Nuclear Theory·nucl-th

Wednesday·April 3, 2024

9 papers—4 primary·5 cross-listed

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
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 $p$ , $s d$ , and $p f$ shells, i.e. $^{6}$ He, $^{18}$ O, and $^{42}$ 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 $0.1 %$ error in the energy for $^{6}$ He and $^{18}$ O and at most $1 %$ error for $^{42}$ 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
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 $0 p_{3/2}$ and $0 p_{1/2}$ single-particle levels in $p$ -shell nuclei, while the rank-2 component makes a subdominant contribution. Since the rank-1 component originates exclusively from the $2 π$ -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
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
05
[Submitted on 1 Apr 2024] (cross-list from hep-ph)
Electrical conductivity of hot relativistic plasma in a strong magnetic field
Ritesh Ghosh🇺🇸 · Igor A. Shovkovy🇺🇸
We employ first-principles quantum field theoretical methods to investigate the longitudinal and transverse electrical conductivities of a strongly magnetized hot quantum electrodynamics (QED) plasma at the leading order in coupling. The analysis employs the fermion damping rate in the Landau-level representation, calculated with full kinematics and exact amplitudes of one-to-two and two-to-one QED processes. In the relativistic regime, both conductivities exhibit an approximate scaling behavior described by $σ_{∥, ⊥} = T σ ~_{∥, ⊥}$ , where $σ ~_{∥, ⊥}$ are functions of the dimensionless ratio $∣ e B ∣/ T^{2}$ (with $T$ denoting temperature and $B$ magnetic field strength). We argue that the mechanisms for the transverse and longitudinal conductivities differ significantly, leading to a strong suppression of the former in comparison to the latter.
Comments:
7 pages, 1 figure; v3: final version accepted for publication in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2404.01388 [pdf]
PRD(2024)·15 citations
06
[Submitted on 2 Apr 2024] (cross-list from nucl-ex)
Investigation of reaction and $α$ production cross sections with $^{9}$ Be projectile
Satbir Kaur · V. V. Parkar · S. K. Pandit · A. Shrivastava · K. Mahata · K. Ramachandran · Sangeeta Dhuri · P. C. Rout · A. Kumar · Shilpi Gupta
In order to investigate the contribution of $α$ production in the reaction cross sections, measurements of elastic scattering and inclusive $α$ particle angular distributions have been carried out with the $^{9}$ Be projectile on $^{89}$ Y, $^{124}$ Sn, $^{159}$ Tb, $^{198}$ Pt, and $^{209}$ Bi targets over a wide angular range at energies near the Coulomb barrier. The measured elastic scattering angular distributions were fitted with optical model calculations, and reaction cross sections were extracted. The same data were also analysed using both global optical model potentials (Global OMP) and microscopic S $a ~$ o Paulo potentials (SPP), to obtain the reaction cross sections. The data available in the literature for $^{9}$ Be projectile includes the elastic scattering angular distributions, $α$ production cross sections, and complete fusion cross sections on these and other targets at several energies are also utilised for comparative studies. The reaction cross section extracted from the three potentials (Best Fit, Global OMP and SPP) are in reasonable agreement for all the targets except for the energies below the barrier where the results from SPP deviate by 30-50 \%. Inclusive $α$ particle production cross sections were also extracted by integrating the $α$ particle angular distributions. The present data and data available from literature of reaction and $α$ -particle production cross sections were utilised to make systematic studies. Systematics of reaction and $α$ -particle production cross sections revealed their universal behaviour.
Comments:
16 pages, 9 figures
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.01653 [pdf]
NPA(2024)·7 citations
07
[Submitted on 2 Apr 2024] (cross-list from astro-ph.HE)
Validity of a finite temperature expansion for dense nuclear matter
Debora Mroczek🇺🇸 · Nanxi Yao🇺🇸 · Katherine Zine🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸 · Liam Brodie🇺🇸 · Veronica Dexheimer🇺🇸 · Alexander Haber🇺🇸 · Elias R. Most🇺🇸
