Nuclear Theory·nucl-th

Tuesday·March 17, 2020

11 papers—6 primary·5 cross-listed

07
[Submitted on 14 Mar 2020] (cross-list from hep-ph)
Relaxation time for the alignment between the spin of a finite-mass quark/antiquark and the thermal vorticity in relativistic heavy-ion collisions
Alejandro Ayala🇲🇽 · David de la Cruz🇲🇽 · L. A. Hernández🇲🇽 · Jordi Salinas🇲🇽
We study the relaxation time required for the alignment between the spin of a finite-mass quark/antiquark and the thermal vorticity, at finite temperature and baryon chemical potential, in the context of relativistic heavy-ion collisions. The relaxation time is computed as the inverse of the total reaction rate that in turn is obtained from the imaginary part of the quark/antiquark self-energy. We model the interaction between spin and thermal vorticity within the medium by means of a vertex coupling quarks and thermal gluons that, for a uniform temperature, is proportional to the global angular velocity and inversely proportional to the temperature. We use realistic estimates for the angular velocities for different collision energies and show that the effect of the quark mass is to reduce the relaxation times as compared to the massless quark case. Using these relaxation times we estimate the intrinsic quark and antiquark polarizations produced by the thermal vorticity. We conclude by pointing out that, in spite of the former being larger than the latter, it is still possible to understand recent results from the STAR Beam Energy Scan when accounting for the fact that only a portion of quarks/antiquarks come from the denser and thus thermalized region in the collision.
Comments:
6 pages, 7 figures. Expanded discussion, conclusions unchanged. arXiv admin note: text overlap with arXiv:1909.00274
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.06545 [pdf]
PRD(2020)·36 citations
08
[Submitted on 14 Mar 2020] (cross-list from hep-ph)
Deuteron polarizations in the proton-deuteron Drell-Yan process for finding the gluon transversity
S. Kumano🇯🇵 · Qin-Tao Song🇨🇳
The gluon transversity distribution in the deuteron is defined by the matrix element between linearly-polarized deuteron states, and it could be investigated in proton-deuteron collisions in addition to lepton-deuteron scattering. The linear polarization of photon is often used, whereas it is rarely used for the spin-1 deuteron. Therefore, it is desirable to express deuteron-reaction cross sections in term of conventional deuteron spin polarizations for actual experimental measurements. In this work, we investigate how proton-deuteron Drell-Yan cross sections are expressed by the conventional polarizations for finding the gluon transversity distribution. In particular, we show that the gluon transversity can be measured in the proton-deuteron Drell-Yan process by taking the cross-section difference between the deuteron spin polarizations along the two-transverse axes. Since the gluon transversity does not exist for the spin-1/2 nucleons, a finite gluon transversity of the deuteron could indicate an "exotic" mechanism beyond the simple bound system of the nucleons in the deuteron. Therefore, the gluon transversity is an interesting and appropriate observable to shed light on a new hadronic mechanism in nuclei.
Comments:
8 pages, 2 figures, published in Phys. Rev. D 101 (2020) 094013. Some notations are changed
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
2003.06623 [pdf]
PRD(2020)·19 citations
09
[Submitted on 15 Mar 2020] (cross-list from hep-ph)
Identify the hidden charm pentaquark signal from non-resonant background in electron-proton scattering
Zhi Yang🇨🇳 · Xu Cao🇨🇳 · Yu-Tie Liang🇨🇳 · Jia-Jun Wu🇨🇳
We study the electroproduction of the LHCb pentaquark states with the assumption that they are resonant states. The main concern here is to investigate the final state distribution in the phase space in order to extract the feeble pentaquark signal from the large non-resonant background. Our results show that the ratio of the signal to background would increase significantly with proper kinematic cut, which would be very helpful for future experimental analysis.
Comments:
16 pages, 5 figures, some minor modifications, accepted for publication in Chinese Physics C
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2003.06774 [pdf]
CPC(2020)·14 citations
10
[Submitted on 16 Mar 2020] (cross-list from hep-ph)
Non-zero tensor condensates in cold quark matter within the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction
A. Kagawa (Kochi Univ., Japan)🇯🇵 · M. Morimoto (Kochi Univ., Japan)🇯🇵 · Y. Tsue (Kochi Univ., Japan)🇯🇵 · J. da Providencia (Univ. de Coimbra, Portugal)🇯🇵 · C. Providencia (Univ. de Coimbra, Portugal)🇯🇵 · M. Yamamura (Kansai Univ., Japan)🇯🇵
The possible formation of tensor condensates originated from a tensor-type interaction between quarks is investigated in the three-flavor Nambu-Jona-Lasinio model including the Kobayashi-Maskawa-'t Hooft interaction, which leads to flavor mixing. It is shown that independent two tensor condensates appear and a tensor condensate related to the strange quark easily occurs by the effect of the flavor mixing compared with one related to light quarks. Also, it is shown that the tensor condensate related to the strange quark appears at a slightly smaller chemical potential if the Kobayashi-Maskawa-'t Hooft interaction is included, due to the flavor mixing effect. It is also shown that the two kinds of tensor condensates may coexist in a certain quark chemical potential due to the flavor mixing.
Comments:
13 pages, 9 figures, using PTPTeX. arXiv admin note: text overlap with arXiv:1910.03221
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
2003.06996 [pdf]
IJMPE(2020)·2 citations
11
[Submitted on 16 Mar 2020] (cross-list from hep-ph)
Role of the low-lying nucleon resonances in the $p p ˉ \to ψ η$ reaction
Qin-Song Zhou🇨🇳 · Jun-Zhang Wang🇨🇳 · Ju-Jun Xie🇨🇳 · Xiang Liu🇨🇳
Within the effective Lagrangian approach, we study the $p p ˉ \to ψ η$ [ $ψ \equiv ψ (3686)$ , $J / ψ$ ] reaction at the low energy where the contributions from nucleon pole and low-lying nucleon resonances, $N (1520)$ , $N (1535)$ and $N (1650)$ are considered. All the model parameters are determined with the help of current experimental data on the decay of $ψ \to p p ˉ η$ . Within the model parameters, the total and differential cross sections of the $p p ˉ \to ψ η$ reaction are predicted. We show that the relative phases between different amplitudes of different nucleon resonance will change significantly the angular distributions of the $p ˉ p \to ψ η$ reaction. Therefore, we conclude that these reactions are suitable to study experimentally the properties of the low-lying nucleon resonance and the reaction mechanisms. We hope that these theoretical calculations can be tested by future experiments.
Comments:
8 pages, 9 figures and 3 tables. Accepted by Phys. Rev. D
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Experiment (hep-ex); Nuclear Theory (nucl-th)
arXiv:
2003.07135 [pdf]
PRD(2020)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Relaxation time for the alignment between the spin of a finite-mass quark/antiquark and the thermal vorticity in relativistic heavy-ion collisions

Deuteron polarizations in the proton-deuteron Drell-Yan process for finding the gluon transversity

Identify the hidden charm pentaquark signal from non-resonant background in electron-proton scattering

Non-zero tensor condensates in cold quark matter within the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction

Role of the low-lying nucleon resonances in the ppˉ​→ψη reaction

Affiliations

Role of the low-lying nucleon resonances in the $p p ˉ \to ψ η$ reaction