Nuclear Theory·nucl-th

Wednesday·August 7, 2019

13 papers—10 primary·3 cross-listed

01
The union of rotational and vibrational modes in generator-coordinate-type calculations, with application to neutrinoless double-beta decay
Changfeng Jiao🇺🇸 · Calvin W. Johnson🇺🇸
Good many-body methods for medium and heavy nuclei are important. Here we combine ideas from standard generator-coordinate methods (GCM) and the so-called Monte Carlo shell model, and set forth a novel approach: starting from a mean-field solution (Hartree-Fock-Bogoliubov), we create a set of non-orthogonal basis states, by using low-lying vibrational quasiparticleTamm-Dancoff modes, and then project onto states of good angular momentum and particle number. The results we benchmark against full shell model calculations. Even with just a few such modes we find improvement over standard GCM calculations in excitation spectra. We also find significant improvement in $0 ν β β$ nuclear matrix elements.
nucl-thPRC(2019)·17 citations
02
Properties of strange quark stars with isovector interactions
He Liu🇨🇳 · Jun Xu🇨🇳 · Che Ming Ko🇺🇸
We study the properties of strange quark stars by employing a 3-flavor Nambu-Jona-Lasinio model with both scalar-isovector and vector-isovector interactions. Using the constraint on the vector-isoscalar interaction strength obtained from the elliptic flow splitting between particles and their antiparticles in relativistic heavy-ion collisions, we investigate the dependence of the properties of strange quark stars on the vector-isovector and the scalar-isovector interactions, and compare the results with the state-of-art astrophysical constraints on the compact star radius and mass as well as its tidal deformability from the GW170817 event. Results from our study reinforce the prospect of using both heavy-ion collisions and astrophysical observations to provide constraints on the isovector coupling strength in quark matter and thus the quark matter equation of state as well as the QCD phase structure at finite isospin chemical potentials.
nucl-thastro-ph.HEastro-ph.SRhep-phPLB(2020)·14 citations
03
$Ξ$ hyperons in the nuclear medium described by chiral NLO interactions
M. Kohno🇯🇵
Properties of the baryon-baryon interactions in the strangeness $S = - 2$ sector of chiral effective field theory at the next-to-leading order (NLO) level are explored by calculating $Ξ$ single-particle potentials in symmetric nuclear matter. The results are transformed to the $Ξ$ potential in finite nuclei by a local-density approximation with convolution by a Gaussian form factor to simulate finite-range effects. The $Ξ$ potential is repulsive in a central region, and attractive in a surface area when the $Ξ$ energy is low. The attractive pocket can lower the $Ξ^{-}$ $s$ and $p$ atomic states. The obtained binding energies in $^{12}$ C and $^{14}$ N are found to be conformable with those found in emulsion experiments at Japan's National Laboratory for High Energy Physics (KEK). $K^{+}$ spectra of $(K^{-}, K^{+})$ $Ξ$ production inclusive processes on $^{9}$ Be and $^{12}$ C are also evaluated, using a semi-classical distorted wave method. The absolute values of the cross section are properly reproduced for $^{9}$ Be, but the peak locates at a lower energy position than that of the experimental data. The calculated spectrum of $^{12}$ C should be compared with the forthcoming result from the new experiments recently carried out at KEK with better resolution than before. The comparison would be valuable to improve the understanding of the $Ξ N$ interaction, the parametrization of which has still large uncertainties.
nucl-thPRC(2019)·24 citations
04
Analysis of Bohr formula of momentum of inertia for even-even atomic nuclei
Mohd Kh. M. Abu El-Sheikh · Abdurahim Okhunov
The moment of inertia of even-even deformed nuclei which are derived on the basis of hydrodynamical model yield values that are too small compared with the experimental [Davidson 1965] ones. We expect that these contradictions come from the consideration only the first term in $R$ - expansion in spite of not containing parameters indicating deformity of the nucleus, and neglecting all other terms which include the deformation parameters $α λ μ$ . In this work, the first three terms in $R$ - expansion are taken into account. The results are more realistic and too much better the previous ones.
nucl-th0 citations
05
Coexistence and evolution of shapes: mean-field-based interacting boson model
Kosuke Nomura
A method of deriving the Hamiltonian of the interacting boson model, that is based on the microscopic framework of the nuclear energy density functional, is presented. The constrained self-consistent mean-field calculation with a given energy density functional provides potential energy surface within the relevant collective coordinates, which is subsequently mapped onto the expectation value of the interacting-boson Hamiltonian in the boson condensate state. This procedure completely determines the strength parameters of the IBM, and the diagonalization of the mapped Hamiltonian yields excitation spectra and transition rates for a given nucleus. Two recent applications of the method are discussed, that is, the descriptions of the intruder states in Cadmium isotopes and the octupole correlations in neutron-rich odd-mass Barium isotopes.
nucl-thEPJ Web Conf.(2019)·0 citations
06
Systematic study of $α$ -decay half-lives of super-heavy nuclei with 106 $\leq$ Z $\leq$ 118
