RESEARCH INTERESTS AND GOALS (4/25/2007)

 The goal of my research is to understand the properties of dense matter as encountered in compact stars and nuclei, while bearing in mind observations of neutron stars and heavy-ion collision experiments at various energies. I am primarily interested in theoretical study of phase transitions in dense matter, which range from composition and shape changes in inhomogeneous nuclear matter in neutron star crusts to superfluid transition in dense quark matter that might be present in neutron star cores. My research has been focused on what kind of many-body effects arising from the constituents and their interactions are relevant to such phase transitions and related phenomena.

In studying a variety of dense systems, I have mainly examined the equilibrium properties of these materials such as the equation of state and the composition by incorporating many-body effects relevant in real situations: strong coupling corrections, thermal fluctuations, finite-size effects, charge screening, and so on. These properties are directly related to the observed mass and size of nuclei and neutron stars, while underlying the understanding of the thermal, magnetic, and rotational evolution observed from pulsars. For this understanding, I have been also interested in how the system responds to external magnetic fields and rotation and how a stable phase nucleates in a metastable phase. The latter bears relevance to quantum tunneling nucleation observed in helium experiments.

The way I have approached dense matter is a phenomenological one based on related experimental and Monte Carlo simulation data, while at the same time I have been paying attention to self-consistency conditions that connect the long-wavelength behavior of correlation functions with macroscopic observables and rigorous calculations in the weak coupling limit. For future applications, I have constructed parametrized expressions for free energies and correlation functions of electron systems, nuclear masses and radii, and so on.

Currently, I am interested in a detailed description of the color superconducting properties of dense quark matter, both near the transition temperature where thermal fluctuations play a role and at zero temperature where a homogeneous gapless phase can become unstable against inhomogeneities. Another primary interest is in using future data on the size of heavy unstable nuclei to be produced as RI beams in RIKEN and GSI to deduce the density dependence of the symmetry energy and thereby understand the properties of extremely neutron-rich nuclei in neutron star crusts and their relation to the quiescent X-ray emission observed from low-mass X-ray binary systems. In the course of this study, a black sphere picture of nuclei has been utilized in analyzing existing data for proton elastic scattering and total reaction cross section and shown to give an empirical relation between them for stable nuclei. I hope that this picture will open a systematic way of studying the structure of unstable nuclei. I am also interested in understanding how finite-size effects affect the properties of quark-gluon plasmas expected to be created in highly energetic heavy ion collisions such as thermalization and collective excitations.

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