07*
Higgs-Induced Screening Mechanisms in Scalar-Tensor Theories
Clare Burrage🇬🇧 · Peter Millington🇬🇧
We consider the theory of a light conformally coupled scalar field, i.e., one that is coupled directly to the Ricci scalar of the gravitational sector. This theory can be written equivalently as one of a light scalar that is coupled to the Standard Model of particle physics with a particular combination of Higgs-portal couplings. When the conformal coupling function contains terms that are linear and quadratic in the conformally coupled scalar, we find that the effective mass of the light propagating mode and its coupling to matter fields, obtained after expanding around a minimum of the classical potential, depend on the energy density of the background environment. This is despite the absence of non-linear terms in the original equation of motion for the light conformally coupled field. Instead, we find that the non-linearities of the prototype Higgs potential are communicated to the light mode. In this way, we present a novel realisation of screening mechanisms, in which light degrees of freedom coupled to the Standard Model are able to avoid experimental constraints through environmental and thin-shell effects.
hep-phastro-ph.COgr-qcAnnals N.Y.Acad.Sci.(2024)·2 citations
08*
Direct quarkonium-plus-gluon production in DIS in the Color Glass Condensate
Zhong-Bo Kang🇺🇸 · Emilie Li🇫🇷 · Farid Salazar🇺🇸
We compute the differential cross-section for direct quarkonium production accompanied by a gluon in high-energy deep inelastic scattering (DIS) at small- $x$ . We employ the Non-Relativistic QCD factorization framework, focusing on the $S$ -wave contribution to the formation of the quarkonium, and including both color singlet and octet contributions. Our short distance coefficients for the production of the heavy quark pair are obtained within the Color Glass Condensate effective field theory. Our results pave the way towards the next-to-leading order computation of direct quarkonium in DIS, as well as the study of azimuthal correlations of direct quarkonium and jet.
hep-phnucl-thJHEP(2024)·19 citations
09*
Features in the Inflaton Potential and the Spectrum of Cosmological Perturbations
Ioannis Dalianis🇬🇷
Cosmological perturbations, originating in the quantum fluctuations of the fields that drive inflation, are observed to be nearly scale invariant at the largest scales. At smaller scales, however, perturbations are not severely constrained and might be of particular importance if their amplitude is large. They can trigger the creation of primordial black holes (PBHs) or stochastic gravitational waves (GWs). Small-scale perturbations are generated during the later stages of inflation, when possible strong features in the inflaton potential can break scale invariance and leave characteristic imprints on the spectrum. We focus on and review three types of features: inflection points and steep steps in the potential, as well as sharp turns in the inflationary trajectory in field space. We show that such features induce a strong enhancement of the curvature spectrum within a certain wavenumber range. In particular cases, they also generate characteristic oscillatory patterns that are transferred in the spectrum of secondary GWs, which are potentially observable by operating or designed experiments. We demonstrate these effects through the calculation of the primordial power spectrum and the PBH abundance in the context of $α$ -attractors and supergravity (SUGRA) models of inflation.
↳ astro-ph.COgr-qchep-phhep-th5 citations
10*
Causal hydrodynamic fluctuations in a one-dimensional expanding system
Shin-ei Fujii🇯🇵 · Tetsufumi Hirano🇯🇵
We derive equations of motion of hydrodynamic fluctuations performing perturbative expansion of the energy-momentum conservation equations around the boost invariant solution in one-dimensional expanding system. In the course of derivation, we do not assume any specific forms of constitutive equations for shear stress tensor $π^{μν}$ and bulk pressure $Π$ . Therefore, the framework enables us to employ any constitutive equations beyond the Navier-Stokes theory which satisfy the causality. Employing Israel-Stewart equations as examples of the constitutive equations, we demonstrate the dynamics of causal hydrodynamic fluctuations in (1+1)-dimensional Milne coordinates. We observe that structure of energy density fluctuations is almost frozen in the early stage of the expansion. Two-point correlations of energy density fluctuations turn out to be closely related with the properties of the medium such as sound velocity, viscosity, and relaxation time. Furthermore, we show that two-particle correlation functions of final hadrons after freezeout inherit correlations of thermodynamic variables and flow rapidity. This opens a new door for an analysis of transport properties of the medium produced in relativistic heavy ion collisions.
