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Nuclear Theory·nucl-th

Wednesday·April 3, 2024

9 papers—4 primary·5 cross-listed

All9Primary4Cross-lists5
  1. 01

    [Submitted on 1 Apr 2024]

    Transport Coefficients of relativistic matter: A detailed formalism with a gross knowledge of their magnitude

    Ashutosh Dwibedi🇮🇳 · Nandita Padhan🇮🇳 · Arghya Chatterjee🇮🇳 · Sabyasachi Ghosh🇮🇳

    The present review article has attempted a compact formalism description of transport coefficient calculations for relativistic fluid, which is expected in heavy ion collision experiments. Here, we first address the macroscopic description of relativistic fluid dynamics and then its microscopic description based on the kinetic theory framework. We also address different relaxation time approximation-based models in Boltzmann transport equations, which make a sandwich between Macro and Micro frameworks of relativistic fluid dynamics and finally provide different microscopic expressions of transport coefficients like the fluid's shear viscosity and bulk viscosity. In the numeric part of this review article, we put stress on the two gross components of transport coefficient expressions: relaxation time and thermodynamic phase-space part. Then, we try to tune the relaxation time component to cover earlier theoretical estimations and experimental data-driven estimations for RHIC and LHC matter. By this way of numerical understanding, we provide the final comments on the values of transport coefficients and relaxation time in the context of the (nearly) perfect fluid nature of the RHIC or LHC matter.

    Subjects:
    Nuclear Theory (nucl-th); Statistical Mechanics (cond-mat.stat-mech)
    arXiv:
    2404.01421 [pdf]
    Universe(2024)·4 citations
  2. 02

    [Submitted on 2 Apr 2024]

    Accurate and precise quantum computation of valence two-neutron systems

    Sota Yoshida🇯🇵 · Takeshi Sato🇯🇵 · Takumi Ogata🇯🇵 · Tomoya Naito🇯🇵 · Masaaki Kimura🇯🇵

    Developing methods to solve nuclear many-body problems with quantum computers is an imperative pursuit within the nuclear physics community. Here, we introduce a quantum algorithm to accurately and precisely compute the ground state of valence two-neutron systems leveraging presently available Noisy Intermediate-Scale Quantum devices. Our focus lies on the nuclei having a doubly-magic core plus two valence neutrons in the , , and shells, i.e. He, O, and Ca, respectively. Our ansatz, quantum circuit, is constructed in the pair-wise form, taking into account the symmetries of the system in an explicit manner, and enables us to reduce the number of qubits and the number of CNOT gates required. The results on a real quantum hardware by IBM Quantum Platform show that the proposed method gives very accurate results of the ground-state energies, which are typically within error in the energy for He and O and at most error for Ca. Furthermore, our experiments using real quantum devices also show the pivotal role of the circuit layout design, attuned to the connectivity of the qubits, in mitigating errors.

    Comments:
    12 pages, 12 figures; discussions and references added
    Subjects:
    Nuclear Theory (nucl-th); Quantum Physics (quant-ph)
    arXiv:
    2404.01694 [pdf]
    PRC(2024)·14 citations
  3. 03

    [Submitted on 2 Apr 2024]

    Uncovering the mechanism of chiral three-nucleon force in driving spin-orbit splitting

    Tokuro Fukui🇯🇵 · Giovanni De Gregorio🇮🇹 · Angela Gargano🇮🇹

    The three-nucleon force (3NF) is crucial in shaping the shell structure of atomic nuclei, particularly impacting the enhancement of spin-orbit (SO) splitting, especially in nuclei with significant deviations from stability. Despite its importance, the specific mechanisms driving this enhancement remain unclear. In this study, we introduce a decomposition scheme based on the rank of irreducible tensors forming the 3NF, derived from chiral effective field theory at next-to-next-to-leading order, to elucidate their influence on SO splitting. Within the shell-model framework, our analysis reveals that the rank-1 component of the 3NF is the primary factor enlarging the energy gap between the and single-particle levels in -shell nuclei, while the rank-2 component makes a subdominant contribution. Since the rank-1 component originates exclusively from the -exchange 3NF, our finding will not depend on the choice of the low-energy constants of contact terms. We also remark on the antisymmetry of the rank-1 3NF, which can affect the quantum entanglement of spin states. This study lays the groundwork for further exploration into this field toward a microscopic understanding of the 3NF impact on the nuclear shell structure.

    Comments:
    11 pages, 3 figures, 2 tables
    Subjects:
    Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
    arXiv:
    2404.02007 [pdf]
    PLB(2024)·11 citations
  4. 04

    [Submitted on 2 Apr 2024]

    Exploring Spin Polarization of Heavy Quarks in Magnetic Fields and Hot Medium

    Zhiwei Liu🇨🇳 · Yunfan Bai🇬🇧 · Shiqi Zheng🇺🇸 · Anping Huang🇨🇳 · Baoyi Chen🇨🇳

    Relativistic heavy-ion collisions give rise to the formation of both deconfined QCD matter and a strong magnetic field. The spin of heavy quarks is influenced by interactions with the external magnetic field as well as by random scatterings with thermal light partons. The presence of QCD matter comprising charged quarks can extend the lifetime and strength of the magnetic field, thereby enhancing the degree of heavy quark polarization. However, the random scatterings with QCD matter tend to diminish heavy quark polarization. In this study, we utilize the Landau-Lifshitz-Gilbert (LLG) equation to investigate both these contributions. Taking into account the realistic evolutions of medium temperatures and the in-medium magnetic fields at the Relativistic Heavy-Ion Collider (RHIC) and the Large Hadron Collider (LHC), we observe that heavy quark polarization is limited by the short lifetime of the magnetic field and the high temperatures of the medium. Furthermore, we explore the mass dependence of quark polarization, revealing that the polarization degree of strange quarks is much larger than that of charm quarks.

    Comments:
    7 pages, 13 figures
    Subjects:
    Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
    arXiv:
    2404.02032 [pdf]
    PRC(2024)·8 citations

Affiliations

first authorsco-authorsvia INSPIRE