The SD-pair shell model (SDPSM) is shown to reproduce approximately typical spectra, $E2$ transition strengths, and wave functions of the $U(5)$, $\mathrm{SO}(6)$, and $\mathrm{SU}(3)$ limits of the interacting boson model (IBM). Consequently, the analysis confirms that the IBM has a sound shell-model foundation; it also demonstrates that the truncation scheme adopted in the SDPSM is reasonable.

A modified version of the time-differential recoil-in-vacuum (or plunger) technique is proposed as a method for measuring the g factors of excited states in rapidly moving exotic nuclei with $Z\lesssim 20$.

${}^{229}\mathrm{Th}$ has an isomeric state of unusually low energy, whose adopted value is by now 3.5(10) eV. This value was determined indirectly, based on several very precise γ-ray energies, between 25 and 217 keV, from the $\alpha$ decay of ${}^{233}\mathrm{U}$. Two recent works suggest that the decay pattern of the transitions that link the low-energy levels of ${}^{229}\mathrm{Th}$ is different from that assumed in earlier works, but there also is a difference between them. In this article we investigate the effect on the value determined for the excitation energy of that isomeric state if those different assumptions regarding the γ-ray transitions in ${}^{229}\mathrm{Th}$ are considered. We use published data and a statistical method that takes into account both variances and correlations between data. Adopting the statistically most acceptable assumption regarding the decay pattern of ${}^{229}\mathrm{Th}$, we deduced the value of 5.5(10) eV for the excitation energy of that isomeric state, with consequences for both theoretical and experimental studies related to that level.

We calculate $\eta d$ elastic scattering using a relativistic three-body model with separable interactions in order to study the position of the quasivirtual $\eta \mathit{NN}$ state in the complex plane. The inputs of the model are the separable potentials of the $\mathit{NN}$ and mN subsystems, where m is a meson ($m=\eta ,\pi$, or σ). σ is not treated as a stable particle but as a $\pi \pi$ resonance so that we include its mass and width as deduced from the phase shift of the $I=J=0$ resonance. In all cases, we find that the nearest pole corresponds to a quasivirtual state even if Re $A_{\eta d}$ is negative.

The heavy-ion radiative capture reaction, ${}^{12}\mathrm{C}({}^{12}\mathrm{C},\gamma )$, has been investigated at beam energies around 16 MeV. Two different experiments were performed. Capture cross sections were obtained by measuring fused ${}^{24}\mathrm{Mg}$ residues and were found to significantly exceed values reported earlier. Subsequently, the decay pathways associated with radiative capture were delineated using the Gammasphere array. A substantial fraction of the decay was found to proceed through a few high-lying doorway states near 10 MeV in excitation.

We develop a perturbative model to treat the off-diagonal components in the Hartree-Fock-Bogoliubov (HFB) transformation matrix, which are neglected in the Bardeen-Cooper-Schrieffer (BCS) approximation. Applying the perturbative model to a weakly bound nucleus ${}^{84}\mathrm{Ni}$, it is shown that the perturbative approach reproduces well the solutions of the HFB method both for the quasiparticle energies and the radial dependence of quasiparticle wave functions. We find that the nonresonant part of the continuum single-particle state can acquire an appreciable occupation probability when there exists a weakly bound state close to the Fermi surface. This result originates from the strong coupling between the continuum particle state and the weakly bound state, and it is absent in the BCS approximation. The limitations of the BCS approximation are pointed out in comparison with the HFB and the present perturbative model.

We study the collective flow of open charm mesons and charmonia in $\text{Au}+\text{Au}$ collisions at $\sqrt{s}=200\hspace{1em}\mathrm{GeV}$ within the hadron-string-dynamics (HSD) transport approach. The detailed studies show that the coupling of $D,\overline{D}$ mesons to the light hadrons leads to comparable directed and elliptic flow as for the light mesons. This also holds approximately for $J/\Psi$ mesons since more than 50% of the final charmonia for central and midcentral collisions stem from $D+\overline{D}$ induced reactions in the transport calculations. The transverse momentum spectra of $D,\overline{D}$ mesons and $J/\Psi$'s are only very moderately changed by the (pre-)hadronic interactions in HSD, which can be traced back to the collective flow generated by elastic interactions with the light hadrons.

