Nuclear Theory·nucl-th

Tuesday·May 31, 2022

12 papers—6 primary·6 cross-listed

07
[Submitted on 28 May 2022] (cross-list from hep-ph)
Thermal and thermoelectric responses of hot QCD medium in time-varying magnetic fields
Gowthama K K🇮🇳 · Manu Kurian🇮🇳 · Vinod Chandra🇮🇳
The thermal response of the hot QCD matter has been studied in the presence of a time-varying magnetic field. The impact of magnetic field, its time dependence, and the collision aspects of the medium on thermal transport have been studied within the relativistic kinetic theory. The decay time of the magnetic field in the medium seems to have a strong dependence on thermal conductivity. The applicability of the Wiedemann-Franz law for the QCD medium has been investigated in the presence of time-varying external electromagnetic fields. The phenomenological significance of thermal transport in heavy-ion collision experiments has also been investigated by relating the thermal conductivity to the elliptic flow through the Knudsen number. The investigations are extended to study the thermoelectric behavior of hot QCD medium and its dependence on the magnetic field. The time dependent magnetic field is observed to significantly influence the thermoelectric behavior of the medium.
Comments:
11 pages, 6 figures, The version accepted in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2205.14427 [pdf]
PRD(2022)·23 citations
08
[Submitted on 28 May 2022] (cross-list from hep-ph)
Comment on "A phenomenological $π^{-} p$ scattering length from pionic hydrogen''
Evangelos Matsinos
This short technical note addresses a number of issues regarding the estimates of the 2004 paper by Ericson, Loiseau, and Wycech for the corrections $δ_{ϵ}$ and $δ_{Γ}$ , which aim at the removal of the effects of electromagnetic origin from the measurements of the strong-interaction shift $ϵ_{1 s}$ and of the total decay width $Γ_{1 s}$ of the ground state in pionic hydrogen.
Comments:
Nine pages. Minor changes to the first version; correction of Ref. [6]
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2205.14441 [pdf]
1 citation
09
[Submitted on 29 May 2022] (cross-list from hep-ph)
Momentum-dependence of $ρ - ω$ mixing in the pion vector form factor and its effect on $(g - 2)_{μ}$
Yun-Hua Chen🇨🇳 · Meng-Ge Qin🇨🇳
The inclusion of the $ρ - ω$ mixing effect is essential for a precise description of the pion electromagnetic form factor in the $e^{+} e^{-} \to π^{+} π^{-}$ process, which quantifies the two-pion contribution to the anomalous magnetic moment of the muon $a_{μ}$ . In this paper, we analyse the momentum dependence of the $ρ - ω$ mixing by considering loop contributions at the next-to-leading order in the $1/ N_{C}$ expansion within the framework of resonance chiral theory. We revisit the work [Y. H. Chen, D. L. Yao, and H. Q. Zheng, Commun. Theor. Phys. 69 (2018) 1], considering the contribution arising from the kaon mass splitting in the kaon loops and the latest experimental data. We perform two kinds of fits (with momentum-independent or momentum-dependent $ρ - ω$ mixing amplitude) to describe the $e^{+} e^{-} \to π^{+} π^{-}$ and $τ \to ν_{τ} 2 π$ data within the energy region of 600 $\sim$ 900 MeV and the decay width of $ω \to π^{+} π^{-}$ , and compare their results. Our findings indicate that both the momentum-independent and momentum-dependent $ρ - ω$ mixing schemes provide appropriate descriptions of the data. However, the momentum-dependent scheme exhibits greater self-consistency, considering the reasonable imaginary part of the mixing matrix element $Π_{ρ ω}$ obtained. Regarding the contribution to the anomalous magnetic moment of the muon, $a_{μ}^{π π} ∣_{[0.6, 0.9] GeV}$ , the results obtained from the fits considering the momentum-dependent $ρ - ω$ mixing amplitude agree well with those obtained without incorporating the momentum dependence of the $ρ - ω$ mixing, within the margin of errors. Furthermore, based on the fitted values of the relevant parameters, we observe that the decay width of $ω \to π^{+} π^{-}$ is predominantly influenced by the $ρ - ω$ mixing effect.
Comments:
24 pages, 4 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2205.14656 [pdf]
CPC(2023)·1 citation
10
[Submitted on 29 May 2022] (cross-list from hep-ph)
Exposing the dead-cone effect of jet quenching in QCD medium
Yun-Fan Liu🇨🇳 · Wei Dai🇨🇳 · Ben-Wei Zhang🇨🇳 · Enke Wang🇨🇳