↳ nucl-thhep-phnucl-exPRC(2024)·3 citations
11*
On gravity unification in SL(2N,C) gauge theories
J.L. Chkareuli🇬🇪
The local $S L (2 N, C)$ symmetry is shown to provide, when appropriately constrained, a viable framework for a consistent unification of the known elementary forces, including gravity. Such a covariant constraint implies that an actual gauge field multiplet in the $S L (2 N, C)$ theory is ultimately determined by the associated tetrad fields which not only specify the geometric features of spacetime but also govern which local internal symmetries are permissible within it. As a consequence, upon the covariant removal of all "redundant" gauge field components, the entire theory only exhibits the effective $S L (2, C) \times S U (N)$ symmetry, comprising $S L (2, C)$ gauge gravity on one hand and $S U (N)$ grand unified theory on the other. Given that all states involved in the $S L (2 N, C)$ theories are additionally classified according to their spin values, many potential $S U (N)$ GUTs, including the conventional $S U (5)$ theory, appear to be irrelevant for standard spin $1/2$ quarks and leptons. Meanwhile, applying the $S L (2 N, C)$ symmetry to the model of composite quarks and leptons with constituent chiral preons in its fundamental representations reveals, under certain natural conditions, that among all accompanying $S U (N)_{L} \times S U (N)_{R}$ chiral symmetries of preons and their composites only the $S U (8)_{L} \times S U (8)_{R}$ meets the anomaly matching condition ensuring masslessness of these composites at large distances. This, in turn, identifies $S L (16, C)$ with the effective $S L (2, C) \times S U (8)$ symmetry, accommodating all three families of composite quarks and leptons, as the most likely candidate for hyperunification of the existing elementary forces.
↳ hep-thhep-phEPJC(2024)·4 citations
12*
The Gluon Moment and Parton Distribution Function of the Pion from $N_{f} = 2 + 1 + 1$ Lattice QCD
William Good🇺🇸 · Kinza Hasan🇺🇸 · Allison Chevis🇺🇸 · Huey-Wen Lin🇺🇸
We present the first calculation of the pion gluon moment from lattice QCD in the continuum-physical limit. The calculation is done using clover fermions for the valence action with three pion masses, 220, 310 and 690 MeV, and three lattice spacings, 0.09, 0.12, and 0.15 fm, using ensembles generated by MILC Collaboration with 2+1+1 flavors of highly improved staggered quarks (HISQ). On the lattice, we nonperturbatively renormalize the gluon operator in RI/MOM scheme using the cluster-decomposition error reduction (CDER) technique to enhance the signal-to-noise ratio of the renormalization constant. We extrapolate the pion gluon moment to the continuum-physical limit and obtain $0.364 (38)_{stat + NPR} (36)_{mixing}$ in the $MS$ scheme at 2 GeV, with first error being the statistical error and uncertainties in nonperturbative renormalization, and the second being a systematic uncertainty estimating the effect of ignoring quark mixing. Our pion gluon momentum fraction has a central value lower than two recent single-ensemble lattice-QCD results near physical pion mass but is consistent with the recent global fits by JAM and xFitter and with most QCD-model estimates.
↳ hep-lathep-phPRD(2024)·26 citations
13*
Entanglement entropy in a time-dependent holographic Schwinger pair creation
Sebastian Grieninger🇺🇸 · Dmitri E. Kharzeev🇺🇸 · Ismail Zahed🇺🇸
We analyze the entanglement of a Schwinger pair created by a time-dependent pulse. In the semi-classical approximation, the pair creation by a pulse of external electric field is captured by a periodic worldline instanton. At strong gauge coupling, the gauge-gravity dual worldsheet instanton exhibits a falling wormhole in AdS. We identify the tunneling time at the boundary with the inverse Unruh temperature, and derive the pertinent entanglement entropy between the created pair using thermodynamics. The entanglement entropy is enhanced by the sub-barrier tunneling process, and partly depleted by the radiation in the post-barrier process.
↳ hep-thhep-phnucl-thPRD(2023)·19 citations
14*
Vanishing Polyakov Loop for QCD with Twelve Massless Quarks
Seth Grable🇺🇸 · Paul Romatschke🇺🇸
We consider continuum-formulation QCD in four dimensions with twelve massless fundamental quark flavors. Splitting the SU($N$) gauge field into background and fluctuation parts, we use well-developed techniques to calculate the one-loop effective action for the theory. We find that for constant self-dual background field-strength tensor the notorious infrared divergences of the effective action cancel between gauge and matter sectors if the number of massless quark flavors is exactly . The ultraviolet divergencies of the effective action are non-perturbatively renormalized with a $β$ -function that matches the known perturbative result in the high energy limit. The resulting UV- and IR-finite effective action possesses a non-trivial saddle which has lower free energy than the perturbative vacuum, and for which the expectation value of the Polyakov loop vanishes. Inclusion of finite temperature effects points to the presence of a first-order phase transition to the perturbative vacuum with a calculable critical temperature.
