Nuclear Theory·nucl-th

Monday·April 13, 2015

14 papers—8 primary·6 cross-listed

01
Cross-checking the symmetry energy at high densities
Gao-Chan Yong🇨🇳
The nuclear symmetry energy determines the birth of neutron stars and the elementary nucleosynthesis in the universe. To constrain the nuclear symmetry energy, besides the studies in astrophysics, many terrestrial nuclear experiments are being carried out using a wide variety of advanced new facilities. In this paper, by cross-checking two unrelated experimental measurements using the newly updated transport model, we obtained a slightly soft symmetry energy at supra-saturation nuclear densities. While extrapolating to low nuclear densities, this result is compatible with the recent finding by comparing the available data on the electric dipole polarizability with the theoretical predictions. Our finding is expected to push the studies of nuclear physics and astrophysics forward.
nucl-thnucl-exPRC(2016)·36 citations
02
Collective flow without hydrodynamics: simulation results for relativistic ion collisions
Paul Romatschke🇺🇸
Flow signatures in experimental data from relativistic ion collisions are usually interpreted as a fingerprint of the presence of a hydrodynamic phase during the evolution of these systems. In this work, flow signatures arising from event-by-event viscous hydrodynamics are compared to those arising from event-by-event non-interacting particle dynamics (free-streaming), both followed by a late-stage hadronic cascade, in d+Au, 3He+Au at sqrt(s)=200 GeV and p+Pb collisions at sqrt(s)=5 TeV, respectively. For comparison, also Pb+Pb collisions at sqrt(s)=2.76 TeV are simulated. It is found that non-hydrodynamic evolution can give rise to equal or larger radial flow than hydrodynamics with eta/s=0.08 in all simulated collision systems. In light-on-heavy-ion collisions, free-streaming gives rise to triangular and quadrupolar flow comparable to or larger than that from hydrodynamics, but it generally leads to considerably smaller elliptic flow. As expected, free-streaming leads to considerably less elliptic, triangular and quadrupolar flow than hydrodynamics in nucleus-nucleus collisions, such as event-by-event Pb+Pb collisions at sqrt(s)=2.76 TeV.
nucl-thhep-phphysics.flu-dynEPJC(2015)·43 citations
03
Exotic Nuclei and Matter in a Chirally Effective Approach
S. Schramm🇩🇪
A relativistic approach to describe nuclear and in general strongly interacting matter is introduced and discussed. Here, not only the nuclear forces but also the masses of the nucleons are generated through meson fields. Within this framework it is possible to calculate properties of finite nuclei at a level of accuracy similar to dedicated relativistic nuclear structure models. Due to the more general approach, a wider range of properties of hadronic states can be investigated. A number of results for heavy and neutron-rich nuclei toward the drip line are presented.
nucl-th2 citations
04
Robust correlations between quadrupole moments of low-lying $2^{+}$ states within random-interaction ensembles
Y. Lei
In the random-interaction ensembles, three proportional correlations between quadrupole moments of the first two $I^{π} = 2^{+}$ states robustly emerge, including $Q (2_{1}^{+}) = \pm Q (2_{2}^{+})$ correlations consistently with realistic nuclear survey, and the $Q (2_{2}^{+}) = - \frac{3}{7} Q (2_{1}^{+})$ correlation, which is only observed in the $s d$ -boson space. These correlations can be microscopically characterized by the rotational SU(3) symmetry and quadrupole vibrational U(5) limit, respectively, according to the Elliott model and the $s d$ -boson mean-field theory. The anharmonic vibration may be another phenomenological interpretation for the $Q (2_{1}^{+}) = - Q (2_{2}^{+})$ correlation, whose spectral evidence, however, is insufficient.
nucl-thnucl-exPRC(2016)·7 citations
05
Proton and neutron correlations in $^{10}$ B
Yoshiko Kanada-En'yo · Hiroyuki Morita · Fumiharu Kobayashi
We investigate positive-parity states of $^{10}$ B with the calculation of antisymmetrized molecular dynamics focusing on $p n$ pair correlations. We discuss effects of the spin-orbit interaction on energy spectra and $p n$ correlations of the $J^{π} T = 1_{1}^{+} 0$ , $= 3_{1}^{+} 0$ , and $0_{1}^{+} 1$ states. The $1_{1}^{+} 0$ state has almost no energy gain of the spin-orbit interaction, whereas the $3_{1}^{+} 0$ state gains the spin-orbit interaction energy largely to come down to the ground state. We interpret a part of the two-body spin-orbit interaction in the adopted effective interactions as a contribution of the genuine $N N N$ force, and find it to be essential for the level ordering of the $3_{1}^{+} 0$ and $1_{1}^{+} 0$ states in $^{10}$ B. We also apply a $2 α + p n$ model to discuss effects of the spin-orbit interaction on $T = 0$ and $T = 1$ $p n$ pairs around the 2 $α$ core. In the spin-aligned $J^{π} T = 3^{+} 0$ state, the spin-orbit interaction affects the $(S T) = (10)$ pair attractively and keeps the pair close to the core, whereas, in the $1^{+} 0$ state, it gives a minor effect to the $(S T) = (10)$ pair. In the $0^{+} 1$ state, the $(S T) = (01)$ pair is somewhat dissociated by the spin-orbit interaction.
