Nuclear Theory·nucl-th

Thursday·October 22, 2015

10 papers—5 primary·5 cross-listed

01
[Submitted on 20 Oct 2015]
Jacobi no-core shell model for p-shell nuclei
S. Liebig · U.-G. Meißner · A. Nogga
We introduce an algorithm to obtain coefficients of fractional parentage for light $p$ -shell nuclei. The coefficients enable to use Jacobi coordinates in no-core shell model calculations separating off the center-of-mass motion. Fully antisymmetrized basis states are given together with recoupling coefficients that allow one to apply two- and three-nucleon operators. As an example, we study the dependence on the harmonic oscillator frequency of $^{3}$ H, $^{4}$ He, $^{6}$ He, $^{6}$ Li and $^{7}$ Li and extract their binding and excitation energies. The coefficients will be made openly accessible as HDF5 data files.
Comments:
23 pages, 17 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1510.06070 [pdf]
EPJA(2016)·34 citations
02
[Submitted on 21 Oct 2015]
Hyperon-mixed neutron star with universal many-body repulsion
Y. Yamamoto🇯🇵 · T. Furumoto🇯🇵 · N. Yasutake🇯🇵 · Th.A. Rijken🇳🇱
Neutron stars with large masses $\sim 2 M_{⊙}$ require the hard stiffness of equation of state (EoS) of neutron-star matter. On the other hand, hyperon mixing brings about remarkable softening of EoS. In order to solve this problem, a multi-pomeron exchange potential (MPP) is introduced as a model for the universal many-body repulsion in baryonic systems on the basis of the Extended Soft Core (ESC) baryon-baryon interaction. The strength of MPP is determined by analyzing the nucleus-nucleus scattering with the G-matrix folding model. The interactions in $Λ N$ , $Σ N$ and $Ξ N$ channels are shown to be consistent with experimental indications. The EoS in neutron-star matter with hyperon mixing is obtained from ESC in addition of MPP, and mass-radius relations of neutron stars are derived. The maximum mass is shown to reach $2 M_{⊙}$ even in the case of including hyperon mixing on the basis of model-parameters determined by terrestrial experiments.
Comments:
prepared for the 2015 EPJA Topical Issue on "Exotic Matter in Neutron Stars"
Subjects:
Nuclear Theory (nucl-th); Solar and Stellar Astrophysics (astro-ph.SR)
arXiv:
1510.06099 [pdf]
EPJA(2016)·50 citations
03
[Submitted on 21 Oct 2015]
Do hyperons exist in the interior of neutron stars ?
Debarati Chatterjee🇫🇷 · Isaac Vidana🇵🇹
In this work we review the role of hyperons on the properties of neutron and proto-neutron stars. In particular, we revise the so-called "hyperon puzzle", go over some of the solutions proposed to tackle it, and discuss the implications that the recent measurements of unusually high neutron star masses have on our present knowledge of hypernuclear physics. We reexamine also the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.
Comments:
19 pages, 9 figures, 1 table. Accepted for publication in the 2015 EPJA Topical Issue on "Exotic Matter in Neutron Stars"
Subjects:
Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
arXiv:
1510.06306 [pdf]
EPJA(2016)·277 citations
04
[Submitted on 21 Oct 2015]
Phenomenological analysis of near threshold periodic modulations of the proton timelike form factor
A. Bianconi🇮🇹 · E. Tomasi-Gustafsson🇫🇷
We have recently highlighted the presence of a periodically oscillating 10 \% modulation in the BABAR data on the proton timelike form factors, in the reaction $e^{+} + e^{-}$ $\to$ $p ˉ + p$ . Here we deepen our previous data analysis, and confirm that in the case of several standard parametrizations it is possible to write the form factor in the form $F_{0}$ $+$ $F_{osc}$ , where $F_{0}$ is a parametrization expressing the long-range trend of the form factor (for $q^{2}$ ranging from the $p ˉ p$ threshold to 36 GeV $^{2}$ ), and $F_{osc}$ is a function of the form $exp (- B p) cos (C p)$ , where $p$ is the relative momentum of the final $p ˉ p$ pair. Error bars allow for a clean identification of the main features of this modulation for $q^{2}$ $<$ 10 GeV $^{2}$ . Assuming this oscillatory modulation to be an effect of final state interactions between the forming proton and the antiproton, we propose a phenomenological model based on a double-layer imaginary optical potential. This potential is flux-absorbing when the distance between the proton and antiproton centers of mass is $≳$ 1.7-1.8 fm and flux-generating when it is $≲$ 1.7-1.8 fm. The main features of the oscillations may be reproduced with some freedom in the potential parameters, but the transition between the two layers must be sudden (0-0.2 fm) to get the correct oscillation period. The flux-absorbing part of the $p ˉ p$ interaction is due to the annihilation of $p ˉ p$ pairs into multi-meson states. We interpret the flux-creating part of the potential as due to the creation of a $1/ q$ -ranged state when the virtual photon decays into a set of current quarks and antiquarks, including heavy ones, that may exist for a short time. The decay of these large mass states leads to an intermediate stage regeneration of the $p ˉ p$ channel.
Comments:
25 pages, 8 figures - revised version - new section 5 with extended discussion
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1510.06338 [pdf]
PRC(2016)·52 citations
05
[Submitted on 21 Oct 2015]
A MUSTA-FORCE algorithm for solving partial differential equations of relativistic hydrodynamics
J. Porter-Sobieraj · M. Słodkowski · D. Kikoła · J. Sikorski · P. Aszklar
Understanding event-by-event correlations and fluctuations is crucial for the comprehension of the dynamics of heavy ion collisions. Relativistic hydrodynamics is an elegant tool for modeling these phenomena; however, such simulations are time-consuming, and conventional CPU calculations are not suitable for event-by-event calculations. This work presents a feasibility study of a new hydrodynamic code that employs graphics processing units together with a general MUSTA-FORCE algorithm (Multi-Stage Riemann Algorithm - First Order Centered scheme) to deliver a high-performance yet universal tool for event-by-event hydrodynamic simulations. We also investigate the performance of selected slope limiters that reduce the amount of numeric oscillations and diffusion in the presence of strong discontinuities and shock waves. The numerical results are compared to the exact solutions to assess the code's accuracy.
Comments:
22 pages, 10 figures, preprint draft to International Journal of Nonlinear Sciences and Numerical Simulation
Subjects:
Computational Physics (physics.comp-ph); Nuclear Theory (nucl-th)
arXiv:
1510.06340 [pdf]
Int.J.Nonlin.Sci.Numer.Simul.(2017)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE

Jacobi no-core shell model for p-shell nuclei

Hyperon-mixed neutron star with universal many-body repulsion

Do hyperons exist in the interior of neutron stars ?

Phenomenological analysis of near threshold periodic modulations of the proton timelike form factor

A MUSTA-FORCE algorithm for solving partial differential equations of relativistic hydrodynamics

Affiliations