Nuclear Theory·nucl-th

Tuesday·August 20, 2024

11 papers—3 primary·8 cross-listed

04
[Submitted on 16 Aug 2024] (cross-list from hep-lat)
Coulomb confinement in the Hamiltonian limit
Sebastian M. Dawid🇺🇸 · Wyatt A. Smith🇺🇸 · Arkaitz Rodas🇺🇸 · Robert J. Perry🇪🇸 · César Fernández-Ramírez🇪🇸 · Eric S. Swanson🇺🇸 · Adam P. Szczepaniak🇺🇸
The Gribov--Zwanziger scenario attributes the phenomenon of confinement to the instantaneous interaction term in the QCD Hamiltonian in the Coulomb gauge. For a static quark-antiquark pair, it leads to a potential energy that increases linearly with the distance between them. Lattice studies of the SU(2) Yang--Mills theory determined the corresponding (Coulomb) string tension for sources in the fundamental representation, $σ_{C}$ , to be about three times larger than the Wilson loop string tension, $σ_{F}$ . It is far above the Zwanziger variational bound, $σ_{C} \geq σ_{F}$ . We argue that the value established in the literature is artificially inflated. We examine the lattice definition of the instantaneous potential, find the source of the string tension's enhancement, and perform its improved determination in SU(2) lattice gauge theory. We report our conservative estimate for the value of the Coulomb string tension as $σ_{C} / σ_{F} = 2.0 \pm 0.4$ and discuss its phenomenological implications.
Comments:
13 pages, 6 figures
Subjects:
High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2408.09007 [pdf]
PRD(2024)·3 citations
05
[Submitted on 17 Aug 2024] (cross-list from nucl-ex)
Study of $^{7}$ Li+ $^{10}$ B elastic scattering and the lithium-induced reaction of one-nucleon transfers from $^{10}$ B( $^{7}$ Li, $^{6}$ Li) $^{11}$ B
Sergey Stukalov · Yuri Sobolev · Yuri Penionzhkevich · Nassurlla Burtebayev · Sergey Goncharov · Yuri Gurov · Andrey Danilov · Alla Demyanova · Sergey Dmitriev · Maulen Nassurlla · Viktar Starastsin · Alexey Shakhov · Semyon Raidun · Nguyen Hoai Chau
The angular distributions of elastic scattering of $^{7}$ Li, as well as the lithium-induced reaction of one-nucleon transfers $^{10}$ B( $^{7}$ Li, $^{6}$ Li) $^{11}$ B were measured at $E_{lab}$ = 58 MeV. Experiment was done using U-400 accelerator beam of the FLNR JINR, Dubna. Angular distribution for reaction $^{10}$ B( $^{7}$ Li, $^{6}$ Li) $^{11}$ B with excitation of the 3.56 MeV state ( $^{6}$ Li*) is presented for the first time. The DWBA analysis of the differential cross section of the $^{10}$ B( $^{7}$ Li, $^{6}$ Li) $^{11}$ B ground state (g.s.) transition and excited ( $J^{π}$ = 0 $^{+}$ , $T$ = 1, $E$ = 3.56 MeV) state of $^{6}$ Li transition was performed. The optical model potentials were obtained by fitting of measured elastic scattering data and evaluating parameters for the output reaction channels. Phenomenological approach based on solving an approximate equation for the reaction form factor was used to determine its radial dependence and empirical values of asymptotic normalization coefficient (ANC). Obtained values of ANCs for the $^{6}$ Li $_{g.s.}$ and $^{6}$ Li*(3.56 MeV) states are in agreement with the literature ones. Comparison of the radial dependences of form factors shows that the wave function of the $^{6}$ Li nucleus in excited ( $J^{π}$ = 0 $^{+}$ , $T$ = 1, $E$ = 3.56 MeV) state has increased spatial dimension compared to the ground state. This result is an argument in favor of a halo existence in $^{6}$ Li*(3.56 MeV) state, while the question of a halo in $^{6}$ Li $_{g.s.}$ still leaves open.
Comments:
The article has undergone several updates: the title has been changed, Sergey Dmitriev has been added as an author, and acknowledgments to the research team have been added. Expansions and clarifications have been added to all chapters of the article. Typos have been corrected. The original results remain unchanged
Subjects:
Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
2408.09231 [pdf]
1 citation
06
[Submitted on 18 Aug 2024] (cross-list from hep-ph)
Dissecting a strongly coupled scalar nucleon
Xianghui Cao🇨🇳 · Yang Li🇨🇳 · James P. Vary🇺🇸
