Nuclear Theory·nucl-th

Monday·December 4, 2023

8 papers—2 primary·6 cross-listed

03
Spherically symmetric anisotropic strange stars
Luiz L. Lopes🇧🇷 · H. C. Das🇮🇹
In this work, we made an extensive study about the possible presence of anisotropies in strange stars. To accomplish this task, we use three different configurations for the strange matter: the unpaired matter, a two-flavor super-conducting (2SC) strange matter, and a fully three-flavor super-conducting strange matter (CFL). For each configuration, we calculate the relevant quantities for the strange stars, such as the mass-radius relation, the dimensionless tidal parameter, the moment of inertia, and the surface curvature for different degrees of anisotropies. Whenever possible, we compare our results with constraints found in the literature, especially focusing on the existence of very massive pulsars (PSR J0952-0607), as well as very light compact objects (HESS J1731-347).
↳ hep-phastro-ph.HEnucl-thEPJC(2024)·9 citations
04
Jet quenching parameter in QCD kinetic theory
Kirill Boguslavski🇦🇹 · Aleksi Kurkela🇳🇴 · Tuomas Lappi🇫🇮 · Florian Lindenbauer🇦🇹 · Jarkko Peuron🇫🇮
We study the jet quenching parameter $q^$ in a non-equilibrium plasma using the QCD effective kinetic theory. We discuss subleading terms at large jet momentum p, show that our expression for $q^$ reproduces thermal results at small and large transverse momentum cutoffs for infinite p and construct an interpolation between these limits to be used in phenomenological applications. Using simple non-equilibrium distributions that model pertinent features of the bottom-up thermalization scenario, we analytically assess how anisotropy, under- or overoccupation affect the jet quenching parameter. Our work provides more details on the $q^$ formula used in our preceding work [arXiv:2303.12595] and sets the stage for further numerical studies of jet momentum broadening in the initial stages of heavy-ion collisions from QCD kinetic theory.
↳ hep-phnucl-thPRD(2024)·42 citations
05
Comparing phenomenological estimates of dilepton decays of pseudoscalar mesons with lattice QCD
Bai-Long Hoid🇨🇭 · Martin Hoferichter🇨🇭 · Jacobo Ruiz de Elvira🇪🇸
Dilepton decays of pseudoscalar mesons have been drawing particular interest, thanks to their sensitivity to both the QCD dynamics at low energy and also signals beyond the Standard Model. In this context, we shortly review our recent study on an improved Standard-Model prediction for the rare decay $π^{0} \to e^{+} e^{-}$ , and compare it with the first determination on the lattice that predicted also the $π^{0} \to γ γ$ decay width as a byproduct. In addition, we discuss our recent work on $K_{L} \to ℓ^{+} ℓ^{-}$ decays and its connection to lattice QCD. We comment on the current uncertainty estimates and discuss how they could be improved profiting from future experiments and progress in lattice QCD.
↳ hep-lathep-exhep-phnucl-thPoS(2024)·4 citations
06
Partial-wave projection of the one-particle exchange in three-body scattering amplitudes
Andrew W. Jackura🇺🇸 · Raúl A. Briceño🇺🇸
As the study of three-hadron physics from lattice QCD matures, it is necessary to develop proper analysis tools in order to reliably study a variety of phenomena, including resonance spectroscopy and nuclear structure. Reconstructing the three-particle scattering amplitude requires solving integral equations, which can be written in terms of data-constrained dynamical functions and physical on-shell quantities. The driving term in these equations is the so-called one-particle exchange, which leads to a kinematic divergence for particles on-mass-shell. A vital component in defining three-particle amplitudes with definite parity and total angular momentum, which are used in spectroscopic studies, is to project the one-particle exchange into definite partial waves. We present a general procedure to construct exact analytic partial wave projections of the one-particle exchange contribution for any system composed of three spinless hadrons. Our result allows one full control over the analytic structure of the projection, which we explore for some low-lying partial waves with applications to three pions.
↳ hep-phhep-lathep-thnucl-thPRD(2024)·27 citations
07
Functional Renormalization Group Study of Thermodynamic Geometry Around the Phase Transition of Quantum Chromodynamic
