The $\gamma$-ray decay of isomeric states in the even-even nucleus ${}^{128}\mathrm{Cd}$ has been observed. The nucleus of interest was produced both by the fragmentation of ${}^{136}\mathrm{Xe}$ and the fission of ${}^{238}\mathrm{U}$ primary beams. The level scheme was unambiguously constructed based on $\gamma \gamma$ coincidence relations in conjunction with detailed lifetime analysis employed for the first time on this nucleus. Large-scale shell-model calculations, without consideration of excitations across the $N=82$ shell closure, were performed and provide a consistent description of the experimental level scheme. The structure of the isomeric states and their decays exhibit coexistence of proton, neutron, and strongly mixed configurations due to $\pi \nu$ interaction in overlapping orbitals for both proton and neutron holes.

We have studied the reaction $p+$${}^{27}\mathrm{Al}$ $\to$ ${}^3\mathrm{He}$$+p+{\pi }^{-}+X$ at recoil-free kinematics. An $\eta$ meson possibly produced in this reaction would be thus almost at rest in the laboratory system and could therefore be bound with high probability, if nuclear $\eta$ states exist. The decay of such a state through the $N^{*}(1535)$ resonance would lead to a proton-${\pi }^{-}$ pair emitted in opposite directions. For these conditions we find some indication of such a bound state. An upper limit of $\approx 0.5$ nb is found.

We have studied the one-neutron removal reactions of ${}^{18}\mathrm{C}$ at 81 MeV/nucleon and ${}^{19}\mathrm{C}$ at 68 MeV/nucleon on a liquid hydrogen target. Transverse-momentum distributions of the core fragments ${}^{17}\mathrm{C}$ and ${}^{18}\mathrm{C}$, and their partial cross sections, are measured using coincidences with the $\gamma$ rays. These are compared to theoretical calculations based on the continuum-discretized coupled-channels (CDCC) method. We have found that the transverse-momentum distributions of ${}^{17}\mathrm{C}$ are well described by the CDCC calculations, and the agreement provides evidence for the spin-parity assignments of $J^{\pi }=1/2^{+}$ for the 0.21-MeV state and $J^{\pi }=5/2^{+}$ for the 0.33-MeV state in ${}^{17}\mathrm{C}$. The $J^{\pi }=(2,3){}^{+}$ assignment for the 4.0-MeV state in ${}^{18}\mathrm{C}$ is obtained for the first time based on the momentum distribution of ${}^{18}\mathrm{C}$. The measured partial cross sections are consistent with the CDCC calculations combined with shell-model spectroscopic factors. The present study demonstrates that the transverse-momentum distribution obtained in a one-neutron removal reaction on a proton target is as useful as the conventional longitudinal-momentum distribution measured with the heavier Be or C targets for determining the orbital angular momentum of a removed neutron.

We have made the first measurements of the virtual Compton scattering (VCS) process via the $\mathrm{H}$($e$, $e^{\text{'}}p$)$\gamma$ exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the $W$-dependence at fixed $Q^2=1\hspace{0.5em}{\mathrm{GeV}}^2$ and for the $Q^2$ dependence at fixed $W$ near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed $Q^2$ dependence is smooth. The measured ratio of $\mathrm{H}$($e$, $e^{\text{'}}p$)$\gamma$ to $\mathrm{H}$($e$, $e^{\text{'}}p$)${\pi }^0$ cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to real Compton scattering (RCS) at high energy and large angles, our VCS data at the highest $W$ ($1.8\text{−}1.9$ GeV) show a striking $Q^2$ independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.

High-precision data of backward-angle elastic and quasielastic scattering for the weakly bound ${}^6\mathrm{Li}$ projectile on ${}^{144}\mathrm{Sm}$ target at deep–sub-barrier, near-, and above-barrier energies were measured. From the deep–sub-barrier data, the surface diffuseness of the nuclear interacting potential was studied. Barrier distributions were extracted from the first derivatives of the elastic and quasielastic excitation functions. It is shown that sequential breakup through the first resonant state of the ${}^6\mathrm{Li}$ is an important channel to be included in coupled-channels calculations, even at deep–sub-barrier energies.

We analyze the accuracy of BCS-based approximations for calculating correlation energies and odd-even energy differences in two-component fermionic systems with a small number of pairs. The analysis is focused on comparing BCS and projected BCS treatments with the exact solution of the pairing Hamiltonian, considering parameter ranges appropriate for nuclear pairing energies. We find that the projected BCS is quite accurate over the entire range of coupling strengths in spaces of up to about $~20$ doubly degenerate orbitals. It is also quite accurate for two cases we considered with a more realistic Hamiltonian, representing the nuclei around ${}^{117}\mathrm{Sn}$ and ${}^{207}\mathrm{Pb}$. However, the projected BCS significantly underestimates the energies for much larger spaces when the pairing is weak.