O.N.Ghodsi · M.Hassanzad
The $α$ - decay half-lives of the superheavy nuclei are systematically studied using different versions of proximity potential and a exact method to calculate Coulomb potential between spherical and deformed nuclei in the framework of the double folding model. To reproduce the $α$ -decay half-life, the experimental $α$ -decay energy and Wentzel-Kramers-Brillouin approximation have been used. It is found that the computed values by the Ng $o^$ 80 are in good compromise with the experimental half-lives in comparison with other versions. Also, by using this version and within $Q_{W S 4}$ for determination $α$ -decay energies for superheavy elements, we had predicted the $α$ -decay half-lives for superheavy nuclei which have not been reported yet. The long half-lives with magnitude about $100$ seconds are predicted for the superheavy nuclei which are not in stability islands which indicating remarkable stability in comparison with their neighbors. These results are also in good agreement with the predictions of other semi-empirical formulas.
nucl-thNPA(2019)·22 citations
07
Nucleon spin polarization in intermediate-energy heavy-ion collisions
Yin Xia🇨🇳 · Jun Xu🇨🇳
Based on a spin-dependent Boltzmann-Uehling-Uhlenbeck transport model with spin-dependent potentials incorporated using the lattice Hamiltonian method, we have studied the global spin polarization perpendicular to the reaction plane as well as the local spin polarization in the longitudinal direction in non-central intermediate-energy heavy-ion collisions, as an extension of similar studies in relativistic heavy-ion collisions. Both the global and the local spin polarizations are found to be mostly dominated by the time-odd component of the nuclear spin-orbit potential. Impacts of various theoretical uncertainties on the nucleon spin polarization as well as its dependence on the beam energy and impact parameter are discussed. Our study serves as a baseline for understanding the spin polarization mechanism of strongly interacting matter produced in heavy-ion collisions dominated by nucleon degree of freedom.
nucl-thhep-exnucl-exPLB(2020)·8 citations
08
The First fm/c of Heavy-Ion Collisions
Soeren Schlichting🇩🇪 · Derek Teaney🇺🇸
We present an introductory review of the early time dynamics of high-energy heavy-ion collisions and the kinetics of high temperature QCD. The equilibration mechanisms in the quark-gluon plasma uniquely reflect the non-abelian and ultra-relativistic character of the many body system. Starting with a brief expose of the key theoretical and experimental questions, we provide an overview of the theoretical tools employed in weak coupling studies of the early time non-equilibrium dynamics. We highlight theoretical progress in understanding different thermalization mechanisms in weakly coupled non-abelian plasmas, and discuss their relevance in describing the approach to local thermal equilibrium during the first $fm / c$ of a heavy-ion collision. Some important connections to the phenomenology of heavy-ion collisions are also briefly discussed.
nucl-thhep-phhep-thAnn.Rev.Nucl.Part.Sci.(2019)·162 citations
09
Neutron valence structure from nuclear deep inelastic scattering
E.P. Segarra🇺🇸 · A. Schmidt🇺🇸 · T. Kutz🇺🇸 · D.W. Higinbotham🇺🇸 · E. Piasetzky🇮🇱 · M. Strikman🇺🇸 · L.B. Weinstein🇺🇸 · O. Hen🇺🇸
Mechanisms of spin-flavor SU(6) symmetry breaking in Quantum Chromodynamics (QCD) are studied via an extraction of the free neutron structure function from a global analysis of deep inelastic scattering (DIS) data on the proton and on nuclei from $A = 2$ (deuterium) to 208 (lead). Modification of the structure function of nucleons bound in atomic nuclei (known as the EMC effect) are consistently accounted for within the framework of a universal modification of nucleons in short-range correlated (SRC) pairs. Our extracted neutron-to-proton structure function ratio $F_{2}^{n} / F_{2}^{p}$ becomes constant for $x_{B} \geq 0.6$ , equalling $0.47 \pm 0.04$ as $x_{B} \to 1$ , in agreement with theoretical predictions of perturbative QCD and the Dyson Schwinger equation, and in disagreement with predictions of the Scalar Diquark dominance model. We also predict $F_{2}^{^{3} He} / F_{2}^{^{3} H}$ , recently measured, yet unpublished, by the MARATHON collaboration, the nuclear correction function that is needed to extract $F_{2}^{n} / F_{2}^{p}$ from $F_{2}^{^{3} He} / F_{2}^{^{3} H}$ , and the theoretical uncertainty associated with this extraction.
nucl-thhep-exhep-phnucl-exPRL(2020)·43 citations
10
Dynamical Nucleon-Pion System via Basis Light-Front Quantization
Weijie Du🇺🇸 · Yang Li🇺🇸 · Xingbo Zhao🇨🇳 · James P. Vary🇺🇸
We present the first application of the Basis Light-Front Quantization method to study a simple chiral model of the nucleon-pion system via an ab initio, non-perturbative, Hamiltonian approach. As a test problem, we consider the physical proton as the relativistic bound state of the nucleon-pion system. Based on the chiral model of the nucleon-pion system, we construct the mass-squared matrix of the system within our light-front basis representation. We obtain the proton's mass and the corresponding light-front wave function by solving the eigenvalue problem of the mass-squared matrix. With the resulting boost-invariant light-front wave function, we also compute the proton's parton distribution function.
nucl-th4 citations

Affiliations

first authorsco-authorsvia INSPIRE