We continue our investigation of the stress within a strongly coupled scalar nucleon, and now dissect the gravitational form factors into contributions from its constituents, the (mock) nucleon and the (mock) pion. The computation is based on a non-perturbative solution of the scalar Yukawa model in the light-front Hamiltonian formalism with a Fock sector expansion including up to one nucleon and two pions. By employing the ``good currents" $T_{i}^{++}$ , $T_{i}^{+-}$ and $T_{i}^{12}$ , we extract the full set of gravitational form factors $A_{i}$ , $D_{i}$ , $c ˉ_{i}$ without the contamination of the spurious form factors, and free of uncanceled UV divergences. With these results, we decompose the mass of the system into its constituents and compute the matter and mechanical radii, gaining insights into the strongly coupled system.
Comments:
11 pages, 4 figures; published in PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2408.09535 [pdf]
PRD(2024)·6 citations
07
[Submitted on 19 Aug 2024] (cross-list from hep-ph)
Gravitational form factor $D$ of charmonium from shear stress
Tianyang Hu🇨🇳 · Xianghui Cao🇨🇳 · Siqi Xu🇨🇳 · Yang Li🇨🇳 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
Based on our recent analysis of the hadronic matrix element of the stress-energy tensor in covariant light front dynamics, we extract the charmonium gravitational form factor $D (Q^{2})$ from shear stress $T^{12}$ . This is in contrast to our recent work using the (light-front) energy density $T^{+-}$ . Indeed, by comparing these two currents, we identify terms that are responsible for the violation of the current conservation. Numerical results based on basis light-front quantization show that the violation effects are small and the $D$ -term extracted from the two currents are close to each other, hence validating our previous work using $T^{+-}$ .
Comments:
9 pages, 4 figures, published in Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2408.09689 [pdf]
PRD(2025)·12 citations
08
[Submitted on 19 Aug 2024] (cross-list from hep-ph)
Transport coefficients of the heavy quark in the domain of the non-perturbative and non-eikonal gluon radiation
Surasree Mazumder🇮🇳 · Natasha Sharma🇮🇳 · Lokesh Kumar🇮🇳
Drag and diffusion coefficients of the Heavy Quarks (HQs), such as charm and bottom, are one of the prime tools for discerning the properties of the deconfined QCD medium created in the Heavy Ion Collisions experiments. The innate non-perturbative nature of the QCD medium renders it imperative to estimate the transport coefficients in that domain. The present work evaluates the drag and diffusion coefficients of the moving HQ interacting with the medium particles via two-body collisional and three-body radiative processes to the first order in opacity by employing Gribov mechanism for the non-perturbative regime. We proffer the latest results of the HQ transport coefficients computed for the non-perturbative and non-eikonal gluon radiation off the HQ. The calculations show significant increment of the transport coefficients with the increasing non-eikonality by juxtaposing the results with those of the pertubative and eikonal regions. We hope to shed fresh light towards explaining the experimental data on the nuclear modification facor, $R_{AA}$ , the elliptic flow, $v_{2}$ of the HQ by advocating the importance of the non-eikonality of the gluon radiation off the HQ.
Comments:
9 pages, 8 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2408.09824 [pdf]
PRC(2025)·2 citations
09
[Submitted on 19 Aug 2024] (cross-list from hep-ph)
Collisional corrections to spin polarization from quantum kinetic theory using Chapman-Enskog expansion
Shuo Fang🇨🇳 · Shi Pu🇨🇳
We have investigated the collisional corrections to the spin polarization pseudo-vector, $δ P^{μ}$ , using quantum kinetic theory in Chapman-Enskog expansion. We derive the spin Boltzmann equation incorporating Møller scattering process. We further consider two distinct scenarios using hard thermal loop approximations for simplification. In scenario (I), the vector charge distribution function is treated as off-equilibrium under the validity domain of gradient expansion. Remarkably, the polarization induced by gradients of thermal chemical potential and shear viscous tensors are modified, but $δ P_{μ}$ in this scenario does not depend on the coupling constant. In scenario (II), the vector charge distribution function is assumed to be in local thermal equilibrium. Then collisional corrections $δ P_{μ}$ in this scenario are at $O (ℏ^{2} \partial^{2})$ . Additionally, we evaluate the $δ P^{μ}$ using relaxation time approach for comparative analysis. Our results establish the theoretical framework necessary for the future numerical investigations on the interaction corrections to spin polarization.
