Nuclear Theory·nucl-th

Friday·February 23, 2018

9 papers—8 primary·1 cross-listed

01
[Submitted on 20 Feb 2018]
Production of $N^{*} (1535)$ and $N^{*} (1650)$ in $Λ_{c} \to K ˉ^{0} η p$ $(π N)$ decay
R. Pavao🇪🇸 · S. Sakai🇪🇸 · E. Oset🇪🇸
In order to study the properties of the $N^{*}$ (1535) and $N^{*}$ (1650) we calculate the mass distributions of $M B$ in the $Λ_{c} \to K ˉ^{0} M B$ decay, with $M B = π N (I = 1/2), η p$ and $K Σ (I = 1/2)$ . We do this by calculating the tree-level and loop contributions, mixing pseudoscalar-baryon and vector-baryon channels using the local hidden gauge formalism. The loop contributions for each channel are calculated using the chiral unitary approach. We observe that for the $η N$ mass distribution only the $N^{*}$ (1535) is seen, with the $N^{*}$ (1650) contributing to the width of the curve, but for the $π N$ mass distribution both resonances are clearly visible. In the case of $M B = K Σ$ , we found that the strength of the $K Σ$ mass distribution is smaller than that of the mass distributions of the $π N$ and $η p$ in the $Λ_{c}^{+} \to K ˉ^{0} π N$ and $Λ_{c}^{+} \to K ˉ^{0} η p$ processes, in spite of this channel having a large coupling to the $N^{*} (1650)$ . This is because the $K Σ$ pair production is suppressed in the primary production from the $Λ_{c}$ decay.
Comments:
8 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1802.07882 [pdf]
PRC(2018)·18 citations
02
[Submitted on 22 Feb 2018]
Bulk viscosity of a hot QCD/QGP medium in strong magnetic field within relaxation-time approximation
Manu Kurian🇮🇳 · Vinod Chandra🇮🇳
The bulk viscosity of hot QCD medium has been obtained in the presence of strong magnetic field. The present investigation involves the estimation of the quark damping rate and subsequently the thermal relaxation time for quarks in the presence of magnetic field while realizing the hot QCD medium as an effective Grand-canonical ensemble of effective gluons and quarks-antiquarks. The dominant process in the strong field limit is $1 \to 2$ ( $g \to q q ˉ$ ) which contributes to the bulk viscosity in a most significant way. Further, setting up the linearized transport equation in the framework of an effective kinetic theory with hot QCD medium effects and employing the relaxation time approximation, the bulk viscosity has been estimated in lowest Landau level (LLL) and beyond. The temperature dependence of the ratio of the bulk viscosity to entropy density indicates towards its rising behavior near the transition temperature.
Comments:
10 pages, 7 figures, Two column: v2: revised version, new refs. added
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1802.07904 [pdf]
PRD(2018)·47 citations
03
[Submitted on 22 Feb 2018]
Surface Interaction Effects to a Klein-Gordon Particle Embedded in a Woods-Saxon Potential Well in terms of Thermodynamic Functions
B.C. Lütfüoğlu
Recently, it has been investigated how the thermodynamic functions vary when the surface interactions are taken into account for a nucleon which is confined in a Woods-Saxon potential well, with a non-relativistic point of view. In this manuscript, the same problem is handled with a relativistic point of view. More precisely, the Klein-Gordon equation is solved in presence of mixed scalar-vector generalized symmetric Woods-Saxon potential energy that is coupled to momentum and mass. Employing the continuity conditions the bound state energy spectra of an arbitrarily parameterized well are derived. It is observed that, when a term representing the surface effect is taken into account, the character of Helmholtz free energy and entropy versus temperature are modified in a similar fashion as this inclusion is done in the non-relativistic regime. Whereas it is found that this inclusion leads to different characters to internal energy and specific heat functions for relativistic and non-relativistic regimes.
Comments:
18 pages, 2 tables and 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1802.07949 [pdf]
Can.J.Phys.(2018)·5 citations
04
[Submitted on 22 Feb 2018]
Relativistic Brueckner-Hartree-Fock theory for neutron drops
Shihang Shen · Haozhao Liang · Jie Meng · Peter Ring · Shuangquan Zhang
Neutron drops confined in an external field are studied in the framework of relativistic Brueckner-Hartree-Fock theory using the bare nucleon-nucleon interaction. The ground state energies and radii of neutron drops with even numbers from $N = 4$ to $N = 50$ are calculated and compared with results obtained from other nonrelativistic \textit{ab initio} calculations and from relativistic density functional theory. Special attention has been paid to the magic numbers and to the sub-shell closures. The single-particle energies are investigated and the monopole effect of the tensor force on the evolutions of the spin-orbit and the pseudospin-orbit splittings is discussed. The results provide interesting insight of neutron rich systems and can form an important guide for future density functionals.
Comments:
31 pages, 12 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1802.08108 [pdf]
PRC(2018)·33 citations
05
[Submitted on 22 Feb 2018]
Spin symmetry in the Dirac sea derived from the bare nucleon-nucleon interaction
