Nuclear Theory·nucl-th

Monday·February 23, 2015

8 papers—4 primary·4 cross-listed

01
Quarkonium formation time in relativistic heavy-ion collisions
Taesoo Song🇩🇪 · Che Ming Ko🇺🇸 · Su Houng Lee🇰🇷
We calculate the quarkonium formation time in relativistic heavy-ion collisions from the space-time correlator of heavy quark vector currents in a hydrodynamics background with the initial nonequilibrium stage expanding only in the longitudinal direction. Using in-medium quarkonia properties determined with the heavy quark potential taken to be the free energy from lattice calculations and the fact that quarkonia can only be formed below their dissociation temperatures due to color screening, we find that $Υ$ (1S), $Υ$ (2S), $Υ$ (3S), $J / ψ$ and $ψ^{'}$ are formed, respectively, at 1.2, 6.6, 8.8, 5.8, and 11.0 fm/c after the quark pair are produced in central Au+Au collisions at the top energy of Relativistic Heavy Ion Collider (RHIC), and these times become shorter in semi-central collisions. We further show, as an example, that including the effect of formation time enhances appreciably the survivability of $Υ$ (1S) in the produced hot dense matter.
nucl-thPRC(2015)·19 citations
02
Shell-model study of quadrupole collectivity in light tin isotopes
L. Coraggio🇮🇹 · A. Covello🇮🇹 · A. Gargano🇮🇹 · N. Itaco🇮🇹 · T. T. S. Kuo🇺🇸
A realistic shell-model study is performed for neutron-deficient tin isotopes up to mass A=108. All shell-model ingredients, namely two-body matrix elements, single-particle energies, and effective charges for electric quadrupole transition operators, have been calculated by way of the many-body perturbation theory, starting from a low-momentum interaction derived from the high-precision CD-Bonn free nucleon-nucleon potential. The focus has been put on the enhanced quadrupole collectivity of these nuclei, which is testified by the observed large B(E2;0+ -> 2+)s. Our results evidence the crucial role played by the Z=50 cross-shell excitations that need to be taken into account explicitly to obtain a satisfactory theoretical description of light tin isotopes. We find also that a relevant contribution comes from the calculated neutron effective charges, whose magnitudes exceed the standard empirical values. An original double-step procedure has been introduced to reduce effectively the model space in order to overcome the computational problem.
nucl-thPRC(2015)·38 citations
03
Gamow-Teller properties of the double beta-decay partners 116Cd(Sn) and 150Nd(Sm)
D. Navas-Nicolas · P. Sarriguren
The two Gamow-Teller (GT) branches connecting the double-beta decay partners (116Cd, 116Sn) and (150Nd, 150Sm) with the intermediate nuclei 116In and 150Pm are studied within a microscopic approach based on a deformed proton-neutron quasiparticle random-phase approximation built on a Skyrme selfconsistent mean field with pairing correlations and spin-isospin residual forces. The results are compared with the experimental GT strength distributions extracted from charge-exchange reactions. Combining the two branches, the nuclear matrix elements for the two-neutrino double-beta decay are evaluated and compared to experimental values derived from the measured half-lives.
nucl-thPRC(2015)·10 citations
04
Benchmarking Nuclear Fission Theory
G.F. Bertsch · W. Loveland · W. Nazarewicz · P. Talou
We suggest a small set of fission observables to be used as test cases for validation of theoretical calculations. The purpose is to provide common data to facilitate the comparison of different fission theories and models. The proposed observables are chosen from fission barriers, spontaneous fission lifetimes, fission yield characteristics, and fission isomer excitation energies.
nucl-thnucl-exJ.Phys.G(2015)·30 citations
05
QCD and Hadron Physics
Stanley J. Brodsky🇺🇸 · Abhay L. Deshpande🇺🇸 · Haiyan Gao🇺🇸 · Robert D. McKeown🇺🇸 · Curtis A. Meyer🇺🇸 · Zein-Eddine Meziani🇺🇸 · Richard G. Milner🇺🇸 · Jianwei Qiu🇺🇸 · David G. Richards🇺🇸 · Craig D. Roberts🇺🇸
This document presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. It highlights progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and presents a vision for the future by identifying key questions and plausible paths to solutions which should define our next decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (roughly 5 years) and longer term (beyond 10 years) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential in hadronic physics worldwide. In this connection, the potential of an electron ion collider is highlighted.
↳ hep-phhep-exhep-latnucl-ex+136 citations
06
Perfect fluidity of a dissipative system: Analytical solution for the Boltzmann equation in $AdS_{2} \otimes S_{2}$
Jorge Noronha🇺🇸 · Gabriel S. Denicol🇨🇦
In this paper we obtain an analytical solution of the relativistic Boltzmann equation under the relaxation time approximation that describes the out-of-equilibrium dynamics of a radially expanding massless gas. This solution is found by mapping this expanding system in flat spacetime to a static flow in the curved spacetime $AdS_{2} \otimes S_{2}$ . We further derive explicit analytic expressions for the momentum dependence of the single particle distribution function as well as for the spatial dependence of its moments. We find that this dissipative system has the ability to flow as a perfect fluid even though its entropy density does not match the equilibrium form. The non-equilibrium contribution to the entropy density is shown to be due to higher order scalar moments (which possess no hydrodynamical interpretation) of the Boltzmann equation that can remain out of equilibrium but do not couple to the energy-momentum tensor of the system. Thus, in this system the slowly moving hydrodynamic degrees of freedom can exhibit true perfect fluidity while being totally decoupled from the fast moving, non-hydrodynamical microscopic degrees of freedom that lead to entropy production.
↳ hep-phhep-thnucl-thPRD(2015)·20 citations
07
Analytic solutions of the relativistic Boltzmann equation
Yoshitaka Hatta🇯🇵 · Mauricio Martinez🇺🇸 · Bo-Wen Xiao🇨🇳
We present new analytic solutions to the relativistic Boltzmann equation within the relaxation time approximation. We first obtain spherically expanding solutions which are the kinetic counterparts of the exact solutions of the Israel-Stewart equation in the literature. This allows us to compare the solutions of the kinetic and hydrodynamic equations at an analytical level. We then derive a novel boost-invariant solution of the Boltzmann equation which has an unconventional dependence on the proper time. The existence of such a solution is also suggested in second order hydrodynamics and fluid-gravity correspondence.
↳ hep-thhep-phnucl-thphysics.flu-dynPRD(2015)·19 citations
08
Linear Boltzmann-like equation, describing non-classical particle transport, and related asymptotic solutions for small mean free paths
Sergey A. Rukolaine
In classical kinetic or kinetic-like models a particle free path distribution is exponensial, but this is more likely to be an exception than a rule. In this paper we derive a linear Boltzmann-like equation for a general free path distribution in the framework of Alt's model J. Math. Biol. 9:147 (1980). In the special case that the free path distribution has at least first and second finite moments we construct an asymptotic solution of the equation for small mean free paths. The asymptotic solution becomes a diffusion approximation to the one-speed Boltzmann-like equation.
↳ cond-mat.stat-mechmath-phmath.MPnucl-th+2Physica A(2016)·1 citation

Affiliations

first authorsco-authorsvia INSPIRE