Nuclear Theory·nucl-th

Tuesday·October 20, 2015

16 papers—10 primary·6 cross-listed

01
[Submitted on 17 Oct 2015]
Chiral phase transition and Schwinger mechanism in a pure electric field
Gaoqing Cao🇨🇳 · Xu-Guang Huang🇨🇳
We systematically study the chiral symmetry breaking and restoration in the presence of a pure electric field in the Nambu--Jona-Lasinio (NJL) model at finite temperature and baryon chemical potential. In addition, we also study the effect of the chiral phase transition on the charged pair production due to the Schwinger mechanism. For these purposes, a general formalism for parallel electric and magnetic fields is developed at finite temperature and chemical potential for the first time. In the pure electric field limit $B \to 0$ , we compute the order parameter, the transverse-to-longitudinal ratio of the Goldstone mode velocities, and the Schwinger pair production rate as functions of the electric field. The inverse catalysis effect of the electric field to chiral symmetry breaking is recovered. And the Goldstone mode is find to disperse anisotropically such that the transverse velocity is always smaller than the longitudinal one, especially at nonzero temperature and baryon chemical potential. As expected, the quark-pair production rate is greatly enhanced by the chiral symmetry restoration.
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1510.05125 [pdf]
PRD(2016)·30 citations
02
[Submitted on 17 Oct 2015]
Statistical theory of light nucleus reaction and application to $^{9}$ Be(p, xn) reaction
Xiaojun Sun🇨🇳 · Jingshang Zhang🇨🇳
A statistical theory of light nucleus reaction (STLN) is proposed to describe both neutron and light charged particle induced nuclear reactions with 1p-shell light nuclei involved. The dynamic of STLN is described by the unified Hauser-Feshbach and exciton model, of which the angular momentum and parity conservations are considered in equilibrium and pre-equilibrium processes. The Coulomb barriers of the incident and outgoing charged particles, which seriously influence the open reaction channels, could be reasonably considered in the incident channel and the different outgoing channels. In kinematics, the recoiling effects in various emission processes are taken strictly into account. Taking $^{9}$ Be(p, xn) reaction as an example, we calculate the double-differential cross sections of outgoing neutrons and charged particles using PUNF code in the frame of STLN. The calculated results agree very well with the existing experimental neutron double-differential cross sections at $E_{p} = 18$ MeV, and indicate that PUNF code is a powerful tool to set up file-6 in the reaction data library for the light charged particle induced nuclear reactions with 1p-shell light nuclei involved.
Comments:
30 pages, 5 figures, 44 references. arXiv admin note: text overlap with arXiv:1510.04580
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.05163 [pdf]
PRC(2016)·7 citations
03
[Submitted on 18 Oct 2015]
Anatomy of molecular structures in $^{20}$ Ne
E. F. Zhou🇨🇳 · J. M. Yao🇨🇳 · Z. P. Li🇨🇳 · J. Meng🇨🇳 · P. Ring🇨🇳
We present a beyond mean-field study of clusters and molecular structures in low-spin states of $^{20}$ Ne with a multireference relativistic energy density functional, where the dynamical correlation effects of symmetry restoration and quadrupole-octupole shapes fluctuation are taken into account with projections on parity, particle number and angular momentum in the framework of the generator coordinate method. Both the energy spectrum and the electric multipole transition strengths for low-lying parity-doublet bands are better reproduced after taking into account the dynamical octupole vibration effect. Consistent with the finding in previous studies, a rotation-induced dissolution of the $α +^{16}$ O molecular structure in $^{20}$ Ne is predicted.
Comments:
6 pages with 6 figures, version to be published in Phys. Lett. B
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1510.05232 [pdf]
PLB(2016)·59 citations
04
[Submitted on 19 Oct 2015]
Systematical shell-model calculation in the pairing-plus-multipole Hamiltonian with a monopole interaction for the pf5/2g9/2 shell
K. Kaneko🇯🇵 · T. Mizusaki🇯🇵 · Y. Sun🇨🇳 · S. Tazaki🇯🇵
The recently-proposed effective shell-model interaction, the pairing-plus-multipole Hamiltonian with the monopole interaction obtained by empirical fits starting from the monopole-based universal force (PMMU), is systematically applied to nuclei of the pf5/2g9/2 shell region. It is demonstrated that the calculation describes reasonably well a wide range of experimental data, including not only the low-lying and high-excitation spectra, E2 transitions, quadrupole moments, and magnetic moments, but also the binding energies, for Ni, Cu, Zn, Ga, Ge, As, and Se isotopes with A=64-80. In particular, a structure of the neutron-rich Ge and Se isotopes is discussed in detail.
Comments:
21 pages, 31 figures, accepted in Phys. Rev. C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.05340 [pdf]
PRC(2015)·37 citations
05
[Submitted on 19 Oct 2015]
Global $α$ -decay study based on the mass table of the relativistic continuum Hartree-Bogoliubov theory
Linfeng Zhang🇨🇳 · Xuewei Xia🇨🇳
The $α$ -decay energies ( $Q_{α}$ ) are systematically investigated with the nuclear masses for $10 \leq Z \leq 120$ isotopes obtained by the relativistic continuum Hartree-Bogoliubov (RCHB) theory with the covariant density functional PC-PK1, and compared with available experimental values. It is found that the $α$ -decay energies deduced from the RCHB results present similar pattern as those from available experiments. Owing to the large predicted $Q_{α}$ values ( $\geq$ 4 MeV), many undiscovered heavy nuclei in the proton-rich side and super-heavy nuclei may have large possibilities for $α$ -decay. The influence of nuclear shell structure on $α$ -decay energies is also analysed.