nucl-thPRC(2015)·16 citations
06
Extended-soft-core Baryon-Baryon ESC08 model III. S=-2 Hyperon-hyperon/nucleon Interaction
M.M. Nagels🇳🇱 · Th.A. Rijken🇯🇵 · Y. Yamamoto🇯🇵
This paper presents the Extended-Soft-Core (ESC) potentials ESC08c for baryon-baryon channels with total strangeness S=-2. The potential models for S=-2 are based on SU(3) extensions of ESC potential models for the S=0 and S=-1 sectors, which are fitted to experimental data. Flavor SU(3)-symmetry is broken only kinematically by the masses of the baryons and the mesons. For the S=-2 channels no experimental scattering data exist, and also the information from hypernuclei is rather limited. Nevertheless, in the fit to the S=0 and S=-1 sectors information from the so called NAGARA event and the $Ξ$ -well-depth has been used as constraints to determine the free parameters in the simultaneous fit of the $N N \oplus Y N \oplus Y Y$ data. Therefore, the potentials for the S=-2 sector are determined mainly by the NN-, YN-data, and SU(3)-symmetry.Various properties of the potentials are illustrated by giving results for scattering lengths, effective ranges, bound states, elastic and inelastic phase parameters, and total cross sections. Notably is the prediction of a bound state D $^{*}$ in the $Ξ N (^{3} S_{1}, I = 1)$ -channel with a binding energy $B_{E} = 1.56$ MeV. This state is deuteron-like, i.e. a member of the ${1 0^{*}}$ -decuplet. As for the normal deuteron $D = p n (^{3} S_{1} -^{3} D_{1})$ the strong tensor force is responsible for this state. The features of $Ξ$ hypernuclei predicted by ESC08c are studied on the basis of the G-matrix approch. The well-depth $U_{Ξ} = - 7.0$ MeV, and the $Ξ - ΛΛ$ conversion width is $Γ_{Ξ}^{c} = 4.5$ MeV.
nucl-thPRC(2020)·74 citations
07
Quest of $^{37} M g$ halo structure using Glauber model and microscopic relativistic mean field densities
Mahesh K. Sharma · R. N. Panda · Manoj K. Sharma · S. K. Patra
We have studied the ground state properties (binding energy and charge radius) using relativistic mean filed formalism (RMF) for Mg-isotopes in the valley of stability to drip line region. The RMF densities have been analyzed in context of reaction dynamics. The calculated results of $^{24 - 40}$ Mg+ $^{12}$ C reactions at projectile energy 240 AMeV using Glauber model with the conjunction of densities from relativistic mean field formalism are compared with experimental data. We found remarkable agreement of estimated values of reaction cross sections with experimental data except for $^{37}$ Mg isotope. In view of this, the halo status of $^{37}$ Mg is examined through higher magnitude of rms radius and small value of longitudinal momentum distribution. Finally, an effort is made to explore the structure of $^{37}$ Mg halo candidate using Glauber few body formalism.
nucl-thPRC(2016)·27 citations
08
Chiral Mirror-Baryon-Meson Model and Nuclear Matter beyond Mean-Field
Johannes Weyrich🇩🇪 · Nils Strodthoff🇩🇪 · Lorenz von Smekal🇩🇪
We consider a chiral baryon-meson model for nucleons and their parity partners in mirror assignment interacting with pions, sigma and omega mesons to describe the liquid-gas transition of nuclear matter together with chiral symmetry restoration in the high density phase. Within the mean-field approximation the model is known to provide a phenomenologically successful description of the nuclear-matter transition. Here, we go beyond this approximation and include mesonic fluctuations by means of the functional renormalization group. While these fluctuations do not lead to major qualitative changes in the phase diagram of the model, beyond mean-field, one is no-longer free to adjust the parameters so as to reproduce the binding energy per nucleon, the nuclear saturation density, and the nucleon sigma term all at the same time. However, the prediction of a clear first-order chiral transition at low temperatures inside the high baryon-density phase appears to be robust.
nucl-thhep-phPRC(2015)·57 citations

Affiliations

first authorsco-authorsvia INSPIRE