Nuclear Theory·nucl-th

Wednesday·September 7, 2016

9 papers—4 primary·5 cross-listed

01
[Submitted on 5 Sept 2016]
Isospin dependence of nucleon effective masses in neutron-rich matter
Bao-An Li · Bao-Jun Cai · Lie-Wen Chen · Xiao-Hua Li
In this talk, we first briefly review the isospin dependence of the total nucleon effective mass $M_{J}^{*}$ inferred from analyzing nucleon-nucleus scattering data within an isospin dependent non-relativistic optical potential model, and the isospin dependence of the nucleon E-mass $M_{J}^{*, E}$ obtained from applying the Migdal-Luttinger theorem to a phenomenological single-nucleon momentum distribution in nuclei constrained by recent electron-nucleus scattering experiments. Combining information about the isospin dependence of both the nucleon total effective mass and E-mass, we then infer the isospin dependence of nucleon k-mass using the well-known relation $M_{J}^{*} = M_{J}^{*, E} \cdot M_{J}^{*, k}$ . Implications of the results on the nucleon mean free path (MFP) in neutron-rich matter are discussed.
Comments:
An invited talk given at the 5th International Workshop on Nuclear Dynamics in Heavy-Ion Reactions (IWND2016), Xinxiang, China, May 15-20, 2016
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex)
arXiv:
1609.01324 [pdf]
Nucl.Sci.Tech.(2016)·10 citations
02
[Submitted on 6 Sept 2016]
3 $α$ -cluster structure and monopole transition in $^{12}$ C and $^{14}$ C
Yuta Yoshida · Yoshiko Kanada-En'yo
3 $α$ -cluster structures and monopole transitions of $0^{+}$ states in $^{12}$ C and $^{14}$ C were investigated with $3 α$ - and $^{10}$ Be+ $α$ -cluster models. A gas-like $3 α$ state and a bending-chain $3 α$ state were obtained in the $0_{2}^{+}$ and $0_{3}^{+}$ states of $^{12}$ C, respectively. In $^{14}$ C, a linear-chain 3 $α$ structure is found in the $0_{4}^{+}$ state near the $^{10}$ Be+ $α$ threshold, but a cluster gas-like state does not appear because valence neutrons attract $α$ clusters and suppress spatial development of 3 $α$ clustering. It was found that the linear-chain state in $^{14}$ C is stabilized against the bending and $α$ escaping modes by valence neutrons. The monopole transition strengths in $^{12}$ C are enhanced by $3 α$ -cluster developing, whereas, those in $^{14}$ C are not enhanced so much because of the tight binding of $α$ clusters by valence neutrons.
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1609.01407 [pdf]
1 citation
03
[Submitted on 6 Sept 2016]
Baryon Number Fluctuations in Quasi-particle Model
Ameng Zhao🇨🇳 · Xiaofeng Luo🇨🇳 · Hongshi Zong🇨🇳
Baryon number fluctuations are sensitive to the QCD phase transition and QCD critical point. According to the Feynman rules of finite-temperature field theory, we calculated various order moments and cumulants of the baryon number distributions in the quasi-particle model of quark gluon plasma. Furthermore, we compared our results with the experimental data measured by the STAR experiment at RHIC. It is found that the experimental data can be well described by the model for the colliding energies above 30 GeV and show large discrepancies at low energies. It can put new constraint on qQGP model and also provide a baseline for the QCD critical point search in heavy-ion collisions at low energies.
Comments:
13 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:
1609.01416 [pdf]
EPJC(2017)·6 citations
04
[Submitted on 6 Sept 2016]
Microscopic phase-space exploration modeling of $^{258}$ Fm spontaneous fission
Yusuke Tanimura🇫🇷 · Denis Lacroix🇫🇷 · Sakir Ayik🇺🇸
We show that the total kinetic energy (TKE) of nuclei after the spontaneous fission of $^{258}$ Fm can be well reproduced using simple assumptions on the quantum collective phase-space explored by the nucleus after passing the fission barrier. Assuming energy conservation and phase-space exploration according to the stochastic mean-field approach, a set of initial densities is generated. Each density is then evolved in time using the nuclear time-dependent density-functional theory. This approach goes beyond mean-field by allowing spontaneous symmetry breaking as well as a wider dynamical phase-space exploration leading to larger fluctuations in collective space. The total kinetic energy and mass distributions are calculated. New information on the fission process: fluctuations in scission time, strong correlation between TKE and collective deformation of daughter nuclei as well as pre- and post-scission particle emission, are obtained.
Comments:
Accepted to PRL (Supplement material available upon demand). All calculations made with dynamical pairing
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1609.01424 [pdf]
PRL(2017)·102 citations
05
[Submitted on 31 Aug 2016] (cross-list from nucl-ex)
K-Long Facility for JLab and its Scientific Potential
Igor I. Strakovsky🇺🇸
Our main interest in creating a secondary high-quality KL-beam is to investigate hyperon spectroscopy through both formation and production processes. We propose to study two-body reactions induced by the KL-beam on the proton target. The experiment should measure both differential cross sections and self-analyzed polarizations of the produced $Λ$ -, $Σ$ -, and $Ξ$ -hyperons using the GlueX detector at the Jefferson Lab Hall D. New data will greatly constrain partial-wave analysis and reduce model-dependent uncertainties in the extraction of strange resonance properties, providing a new benchmark for comparisons with QCD-inspired models and LQCD calculations. The measurements will span c.m. $cos θ$ from -0.95 to 0.95 in c.m. range above W = 1490MeV and up to 4000 MeV.
Comments:
7 pages, 4 figures, contribution to the Proceedings of 14th International Workshop on Meson Production, Properties and Interaction Krakow, Poland, 2nd - 7th June 2016