Fabrizio Murgana🇮🇹 · Vincenzo Greco🇮🇹 · Marco Ruggieri🇮🇹 · Dario Zappalà🇮🇹
We investigate the thermodynamic geometry of the quark-meson model at finite temperature, $T$ , and quark number chemical potential, $μ$ . We extend previous works by the inclusion of fluctuations exploiting the functional renormalization group approach. We use recent developments to recast the flow equation into the form of an advection-diffusion equation. We adopt the local potential approximation for the effective average action. We focus on the thermodynamic curvature, $R$ , in the $(μ, T)$ plane, in proximity of the chiral crossover, up to the critical point of the phase diagram. We find that the inclusion of fluctuations results in a smoother behavior of $R$ near the chiral crossover. Moreover, for small $μ$ , $R$ remains negative, signaling the fact that bosonic fluctuations reduce the capability of the system to completely overcome the fermionic statistical repulsion of the quarks. We investigate in more detail the small $μ$ region by analyzing a system in which we artificially lower the pion mass, thus approaching the chiral limit in which the crossover is actually a second order phase transition. On the other hand, as $μ$ is increased and the critical point is approached, we find that $R$ is enhanced and a sign change occurs, in agreement with mean field studies. Hence, we completely support the picture that $R$ is sensitive to a crossover and a phase transition, and provides information about the effective behavior of the system at the phase transition.
↳ hep-phcond-mat.stat-mechhep-thnucl-thPRD(2024)·8 citations
08
Theoretical Developments in Lattice Gauge Theory for Applications in Double-beta Decay Processes and Quantum Simulation
Saurabh V. Kadam🇺🇸
Double beta decays are rare nuclear processes that can occur in two modes: two-neutrino double beta decay, observed in the Standard Model, and neutrinoless double beta decay, a hypothetical process with profound implications for Particle Physics. To draw reliable conclusions from their experimental constraints, it is necessary to have accurate predictions of the underlying hadronic interactions described by quantum chromodynamics (QCD), a non-Abelian gauge theory with the symmetry group SU(3). QCD predictions require non-perturbative methods for calculating observables, and lattice QCD (LQCD), a numerical method based on QCD formulated on a finite space-time grid, is the only reliable first-principles technique for obtaining quantitative results. However, LQCD needs formal prescriptions to match numerical results with observables. This thesis provides such prescriptions for double beta decays using the finite volume effects in the LQCD framework. Matching relations that connect two-nucleon double beta decay amplitudes to quantities accessible via LQCD calculations, namely the nuclear matrix elements and two-nucleon energy spectra in a finite volume are provided. The impact of uncertainties is examined on the precision with which low-energy constants of the corresponding effective field theories can be determined from future LQCD calculations. Hamiltonian simulation of QCD is another non-perturbative method of solving QCD which can be more suitable in some cases than the conventional LQCD. The rise of tensor network methods and quantum simulation has made Hamiltonian simulation of lattice gauge theories (LGTs) a reality. Towards the goal of simulating QCD, a loop-string-hadron (LSH) formulation of an SU(3) LGT with matter in 1+1 dimensions is developed in this thesis, motivated by recent studies that showed the LSH formulation of an SU(2) LGT to be advantageous over other formulations.
↳ hep-lathep-phnucl-thquant-ph6 citations

Affiliations

first authorsco-authorsvia INSPIRE

Spherically symmetric anisotropic strange stars

Jet quenching parameter in QCD kinetic theory

Comparing phenomenological estimates of dilepton decays of pseudoscalar mesons with lattice QCD

Partial-wave projection of the one-particle exchange in three-body scattering amplitudes

Functional Renormalization Group Study of Thermodynamic Geometry Around the Phase Transition of Quantum Chromodynamic

Theoretical Developments in Lattice Gauge Theory for Applications in Double-beta Decay Processes and Quantum Simulation

Affiliations