Nuclear Theory·nucl-th

Wednesday·April 26, 2017

11 papers—9 primary·2 cross-listed

01
Hydrodynamics and critical slowing down
M. Stephanov · Y. Yin
We introduce an effective theory which extends hydrodynamics into a regime where the critical slowing down would otherwise make hydrodynamics inapplicable.
nucl-thNPA(2017)·15 citations
02
Towards the global description of nuclear charge radii: exploring the Fayans energy density functional
P.-G. Reinhard · W. Nazarewicz
In this work, we study the odd-even effect in binding energies and charge radii, and systematic behavior of differential radii, to identify the underlying components of the effective nuclear interaction. We apply nuclear density functional theory using a family of Fayans and Skyrme energy density functionals fitted to similar datasets but using different optimization protocols. We inspect various correlations between differential charge radii, odd-even staggering in energies and radii, and nuclear matter properties. Detailed analysis is carried out for medium-mass and heavy semi-magic nuclei with a particular focus on the Ca chain. By making the surface and pairing terms dependent on density gradients, the Fayans functional offers the superb simultaneous description of odd-even staggering effects in energies and charge radii. Conversely, when the data on differential radii are added to the pool of fit-observables, the coupling constants determining the strengths of the gradient terms of Fayans functional are increased by orders of magnitude. The Skyrme functional optimized in this work with the generalized Fayans pairing term offers results of similar quality. We quantify these findings by performing correlation analysis based on the statistical linear regression technique. The nuclear matter parameters characterizing Fayans and Skyrme functionals optimized to similar datasets are fairly close.
nucl-thPRC(2017)·132 citations
03
Nucleon momentum distributions in $^{3}$ He and three-body interactions
S.V.Bekh · A.P.Kobushkin · E.A.Strokovsky
We calculate momentum distributions of neutrons and protons in $^{3}$ He in the framework of a model which includes 3N interactions together with 2N interactions. It is shown that contribution of 3N interactions becomes essential in comparison with contribution coming from 2N interaction for internal momentum in $^{3}$ He $k >$ ~250~MeV/c. We also compare calculated momentum distribution of protons with so-called empirical momentum distribution of protons extracted from A $(^{3} He, p)$ breakup cross-sections measured for protons emitted at zero degree. It is concluded that 3N interactions cannot completely explain the disagreement between the available data on the empirical momentum distribution of protons in $^{3} He$ and calculations based on 2N interaction, which is observed at high momentum region of the momentum distribution, $k >$ ~250~MeV/c.
nucl-thnucl-exUkr.J.Phys.(2017)·1 citation
04
Determination of Quark-Gluon-Plasma Parameters from a Global Bayesian Analysis
Steffen A. Bass🇺🇸 · Jonah E. Bernhard🇺🇸 · J. Scott Moreland🇺🇸
The quality of data taken at RHIC and LHC as well as the success and sophistication of computational models for the description of ultra-relativistic heavy-ion collisions have advanced to a level that allows for the quantitative extraction of the transport properties of the Quark-Gluon-Plasma. However, the complexity of this task as well as the computational effort associated with it can only be overcome by developing novel methodologies: in this paper we outline such an analysis based on Bayesian Statistics and systematically compare an event-by-event heavy-ion collision model to data from the Large Hadron Collider. We simultaneously probe multiple model parameters including fundamental quark-gluon plasma properties such as the temperature-dependence of the specific shear viscosity $η / s$ , calibrate the model to optimally reproduce experimental data, and extract quantitative constraints for all parameters simultaneously. The method is universal and easily extensible to other data and collision models.
nucl-thhep-phnucl-exNPA(2017)·47 citations
05
Pre-equilibrium Longitudinal Flow in the IP-Glasma Framework for Pb+Pb Collisions at the LHC
Scott McDonald🇨🇦 · Chun Shen🇺🇸 · Francois Fillion-Gourdeau🇨🇦 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦
In this work, we debut a new implementation of IP-Glasma and quantify the pre-equilibrium longitudinal flow in the IP-Glasma framework. The saturation physics based IP-Glasma model naturally provides a non-zero initial longitudinal flow through its pre-equilibrium Yang-Mills evolution. A hybrid IP-Glasma+MUSIC+UrQMD frame- work is employed to test this new implementation against experimental data and to make further predictions about hadronic flow observables in Pb+Pb collisions at 5.02 TeV. Finally, the non-zero pre-equilibrium longitudinal flow of the IP-Glasma model is quantified, and its origin is briefly discussed.
nucl-thhep-phnucl-exNucl.Part.Phys.Proc.(2017)·3 citations
06
Simplified Thermal Evolution of Proto-hybrid Stars
M. Mariani🇦🇷 · M. Orsaria🇦🇷 · H. Vucetich🇦🇷
We study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. Furthermore, we analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J1614-2230. We obtain cold hybrid stars with maximum masses $\geq 2$ M $_{⊙}$ . Our study also suggest that during the proto-hybrid star evolution a late phase transition between hadronic matter and quark matter could occur, in contrast with previous studies of proto-neutron stars.
nucl-thastro-ph.HEInt.J.Mod.Phys.Conf.Ser.(2017)·2 citations
07
Estrellas híbridas: una aproximación semi-analítica a T finita
M. Mariani🇦🇷 · M. G. Orsaria🇦🇷
Starting from the semi-analytic construction of a equation of state (EoS) which takes into account nuclear and quark matter at finite temperature, we study the possibility that proto-neutron stars, be proto-hybrid stars whose cores are composed of quark matter. We obtain the mass-radius relationship and discuss the latest constraints on masses and radii of neutron stars, considering the pulsars PSR J1614-2230 and PSR J0348 + 0432.
nucl-thastro-ph.HEBAAA, Vol. 58, 2016·0 citations
08
A data-driven analysis of the heavy quark transport coefficient
Yingru Xu🇺🇸 · Marlene Nahrgang🇺🇸 · Jonah E. Bernhard🇺🇸 · Shanshan Cao🇺🇸 · Steffen A. Bass🇺🇸
Using a Bayesian model-to-data analysis, we estimate the temperature dependence of the heavy quark diffusion coefficients by calibrating to the experimental data of $D$ -meson $R_{AA}$ and $v_{2}$ in AuAu collisions ( $s_{N N} = 200$ GeV) and PbPb collisions ( $s_{N N} = 2.76$ TeV)~\cite{Xie:2016iwq}. The spatial diffusion coefficient $D_{s} 2 π T$ is found to be mostly constraint around $(1.3 - 1.5) T_{c}$ and is compatible with lattice QCD calculations. We demonstrate the capability of our improved Langevin model to simultaneously describe the $R_{AA}$ and $v_{2}$ at both RHIC and the LHC energies, as well as the feasibility to apply a Bayesian analysis to quantitatively study the heavy flavor transport in heavy-ion collisions.
nucl-thNPA(2017)·20 citations
09
$A$ -dependence of quasielastic charged-current neutrino-nucleus cross sections
Nils Van Dessel🇧🇪 · Natalie Jachowicz🇧🇪 · Raúl González-Jiménez🇧🇪 · Vishvas Pandey🇺🇸 · Tom Van Cuyck🇧🇪
Background: 12C has been and is still widely used in neutrino-nucleus scattering and oscillation experiments. More recently, 40Ar has emerged as an important nuclear target for current and future experiments. Liquid argon time projection chambers (LArTPCs) possess various advantages in measuring electroweak neutrino-nucleus cross sections. Concurrent theoretical research is an evident necessity. Purpose: 40Ar is larger than 12C, and one expects nuclear effects to play a bigger role in reactions. We present inclusive differential and total cross section results for charged-current neutrino scattering on 40Ar and perform a comparison with 12C, 16O and 56Fe targets, to find out about the A-dependent behavior of model predictions. Method: Our model starts off with a Hartree-Fock description of the nucleus, with the nucleons interacting through a mean field generated by an effective Skyrme force. Long-range correlations are introduced by means of a continuum random phase approximation (CRPA) approach. Further methods to improve the accuracy of model predictions are also incorporated in the calculations. Results: We present calculations for 12C, 16O, 40Ar and 56Fe, showcasing differential cross sections over a broad range of kinematic values in the quasielastic regime. We furthermore show flux-folded results for 40Ar and we discuss the differences between nuclear responses. Conclusions: At low incoming energies and forward scattering we identify an enhancement in the 40Ar cross section compared to 12C, as well as in the high $ω$ (low $T_{μ}$ ) region across the entire studied $E_{ν}$ range. The contribution to the folded cross section of the reaction strength at values of $ω$ lower than 50 MeV for forward scattering is sizeable.
nucl-thhep-exhep-phnucl-exPRC(2018)·26 citations

Affiliations

first authorsco-authorsvia INSPIRE