Using the formalism of the Khalatnikov potential, we derive exact general formulas for the entropy flow $\mathit{dS}/\mathit{dy}$, where $y$ is the rapidity, as a function of temperature for the ($1+1$) relativistic hydrodynamics of a perfect fluid. We study in particular flows dominated by a sufficiently long hydrodynamic evolution and provide an explicit analytical solution for $\mathit{dS}/\mathit{dy}$. We discuss the theoretical implications of our general formulas and some phenomenological applications for heavy-ion collisions.

We perform a theoretical analysis of the $a_1$ resonance mass spectrum in ultrarelativistic heavy ion collisions within a hadron/string transport approach. Predictions for the $a_1$ yield and its mass distribution are given for the GSI-FAIR and the critRHIC energy regime. The potential of the $a_1$ meson as a signal for chiral symmetry restoration is explored. In view of the latest discussion, we investigate the decay channel $a_1\to \gamma \pi$ in detail and find a strong bias toward low $a_1$ masses. This apparent mass shift of the $a_1$, if observed in the $\gamma \pi$ channel, might render a possible mass shift due to chiral symmetry restoration very difficult to disentangle from the decay kinematics.

We investigate charm hadron production in relativistic heavy ion collisions with the quark combination model. The $p_T$ dependencies of the charm baryon-to-meson ratios such as $\frac{{\Lambda }_c+{\overline{\Lambda }}_c}{D^0+{\overline{D}}^0}$, $\frac{{\Lambda }_c+{\overline{\Lambda }}_c}{D^{+}+D^{-}}$, and $\frac{{\Lambda }_c+{\overline{\Lambda }}_c}{D_s^{+}+D_s^{-}}$ in $\mathrm{Au}+\mathrm{Au}$ collisions at 200 GeV are obtained. The charm baryon enhancement in the intermediate $p_T$ range is very prominent, which, together with the strangeness enhancement, further affects the charm hadron ratios. The modified charm hadron ratios lead to a $~17\%$ increase of the charm cross section given by PHENIX. The dependencies of the charm hadron ratios on energy, centrality, and other parameters are also investigated. Predictions of the charm hadron ratios for the upgrade of the BNL Relativistic Heavy Ion Collider (RHIC) and the CERN Large Hadron Collider (LHC) are presented.

We investigate the critical temperature of Bose-Einstein condensation of $K^{-}$ mesons in neutron star matter. This is studied within the framework of relativistic field theoretical models at finite temperature where nucleon-nucleon and (anti)kaon-nucleon interactions are mediated by the exchange of mesons. The melting of the antikaon condensate is studied for different values of antikaon optical potential depths. We find that the critical temperature of antikaon condensation increases with baryon number density. Further it is noted that the critical temperature is lowered as antikaon optical potential becomes less attractive. We also construct the phase diagram of neutron star matter with $K^{-}$ condensate.

With the equations of state provided by the newly developed density-dependent relativistic Hartree-Fock (DDRHF) theory for hadronic matter, the properties of the static and $\beta$-equilibrium neutron stars without hyperons are studied for the first time and compared to the predictions of the relativistic mean-field models and recent observational data. The influences of Fock terms on properties of asymmetric nuclear matter at high densities are discussed in detail. Because of the significant contributions from the σ- and ω-exchange terms to the symmetry energy, large proton fractions in neutron stars are predicted by the DDRHF calculations, which strongly affect the cooling process of the star. A critical mass of about $1.45M_{\odot }$, close to the limit of $1.5M_{\odot }$ determined by modern soft X-ray data analysis, is obtained by DDRHF with the effective interactions PKO2 and PKO3 for the occurrence of the direct Urca process in neutron stars. The maximum masses of neutron stars given by the DDRHF calculations lie between $2.45M_{\odot }$ and $2.49M_{\odot }$, which are in reasonable agreement with the high pulsar mass of $(2.08\pm 0.19)M_{\odot }$ from PSR B1516 $+$ 02B. It is also found that the mass-radius relations of neutron stars determined by DDRHF are consistent with the observational data from thermal radiation measurements in the isolated neutron star RX J1856, quasiperiodic brightness oscillations in the low-mass X-ray binaries 4U 0614 $+$ 09 and 4U 1636-536, and the redshift determined in the low-mass X-ray binary EXO 0748-676.

We present a measurement of the electron-capture branch of ${}^{100}\mathrm{Tc}$. Our value, $B(\mathrm{EC})=(2.6\pm 0.4)\times {10}^{-5}$, implies that the ${}^{100}\mathrm{Mo}$ neutrino absorption cross section to the ground state of ${}^{100}\mathrm{Tc}$ is roughly 50% larger than previously thought. Disagreement between the experimental value and QRPA calculations relevant to double-$\beta$ decay matrix elements persists. We find agreement with previous measurements of the 539.5- and 590.8-keV $\gamma$-ray intensities.

