Nuclear Theory·nucl-th

Tuesday·March 17, 2020

11 papers—6 primary·5 cross-listed

01
[Submitted on 14 Mar 2020]
The Problem of Renormalization of Chiral Nuclear Forces
U. van Kolck🇫🇷
Ever since quantum field theory was first applied to the derivation of nuclear forces in the mid-20th century, the renormalization of pion exchange with realistic couplings has presented a challenge. The implementation of effective field theories (EFTs) in the 1990s promised a solution to this problem but unexpected obstacles were encountered. The response of the nuclear community has been to focus on "chiral potentials" with regulators chosen to produce a good description of data. Meanwhile, a successful EFT without explicit pion exchange --- Pionless EFT --- has been formulated where renormalization is achieved order by order in a systematic expansion of low-energy nuclear observables. I describe how lessons from Pionless EFT are being applied to the construction of a properly renormalized Chiral EFT.
Comments:
40 pages, 9 figures, 3 tables, contribution to Frontiers in Physics' research topic "The Long-Lasting Quest for Nuclear Interactions: The Past, the Present and the Future"
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.06721 [pdf]
Front.in Phys.(2020)·84 citations
02
[Submitted on 15 Mar 2020]
Collision system size scan of collective flows in relativistic heavy-ion collisions
S. Zhang🇨🇳 · Y. G. Ma🇨🇳 · G. L. Ma🇨🇳 · J. H. Chen🇨🇳 · Q. Y. Shou🇨🇳 · W. B. He🇨🇳 · C. Zhong🇨🇳
Initial geometrical distribution and fluctuation can affect the collective expansion in relativistic heavy-ion collisions. This effect may be more evident in small system (such as B + B) than in large one (Pb + Pb). This work presents the collision system dependence of collective flows and discusses about effects on collective flows from initial fluctuations in a framework of a multiphase transport model. The results shed light on system scan on experimental efforts to small system physics.
Comments:
7 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
2003.06747 [pdf]
PLB(2020)·19 citations
03
[Submitted on 15 Mar 2020]
Exploring nuclear exotica at the limits
A.V. Afanasjev · S.E. Agbemava · A. Taninah
The study of nuclear limits has been performed and new physical mechanisms and exotic shapes allowing the extension of nuclear landscape beyond the commonly accepted boundaries have been established. The transition from ellipsoidal to toroidal shapes plays a critical role in potential extension of nuclear landscape to hyperheavy nuclei. Rotational excitations leading to the birth of particle (proton or neutron) bound rotational bands provide a mechanism for an extension of nuclear landscape beyond spin zero proton and neutron drip lines.
Comments:
invited talk presented at XXVI Nuclear Physics Workshop 2019 "Key problems of Nuclear Physics", 24-29 September 2019, Kazimierz Dolny, Poland, Acta Physica Polonica B, in press
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.06888 [pdf]
Acta Phys.Polon.Supp.(2020)·3 citations
04
[Submitted on 16 Mar 2020]
Studying the doublet bands at the borders of the $A \approx 130$ island of chiral candidates: the $^{120}$ I case
Rui Guo🇨🇳 · Yong-Hao Liu🇨🇳 · Jian Li🇨🇳 · Wu-Ji Sun🇨🇳 · Li Li🇨🇳 · Ying-Jun Ma🇨🇳
Based on the reported positive-parity doublet bands in $^{120}$ I, the corresponding experimental characteristics including rotational alignment have been discussed and corresponding configuration assignment is reexamined. The self-consistent tilted axis cranking relativistic mean-field calculations indicates that this doublet bands is built on configuration $π h_{11/2} \otimes ν h_{11/2}^{- 1}$ . In addition, adopting the two quasiparticles coupled with a triaxial rotor model, the excitation energies, energy staggering parameter $S (I)$ , $B (M 1) / B (E 2)$ , effective angles, and $K$ $pl o t s$ have been discussed and also compared with the available data. All of these results support the interpretation of chiral doublet bands for the positive-parity doublet bands in $^{120}$ I, and hence identify this nucleus as the border of the $A \approx 130$ island of chiral candidates.
Comments:
9 pages, 9 figure, to be published in Chinese Physics C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.06960 [pdf]
CPC(2020)·3 citations
05
[Submitted on 16 Mar 2020]
Excited states of odd-mass nuclei with different deformation-dependent mass coefficients
M. Chabab · A. El Batoul · I. El-ilali · A. Lahbas · M. Oulne
Experimental data indicate that the mass tensor of collective Bohr Hamiltonian cannot be considered as a constant but should be considered as a function of the collective coordinates. In this work our purpose is to investigate the properties of low-lying collective states of the odd nuclei $^{173}$ Yb and $^{163}$ Dy by using a new generalized version of the collective quadrupole Bohr Hamiltonian with deformation-dependent mass coefficients. The proposed new version of the Bohr Hamiltonian is solved for Davidson potential in $β$ shape variable, while the $γ$ potential is taken to be equal to the harmonic oscillator. The obtained results of the excitation energies and B(E2) reduced transition probabilities show an overall agreement with the experimental data. Moreover, we investigate the effect of the deformation dependent mass parameter on energy spectra and transition rates in both cases, namely: when the mass coefficients are different and when they are equal. Besides, we will show the positive effect of the present formalism on the moment of inertia.
Comments:
16 pages, 1 figure
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2003.06969 [pdf]
Eur.Phys.J.Plus(2020)·10 citations
06
[Submitted on 16 Mar 2020]
Determination of Photonuclear Reaction Cross-Sections on stable p-shell Nuclei by Using Deep Neural Networks
Serkan Akkoyun · Hüseyin Kaya · Abdulkadir Şeker · Saliha Yeşilyurt
The photonuclear reactions which is induced by high-energetic photon are one of the important type of reactions in the nuclear structure studies. In this reaction, a target material is bombarded by photons with the energies in the range of gamma-ray energy scale and the photons can statistically be absorbed by a nucleus in the target material. In order to get rid of the excess energies of the excited target nuclei, it can first emit protons, neutrons, alphas and light particles according to the separation energy thresholds. After this emitting process, generally an unstable nucleus can be formed. By the investigation of this products forming after photonuclear reactions, nuclear structure information can be obtained. In the present work, ({\gamma}, n) photonuclear reaction cross-sections on stable p-shell nuclei have been estimated by using neural network method. The main purpose of this study is to find neural network structures that give the best estimations on the cross-sections and to compare them with each other and available literature data. According to the results, the method is convenient for this task.
Comments:
14 pages, 1 table, 7 figures. arXiv admin note: text overlap with arXiv:2002.12166
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex); Data Analysis, Statistics and Probability (physics.data-an)
arXiv:
2003.07050 [pdf]
0 citations
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