Shihang Shen🇨🇳 · Haozhao Liang🇯🇵 · Jie Meng🇨🇳 · Peter Ring🇨🇳 · Shuangquan Zhang🇨🇳
The spin symmetry in the Dirac sea has been investigated with relativistic Brueckner-Hartree-Fock theory using the bare nucleon-nucleon interaction. Taking the nucleus $^{16}$ O as an example and comparing the theoretical results with the data, the definition of the single-particle potential in the Dirac sea is studied in detail. It is found that if the single-particle states in the Dirac sea are treated as occupied states, the ground state properties are in better agreement with experimental data. Moreover, in this case, the spin symmetry in the Dirac sea is better conserved and it is more consistent with the findings using phenomenological relativistic density functionals.
Comments:
13 pages, 4 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
1802.08110 [pdf]
PLB(2018)·20 citations
06
[Submitted on 22 Feb 2018]
Scale-Chiral Effective Field Theory for Nuclear Interactions in the Veneziano Limit
Yan-Ling Li🇨🇳 · Peng-Sheng Wen🇨🇳 · Yong-Liang Ma🇨🇳 · Mannque Rho🇫🇷
Following Golterman and Shamir, we develop scale-chiral perturbation theory in the large $N_{c}$ and large $N_{f}$ Veneziano limit that incorporates both light-quark baryons and hidden local symmetric bosons and derive a leading-order scale symmetry Lagrangian applicable in nuclear physics. Some applications in the medium-free space and baryonic matter are discussed.
Comments:
8 pages
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
1802.08140 [pdf]
6 citations
07
[Submitted on 22 Feb 2018]
$^{4} He$ vs. $^{4} Li$ and production of light nuclei in relativistic heavy-ion collisions
Sylwia Bazak🇵🇱 · Stanislaw Mrowczynski🇵🇱
We propose to measure the yields of $^{4} He$ and $^{4} Li$ in relativistic heavy-ion collisions to clarify a mechanism of light nuclei production. Since the masses of $^{4} He$ and $^{4} Li$ are almost equal, the yield of $^{4} Li$ predicted by the thermal model is 5 times bigger than that of $^{4} He$ which reflects the different numbers of internal degrees of freedom of the two nuclides. Their internal structure is, however, very different: the alpha particle is well bound and compact while $^{4} Li$ is weakly bound and loose. Within the coalescence model the ratio of yields of $^{4} Li$ to $^{4} He$ is shown to be significantly smaller than that in the thermal model and the ratio decreases fast from central to peripheral collisions of relativistic heavy-ion collisions because the coalescence rate strongly depends on the nucleon source radius. Since the nuclide $^{4} Li$ is unstable and it decays into $^{3} He$ and $p$ after roughly $30 fm / c$ , the yield of $^{4} Li$ can be experimentally obtained through a measurement of the $^{3} He - p$ correlation function.
Comments:
4 pages, 1 figure, minor improvements, to appear in Mod. Phys. Lett. A
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); Nuclear Experiment (nucl-ex)
arXiv:
1802.08212 [pdf]
Mod.Phys.Lett.A(2018)·36 citations
08
[Submitted on 22 Feb 2018]
How does relativistic kinetic theory remember about initial conditions?
Michal P. Heller🇩🇪 · Viktor Svensson🇩🇪
Understanding hydrodynamization in microscopic models of heavy-ion collisions has been an important topic in current research. Many lessons obtained within the strongly-coupled (holographic) models originate from the properties of transient excitations of equilibrium encapsulated by short-lived quasinormal modes of black holes. This paper aims to develop similar intuition for expanding plasma systems described by a simple model from the weakly-coupled domain, the Boltzmann equation in the relaxation time approximation. We show that in this kinetic theory setup there are infinitely many transient modes carrying information about the initial distribution function. They all have the same exponential damping set by the relaxation time but are distinguished by different power-law suppressions and different frequencies of oscillations, logarithmic in proper time. We also analyze the resurgent interplay between the hydrodynamics and transients in this setup.
Comments:
11 pages, 4 figures; Published in Physical Review D
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph); High Energy Physics — Theory (hep-th)
arXiv:
1802.08225 [pdf]
PRD(2018)·89 citations
09
[Submitted on 22 Feb 2018] (cross-list from hep-ph)
Neutron stars exclude light dark baryons
David McKeen🇺🇸 · Ann E. Nelson🇺🇸 · Sanjay Reddy🇺🇸 · Dake Zhou🇺🇸
Exotic new particles carrying baryon number and with mass of order the nucleon mass have been proposed for various reasons including baryogenesis, dark matter, mirror worlds, and the neutron lifetime puzzle. We show that the existence of neutron stars with mass greater than 0.7 $M_{⊙}$ places severe constraints on such particles, requiring them to be heavier than 1.2 GeV or to have strongly repulsive self-interactions.
Comments:
5 pages, 1 figure
Subjects:
High Energy Physics — Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Nuclear Experiment (nucl-ex); Nuclear Theory (nucl-th)
arXiv:
1802.08244 [pdf]
PRL(2018)·157 citations

Affiliations

first authorsco-authorsvia INSPIRE