Nuclear Theory·nucl-th

Friday·July 15, 2016

17 papers—9 primary·8 cross-listed

01
Radiative proton capture cross sections in the mass range $40 - 55$
Dipti Chakraborty · Saumi Dutta · G. Gangopadhyay · Abhijit Bhattacharyya
Proton capture cross sections in the energy range of astrophysical interest for mass region 40-54 have been calculated in the Hauser-Feshbach formalism with reaction code TALYS1.6. The density dependent M3Y effective nucleon-nucleon interaction folded with target radial matter densities from relativistic mean field approach is used to obtain the semi-microscopic optical potential. A definite normalization of potential-well depths has been used over the entire mass region. The $(p, γ)$ rates of some reactions, important in the astrophysical scenario, are calculated using the potential in the relevant mass region.
nucl-thastro-ph.HEastro-ph.SRPRC(2016)·2 citations
02
Spectra and elliptic flow of (multi-)strange hadrons at RHIC and LHC within viscous hydrodynamics+hadron cascade hybrid model
Xiangrong Zhu🇨🇳
Using the (2+1)-dimensional ultrarelativistic viscous hydrodynamics+hadron cascade, VISHNU, hybrid model, we study the $p_{T}$ -spectra and elliptic flow of $Λ$ , $Ξ$ , and $Ω$ in Au+Au collisions at $s_{N N}$ =200 GeV and in Pb+Pb collisions at $s_{N N}$ =2.76 TeV. Comparing our model results with the data measurements, we find that the VISHNU model gives general descriptions of the measurements of these strange and multi-strange hadrons at several centrality classes at RHIC and LHC. Mass ordering of elliptic flow $v_{2}$ among $π$ , $K$ , $p$ , $Λ$ , $Ξ$ , and $Ω$ are further investigated and discussed at the two collision systems. We find, at both RHIC and LHC, the $v_{2}$ mass ordering among $π$ , $K$ , $p$ , and $Ω$ are fairly reproduced within the VISHNU hybrid model, and more improvements are needed to implement for well describing the $v_{2}$ mass ordering among $p$ , $Λ$ , and $Ξ$ .
nucl-thAdv.High Energy Phys.(2016)·7 citations
03
$Δ$ (1232) effects in density-dependent relativistic Hartree-Fock theory and neutron stars
Zhen-Yu Zhu🇨🇳 · Ang Li🇨🇳 · Jin-Niu Hu🇨🇳 · Hiroyuki Sagawa🇯🇵
The density-dependent relativistic Hartree-Fock (DDRHF) theory is extended to include $Δ$ -isobars for the study of dense nuclear matter and neutron stars. To this end, we solve the Rarita-Schwinger equation for spin-3/2 particle. Both the direct and exchange terms of the $Δ$ -isobars' self-energies are evaluated in details. In comparison with the relativistic mean field theory (Hartree approximation), a weaker parameter dependence is found for DDRHF. An early appearance of $Δ$ -isobars is recognized at $ρ_{B} \sim 0.27$ fm $^{- 3}$ , comparable with that of hyperons. Also, we find that the $Δ$ -isobars' softening of the equation of state is found to be mainly due to the reduced Fock contributions from the coupling of the isoscalar mesons, while the pion contributions are found negligibly small. We finally conclude that with typical parameter sets, neutron stars with $Δ$ -isobars in their interiors could be as heavy as the two massive pulsars whose masses are precisely measured, with slightly smaller radii than normal neutron stars.
nucl-thastro-ph.HEastro-ph.SRPRC(2016)·67 citations
04
Production of $ΛΛ$ and $Λ n ˉ$ in central Pb+Pb collisions at $s_{N N}$ =2.76 TeV within a covariant coalescence model
Kai-Jia Sun🇨🇳 · Lie-Wen Chen🇨🇳
We study the production of $ΛΛ$ and $Λ n$ exotic states in central Pb+Pb collisions at $s_{N N} = 2.76$ TeV at LHC via both hadron and quark coalescence within a covariant coalescence model with a blast-wave-like parametrization for the phase-space configurations of constituent particles at freezeout. In the hadron coalescence, the two states are considered as molecular states while they are considered as six-quark states in the quark coalescence.For $Λ n$ , we find that the yields of both molecular and six-quark states are much larger than the experimental upper-limits. For $ΛΛ$ , while the molecule-state yield is much larger than the experimental upper-limits, the six-quark-state yield could be lower than the upper-limits. The higher molecule-state yields are mainly due to the large contribution of short-lived strong resonance decays into (anti-)nucleons and (anti-) $Λ$ which can significantly enhance the molecule-state yields of $ΛΛ$ and $Λ n$ via hadron coalescence. Our results suggest that the current experimental measurement at LHC cannot exclude the existence of the $ΛΛ$ as an exotic six-quark state, and if $ΛΛ$ is a six-quark state, it is then on the brink of being discovered.
nucl-thhep-phnucl-exPRC(2016)·14 citations
05
Chiral symmetry restoration in heavy-ion collisions at intermediate energies
A. Palmese🇩🇪 · W. Cassing🇩🇪 · E. Seifert🇩🇪 · T. Steinert🇩🇪 · P. Moreau🇩🇪 · E. L. Bratkovskaya🇩🇪
