Nuclear Theory·nucl-th

Friday·July 17, 2015

12 papers—6 primary·6 cross-listed

01
Polarized Lepton-Nucleon Elastic Scattering and a Search for a Light Scalar Boson
Yu-Sheng Liu🇺🇸 · Gerald A. Miller🇺🇸
Lepton-nucleon elastic scattering, using the one-photon and one-scalar-boson exchange mechanisms considering all possible polarizations, is used to study searches for a new scalar boson and suggest new measurements of the nucleon form factors. A new light scalar boson, which feebly couples to leptons and nucleons, may account for the proton radius and muon $g - 2$ puzzles. We show that the scalar boson produces relatively large effects in certain kinematic region when using sufficient control of lepton and nucleon spin polarization. We generalize current techniques to measure the ratio $G_{E} / G_{M}$ and present a new method to separately measure $G_{M}^{2}$ and $G_{E}^{2}$ using polarized incoming and outgoing muons.
nucl-thhep-phnucl-exPRC(2015)·12 citations
02
Femto-cyclones and hyperon polarization in Heavy-Ion Collisions
M.I. Baznat🇷🇺 · K.K. Gudima🇷🇺 · A.S. Sorin🇷🇺 · O.V. Teryaev🇷🇺
We study the structure of vorticity and hydrodynamic helicity fields in peripheral heavy-ion collisions using the kinetic Quark-Gluon String Model. The angular momentum conservation within this model holds with a good accuracy. We observe the formation of specific toroidal structures of vorticity field (vortex sheets). Their existence is mirrored in the polarization of hyperons of the percent order.
nucl-thhep-phnucl-exPRC(2016)·67 citations
03
Isospin splitting of nucleon effective mass from giant resonances in $^{208}$ Pb
Zhen Zhang🇨🇳 · Lie-Wen Chen🇨🇳
Based on mean field calculations with Skyrme interactions, we extract a constraint on the isovector effective mass in nuclear matter at saturation density $ρ_{0}$ , i.e., $m_{v}^{*} (ρ_{0}) = (0.77 \pm 0.03) m$ by combining the experimental data of the centroid energy of the isovector giant dipole resonance (IVGDR) and the electric dipole polarizability $α_{D}$ in $^{208}$ Pb. Meanwhile, the isoscalar effective mass at $ρ_{0}$ is determined to be $m_{s}^{*} (ρ_{0}) = (0.91 \pm 0.05) m$ by analyzing the measured excitation energy of the isoscalar giant quadrupole resonance (ISGQR) in $^{208}$ Pb. From the constrained $m_{s}^{*} (ρ_{0})$ and $m_{v}^{*} (ρ_{0})$ , we obtain the isospin splitting of nucleon effective mass in asymmetric nuclear matter of isospin asymmetry $δ$ at $ρ_{0}$ as $[m_{n}^{*} (ρ_{0}, δ) - m_{p}^{*} (ρ_{0}, δ)] / m = Δ m_{1}^{*} (ρ_{0}) δ + O (δ^{3})$ with the linear isospin splitting coefficient $Δ m_{1}^{*} (ρ_{0}) = 0.33 \pm 0.16$ . We notice that using the recently corrected data on the $α_{D}$ in $^{208}$ Pb with the contribution of the quasideuteron effect subtracted slightly enhances the isovector effective mass to $m_{v}^{*} (ρ_{0}) = (0.80 \pm 0.03) m$ and reduces the linear isospin splitting coefficient to $Δ m_{1}^{*} (ρ_{0}) = 0.27 \pm 0.15$ . Furthermore, the constraints on $m_{v}^{*} (ρ)$ , $m_{s}^{*} (ρ)$ and $Δ m_{1}^{*} (ρ)$ at other densities are obtained from the similar analyses and we find that the $Δ m_{1}^{*} (ρ)$ increases with the density.
nucl-thastro-ph.SRhep-phnucl-exPRC(2016)·51 citations
04
Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei
Chunli Zhang · Gowhar Bhat · Witek Nazarewicz · Javid Sheikh · Yue Shi
