Liu Yu-Xin

Collective perspective on advances in Dyson-Schwinger Equation QCD

We survey contemporary studies of hadrons and strongly interacting quarks using QCDs Dyson—Schwinger equations, addressing the following aspects: confinement and dynamical chiral symmetry breaking; the hadron spectrum; hadron elastic and transition form factors, from small- to large-Q2; parton distribution functions; the physics of hadrons containing one or more heavy quarks; and properties of the quark gluon plasma.

Theoretical study on the rotational bands and shape coexistence of (179,) (181,183) Au in the particle-triaxial-rotor model

We perform a series of theoretical calculations and investigation for nuclei Au-179,Au-181,Au-183 in the particle-triaxial-rotor model with variable moment of inertia. The calculated energy spectra in Au-179,Au-181,Au-183 agree well with the experimental data globally. The obtained results indicate that the nuclei 179,181,183 An have prolate deformation and involve shape coexistence with different deformation parameters in different bands. The main configuration of bands 1, 2, 3 and 5 in these nuclei are identified as [541]1/2(-) (pi h(9/2), alpha = 1/2), [541]1/2(-) (pi h(9/2), alpha = -1/2), [530]1/2(-) (pi f(7/2)) and [660]1/2(+) (pi i(13/2)), respectively.

Evidence for a possible E(5) symmetry in 130Xe

By analysing the energy spectrum and E2 transition branching ratios, we show that the E(5) symmetry predictions agree well with the experimental data of nucleus 130Xe. Compared the calculated results with those within the framework of the interacting boson model, it is found that the nucleus 130Xe is definitely a nucleus in the transitional region from U(5) to O(6) symmetry. 130Xe is then another empirical evidence of the nucleus with E(5) symmetry.

Rotational Property of 249Cm in Particle-Triaxial-Rotor Model

We study the rotational energy spectrum and deformation feature of very heavy nucleus 249Cm in the particle-triaxial-rotor model with variable moment of inertia. Such a nucleus is the unique one involving both multi-band structure and high spin states and locating very near the superheavy region. By calculating the energy spectrum, we determine the configurations and quadrupole and triaxial deformation parameters β and γ of the nucleus. The calculated results indicate that the high spin band of 249Cm is built upon the configuration with deformation parameters β = 0.296 and γ = 7.5° and the bands based on the configuration respectively are also the ones with quite large axial deformation but small triaxial deformation.

Comparison of Properties of the Simplest Neutron Stars in Three RMF Models

We study some properties of the simplest neutron stars (NSs) in the Glendenning–Moszkowski (GM) model, the hybrid derivative coupling (HD) model and the Zimanyi–Moszkowski (ZM) model in the framework of relativistic mean field (RMF) theory with and without the interaction by exchanging the S-meson. We show that the maximal mass of the NSs becomes smaller, but the redshift becomes larger from the GM model to the HD model, then to the ZM model. The interaction with the S-meson exchange enlarges the maximal mass of neutron stars, increases the relative population of charged particles (proton, electron and muon) and descends the relative population of neutron.We study some properties of the simplest neutron stars (NSs) in the Glendenning–Moszkowski (GM) model, the hybrid derivative coupling (HD) model and the Zimanyi–Moszkowski (ZM) model in the framework of relativistic mean field (RMF) theory with and without the interaction by exchanging the S-meson. We show that the maximal mass of the NSs becomes smaller, but the redshift becomes larger from the GM model to the HD model, then to the ZM model. The interaction with the S-meson exchange enlarges the maximal mass of neutron stars, increases the relative population of charged particles (proton, electron and muon) and descends the relative population of neutron.

Rotation Driven Shape-Phase Transition of the Yrast Nuclear States with O(6) Symmetry in the Interacting Boson Model

In a framework of the interacting boson model (usually referred to as IBM-1) with angular momentum projection on the coherent state, we obtain the energy surface functional of nuclei in terms of angular momentum and shape parameters. Analysing the rotation driven effect on the equilibrium shape shows that the yrast states of the nuclei with O(6) symmetry will experience a shape-phase transition from gamma-soft deformed to triaxially deformed and then to spherical shape along the yrast line as the angular momentum increases.

Proton Fraction in Hot Neutron Star Matter with a Chiral Hadronic Model

In the framework of a chiral hadronic model it has been numerically proven that the parabolic expansion with respect to delta(2) at finite density and temperature is a good approximation in the relativistic mean field theory. It is also shown that the proton fraction in the modified Urca process is considerably restrained in comparison with that of the direct Urca process. Then, we discuss the influences of the density-dependent and temperature-dependent asymmetry energy on the proton fraction in hot neutron star matter.

The Structure of the Neutron-Rich Nd Isotopes in the IBM*

The spectra and E2 transition properties of Nd146-156 isotopes are studied in the interacting boson model in the light of new experimental data. It is found that Nd146-150 are in the transition from the vibrational limit to the rotational limit. From Nd-152 onward, the isotopes are nearly perfect rotors. Possible deformation saturation is discussed in the interacting boson model.

Calculation of fσ on Quark Level

With the recently obtained vacuum configuration of the bilocal field, we have calculated the decay constant f(sigma) of sigma-meson in a quantum chromodynamics-based model field theory. From investigating the calculated result, it can be seen that the obtained value of f(sigma) is quite reasonable.

Pion and σ-meson Properties in a Strong Magnetic Field*

With the Nambu–Jona-Lasinio (NJL) model we calculate the properties of pion and σ-meson at finite temperature and finite magnetic field. The obtained temperature and magnetic field strength dependence of the constituent quark mass M, the pion and σ-meson masses and the neutral pion decay constant indicates that, in the simple four fermion interaction model, there exists the magnetic catalysis effect. It also shows that the Gell-Mann–Oakes–Renner relation is violated obviously with the increasing of the temperature, and the effect of the magnetic field becomes pronounced only around the critical temperature. The deviation of the critical temperatures obtained with different criteria indicates that the chiral phase transition driven by the temperature in the magnetic field strength region we have considered is in fact a crossover.