Ik Jae Shin

Holographic QCD: Past, Present, and Future

At the dawn of a new theoretical tool based on the AdS/CFT correspondence for non-perturbative aspects of quantum chromodynamics, we give an interim review on the new tool, holographic QCD, with some of its accomplishment. We try to give an A-to-Z picture of the holographic QCD, from string theory to a few selected top-down holographic QCD models with one or two physical applications in each model. We may not attempt to collect diverse results from various holographic QCD model studies.

Symmetry energy of dense matter in holographic QCD

We study the nuclear symmetry energy of dense matter using holographic QCD. To this end, we consider two flavor branes with equal quark masses in a D4/D6/D6 model. We find that at all densities the symmetry energy monotonically increases. At small densities, it exhibits a power law behavior with the density, Esym ~ ρ1/2.

Explicit flavor symmetry breaking and holographic compact stars

We study the effects of flavor symmetry breaking on holographic dense matter and compact stars in the D4/D6 model. To this end, two light flavors and one intermediate mass flavor are considered. For two light quarks, we investigate how the strong isospin violation affects the properties of holographic dense matter and compact stars. We observe that quark-antiquark condensates are flavor dependent and show interesting behavior near the transition from dense matter with only one flavor to matter with two flavors. An intermediate mass quark is introduced to investigate the role of the third flavor. The mass-radius relations of holographic compact stars with three flavors show that the mass-radius curve changes drastically at a transition density from which the third flavor begins to appear in the matter.

Ab initio no-core solutions for Li-6

We solve for properties of Li-6 in the ab initio no-core full configuration (NCFC) approach and we separately solve for its ground state and J(pi) = 2(2)(+) resonance with the Gamow shell model (GSM) in the Berggren basis. We employ both the JISP16 and chiral NNLOopt realistic nucleon-nucleon interactions and investigate the ground state energy, excitation energies, point proton root mean square (rms) radius and a suite of electroweak observables. We also extend and test methods to extrapolate the ground state energy, point proton rms radius, and electric quadrupole moment. We attain improved estimates of these observables in the NCFC approach by using basis spaces up through N-max = 18 that enable more definitive comparisons with experiment. Using the density matrix renormalization group approach with the JISP16 interaction, we find that we can significantly improve the convergence of the GSM treatment of the Li-6 ground state and J(pi) = 2(2)(+) resonance by adopting a natural orbital single-particle basis.

Ab initio no core full configuration approach for light nuclei

Comprehensive understanding of the structure and reactions of light nuclei poses theoretical and computational challenges. Still, a number of ab initio approaches have been developed to calculate the properties of atomic nuclei using fundamental interactions among nucleons. Among them, we work with the ab initio no core full configuration (NCFC) method and ab initio no core Gamow Shell Model (GSM). We first review these approaches and present some recent results.

Equations of state and compact stars in gauge/gravity duality

A bstractWe propose a new doorway to study the interplay between equations of state of dense matter and compact stars in gauge/gravity correspondence. For this we construct a bulk geometry near the boundary of five-dimensional spacetime. By solving a constraint equation derived from the bulk equation of motion together with the Tolman-Oppenheimer-Volkoff equation, we determine the equations of state for compact stars. The input parameters in this study are the energy density and pressure at the center of the compact objects. We also study how the equation of state depends on the parameters.