Background: Recently, transition quadrupole moments in rotational bands of even-mass neutron-rich isotopes of molybdenum and ruthenium nuclei have been measured. The new data have provided a challenge for theoretical descriptions invoking stable triaxial deformations. Purpose: To understand experimental data on rotational bands in the neutron-rich Mo-Ru region, we carried out theoretical analysis of moments of inertia, shapes, and transition quadrupole moments of neutron-rich even-even nuclei around $^{110}$ Ru using self-consistent mean-field and shell model techniques. Methods: To describe yrast structures in Mo and Ru isotopes, we use nuclear Density Functional Theory (DFT) with the optimized energy density functional UNEDF0. We also apply Triaxial Projected Shell Model (TPSM) to describe yrast and positive-parity, near-yrast band structures. Results: Our self-consistent DFT calculations predict triaxial ground-state deformations in $^{106, 108}$ Mo and $^{108.110, 112}$ Ru and reproduce the observed low-frequency behavior of moments of inertia. As the rotational frequency increases, a negative- $γ$ structure, associated with the aligned $ν (h_{11/2})^{2}$ pair, becomes energetically favored. The computed transition quadrupole moments vary with angular momentum, which reflects deformation changes with rotation; those variations are consistent with experiment. The TPSM calculations explain the observed band structures assuming stable triaxial shapes. Conclusions: The structure of neutron-rich even-even nuclei around $^{110}$ Ru is consistent with triaxial shape deformations. Our DFT and TPSM frameworks provide a consistent and complementary description of experimental data.
nucl-thPRC(2015)·47 citations
05
Ab Initio No Core Shell Model - Recent Results and Further Prospects
James P. Vary · Pieter Maris · Hugh Potter · Mark A. Caprio · Robin Smith · Sven Binder · Angelo Calci · Sebastian Fischer · Joachim Langhammer · Robert Roth · Hasan Metin Aktulga · Esmond Ng and 5 other authors
There has been significant recent progress in solving the long-standing problems of how nuclear shell structure and collective motion emerge from underlying microscopic inter-nucleon interactions. We review a selection of recent significant results within the ab initio No Core Shell Model (NCSM) closely tied to three major factors enabling this progress: (1) improved nuclear interactions that accurately describe the experimental two-nucleon and three-nucleon interaction data; (2) advances in algorithms to simulate the quantum many-body problem with strong interactions; and (3) continued rapid development of high-performance computers now capable of performing $20 \times 1 0^{15}$ floating point operations per second. We also comment on prospects for further developments.
nucl-th4 citations
06
Core-crust transition and crustal fraction of moment of inertia in neutron stars
Debasis Atta · Somnath Mukhopadhyay · D. N. Basu
The crustal fraction of moment of inertia in neutron stars is calculated using $β$ -equilibrated nuclear matter obtained from density dependent M3Y effective interaction. The transition density, pressure and proton fraction at the inner edge separating the liquid core from the solid crust of the neutron stars determined from the thermodynamic stability conditions are found to be $ρ_{t} =$ 0.0938 fm $^{- 3}$ , P $_{t} =$ 0.5006 MeV fm $^{- 3}$ and $x_{p (t)} =$ 0.0308, respectively. The crustal fraction of the moment of inertia can be extracted from studying pulsar glitches and is most sensitive to the pressure as well as density at the transition from the crust to the core. These results for pressure and density at core-crust transition together with the observed minimum crustal fraction of the total moment of inertia provide a new limit for the radius of the Vela pulsar: $R \geq 4.10 + 3.36 M / M_{⊙}$ kms.
nucl-thIndian J.Phys.(2017)·13 citations

Affiliations

first authorsco-authorsvia INSPIRE

Polarized Lepton-Nucleon Elastic Scattering and a Search for a Light Scalar Boson

Femto-cyclones and hyperon polarization in Heavy-Ion Collisions

Isospin splitting of nucleon effective mass from giant resonances in 208Pb

Theoretical study of triaxial shapes of neutron-rich Mo and Ru nuclei

Ab Initio No Core Shell Model - Recent Results and Further Prospects

Core-crust transition and crustal fraction of moment of inertia in neutron stars

Affiliations

Isospin splitting of nucleon effective mass from giant resonances in $^{208}$ Pb