Effective meson masses, effective meson-nucleon couplings and neutron star radii

Using the generalized mean field theory, we have studied the relation among the effective meson masses, the effective meson-nucleon couplings and the equation of state (EOS) in asymmetric nuclear matter. If the effective omega-meson mass becomes smaller at high density, the EOS becomes stiffer. However, if we require that the omega-meson mean field is proportional to the baryon density, the effective omega-nucleon coupling automatically becomes smaller at the same time as the effective omega-meson mass becomes smaller. Consequently, the EOS becomes softer. A similar relation is found for the effective rho-meson mass and the effective rho-nucleon coupling. We have also studied the relation among the effective meson masses, the effective meson-nucleon couplings and a radius R of a neutron star. The R depends somewhat on the value of the effective omega-meson mass and the effective omega-nucleon coupling.Comment: 29pages, 24 figure

Quantifying physical insights cooperatively with exhaustive search for Bayesian spectroscopy of X-ray photoelectron spectra

We analyzed the X-ray photoemission spectra (XPS) of carbon 1s states in graphene and oxygen-intercalated graphene grown on SiC(0001) using Bayesian spectroscopy. To realize highly accurate spectral decomposition of the XPS spectra, we proposed a framework for discovering physical constraints from the absence of prior quantified physical knowledge, in which we designed the prior probabilities based on the found constraints and the physically required conditions. This suppresses the exchange of peak components during replica exchange Monte Carlo iterations and makes possible to decompose XPS in the case where a reliable structure model or a presumable number of components is not known. As a result, we have successfully decomposed XPS of one monolayer (1ML), two monolayers (2ML), and quasi-freestanding 2ML (qfs-2ML) graphene samples deposited on SiC substrates with the meV order precision of the binding energy, in which the posterior probability distributions of the binding energies were obtained distinguishably between the different components of buffer layer even though they are observed as hump and shoulder structures because of their overlapping

Bayesian spectroscopy on polarization dependent photoluminescence spectra of doubly-split excitons in a Cu2O thin-crystal sandwiched by MgO substrates

By using Bayesian spectroscopy, we studied polarization dependence of photoluminescence (PL) spectra in doubly-split 1S yellow ortho-excitons in a Cu2O thin-crystal recrystallized in a small gap between paired MgO substrates. In these thin-crystals, biaxial stresses are expected to be involved due to a small lattice mismatch between Cu2O and MgO. The ortho-exciton state splits into two states due to symmetry lowering. To elucidate such biaxial stress effect, we measured polarization dependence of the PL spectra. Although resonant weak PL bands of the doubly-split exciton states and their intense phonon sidebands co-exist, we succeeded in decomposing to the respective spectral components by the Bayesian spectroscopy. As a result, it was found that the resonant PL band appearing on higher energy side shows hardly polarization dependence, whereas the resonant PL band at lower energy side is further weak and shows polarization dependence. These results can be explained by the selection rule and polarization dependences on the transition matrix elements of quadrupole transitions of the ortho-exciton states, and it clearly shows that the crystal symmetry degrades to tetragonal one by the isotropic biaxial stress involved in the Cu2O thin-crystals