We studied the roles of the tensor and pairing correlations on the halo formation in ${}^{11}\mathrm{Li}$ with an extended ${}^9\mathrm{Li}+n+n$ model. We first solved the ground state of ${}^9\mathrm{Li}$ in the shell-model basis by taking 2p-2h states using the Gaussian functions with variational size parameters to take into account the tensor correlation fully. In ${}^{11}\mathrm{Li}$, the tensor and pairing correlations in ${}^9\mathrm{Li}$ are Pauli blocked by additional two neutrons, which work coherently to make the configurations containing the $0p_{1/2}$-state pushed up and close to those containing the $1s_{1/2}$-state. Hence, the pairing interaction works efficiently to mix the two configurations by equal amount and develop the halo structure in ${}^{11}\mathrm{Li}$. For ${}^{10}\mathrm{Li}$, the inversion phenomenon of $s$- and $p$-states is reproduced in the same framework. Our model furthermore explains the recently observed Coulomb breakup strength and charge radius for ${}^{11}\mathrm{Li}$.

The structure of the $\phi$ photoproduction amplitude in the $\sqrt{s}\sim 2-5\mathrm{GeV}$ region is analyzed based on Pomeron-exchange and meson-exchange mechanisms. The SU(3) symmetry and the $\phi$ decay widths are exploited to determine the parameters that are needed to predict the amplitudes due to pseudoscalar mesons $({\pi }^0,\eta )$ exchange, scalar mesons $\left(\sigma {,a}_0{,f}_0\right)$ exchange, and the $\phi$ radiation from the nucleon. In addition to the universally accepted Pomeron exchange with an intercept $\alpha \mathrm{}\left(0\right)\mathrm{}\sim 1.08,$ we investigate the role of a second Pomeron with $\alpha \mathrm{}\left(0\right)<0,$ as inspired by the glueball ${(J}^{\pi }{=0\mathrm{}}^{+}{,M}_b^2\sim 3{\mathrm{GeV}}^2)$ predicted by the lattice QCD calculation and dual Ginsburg-Landau model. It is found that the existing limited data at low energies near threshold can accommodate either the second Pomeron or the scalar mesons exchange. The differences between these two competing mechanisms are shown to have profound effects on various density matrices which can be used to calculate the cross sections as well as various single and double polarization observables. We predict a definite isotopic effect: polarization observables of $\phi$ photoproduction on the proton and neutron targets can have differences of a factor 2 and more.

We calculate $$\beta${}$-transition rates for URCA nuclear pairs using the $sd$-shell-model framework of Wildenthal [B. H. Widenthal, Prog. Part. Nucl. Phys. 11, 5 (1984)] with the modified Hamiltonian. We consider many $$\beta${}$ transitions including excited states necessary for electron capture and $$\beta${}$ decay with high Fermi energy of electrons at high electron density $$\rho${}{Y}_{e}$ and temperature $T$ relevant for the massive star and super-asymptotic-giant-branch star evolution. We provide $$\beta${}$-transition rates for URCA nuclear pairs ($A=23$, 25, and 27) in the range of density 8.0 $<{\mathrm{log}}_{10}$\rho${}{Y}_{e}<$ 9.2 in steps of 0.02 (${Y}_{e}$ is the electron mole number and $$\rho${}$ is the nucleon density in units of g cm${}^{$-${}3}$) and temperature 8.0 $<{\mathrm{log}}_{10}T<$ 9.2 in steps of 0.05 ($T$ is the temperature in units of K). This fine mesh is able to provide clearly the URCA density at ${\mathrm{log}}_{10}$\rho${}{Y}_{e}=8.92$ for $A=23$ and at ${\mathrm{log}}_{10}$\rho${}{Y}_{e}=8.81$ for $A=25$, while the URCA density is not clear for $A=27$. For the evolution of 8\char21{}10${M}_{$\bigodot${}}$ stars, the use of the fine mesh is found to increase the cooling effect and affects the final fate of these stars.

We study nuclear matter and finite nuclei in terms of the quark mean field (QMF) model, in which we describe the nucleon using the constituent quark model. The meson mean fields, in particular the $\sigma$ meson, created by other nucleons act on quarks inside a nucleon and change the nucleon properties in nuclear medium. The QMF model predicts an increasing size of the nucleon as well as a reduction of the nucleon mass in the nuclear environment. The present model is applied to study the properties of finite nuclei after fixing all the parameters by the nuclear matter properties, and it is found to give satisfactory results on the nuclear properties.

We study the possibility of the existence of a finite pion mean field in finite nuclei in the relativistic mean-field (RMF) theory. We are led to conjecture this existence by findings of the essential role of the pion in few-body systems and (p,n) experiments for spin-isospin excitations of medium and heavy nuclei. We carry out explicit calculations for various N=Z closed shell nuclei with a finite pion mean field in the RMF theory with the standard parameter set and pion-nucleon coupling in free space. We find that the finite pion mean field breaks the parity symmetry of the intrinsic single-particle states. We demonstrate the actual existence and elucidate the properties of the finite pion mean field, whose qualitative consequences for various observables are also briefly discussed.