Comments:
32 pages, 1 figure; version accepted for publication of PRD
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
2408.09877 [pdf]
PRD(2025)·25 citations
10
[Submitted on 19 Aug 2024] (cross-list from physics.atom-ph)
Recent advancements in atomic many-body methods for high-precision studies of isotope shifts
B. K. Sahoo · S. Blundell · A. V. Oleynichenko · R. F. Garcia Ruiz · L. V. Skripnikov · B. Ohayon
The development of atomic many-body methods, capable of incorporating electron correlation effects accurately, is required for isotope shift (IS) studies. In combination with precise measurements, such calculations help to extract nuclear charge radii differences, and to probe for signatures of physics beyond the Standard Model of particle physics. We review here a few recently-developed methods in the relativistic many-body perturbation theory (RMBPT) and relativistic coupled-cluster (RCC) theory frameworks for calculations of IS factors in the highly charged ions (HCIs), and neutral or singly-charged ions, respectively. The results are presented for a wide range of atomic systems in order to demonstrate the interplay between quantum electrodynamics (QED) and electron correlation effects. In view of this, we start our discussions with the RMBPT calculations for a few HCIs by rigorously treating QED effects; then we outline methods to calculate IS factors in the one-valence atomic systems using two formulations of the RCC approach. Then we present calculations for two valence atomic systems, by employing the Fock-space RCC methods. For completeness, we briefly discuss theoretical input required for the upcoming experiments, their possibilities to probe nuclear properties and implications to fundamental physics studies.
Comments:
Topical Review Preprint for J. Phys. B, Comments and Suggestions are welcome!
Subjects:
Atomic Physics (physics.atom-ph); Nuclear Theory (nucl-th); Computational Physics (physics.comp-ph)
arXiv:
2408.09959 [pdf]
J.Phys.B(2025)·11 citations
11
[Submitted on 19 Aug 2024] (cross-list from cond-mat.quant-gas)
Comparison of renormalized interactions using one-dimensional few-body systems as a testbed
Fabian Brauneis · Hans-Werner Hammer · Stephanie M. Reimann · Artem G. Volosniev
Even though the one-dimensional contact interaction requires no regularization, renormalization methods have been shown to improve the convergence of numerical ab initio calculations considerably. In this work, we compare and contrast these methods: `the running coupling constant' where the two-body ground state energy is used as a renormalization condition, and two effective interaction approaches that include information about the ground as well as excited states. In particular, we calculate the energies and densities of few-fermion systems in a harmonic oscillator with the configuration interaction method, and compare the results based upon renormalized and bare interactions. We find that the use of the running coupling constant instead of the bare interaction improves convergence significantly. A comparison with an effective interaction, which is designed to reproduce the relative part of the energy spectrum of two particles, showed a similar improvement. The effective interaction provides an additional improvement if the center-of-mass excitations are included in the construction. Finally, we discuss the transformation of observables alongside the renormalization of the potential, and demonstrate that this might be an essential ingredient for accurate numerical calculations.
Comments:
Version accepted for publication in Phys. Rev. A
Subjects:
Quantum Gases (cond-mat.quant-gas); Nuclear Theory (nucl-th)
arXiv:
2408.10052 [pdf]
PRA(2025)·7 citations

Affiliations

first authorsco-authorsvia INSPIRE