Comments:
7 pages, 4 figures. arXiv admin note: text overlap with arXiv:1309.3987 by other authors
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.05375 [pdf]
CPC(2016)·12 citations
06
[Submitted on 19 Oct 2015]
Evolution of $N = 28$ shell closure in relativistic continuum Hartree-Bogoliubov theory
Xuewei Xia
The $N = 28$ shell gap in sulfur, argon, calcium and titanium isotopes is investigated in the framework of relativistic continuum Hartree-Bogoliubov (RCHB) theory. The evolutions of neutron shell gap, separation energy, single particle energy and pairing energy are analyzed, and it is found that $N = 28$ shell gap is quenched in sulfur isotopes but persists in argon, calcium and titanium isotopes. The evolution of $N = 28$ shell gap in $N = 28$ isotonic chain is discussed, and the erosion of $N = 28$ shell gap is understood with the evolution of potential with proton number.
Comments:
9 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.05381 [pdf]
CPC(2016)·3 citations
07
[Submitted on 7 Aug 2015]
Can Tsallis distribution fit all the particle spectra produced at RHIC and LHC?
H. Zheng🇮🇹 · Lilin Zhu🇨🇳
The Tsallis distribution has been tested to fit the all particle spectra at mid-rapidity from central events produced in d+Au, Cu+Cu, Au+Au collisions at RHIC and p+Pb, Pb+Pb collisions at LHC. Even though there are strong medium effects in Cu+Cu and Au+Au collisions, the results show that the Tsallis distribution can be used to fit most of particle spectra in the collisions studied except in Au+Au collisions where some deviations are seen for proton and $Λ$ at low $p_{T}$ . In addition, as the Tsallis distribution can only fit part of the particle spectra produced in Pb+Pb collisions where $p_{T}$ is up to 20 GeV/c, a new formula with one more fitting degree of freedom is proposed in order to reproduce the entire $p_{T}$ region.
Comments:
8 pages, 6 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1510.05449 [pdf]
Adv.High Energy Phys.(2015)·60 citations
08
[Submitted on 17 Sept 2015]
Green's Function Monte Carlo Calculations with Two- and Three-Nucleon Interactions from Chiral Effective Field Theory
J. E. Lynn🇺🇸
I discuss our recent work on Green's function Monte Carlo (GFMC) calculations of light nuclei using local nucleon-nucleon interactions derived from chiral effective field theory (EFT) up to next-to-next-to-leading order (N $^{2}$ LO). I present the natural extension of this work to include the consistent three-nucleon (3N) forces at the same order in the chiral expansion. I discuss our choice of observables to fit the two low-energy constants which enter in the 3N sector at N $^{2}$ LO and present some results for light nuclei.
Comments:
Contribution to the Proceedings of the 21st International Conference on Few-Body Problems in Physics. May 18-22, 2015. Chicago, Illinois, USA
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1510.05450 [pdf]
EPJ Web Conf.(2016)·1 citation
09
[Submitted on 19 Oct 2015]
Deformation-induced splitting of the monopole giant resonance in 24Mg
J. Kvasil · V.O. Nesterenko · A. Repko · P.-G. Reinhard · W. Kleinig
The strong deformation splitting of the isoscalar giant monopole resonance (ISGMR), recently observed in ( $α, α^{'}$ ) reaction in prolate $^{24}$ Mg, is analyzed in the framework of the Skyrme quasiparticle random-phase-approximation (QRPA) approach with the Skyrme forces SkM*, SVbas and SkP $^{δ}$ . The calculations with these forces give close results and confirm that the low-energy E0-peak is caused by the deformation-induced coupling of ISGMR with the K=0 branch of the isoscalar giant quadrupole resonance.
Comments:
3 pages, 1 figure, to be published in EPJ Web of Conferences (Proceedings of the International Conference NSRT15, Dubna, Russia, 2015)
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.05499 [pdf]
EPJ Web Conf.(2016)·8 citations
10
[Submitted on 19 Oct 2015]
Net-proton number kurtosis and skewness in nuclear collisions: Influence of deuteron formation
Zuzana Feckova🇸🇰 · Jan Steinheimer🇩🇪 · Boris Tomasik🇸🇰 · Marcus Bleicher🇩🇪
We explore the influence of deuteron formation in the late stage of nucleus-nucleus reactions on the fluctuations observed in the final net-proton yields around midrapidity. At each investigated energy, the produced (anti-)proton yield at chemical freeze-out is assumed to fluctuate according to a Poisson distribution and in each event the probability for deuteron formation by coalescence is proportional to $(d N_{proton} / d y)^{2}$ . The protons that are then clustered in deuterons are usually not included in the experimental measurement of the net-proton fluctuations, therefore, we subtract these clustered protons from the final state proton number for the calculation of the net-proton fluctuations (the same is done in the anti-proton sector). Due to the non-linear deuteron formation probability the resulting distribution is not a Skellam distribution, but shows the interesting feature of a decrease in the kurtosis $κ σ^{2}$ and a local maximum in the skewness $S σ$ observables as the collision energy decreases.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1510.05519 [pdf]
PRC(2015)·24 citations

Affiliations

first authorsco-authorsvia INSPIRE