Nuclear Theory·nucl-th

Monday·February 29, 2016

5 papers—3 primary·2 cross-listed

01
Equation of state for neutron stars with hyperons by the variational method
H. Togashi🇯🇵 · E. Hiyama🇯🇵 · Y. Yamamoto🇯🇵 · M. Takano🇯🇵
We investigate the effects of the odd-state part of bare $ΛΛ$ interactions on the structure of neutron stars (NSs) by constructing equations of state (EOSs) for uniform nuclear matter containing $Λ$ and $Σ^{-}$ hyperons with use of the cluster variational method. The isoscalar part of the Argonne v18 two-nucleon potential and the Urbana IX three-nucleon potential are employed as the interactions between nucleons, whereas, as the bare $Λ N$ and even-state $ΛΛ$ interactions, two-body central potentials that are determined so as to reproduce the experimental data on single- and double- $Λ$ hypernuclei are adopted. In addition, the $Σ^{-} N$ interaction is constructed so as to reproduce the empirical single-particle potential of $Σ^{-}$ in symmetric nuclear matter. Since the odd-state part of the $ΛΛ$ interaction is not known owing to lack of experimental data, we construct four EOSs of hyperonic nuclear matter, each with a different odd-state part of the $ΛΛ$ interaction. The EOS obtained for NS matter becomes stiffer as the odd-state $ΛΛ$ interaction becomes more repulsive, and correspondingly the maximum mass of NSs increases. It is interesting that the onset density of $Σ^{-}$ depends strongly on the repulsion of the odd-state $ΛΛ$ interaction. Furthermore, we take into account the three-baryon repulsive force to obtain results that are consistent with observational data on heavy NSs.
nucl-thastro-ph.HEPRC(2016)·68 citations
02
Global correlations between electromagnetic and spectroscopic properties of collective $2_{1}^{+}$ and $2_{2}^{+}$ states
Z. Z. Qin · Y. Lei · S. Pittel
By using the general triaxial rotor model (TRM) and the phonon-configuration mixing scheme within an anharmonic-vibrator(AHV) framework, a series of global correlations between electromagnetic properties of nuclear $2_{1}^{+}$ and $2_{2}^{+}$ states are analytically established. The correlations from both models can roughly describe the experimental data involving quadrupole collectivity with few exceptions. Furthermore, there seems to be a robust orthogonal transformation between the AHV and TRM bases for realistic nuclear systems, suggesting that the two models may in fact be describing the collective features of nuclear low-lying states in similar model spaces.
nucl-thPRC(2016)·2 citations
03
Thermodynamics and kinetics of Gribov-Zwanziger plasma with temperature dependent Gribov parameter
Viktor Begun🇵🇱 · Wojciech Florkowski🇵🇱 · Radoslaw Ryblewski🇵🇱
A Gribov-type dispersion relation is treated as an effective description of interacting gluons forming a hot medium. Temperature dependence of the Gribov parameter is determined from the fit to the lattice Yang-Mills results describing thermodynamic functions. To maintain thermodynamic consistency of the approach, a temperature dependent bag pressure is introduced. The results obtained for equilibrium functions are generalised in the next step to non-equilibrium conditions. We derive formulas for the bulk and shear viscosity coefficients within the relaxation time approximation. We find evidence for largely enhanced bulk viscosity in the region of the phase transition.
nucl-thhep-phActa Phys.Polon.B(2017)·13 citations
04
Generation of random deviates for relativistic quantum-statistical distributions
Boris Tomášik · Ivan Melo · Jakub Cimerman
We provide an algorithm for generation of momenta (or energies) of relativistic particles according to the relativistic Bose-Einstein or Fermi-Dirac distributions. The algorithm uses rejection method with effectively selected comparison function so that the acceptance rate of the generated values is always better than 0.9. It might find its use in Monte-Carlo generators of particles from reactions in high-energy physics.
↳ physics.comp-phhep-phnucl-th0 citations
05
$χ_{c 0}^{†} (3915)$ As the Lightest $c c ˉ s s ˉ$ State
Richard F. Lebed🇺🇸 · Antonio D. Polosa🇮🇹
The state $χ_{c 0}^{†} (3915)$ has recently been demoted by the Particle Data Group from its previous status as the conventional $c c ˉ$ $2^{3} P_{0}$ state, largely due to the absence of expected $D D ˉ$ decays. We propose that $χ_{c 0}^{†} (3915)$ is actually the lightest $c c ˉ s s ˉ$ state, and calculate the spectrum of such states using the diquark model, identifying many of the observed charmoniumlike states that lack open-charm decay modes as $c c ˉ s s ˉ$ . Among other results, we argue that $Y (4140)$ is a $J^{P C} = 1^{++}$ $c c ˉ s s ˉ$ state that has been not been seen in two-photon fusion largely as a consequence of the Landau-Yang theorem.
↳ hep-phnucl-thPRD(2016)·97 citations

Affiliations

first authorsco-authorsvia INSPIRE

Equation of state for neutron stars with hyperons by the variational method

Global correlations between electromagnetic and spectroscopic properties of collective 21+​ and 22+​ states

Thermodynamics and kinetics of Gribov-Zwanziger plasma with temperature dependent Gribov parameter

Generation of random deviates for relativistic quantum-statistical distributions

χc0†​(3915) As the Lightest ccˉssˉ State

Affiliations

Global correlations between electromagnetic and spectroscopic properties of collective $2_{1}^{+}$ and $2_{2}^{+}$ states

$χ_{c 0}^{†} (3915)$ As the Lightest $c c ˉ s s ˉ$ State