Exploring the limits of nuclear existence plays an important role in understanding the particle stability of neutron-rich and proton-rich nuclei. It provides many opportunities to study exotic nuclear structures, nuclear reactions and nuclear astrophysics, and it can be a benchmark for theoretical mass models at the extremely exotic region.

In this talk, the research on the rare isotope...

I will start by introducing a gravitational theory that string theory predicts. It differs from general relativity, and can probe not only the mass but also pressure, hence generically equations of state parameters. For the theory to be consistent with observations, ordinary baryonic matter should be ultra-relativistic, which may be so at subhadronic level. This talk is based on a work with...

The nuclear optical potential provides an essential tool for studying nucleon-nucleus elastic scattering and reaction cross sections by incorporating the complexity of many-body correlations into an effective one-body mean field between projectile and target. We develop for the first time a microscopic global nucleon-nucleus optical potential with quantified uncertainties suitable for...

I discuss direct and fusion reactions including weakly-bound and halo nuclei. At first, to this end, I introduce the expended optical potential for direct reaction calculations as elastic scattering, inelastic, and breakup from strand optical model formalism, and emphasize the benefit of extended optical model. Then, I review previous results of direct reactions which include neutron halo...

The elastic alpha-carbon-12 scattering at low energies for $l=0,1,2,3,4,5,6$ is studied in effective field theory (EFT). We discuss a construction of the S matrices of elastic alpha-carbon-12 scattering in terms of the amplitudes of sub-threshold bound and resonant states of oxygen-16. The parameters appearing in the S matrices are fitted to the phase shift data below the proton-nytrogen-15...

We investigate the tensor force (TF) effect on the Gamow–Teller (GT) transition strength distributions in 42Ca, 46Ti, and 18O, which are known to have strong low-energy GT states,the so-called low-energy super GT (LeSGT) transition, peculiar to nuclei retaining a neutron number N = Z + 2. The TF is explicitly taken into account in the pairing channels of the residual interaction on top of the...

As experiments searching for neutrinoless double beta decay are in the planning phase of a next generation with hopes to completely probe the inverted mass hierarchy, the need for reliable nuclear matrix elements, which govern the rate of this decay, is stronger than ever. Since a large discrepancy is found when computing this quantity with different nuclear models, a large unknown still...

Shell evolution of Sn isotopes is an active research area in nuclear structure. Recently, Monte Carlo Shell Model calculations predicted shape evolution and active proton core excitations, as explanations for the enhancement of B(E2) values in the light Sn isotopes toward the doubly magic $^{100}$Sn, relative to the simple seniority scheme. Several Coulomb excitation experiments were carried...

We present shape coexistence in the odd-odd Sb (Z=51) and I (Z=53) nuclides; spherical and deformed shapes. With a specific focus on the intruder proton (p) and neutron (n) h11/2 orbitals, we show the deformed rotational bands in Sb and I with N = 63 to 67 as discussing systematic features emerged in the neutron-shell space of 50 < N < 82. In addition, we discuss the chiral-like double bands...

We extend chiral perturbation theory to include vector mesons as well as pions and nucleons. By counting the vector meson mass as heavy while treating the associated momentum as light, a consistent scheme can be obtained with a well-defined power counting rule. We find that the extended theory can describe the electric form factors of pions and nucleons far better than the conventional ChPT...

We examine the nuclear reactions 7Li(p,$\gamma$)8Be and 7Li(p,e+e-)8Be from an ab initio perspective.

Using the no-core shell model with continuum technique, with chiral nucleon-nucleon and three-nucleon forces as input, we obtain an accurate description of both 8Be bound states and p+7Li scattering states.

We calculate radiative capture reactions in which enough energy is released to...

Skyrmions, the stable soliton solutions in an EFT introduced by Tony Skyrme, have been constructed for many baryon numbers (atomic mass numbers). They have interesting intrinsic shapes and also an intrinsic pion field structure. So a Skyrmion spontaneously breaks translational, rotational and isorotational symmetry. These symmetries are restored through quantization of the collective motion...

We study Skrymion like configurations in the coset space SO(8)/SU(3). \Pi_3(SO(8)/SU(3))=Z_3, hence the Skyrmions have a sort of triality. We establish the existence of the Skyrmions and give some explicit configurations. We speculate as to their physical import.