Nuclear Theory·nucl-th

Friday·March 22, 2024

7 papers—2 primary·5 cross-listed

03
Mixed Species Charge and Baryon Balance Functions Studies with PYTHIA
Claude Pruneau🇺🇸 · Sumit Basu🇸🇪 · Victor Gonzalez🇺🇸 · Brian Hanley🇺🇸 · Ana Marin🇩🇪 · Alexandru F. Dobrin🇷🇴 · Alexandru Manea🇷🇴
Mixed species charge and baryon balance functions are computed based on proton--proton (pp) collisions simulated with the PYTHIA8 model. Simulations are performed with selected values of the collision energy $s$ and the Monash tune and the Ropes and Shoving modes of PYTHIA8 to explore whether such measurements provide useful new information and constraints on mechanisms of particle production in pp collisions. Charge balance functions are studied based on mixed pairs of pions, kaons, and protons, whereas baryon balance functions are computed for mixed low mass strange and non-strange baryons. Both charge and baryon balance functions of mixed particle pairs feature shapes and amplitudes that sensitively depend on the particle considered owing largely to the particle production mechanisms implemented in PYTHIA. The evolution of balance functions integrals with the longitudinal width of the acceptance are presented and one finds that sums of such integrals for a given reference particle obey expected sum rules for both charge and baryon balance functions. Additionally, both types of balance functions are found to evolve in shape and amplitude with increasing collision energy $s$ and the PYTHIA tunes considered.
↳ hep-phhep-exnucl-exnucl-thPRC(2024)·4 citations
04
Revisiting shear stress tensor evolution: Non-resistive magnetohydrodynamics with momentum-dependent relaxation time
Sunny Kumar Singh🇮🇳 · Manu Kurian🇺🇸 · Vinod Chandra🇮🇳
This study aims to develop second-order relativistic viscous magnetohydrodynamics (MHD) derived from kinetic theory within an extended relaxation time approximation (momentum/energy dependent) for the collision kernel. The investigation involves a detailed examination of shear stress tensor evolution equations and associated transport coefficients. The Boltzmann equation is solved using a Chapman-Enskog-like gradient expansion for a charge-conserved conformal system, incorporating a momentum-dependent relaxation time. The derived relativistic non-resistive, viscous second-order MHD equations for the shear stress tensor reveal significant modifications in the coupling with dissipative charge current and magnetic field due to the momentum dependence of the relaxation time. By utilizing a power law parametrization to quantify the momentum dependence of the relaxation time, the anisotropic magnetic field-dependent shear coefficients in the Navier-Stokes limit have been investigated. The resulting viscous coefficients are seen to be sensitive to the momentum dependence of the relaxation time.
↳ hep-phnucl-thPRD(2024)·12 citations
05
Absence of strong CP violation
Gerrit Schierholz🇩🇪
Quantum Chromodynamics admits a CP-violating contribution to the action, the $θ$ term, which is expected to give rise to a nonvanishing electric dipole moment of the neutron. Despite intensive search, no CP violations have been found in the strong interaction. This puzzle is referred to as the strong CP problem. There is evidence that CP is conserved in the confining theory, to the extent that color charges are totally screened for $θ > 0$ at large distances. It is not immediately obvious that this implies a vanishing dipole moment though. With this Letter I will close the gap. It is shown that in the infinite volume hadron correlation functions decouple from the topological charge, expressed in terms of the zero modes. The reason is that hadrons have a limited range of interaction, while the density of zero modes vanishes with the inverse root of the volume, thus reducing the probability of finding a zero mode in the vicinity to zero. This implies that CP is conserved in the strong interaction.
↳ hep-phhep-lathep-thnucl-ex+1J.Phys.G(2025)·18 citations
06
Study of electron-positron annihilation into $K K ˉ π$ within resonance chiral theory
Bing-Hai Qin🇨🇳 · Wen Qin🇨🇳 · Ling-Yun Dai🇨🇳
In this paper, a coherent study of the $e^{+} e^{-}$ annihilation into $K^{+} K^{-} π^{0}$ , $K_{S}^{0} K_{L}^{0} π^{0}$ and $K_{S}^{0} K^{\pm} π^{\mp}$ is carried out within the framework of resonance chiral theory. The amplitudes are fixed by fitting to the experimental cross-section and invariant mass spectrum. With these amplitudes, one can calculate the hadronic vacuum polarization form factors of these processes. The leading order contributions of $σ (e^{+} e^{-} \to K K ˉ π)$ to the anomalous magnetic moment of the muon, $(g - 2)_{μ}$ , is obtained as $a_{μ}^{HVP, LO} (e^{+} e^{-} \to K K ˉ π) = (3.178 \pm 0.071) \times 1 0^{- 10}$ up to $E_{cm} = 2.3$ GeV.
↳ hep-phnucl-thPRD(2025)·12 citations
07
Qu8its for Quantum Simulations of Lattice Quantum Chromodynamics
Marc Illa🇺🇸 · Caroline E. P. Robin🇩🇪 · Martin J. Savage🇺🇸
We explore the utility of $d = 8$ qudits, qu8its, for quantum simulations of the dynamics of 1+1D SU(3) lattice quantum chromodynamics, including a mapping for arbitrary numbers of flavors and lattice size and a re-organization of the Hamiltonian for efficient time-evolution. Recent advances in parallel gate applications, along with the shorter application times of single-qudit operations compared with two-qudit operations, lead to significant projected advantages in quantum simulation fidelities and circuit depths using qu8its rather than qubits. The number of two-qudit entangling gates required for time evolution using qu8its is found to be more than a factor of five fewer than for qubits. We anticipate that the developments presented in this work will enable improved quantum simulations to be performed using emerging quantum hardware.
↳ quant-phhep-lathep-phnucl-thPRD(2024)·49 citations

Affiliations

first authorsco-authorsvia INSPIRE

Mixed Species Charge and Baryon Balance Functions Studies with PYTHIA

Revisiting shear stress tensor evolution: Non-resistive magnetohydrodynamics with momentum-dependent relaxation time

Absence of strong CP violation

Study of electron-positron annihilation into KKˉπ within resonance chiral theory

Qu8its for Quantum Simulations of Lattice Quantum Chromodynamics

Affiliations

Study of electron-positron annihilation into $K K ˉ π$ within resonance chiral theory