Nuclear Theory·nucl-th

Wednesday·September 30, 2015

15 papers—6 primary·9 cross-listed

01
[Submitted on 28 Sept 2015]
Pion-nucleon correlations in finite nuclei in a relativistic framework: effects on the shell structure
Elena Litvinova🇺🇸
The relativistic particle-vibration coupling (RPVC) model is extended by the inclusion of spin- and isospin-flip excitation modes into the phonon space, introducing a new mechanism of dynamical interaction between nucleons with different isospin in the nuclear medium. Protons and neutrons exchange by collective modes which are formed by isovector $π$ and $ρ$ -mesons, in turn, softened considerably because of coupling to nucleons of the medium. These modes are investigated within the proton-neutron relativistic random phase approximation (pn-RRPA) and relativistic proton-neutron time blocking approximation (pn-RTBA). The appearance of isospin-flip states with sizable transition probabilities at low energies points out that they are likely to couple to the single-particle degrees of freedom and, in addition to isoscalar low-lying phonons, to modify their spectroscopic characteristics. Such a coupling is quantified for the shell structure of $^{100, 132}$ Sn and found significant for the location of the dominant single-particle states.
Comments:
Article; 9 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08499 [pdf]
PLB(2016)·25 citations
02
[Submitted on 29 Sept 2015]
The Unified Hydrodynamics and the Pseudorapidity Distributions in Heavy Ion Collisions at BNL-RHIC and CERN-LHC Energies
Z. J. Jiang🇨🇳 · J. Wang🇨🇳 · K.Ma🇨🇳 · H. L. Zhang🇨🇳
The charged particles produced in nucleus-nucleus collisions are divided into two parts. One is from the hot and dense matter created in collisions. The other is from leading particles. The hot and dense matter is assumed to expand according to unified hydrodynamics and freezes out into charged particles from a space-like hypersurface with a fixed proper time of Tau_FO.The leading particles are conventionally taken as the particles which inherit the quantum numbers of colliding nucleons and carry off most of incident energy. The rapidity distributions of the charged particles from these two parts are formulated analytically, and a comparison is made between the theoretical results and the experimental measurements performed in Au-Au and Pb-Pb collisions at the respective BNL-RHIC and CERN-LHC energies. The theoretical results are well consistent with experimental data.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08555 [pdf]
0 citations
03
[Submitted on 29 Sept 2015]
Transverse momentum and pseudorapidity distributions of final-state particles and spatial structure pictures of interacting system in p-Pb collisions at \sqrt{s_{NN}}=5.02 TeV
Fu-Hu Liu🇨🇳 · Hua-Rong Wei🇨🇳 · Roy A. Lacey🇺🇸
The transverse momentum and pseudorapidity distributions of final-state particles produced in proton-lead (p-Pb) collisions at center-of-mass energy per nucleon pair \sqrt{s_{NN}}=5.02 TeV are studied in the framework of a multisource thermal model. Experimental results measured by the ALICE and CMS Collaborations are described by the Tsallis transverse momentum distribution and the two-cylinder pseudorapidity distribution. Based on the parameter values extracted from the transverse momentum and pseudorapidity distributions, some other quantities are extracted. Then, the structure pictures of interacting system at the stage of kinetic freeze-out in some spaces are obtained.
Comments:
21 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08602 [pdf]
EPJA(2015)·4 citations
04
[Submitted on 29 Sept 2015]
On Productions of Net-baryons in Central Au-Au Collisions at RHIC Energies
Ya-Hui Chen🇨🇳 · Guo-Xing Zhang🇨🇳 · Fu-Hu Liu🇨🇳
The transverse momentum and rapidity distributions of net-baryons (baryons minus anti-baryons) produced in central gold-gold (Au-Au) collisions at 62.4 and 200 GeV are analyzed in the framework of a multisource thermal model. Each source in the model is described by the Tsallis statistics to extract the effective temperature and entropy index from the transverse momentum distribution. The two parameters are used as input to describe the rapidity distribution and to extract the rapidity shift and contribution ratio. Then, the four types of parameters are used to structure some scatter plots of the considered particles in some three-dimensional (3D) spaces at the stage of kinetic freeze-out, which are expected to show different characteristics for different particles and processes. The related methodology can be used in the analyzes of particle production and event holography, which are useful for us to better understand the interacting mechanisms.