When an energetic parton traverses the hot QCD medium it may suffer multiple scattering and lose its energy. The medium-induced gluon radiation for a massive quark will be suppressed relative to that of a light quark due to the dead-cone effect. The development of new declustering techniques of jet evolution makes a direct study of the dead-cone effect in the QCD medium possible for the first time. In this work, we compute the emission angle distribution of the charm-quark initiated splittings in $D^{0}$ meson tagged jet and that of the light parton initiated splittings in an inclusive jet in p+p and Pb+Pb at $5.02$ ~TeV by utilizing the declustering techniques of jet evolution. The heavy quark propagation and indued energy loss in the QCD medium are simulated with the SHELL model based on the Langevin equation. By directly comparing the emission angle distributions of charm-quark-initiated splittings with those of light parton-initiated splittings at the same energy intervals of the initial parton, we provide insights into the fundamental splitting structure in A+A collisions, thereby exploring the possible observation of the dead-cone effect in medium-induced radiation. We further investigate the case of the emission angle distributions normalized to the number of splittings and find the dead-cone effect will broaden the emission angle of the splitting and reduce the possibility to occur such splitting, therefore leading the massive parton to lose less energy. We also find the collisional energy loss mechanism has a negligible impact on the medium modification to the emission angle distribution of the charm-quark initiated splittings for $D^{0}$ -meson tagged jets.
Comments:
7 pages, 4 figures, 2 tables, accepted by CPC
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2205.14668 [pdf]
CPC(2025)·11 citations
11
[Submitted on 30 May 2022] (cross-list from hep-ph)
On the definition of electromagnetic local spatial densities for composite spin- $1/2$ systems
J.Yu. Panteleeva🇩🇪 · E. Epelbaum🇩🇪 · J. Gegelia🇩🇪 · U.-G. Meißner🇩🇪
An unambiguous definition of the electromagnetic spatial densities for a spin-1/2 system is proposed and worked out in the zero average momentum frame and in moving frames. The obtained results are compared with the traditional definition of the densities in terms of the three-dimensional Fourier transforms of the electromagnetic form factors in the Breit frame.
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2205.15061 [pdf]
PRD(2022)·36 citations
12
[Submitted on 30 May 2022] (cross-list from quant-ph)
Digital quantum simulation of an extended Agassi model: Using machine learning to disentangle its phase-diagram
Álvaro Sáiz🇪🇸 · José-Enrique García-Ramos🇪🇸 · José Miguel Arias🇪🇸 · Lucas Lamata🇪🇸 · Pedro Pérez-Fernández🇪🇸
A digital quantum simulation for the extended Agassi model is proposed using a quantum platform with eight trapped ions. The extended Agassi model is an analytically solvable model including both short range pairing and long range monopole-monopole interactions with applications in nuclear physics and in other many-body systems. In addition, it owns a rich phase diagram with different phases and the corresponding phase transition surfaces. The aim of this work is twofold: on one hand, to propose a quantum simulation of the model at the present limits of the trapped ions facilities and, on the other hand, to show how to use a machine learning algorithm on top of the quantum simulation to accurately determine the phase of the system. Concerning the quantum simulation, this proposal is scalable with polynomial resources to larger Agassi systems. Digital quantum simulations of nuclear physics models assisted by machine learning may enable one to outperform the fastest classical computers in determining fundamental aspects of nuclear matter.
Comments:
15 pages, 11 figures. New title and minor changes. Published in PRC
Subjects:
Quantum Physics (quant-ph); Nuclear Theory (nucl-th)
arXiv:
2205.15122 [pdf]
PRC(2022)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Thermal and thermoelectric responses of hot QCD medium in time-varying magnetic fields

Comment on "A phenomenological π−p scattering length from pionic hydrogen''

Momentum-dependence of ρ−ω mixing in the pion vector form factor and its effect on (g−2)μ​

Exposing the dead-cone effect of jet quenching in QCD medium

On the definition of electromagnetic local spatial densities for composite spin-1/2 systems

Digital quantum simulation of an extended Agassi model: Using machine learning to disentangle its phase-diagram

Affiliations

Comment on "A phenomenological $π^{-} p$ scattering length from pionic hydrogen''

Momentum-dependence of $ρ - ω$ mixing in the pion vector form factor and its effect on $(g - 2)_{μ}$

On the definition of electromagnetic local spatial densities for composite spin- $1/2$ systems