Nuclear Theory·nucl-th

Thursday·December 14, 2017

9 papers—6 primary·3 cross-listed

01
[Submitted on 12 Dec 2017]
Light-meson masses in an unquenched quark model
Xiaoyun Chen🇨🇳 · Jialun Ping🇨🇳 · Craig D. Roberts🇺🇸 · Jorge Segovia🇪🇸
We perform a coupled-channels calculation of the masses of light mesons with the quantum numbers $I J^{P = -}$ , $(I, J) = 0, 1$ , by including $q q ˉ$ and $(q q ˉ)^{2}$ components in a nonrelativistic chiral quark model. The coupling between two- and four-quark configurations is realized through a $^{3} P_{0}$ quark-pair creation model. With the usual form of this operator, the mass shifts are large and negative, an outcome which raises serious issues of validity for the quenched quark model. Herein, therefore, we introduce some improvements of the $^{3} P_{0}$ operator in order to reduce the size of the mass shifts. By introducing two simple factors, physically well motivated, the coupling between $q q ˉ$ and $(q q ˉ)^{2}$ components is weakened, producing mass shifts that are around 10-20% of hadron bare masses.
Comments:
10 pages, 1 figure, 7 tables
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.04457 [pdf]
PRD(2018)·31 citations
02
[Submitted on 12 Dec 2017]
Self-consistency in the phonon space of the particle-phonon coupling model
V. Tselyaev · N. Lyutorovich · J. Speth · P.-G. Reinhard
In the paper the non-linear generalization of the time blocking approximation (TBA) is presented. The TBA is one of the versions of the extended random-phase approximation (RPA) developed within the Green-function method and the particle-phonon coupling model. In the generalized version of the TBA the self-consistency principle is extended onto the phonon space of the model. The numerical examples show that this non-linear version of the TBA leads to the convergence of the results with respect to enlarging the phonon space of the model.
Comments:
12 pages, 10 figures, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1712.04494 [pdf]
PRC(2018)·28 citations
03
[Submitted on 12 Dec 2017]
The role of strangeness and isospin in low density expansions of hadronic matter
Thamirys de Oliveira🇧🇷 · Débora P. Menezes🇧🇷 · Marcus B. Pinto🇧🇷 · Francesca Gulminelli🇫🇷
We compare relativistic mean field models with their low density expansion counterparts used to mimic non-relativistic models by consistently expanding the baryonic scalar density in powers of the baryonic number density up to $O (13/3)$ , which goes two orders beyond the order considered in previous works. We show that, due to the non-trivial density dependence of the Dirac mass, the convergence of the expansion is very slow, and the validity of the non-relativistic approximation {\bf is} questionable even at subsaturation densities. In order to analyze the roles played by strangeness and isospin we consider $n - Λ$ and $n - p$ matter separately. Our results indicate that these degrees of freedom play quite different roles in the expansion mechanism and $n - Λ$ matter can be better described by low density expansions than $n - p$ matter in general.
Comments:
35 pages, 26 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1712.04526 [pdf]
PRC(2018)·1 citation
04
[Submitted on 13 Dec 2017]
Probing proton transition momentum in neutron-rich matter
Gao-Chan Yong
Around the nuclear Fermi momentum, there is a transition of nucleon momentum distribution n(k) in nuclear matter, i.e., from a constant to the $1/ k^{4}$ nucleon momentum distribution. While nowadays the transition momentum of minority in asymmetric matter is rarely studied and thus undetermined. In the framework of the IBUU transport model, proton transition momentum in nuclei is first studied. It is found that the transition momentum of proton is sensitive to the $π^{-} / π^{+}$ ratio as well as the energetic photon production in neutron-rich nuclear reaction. This result may push the study of how the proton momentum is distributed in neutron-rich matter forward and help us to better understand the dynamics of both neutron-rich nuclear reactions and neutron stars.
Comments:
5 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1712.04574 [pdf]
PLB(2018)·22 citations
05
[Submitted on 13 Dec 2017]
A flow paradigm in heavy-ion collisions
Li Yan🇨🇦
The success of hydrodynamics in high energy heavy-ion collisions leads to a flow paradigm, to understand the observed features of harmonic flow in terms of the medium collective expansion regarding initial state geometrical properties. In this review, we present some essential ingredients in the flow paradigm, including the hydrodynamic modeling, the characterization of initial state geometry and the medium response relations. The extension of the flow paradigm to small colliding systems is also discussed.
Comments:
Typo corrected, new references added. Published version for Chinese Physics C
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1712.04580 [pdf]
CPC(2018)·42 citations
06
[Submitted on 13 Dec 2017]
Production of light hypernuclei with light-ion beams and targets
Y.L. Sun🇫🇷 · A.S. Botvina🇩🇪 · A. Obertelli🇫🇷 · A. Corsi🇫🇷 · M. Bleicher🇩🇪
Ion-ion collisions at relativistic energies have been shown recently to be a promising technique for the production of hypernuclei. In this article, we further investigate the production of light $Λ$ hypernuclei by use of a hybrid dynamical model, cascade-coalescence followed by Fermi breakup. The predictions are then compared with the available experimental data. The dependence of the production cross section upon the beam energy, beam mass number as well as different projectile-target combinations is investigated. In particular, we evaluate the yields and signal-over-background ratio in the invariant-mass spectrum for carbon projectiles impinging on hydrogen and carbon targets and various coincidence conditions in the experiment using the theoretical calculation as an input. It is found that comparing with carbon target, hydrogen target also leads to sizable hypernuclear yields, even for exotic species, and the hydrogen target could improve significantly signal-over-background ratio in some hypernuclear invariant mass studies.
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
1712.04658 [pdf]
PRC(2018)·16 citations

Affiliations

first authorsco-authorsvia INSPIRE

Light-meson masses in an unquenched quark model

Self-consistency in the phonon space of the particle-phonon coupling model

The role of strangeness and isospin in low density expansions of hadronic matter

Probing proton transition momentum in neutron-rich matter

A flow paradigm in heavy-ion collisions

Production of light hypernuclei with light-ion beams and targets

Affiliations