Subjects:
Nuclear Experiment (nucl-ex); High Energy Physics — Experiment (hep-ex); High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1608.08822 [pdf]
EPJ Web Conf.(2016)·2 citations
06
[Submitted on 5 Sept 2016] (cross-list from hep-ph)
Chiral corrections to the Adler-Weisberger sum rule
Silas R. Beane🇺🇸 · Natalie Klco🇺🇸
The Adler-Weisberger sum rule for the nucleon axial-vector charge, $g_{A}$ , offers a unique signature of chiral symmetry and its breaking in QCD. Its derivation relies on both algebraic aspects of chiral symmetry, which guarantee the convergence of the sum rule, and dynamical aspects of chiral symmetry breaking---as exploited using chiral perturbation theory---which allow the rigorous inclusion of explicit chiral symmetry breaking effects due to light-quark masses. The original derivations obtained the sum rule in the chiral limit and, without the benefit of chiral perturbation theory, made various attempts at extrapolating to non-vanishing pion masses. In this paper, the leading, universal, chiral corrections to the chiral-limit sum rule are obtained. Using PDG data, a recent parametrization of the pion-nucleon total cross-sections in the resonance region given by the SAID group, as well as recent Roy-Steiner equation determinations of subthreshold amplitudes, threshold parameters, and correlated low-energy constants, the Adler-Weisberger sum rule is confronted with experimental data. With uncertainty estimates associated with the cross-section parameterization, the Goldberger-Treimann discrepancy, and the truncation of the sum rule at $O (M_{π}^{4})$ in the chiral expansion, this work finds $g_{A} = 1.248 \pm 0.010 \pm 0.007 \pm 0.013$ .
Comments:
19 pages, 5 figures
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.01350 [pdf]
PRD(2016)·3 citations
07
[Submitted on 6 Sept 2016] (cross-list from hep-ph)
Goldstone-Type Pseudoscalar Mesons: Instantaneous Bethe-Salpeter Models
Wolfgang Lucha🇦🇹
A nontrivial instantaneous variant of the Bethe-Salpeter formalism allows us to discuss massless pseudoscalar mesons from a configuration-space-potential point of view.
Comments:
6 pages, 5 figures, contributed to "Quark Confinement and the Hadron Spectrum XII" (28 August - 3 September 2016, Thessaloniki, Greece)
Subjects:
High Energy Physics — Phenomenology (hep-ph); Nuclear Theory (nucl-th)
arXiv:
1609.01474 [pdf]
EPJ Web Conf.(2017)·5 citations
08
[Submitted on 6 Sept 2016] (cross-list from hep-ph)
Generalized Skyrme model with the loosely bound potential
Sven Bjarke Gudnason🇨🇳 · Baiyang Zhang🇨🇳 · Nana Ma🇨🇳
We study a generalization of the loosely bound Skyrme model which consists of the Skyrme model with a sixth-order derivative term - motivated by its fluid-like properties - and the second-order loosely bound potential - motivated by lowering the classical binding energies of higher-charged Skyrmions. We use the rational map approximation for the Skyrmion of topological charge B=4, calculate the binding energy of the latter and estimate the systematic error in using this approximation. In the parameter space that we can explore within the rational map approximation, we find classical binding energies as low as 1.8% and once taking into account the contribution from spin-isospin quantization we obtain binding energies as low as 5.3%. We also calculate the contribution from the sixth-order derivative term to the electric charge density and axial coupling.
Comments:
RevTeX: 33 pages, 14 figures; V2: comments and references added
Subjects:
High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th); Nuclear Theory (nucl-th)
arXiv:
1609.01591 [pdf]
PRD(2016)·28 citations
09
[Submitted on 6 Sept 2016] (cross-list from cond-mat.quant-gas)
Thermodynamics of one-dimensional SU(4) and SU(6) fermions with attractive interactions
M. D. Hoffman🇺🇸 · A. C. Loheac🇺🇸 · W. J. Porter🇺🇸 · J. E. Drut🇺🇸
Motivated by advances in the manipulation and detection of ultracold atoms with multiple internal degrees of freedom, we present a finite-temperature lattice Monte Carlo calculation of the density and pressure equations of state, as well as Tan's contact, of attractively interacting SU(4)- and SU(6)-symmetric fermion systems in one spatial dimension. We also furnish a nonperturbative proof of a universal relation whereby quantities computable in the SU(2) case completely determine the virial coefficients of the SU( $N_{f}$ ) case. These one-dimensional systems are appealing because they can be experimentally realized in highly constrained traps and because of the dominant role played by correlations. The latter are typically nonperturbative and are crucial for understanding ground states and quantum phase transitions. While quantum fluctuations are typically overpowered by thermal ones in one and two dimensions at any finite temperature, we find that quantum effects do leave their imprint in thermodynamic quantities. Our calculations show that the additional degrees of freedom, relative to the SU(2) case, provide a dramatic enhancement of the density and pressure (in units of their noninteracting counterparts) in a wide region around vanishing $β μ$ , where $β$ is the inverse temperature and $μ$ the chemical potential. As shown recently in experiments, the thermodynamics we explore here can be measured in a controlled and precise fashion in highly constrained traps and optical lattices. Our results are a prediction for such experiments in one dimension with atoms of high nuclear spin.
Comments:
11 pages, 7 figures; published version
Subjects:
Quantum Gases (cond-mat.quant-gas); High Energy Physics — Lattice (hep-lat); Nuclear Theory (nucl-th)
arXiv:
1609.01702 [pdf]
PRA(2017)·6 citations

Affiliations

first authorsco-authorsvia INSPIRE