In both the Sun and the early universe, the ${}^3\mathrm{He}$($\alpha$, $\gamma$)${}^7\mathrm{Be}$ reaction plays a key role. The rate of this reaction is the least certain nuclear input needed to calculate both the primordial ${}^7\mathrm{Li}$ abundance in big-bang nucleosynthesis and the solar neutrino flux. Taking advantage of several recent highly precise experiments, we analyze modern ${}^3\mathrm{He}$($\alpha$, $\gamma$)${}^7\mathrm{Be}$ data using a robust and minimally model-dependent approach capable of handling discrepant data sets dominated by systematic rather than statistical errors. We find $S_{34}(0)=0.580\pm 0.043(0.054)$ keV b at the 68.3(95.4)% confidence level.

The effect of the breakup process on the fusion induced by proton halo projectiles is investigated through the behavior of the quasi-elastic barrier distribution of the system ${}^8\mathrm{B}$ $+$ ${}^{58}\mathrm{Ni}$. The competition between the breakup channel and the inelastic excitations and the behavior of their corresponding polarization potentials are studied by means of continuum discretized coupled channel (CDCC) calculations.

The energy distribution of the ternary $\alpha$ particles in spontaneous fission of ${}^{252}\mathrm{Cf}$ was measured. For the first time an energy threshold as low as 1 MeV was reached. The experiment used an array of unshielded silicon detectors measuring energy and time-of-flight (TOF) of ternary particles in coincidence with fission fragments. The TOF resolution of the system was sufficient for clear separation of ${}^6\mathrm{He}$ and tritons from ${}^4\mathrm{He}$. The statistics were adequate to extract the ${}^6\mathrm{He}$/${}^4\mathrm{He}$ yield ratio. For both ${}^4\mathrm{He}$ and ${}^6\mathrm{He}$, an excess in the yield (as compared to a Gaussian shape) was observed at energies below 9 MeV. The measured ternary $\alpha$ spectrum was corrected for the distortion induced by the detection geometry covering equatorial particle emission only. The emission angle was found to affect mainly the width of the energy distribution by up to 1 MeV.

Measurement of fusion cross sections for the ${}^{6,7}\mathrm{Li}$ $+$ ${}^{24}\mathrm{Mg}$ reactions by the characteristic $\gamma$-ray method has been done at energies from below to well above the respective Coulomb barriers. The fusion cross sections obtained from these $\gamma$-ray cross sections for the two systems are found to agree well with the total reaction cross sections at low energies. The relatively large difference between total cross sections and measured fusion cross sections at higher energies is consistent with the fact that other channels, in particular breakup, open up with an increase of bombarding energy. The breakup channel, however, appears not to have any influence on fusion cross sections. The critical angular momenta ($l_{\mathrm{cr}}$) deduced from the fusion cross sections are found to have an energy dependence similar to other Li-induced reactions.

We discuss mechanisms related to isospin transport in central collisions between neutron-rich systems at Fermi energies to gain information on the nuclear symmetry energy at and below saturation. A fully consistent study of the isospin distillation and expansion dynamics in two-component systems is presented in the framework of a stochastic transport theory. We analyze correlations between fragment observables, focusing on the study of the fragment asymmetry $N/Z$ as a function of their kinetic energy. We find that the relation between these observables allows us to better characterize the fragmentation path and to access new information on the low-density behavior of the symmetry energy.

Based on the general analysis of the grand canonical partition function in the $S$-matrix framework, the calculated results on symmetry energy, free energy, and entropy of dilute warm nuclear matter are presented. At a given temperature and density, the symmetry energy or symmetry free energy of the clusterized nuclear matter in the $S$-matrix formulation deviates, particularly at low temperature and relatively higher density, in a subtle way, from the linear dependence on the square of the isospin asymmetry parameter $X=({\rho }_n-{\rho }_p)/({\rho }_n+{\rho }_p)$, contrary to those obtained for homogeneous nucleonic matter. The symmetry coefficients, in conventional definition, can then be even negative. The symmetry entropy similarly shows a very different behavior.

Spin-flip $M1$ strengths in ${}^{208}\mathrm{Pb}$ have been measured in photon scattering experiments with a quasi-monochromatic, linearly polarized photon beam. The data resolve an $M1$ giant resonance into at least seven, possibly eight, discrete transitions at excitation energies between 7.1 and 7.4 MeV below the neutron separation energy. The $M1$ strengths are measured with uncertainties considerably smaller than those in a previous study, which leads to a reexamination of the total strength. Experimental results are compared with an estimation of self-consistent random phase approximation using a semirealistic interaction.

We develop a new framework of the deformed quasiparticle-random-phase approximation (QRPA) where the Skyrme density functional and the density-dependent pairing functional are consistently treated. Numerical applications are carried out for the isovector dipole and the isoscalar quadrupole modes in the spherical ${}^{20}\mathrm{O}$ and in the deformed ${}^{26}\mathrm{Ne}$ nuclei, and the effect of the momentum-dependent terms of the Skyrme effective interaction for the energy-weighted sum rule is discussed. As a further application, we present for the first time the moments of inertia of ${}^{34}\mathrm{Mg}$ and ${}^{36}\mathrm{Mg}$ using the Thouless-Valatin procedure based on the self-consistent deformed QRPA, and we show the applicability of our new calculation scheme not only for the vibrational modes but also for the rotational modes in deformed neutron-rich nuclei.