B. J. Liu

Physics at BES-III

We give a detailed review of the construction of gauge invariant Lagrangians for free and interacting higher spin fields using the BRST approach developed over the past few years.This physics book provides detailed discussions on important topics in

Asymmetric nuclear matter: The role of the isovector scalar channel

\tau

Neutron stars with isovector scalar correlations

-charm physics that will be explored during the next few years at \bes3 . Both theoretical and experimental issues are covered, including extensive reviews of recent theoretical developments and experimental techniques. Among the subjects covered are: innovations in Partial Wave Analysis (PWA), theoretical and experimental techniques for Dalitz-plot analyses, analysis tools to extract absolute branching fractions and measurements of decay constants, form factors, and CP-violation and \DzDzb-oscillation parameters. Programs of QCD studies and near-threshold tau-lepton physics measurements are also discussed.

Isoscalar-vector interaction and hybrid quark core in massive neutron stars

We try to single out some qualitative effects of coupling to a \ensuremath{\delta}-isovector-scalar meson, introduced in a minimal way in a phenomenological hadronic field theory. Results for the equation of state (EOS) and the phase diagram of asymmetric nuclear matter (ANM) are discussed. We stress the consistency of the \ensuremath{\delta}-coupling introduction in a relativistic approach. Contributions to the slope and curvature of the symmetry energy and to the neutron-proton effective mass splitting appear particularly interesting. A more repulsive EOS for neutron matter at high baryon densities is expected. Effects on the critical properties of warm ANM, mixing mechanical and chemical instabilities and isospin distillation, are also presented. The \ensuremath{\delta} influence is mostly on the isovectorlike collective response. The results are largely analytical, and this makes the physical meaning quite transparent. Implications for nuclear structure properties of drip-line nuclei and for reaction dynamics with radioactive beams are finally pointed out.

Hadron-quark phase transition in asymmetric matter with dynamical quark masses

Neutron stars with the isovector scalar δ-field are studied in the framework of the relativistic mean-field (RMF) approach in a pure-nucleon-plus-lepton scheme. The δ-field leads to a larger repulsion in dense neutron-rich matter and to a definite splitting of proton and neutron effective masses. Both features are influencing the stability conditions of the neutron stars. Two parametrizations for the effective nonlinear Lagrangian density are used to calculate the nuclear equation of state (EOS) and the neutron star properties, and compared to correlated Dirac-Brueckner results. We conclude that in order to reproduce reasonable nuclear structure and neutron star properties within a RMF approach, a density dependence of the coupling constants is required.Abstract. Neutron stars with the isovector scalar δ-field are studied in the framework of the relativistic mean-field (RMF) approach in a pure-nucleon-plus-lepton scheme. The δ-field leads to a larger repulsion in dense neutron-rich matter and to a definite splitting of proton and neutron effective masses. Both features are influencing the stability conditions of the neutron stars. Two parametrizations for the effective nonlinear Lagrangian density are used to calculate the nuclear equation of state (EOS) and the neutron star properties, and compared to correlated Dirac-Brueckner results. We conclude that in order to reproduce reasonable nuclear structure and neutron star properties within a RMF approach, a density dependence of the coupling constants is required.

Phase diagrams in the hadron-Polyakov-Nambu-Jona-Lasinio model

The hadron-quark phase transition in the core of massive neutron stars is studied with a newly constructed two-phase model. For nuclear matter, a nonlinear Walecka type model with general nucleon-meson and meson-meson couplings, recently calibrated by Steiner, Hemper and Fischer, is taken. For quark matter, a modified Polyakov-Nambu-Jona-Lasinio model, which gives consistent results with lattice QCD data, is used. Most importantly, we introduce an isoscalar-vector interaction in the description of quark matter, and we study its influence on the hadron-quark phase transition in the interior of massive neutron stars. With the constraints of neutron star observations, our calculation shows that the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe, and its strength determines the onset density of quark matter, as well as the mass-radius relations of hybrid stars. Furthermore, as a connection with heavy-ion-collision experiments we give some discussions about the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions, in the energy range of the NICA at JINR-Dubna and FAIR at GSI-Darmstadt facilities.

Application of density dependent parametrization models to asymmetric nuclear matter

The two-equation-of-state model is used to describe the hadron-quark phase transition in asymmetric matter formed at high density in heavy-ion collisions. For the quark phase, the three-flavor Nambu-Jona-Lasinio effective theory is used to investigate the influence of dynamical quark mass effects on the phase transition. At variance to the MIT-Bag results, with fixed-current quark masses, the main important effect of the chiral dynamics is the appearance of an end point for the coexistence zone. We show that a first-order hadron-quark phase transition may take place in the region T subset of (50-80) MeV and {rho}{sub B} subset of (2-4){rho}{sub 0}, which is possible to be probed in the new planned facilities, such as FAIR at GSI-Darmstadt and NICA at JINR-Dubna. From the isospin properties of the mixed phase, some possible signals are suggested. The importance of chiral symmetry and dynamical quark mass on the hadron-quark phase transition is stressed. The difficulty of an exact location of a critical end point comes from its appearance in a region of competition between chiral symmetry breaking and confinement, where our knowledge of effective QCD theories is still rather uncertain.

Influence of vector interactions on the hadron-quark/gluon phase transition

G.Y. Shao, M. Di Toro, 2, ∗ V. Greco, 2 M. Colonna, S. Plumari, 2 B. Liu, 4 and Y.X. Liu 6 INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania, Italy Physics and Astronomy Dept., University of Catania, Italy IHEP, Chinese Academy of Sciences, Beijing, 100049 China Theoretical Physics Center for Scientific Facilities, Chinese Academy of Sciences, Beijing, 100049 China Department of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, China Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000, China

Onsite data processing and monitoring for the Daya Bay experiment

Density dependent parametrization models of the nucleon-meson effective couplings, including the isovector scalar delta-field, are applied to asymmetric nuclear matter. The nuclear equation of state and the neutron star properties are studied in an effective Lagrangian density approach, using the relativistic mean field hadron theory. It is known that the introduction of a delta-meson in the constant coupling scheme leads to an increase of the symmetry energy at high density and so to larger neutron star masses, in a pure nucleon-lepton scheme. We use here a more microscopic density dependent model of the nucleon-meson couplings to study the properties of neutron star matter and to reexamine the delta-field effects in asymmetric nuclear matter. Our calculations show that, due to the increase of the effective delta coupling at high density, with density dependent couplings the neutron star masses in fact can be even reduced.

Hadron-quark phase coexistence in a hybrid MIT-Bag model

The hadron-quark/gluon phase transition is studied in the two-phase model. As a further study of our previous work, both the isoscalar and isovector-vector interactions are included in the Polyakov loop modified Nambu-Jona-Lasinio model for the quark phase. The relevance of the exchange (Fock) terms is stressed and suitably accounted for. The calculation shows that the isovector-vector interaction delays the phase transition to higher densities and the range of the mixed phase correspondingly shrinks. Meanwhile, the asymmetry parameter of quark matter in the mixed phase decreases with the strengthening of this interaction channel. This leads to some possible observation signals being weakened, although still present. We show that these can be rather general effects of a repulsion in the quark phase due to the symmetry energy. This is also confirmed by a simpler calculation with the MIT-bag model. However, the asymmetry parameter of quark matter is slightly enhanced with the inclusion of the isoscalar-vector interaction, but the phase transition will be moved to higher densities. The largest uncertainty on the phase transition lies in the undetermined coupling constants of the vector interactions. In this respect, new data on the mixed phase obtained from heavy-ion collisions at intermediate energies appear very important.