Nuclear Theory·nucl-th

Wednesday·January 9, 2019

4 papers—2 primary·2 cross-listed

01
Constraint to chiral invariant masses of nucleons from GW170817 in an extended parity doublet model
Takahiro Yamazaki🇯🇵 · Masayasu Harada🇯🇵
We construct nuclear matter based on an extended parity doublet model including four light nucleons $N (939)$ , $N (1440)$ , $N (1535)$ , and $N (1650)$ . We exclude some values of the chiral invariant masses by requiring the saturation properties of normal nuclear matter; saturation density, binding energy, incompressibility, and symmetry energy. We find further constraint to the chiral invariant masses from the tidal deformability determined by the observation of the gravitational waves from neutron star merger GW170817. Our result shows that the chiral invariant masses are larger than about $600$ MeV. We also give some predictions on the symmetry energy and the slope parameters in the high density region, which will be measured in future experiments.
nucl-thhep-phPRC(2019)·38 citations
02
Description of shape coexistence in $^{96}$ Zr based on the collective quadrupole Bohr Hamiltonian
D.A. Sazonov · E.A. Kolganova · T.M. Shneidman · R.V. Jolos · N. Pietralla · W.Witt
Experimental data on $^{96}$ Zr indicate coexisting spherical and deformed structures with small mixing amplitudes. We investigate the properties of the low-lying collective states of $^{96}$ Zr based on the collective quadrupole Bohr Hamiltonian. The $β$ -dependent collective potential having two minima -- spherical and deformed, is fixed so to describe experimental data in the best way.Good agreement with the experimental data on the excitation energies, $B (E 2)$ and $B (M 1)$ reduced transition probabilities is obtained. It is shown that the low-energy structure of $^{96}$ Zr can be reproduced in a satisfactory way in the geometrical model with a potential function supporting shape coexistence. However, the excitation energy of the $2_{2}^{+}$ state can be reproduced only if the rotation inertia coefficient is taken five times smaller then the vibrational one in the region of the deformed well. It is shown also that shell effects are important for the description of the $B (M 1; 2_{2}^{+} \to 2_{1}^{+})$ value. An indication on the influence of the pairing vibrational mode on the $ρ^{2} (0_{2}^{+} \to 0_{1}^{+})$ value is obtained.
nucl-thPRC(2019)·21 citations
03
General structure of the neutral $ρ$ meson self-energy and its spectral properties in a hot and dense magnetized medium
Snigdha Ghosh🇮🇳 · Arghya Mukherjee · Pradip Roy · Sourav Sarkar
The one loop self energy of the neutral $ρ$ meson is obtained for the effective $ρ π π$ and $ρN N$ interaction at finite temperature and density in the presence of a constant background magnetic field of arbitrary strength. In our approach, the eB-dependent vacuum part of the self energy is extracted by means of dimensional regularization where the ultraviolet divergences corresponding to the pure vacuum self energy manifest as the pole singularities of gamma as well as Hurwitz zeta functions. This improved regularization procedure consistently reproduces the expected results in the vanishing magnetic field limit and can be used quite generally in other self energy calculations dealing with arbitrary magnetic field strength. In presence of the external magnetic field, the general Lorentz structure for the in-medium vector boson self energy is derived which can also be implemented in case of the gauge bosons such as photons and gluons. It has been shown that with vanishing perpendicular momentum of the external particle, essentially two form factors are sufficient to describe the self energy completely. Consequently, two distinct modes are observed in the study of the effective mass, dispersion relations and the spectral function of $ρ^{0}$ where one of the modes possesses two fold degeneracy. For large baryonic chemical potential, it is observed that the critical magnetic field required to block the $ρ^{0} \to π^{+} π^{-}$ decay channel increases significantly with temperature. However, in case of smaller values reaching down to vanishing chemical potential, the critical field follows the opposite trend.
↳ hep-phnucl-thPRD(2019)·28 citations
04
Solar neutrino problem as evidence of new interaction
L.M. Slad🇷🇺
A new concept is proposed to solve the solar neutrino problem, that is based on a hypothesis about the existence of a new interaction of electron neutrinos with nucleons mediated by massless pseudoscalar bosons. At every collision of a neutrino with nucleons of the Sun, its handedness changes from left to right and vice versa, and its energy decreases. The postulated hypothesis, having only one free parameter, provides a good agreement between the calculated and experimental characteristics of all five observed processes with solar neutrinos.
↳ hep-phastro-ph.SRnucl-thJ.Exp.Theor.Phys.(2020)·9 citations

Affiliations

first authorsco-authorsvia INSPIRE

Constraint to chiral invariant masses of nucleons from GW170817 in an extended parity doublet model

Description of shape coexistence in 96Zr based on the collective quadrupole Bohr Hamiltonian

General structure of the neutral ρ meson self-energy and its spectral properties in a hot and dense magnetized medium

Solar neutrino problem as evidence of new interaction

Affiliations

Description of shape coexistence in $^{96}$ Zr based on the collective quadrupole Bohr Hamiltonian

General structure of the neutral $ρ$ meson self-energy and its spectral properties in a hot and dense magnetized medium