Comments:
14 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08606 [pdf]
Adv.High Energy Phys.(2015)·5 citations
05
[Submitted on 29 Sept 2015]
Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the $^{12}$ C test nucleus
C. Robin · N. Pillet · D. Peña Arteaga · J.-F. Berger
Although self-consistent multi-configuration methods have been used for decades to address the description of atomic and molecular many-body systems, only a few trials have been made in the context of nuclear structure. This work aims at the development of such an approach to describe in a unified way various types of correlations in nuclei, in a self-consistent manner where the mean-field is improved as correlations are introduced. The goal is to reconcile the usually set apart Shell-Model and Self-Consistent Mean-Field methods. This approach is referred as "variational multiparticle-multihole configuration mixing method". It is based on a double variational principle which yields a set of two coupled equations that determine at the same time the expansion coefficients of the many-body wave function and the single particle states. The formalism is derived and discussed in a general context, starting from a three-body Hamiltonian. Links to existing many-body techniques such as the formalism of Green's functions are established. First applications are done using the two-body D1S Gogny effective force. The numerical procedure is tested on the $^{12}$ C nucleus in order to study the convergence features of the algorithm in different contexts. Ground state properties as well as single-particle quantities are analyzed, and the description of the first $2^{+}$ state is examined. This study allows to validate our numerical algorithm and leads to encouraging results. In order to test the method further, we will realize in the second article of this series, a systematic description of more nuclei and observables obtained by applying the newly-developed numerical procedure with the same Gogny force. As raised in the present work, applications of the variational multiparticle-multihole configuration mixing method will however ultimately require the use of an extended and more constrained Gogny force.
Comments:
22 pages, 18 figures, accepted for publication in Phys. Rev. C. v2: minor corrections and references added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1509.08694 [pdf]
PRC(2016)·24 citations
06
[Submitted on 29 Sept 2015]
How strange is pion electroproduction?
Mikhail Gorchtein🇩🇪 · Hubert Spiesberger🇩🇪 · Xilin Zhang🇺🇸
We consider pion production in parity-violating electron scattering (PVES) in the presence of nucleon strangeness in the framework of partial wave analysis with unitarity. Using the experimental bounds on the strange form factors obtained in elastic PVES, we study the sensitivity of the parity-violating asymmetry to strange nucleon form factors. For forward kinematics and electron energies above 1 GeV, we observe that this sensitivity may reach about 20\% in the threshold region. With parity-violating asymmetries being as large as tens p.p.m., this study suggests that threshold pion production in PVES can be used as a promising way to better constrain strangeness contributions. Using this model for the neutral current pion production, we update the estimate for the dispersive $γ Z$ -box correction to the weak charge of the proton. In the kinematics of the Qweak experiment, our new prediction reads Re $□_{γ Z}^{V} (E = 1.165 GeV) = (5.58 \pm 1.41) \times 1 0^{- 3}$ , an improvement over the previous uncertainty estimate of $\pm 2.0 \times 1 0^{- 3}$ . Our new prediction in the kinematics of the upcoming MESA/P2 experiment reads Re $□_{γ Z}^{V} (E = 0.155 GeV) = (1.1 \pm 0.2) \times 1 0^{- 3}$ .
Comments:
18 pages, 10 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1509.08780 [pdf]
PLB(2016)·12 citations

Affiliations

first authorsco-authorsvia INSPIRE

Pion-nucleon correlations in finite nuclei in a relativistic framework: effects on the shell structure

The Unified Hydrodynamics and the Pseudorapidity Distributions in Heavy Ion Collisions at BNL-RHIC and CERN-LHC Energies

Transverse momentum and pseudorapidity distributions of final-state particles and spatial structure pictures of interacting system in p-Pb collisions at \sqrt{s_{NN}}=5.02 TeV

On Productions of Net-baryons in Central Au-Au Collisions at RHIC Energies

Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the 12C test nucleus

How strange is pion electroproduction?

Affiliations

Description of nuclear systems with a self-consistent configuration-mixing approach. I: Theory, algorithm, and application to the $^{12}$ C test nucleus