We study the effect of the chiral symmetry restoration (CSR) on heavy-ion collisions observables in the energy range $s_{N N}$ =3-20 GeV within the Parton-Hadron-String Dynamics (PHSD) transport approach. The PHSD includes the deconfinement phase transition as well as essential aspects of CSR in the dense and hot hadronic medium, which are incorporated in the Schwinger mechanism for the hadronic particle production. We adopt different parametrizations of the nuclear equation of state from the non-linear $σ - ω$ model, which enter in the computation of the quark scalar density for the CSR mechanism, in order to estimate the uncertainty in our calculations.
nucl-thhep-phPRC(2016)·85 citations
06
Universality of nucleon-nucleon short-range correlations: the factorization property of the nuclear wave function, the relative and center-of-mass momentum distributions, and the nuclear contacts
Massimiliano Alvioli🇮🇹 · Claudio Ciofi degli Atti · Hiko Morita
The two-nucleon momentum distributions have been calculated for nuclei up to A=40 and various values of the relative and center-of-mass momenta and angle between them. For complex nuclei a parameter-free linked-cluster expansion, based upon a realistic local two-nucleon interaction of the Argonne family and variational wave function featuring central, tensor, spin and iso-spin correlations, has been used. The obtained results show that: 1) independently of the mass number A, at values of the relative momentum k_rel> 2 fm^{-1} the proton-neutron momentum distributions for back-to-back (BB) nucleons (K_cm=0) exhibit the factorization property n_A^{pn}(k_rel,K_cm=0)=C_A^{pn} n_D(k_rel) n_{cm}^{pn}(K_cm=0), where n_D is the deuteron momentum distribution, n_{cm}^{pn}(K_{cm}=0) the momentum distribution of the c.m. motion of the pair and C_A^{pn} the nuclear contact measuring the number of BB pn pairs with deuteron-like momenta; 2) the values of the proton-neutron nuclear contact C_A^{pn} are obtained in a model-independent way from the ratio n_A^{pn}(k_rel,K_cm=0)/n_D(k_rel) n_{cm}^{pn}(K_cm=0); 3) also the K_cm-integrated pn momentum distributions divided by the deuteron momentum distribution exhibits a constant behavior equal to C_A^{pn}, but only at very high values of k_{rel}> 3.5fm^{-1}, where the relative momentum distribution is entirely governed by BB short-range correlated nucleons; 4) the absolute value of the number of pn and pp short-range correlated pairs is calculated, illustrating that the high values (K_cm>1 fm^{-1}) of the pair c.m. momentum appreciably reduce the dominance of the pn over pp pairs produced by the tensor force when K_cm=0; 5) calculations are in good agreement with the VMC calculations for light nuclei and with available experimental on the processes A(e,e'pn)X and A(e,e'pp)X.
nucl-thnucl-exPRC(2016)·44 citations
07
The self-consistent analysis for sub-barrier fusion enhancement effect in Ca + Ca and Ni + Ni
N.R. Ma · H.M. Jia · C.J. Lin · L. Yang · X.X. Xu · L.J. Sun · F. Yang · Z.D. Wu · H.Q. Zhang · Z.H. Liu · D.X. Wang
The fusion dynamic mechanism of heavy-ions at energies near the Coulomb barrier is complicated and still not very clear up to now. Accordingly, a self-consistent method based on the CCFULL calculations has been developed and applied for an ingoing study of the effect of the positive Q-value neutron transfer (PQNT) channels in this work. The typical experimental fusion data of Ca + Ca and Ni + Ni is analyzed within the unified calculation scheme. The PQNT effect in near-barrier fusion is further confirmed based on the self-consistent analysis and extracted quantitatively.
nucl-thCPC(2016)·2 citations
08
Very low-energy nucleon + 16O coupled-channel scattering: results with a phenomenological vibrational model
J. P. Svenne · L. Canton · K. Amos · P. R. Fraser · S. Karataglidis · G. Pisent · D. van der Knijff
We employ a collective vibration coupled-channel model to describe the nucleon-16O cluster systems, obtaining low-excitation spectra for 17O and 17F. Bound and resonance states of the compound systems have been deduced, showing good agreement with experimental spectra. Low energy scattering cross sections of neutrons and protons from 16O also have been calculated and the results compare well with available experimental data.
nucl-thPRC(2017)·9 citations
09
Configuration interaction in symmetry-conserving covariant density functional theory
P. W. Zhao · P. Ring · J. Meng
A new method to calculate spectroscopic properties of deformed nuclei is proposed: configuration interaction on top of projected density functional theory (CI-PDFT). The general concept of this approach is discussed in the framework of covariant density functional theory and its validity is illustrated in an application to the yrast band of the nucleus Cr-54. It is found that the experimentally observed excitation energies for the yrast band in Cr-54 can be well reproduced. In contrast to conventional shell-model calculations, there is no core and only a relatively small number of configurations is sufficient for a satisfying description. No new parameters are necessary, because the effective interaction is derived from an universal density functional given in the literature.
nucl-thnucl-exPRC(2016)·31 citations

Affiliations

first authorsco-authorsvia INSPIRE