↳ hep-thhep-phnucl-thPLB(2025)·7 citations
15*
Fast Parameter Inference on Pulsar Timing Arrays with Normalizing Flows
David Shih🇺🇸 · Marat Freytsis🇺🇸 · Stephen R. Taylor🇺🇸 · Jeff A. Dror🇺🇸 · Nolan Smyth🇺🇸
Pulsar timing arrays (PTAs) perform Bayesian posterior inference with expensive MCMC methods. Given a dataset of ~10-100 pulsars and O(10^3) timing residuals each, producing a posterior distribution for the stochastic gravitational wave background (SGWB) can take days to a week. The computational bottleneck arises because the likelihood evaluation required for MCMC is extremely costly when considering the dimensionality of the search space. Fortunately, generating simulated data is fast, so modern simulation-based inference techniques can be brought to bear on the problem. In this paper, we demonstrate how conditional normalizing flows trained on simulated data can be used for extremely fast and accurate estimation of the SGWB posteriors, reducing the sampling time from weeks to a matter of seconds.
↳ astro-ph.IMastro-ph.HEcs.LGgr-qc+1PRL(2024)·25 citations
16*
Two-detector flavor sensitivity to ultra-high-energy cosmic neutrinos
Federico Testagrossa🇮🇹 · Damiano F. G. Fiorillo🇩🇰 · Mauricio Bustamante🇩🇰
Ultra-high-energy (UHE) cosmic neutrinos, with energies above 100 PeV, could be finally discovered in the near future. Measuring their flavor composition would reveal information about their production and propagation, but new techniques are needed for UHE neutrino telescopes to have the capabilities to do it. We address this by proposing a new way to measure the UHE neutrino flavor composition that does not rely on individual telescopes having flavor-identification capabilities. We manufacture flavor sensitivity from the joint detection by one telescope sensitive to all flavors -- the radio array of IceCube-Gen2 -- and one mostly sensitive to $ν_{τ}$ -- GRAND. From this limited flavor sensitivity, predominantly to $ν_{τ}$ , and even under conservative choices of neutrino flux and detector size, we extract important insight. For astrophysics, we forecast meaningful constraints on the neutrino production mechanism; for fundamental physics, vastly improved constraints on Lorentz-invariance violation. These are the first measurement forecasts of the UHE $ν_{τ}$ content.
↳ astro-ph.HEhep-exhep-phnucl-thPRD(2024)·15 citations
17*
Translation-invariant relativistic Langevin equation derived from first principles
Filippo Emanuele Zadra🇮🇹 · Aleksandr Petrosyan🇬🇧 · Alessio Zaccone🇮🇹
The relativistic Langevin equation poses a number of technical and conceptual problems related to its derivation and underlying physical assumptions. Recently, a method has been proposed in [A. Petrosyan and A. Zaccone, J. Phys. A: Math. Theor. 55 015001 (2022)] to derive the relativistic Langevin equation from a first-principles particle-bath Lagrangian. As a result of the particle-bath coupling, a new ``restoring force'' term appeared, which breaks translation symmetry. Here we revisit this problem aiming at deriving a fully translation-invariant relativistic Langevin equation. We successfully do this by adopting the renormalization potential protocol originally suggested by Caldeira and Leggett. The relativistic renormalization potential is derived here and shown to reduce to Caldeira and Leggett's form in the non-relativistic limit. The introduction of this renormalization potential successfully removes the restoring force and a fully translation-invariant relativistic Langevin equation is derived for the first time. The physically necessary character of the renormalization potential is discussed in analogy with non-relativistic systems, where it emerges due to the renormalization of the tagged particle dynamics due to its interaction with the bath oscillators (a phenomenon akin to level-repulsion or avoided-crossing in condensed matter). We discuss the properties that the corresponding non-Markovian friction kernel has to satisfy, with implications ranging from transport models of the quark-gluon plasma, to relativistic viscous hydrodynamic simulations, and to electrons in graphene.
↳ cond-mat.stat-mechcond-mat.str-elhep-phhep-th+1PRD(2023)·4 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.