In this work we provide a new, well-controlled expansion of the equation of state of dense matter from zero to finite temperatures ( $T$ ) while covering a wide range of charge fractions ( $Y_{Q}$ ), from pure neutron to isospin symmetric nuclear matter. Our expansion can be used to describe neutron star mergers using the equation of state inferred from neutron star observations. We discuss how knowledge from low-energy nuclear experiments and heavy-ion collisions can be directly incorporated into the expansion. We also suggest new thermodynamic quantities of interest that can be calculated from theoretical models or directly inferred by experimental data that can be used to infer the finite temperature equation of state. With our new method, we can quantify the uncertainty in our finite $T$ and $Y_{Q}$ expansions without making assumptions about the underlying degrees of freedom. We can reproduce results from a microscopic equation of state up to $T = 100$ MeV for baryon chemical potential $μ_{B} ≳ 1100$ MeV ( $\sim 1 - 2 n_{sat}$ ) within $5%$ error, with even better results for larger $μ_{B}$ and/or lower $T$ . We investigate the sources of numerical and theoretical uncertainty and discuss future directions of study.
Comments:
Significant text revisions and improved numerics. 19 pages, 11 figures, 2 appendices
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2404.01658 [pdf]
PRC(2026)·21 citations
08
[Submitted on 2 Apr 2024] (cross-list from nucl-ex)
Measurement of the mesonic decay branch of the $K ˉ N N$ quasi-bound state
T. Yamaga🇯🇵 · S. Ajimura🇯🇵 · H. Asano🇯🇵 · G. Beer🇨🇦 · H. Bhang🇰🇷 · M. Bragadireanu🇷🇴 · P. Buehler🇦🇹 · L. Busso🇮🇹 · M. Cargnelli🇦🇹 · S. Choi🇰🇷 · C. Curceanu🇮🇹 · S. Enomoto🇯🇵 and 58 other authors
We conducted measurements of $K^{-} +^{3} He \to π Y N + N^{'}$ reactions using a $1 GeV / c$ $K^{-}$ -beam, with the objective of understanding the broad decay width of $K ˉ N N$ (approximately twice as broad as that of $Λ (1405)$ considered to be the $K ˉ N$ quasi-bound state). We successfully reproduced distributions of the $π Y N$ invariant mass and momentum transfer for $π Y N$ using model fitting functions for $K ˉ N N$ formation and quasi-free $K ˉ$ absorption ( $QF_{K ˉ - abs}$ ) processes. The model can describe the experimental data quite well, and four $K ˉ N N \to π Y N$ cross-sections were obtained. The results indicate that mesonic decay is the dominant decay branch of $K ˉ N N$ . The results also suggest that $Γ_{π Λ N} \sim Γ_{π Σ N}$ , which indicates that the $I_{K ˉ N} = 1$ absorption channel, in addition to the $I_{K ˉ N} = 0$ absorption channel, substantially contribute to the $K ˉ N N$ decay, making the $K ˉ N N$ state approximately twice as unstable as $Λ$ (1405).
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.01773 [pdf]
PRC(2024)·6 citations
09
[Submitted on 2 Apr 2024] (cross-list from astro-ph.HE)
Impact of The Newly Revised Gravitational Redshift of X-ray Burster GS 1826-24 on The Equation of State of Supradense Neutron-Rich Matter
Wen-Jie Xie · Bao-An Li · Nai-Bo Zhang
Thanks to the recent advancement in producing rare isotopes and measuring their masses with unprecedented precision, the updated nuclear masses around the waiting-point nucleus $^{64}$ Ge in the rapid-proton capture process have led to a significant revision of the surface gravitational redshift of the neutron star (NS) in GS 1826-24 by re-fitting its X-ray burst light curve ({\it X. Zhou et al., Nature Physics {\bf 19}, 1091 (2023)}) using Modules for Experiments in Stellar Astrophysics (MESA). The resulting NS compactness $ξ$ is between 0.244 and 0.342 at 95\% confidence level and its upper boundary is significantly smaller than the maximum $ξ$ previously known. Incorporating this new data within a comprehensive Bayesian statistical framework, we investigate its impact on the Equation of State (EOS) of supradense neutron-rich matter and the required spin frequency for GW190814's minor $m_{2}$ with mass $2.59 \pm 0.05$ M $_{⊙}$ to be a rotationally stable pulsar. We found that the EOS of high-density symmetric nuclear matter (SNM) has to be softened significantly while the symmetry energy at supersaturation densities stiffened compared to our prior knowledge from earlier analyses using data from both astrophysical observations and terrestrial nuclear experiments. In particular, the skewness $J_{0}$ characterizing the stiffness of high-density SNM decreases significantly, while the slope $L$ , curvature $K_{sym}$ , and skewness $J_{sym}$ of nuclear symmetry energy all increase appreciably compared to their fiducial values. We also found that the most probable spin rate for the $m_{2}$ to be a stable pulsar is very close to its mass-shedding limit once the revised redshift data from GS 1826-24 is considered, making the $m_{2}$ unlikely the most massive NS observed so far.
Comments:
Additional results and discussions added. Phys. Rev. D in press
Subjects:
High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics — Theory (hep-th); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2404.01989 [pdf]
PRD(2024)·21 citations

Affiliations

first authorsco-authorsvia INSPIRE