Assuming the physical proton as a quark core dressed by a virtual pion cloud, we have calculated the proton spin due to orbital angular momentum of the pion cloud as well as the effect of the pion cloud on the dilution of the proton spin.

The quark-hadron phase transition in a rotating compact star has been studied. The NLZ (nonlinear consistent zero point energy) model has been used for the hadronic sector and the MIT bag model has been used for the quark sector. It has been found that rotating twin star (third family) solutions are obtained up to $\Omega \approx 4000s^{-1}$. Stars that are rotating faster than this limit do not show twin star solution. A backbending in the moment of inertia is also observed in the supermassive rest mass sequences. The braking index is found to diverge for a star having a larger region of mixed phase.

A consistent folding analysis of the elastic $p({}^6\mathrm{He},{}^6\mathrm{He})p$ scattering and charge exchange $p({}^6\mathrm{He},{{}^6\mathrm{Li}}^{*})n$ reaction data measured at $E_{\mathrm{lab}}=41.6A\hspace{1em}\mathrm{MeV}$ has been performed within the coupled channels formalism. We have used the isovector coupling to link the isospin dependence of ${}^6\mathrm{He}+p$ optical potential to the cross section of $p({}^6\mathrm{He},{{}^6\mathrm{Li}}^{*})n$ reaction exciting the 0${}^{+}$ isobaric analog state (IAS) at 3.563 MeV in ${}^6\mathrm{Li}$. Based on these results and the Hartree-Fock calculation of asymmetric nuclear matter using the same isospin-dependent effective nucleon-nucleon interaction, we were able to confirm that the most realistic value of the symmetry energy $E_{\mathrm{sym}}$ is around 31 MeV. Our analysis has also shown that the measured charge exchange $p({}^6\mathrm{He},{{}^6\mathrm{Li}}^{*})n$ data are quite sensitive to the halo tail of the ${}^6\mathrm{He}$ density used in the folding calculation and the IAS of ${}^6\mathrm{Li}$ is likely to have a halo structure similar to that established for the ground state of ${}^6\mathrm{He}$.

The exotic baryon ${\Theta }^{+}(\mathit{uudd}\overline{s})$ is studied with microscopic calculations in a quark model by using a method of antisymmetrized molecular dynamics. We predict that three narrow states, $J^{\pi }=1/2^{+}(I=0),J^{\pi }=3/2^{+}(I=0)$, and $J^{\pi }=3/2^{-}(I=1)$ nearly degenerate with the lowest $1/2^{-}$ state in the $\mathit{uudd}\overline{s}$ system. We discuss $\mathrm{KN}$ decay widths and estimate them to be $\Gamma <7$ for the $J^{\pi }=\{1/2^{+},3/2^{+}\}$, and $\Gamma <1\hspace{1em}\mathrm{MeV}$ for the $J^{\pi }=3/2^{-}$ state. In contrast to these narrow states, the $1/2^{-}$ states should be much broader. We assign the observed ${\Theta }^{+}$ as the $J^{\pi }=\{1/2^{+},3/2^{+}\}$.

The $N^{*}(1440)\to N\pi \pi$ decay is studied by making use of the chiral reduction formula. This formula suggests a scalar-isoscalar pion-baryon contact interaction that is absent in the recent study of Hernández et al. [Phys. Rev. C 66, 065201 (2002)]. The contact interaction is introduced into their model and is found to be necessary for the simultaneous description of $g_{\mathit{RN}\pi \pi }$ and the $\pi \pi$ and $\pi N$ invariant mass distributions.

We show that within a recently developed nonlocal, chiral quark model the critical density for a phase transition to color superconducting quark matter under neutron star conditions can be low enough for these phases to occur in compact star configurations with masses below $1.3M_{\odot }$. We study the cooling of these objects in isolation for different values of the gravitational mass. Our equation of state (EoS) allows for two-flavor color superconductivity (2SC) quark matter with a large quark gap ($~100\text{MeV}$) for $u$ and $d$ quarks of two colors that coexists with normal quark matter within a mixed phase in the hybrid star interior. We argue that, if the phases with unpaired quarks were allowed, the corresponding hybrid stars would cool too fast. If they occurred for $M<1.3M_{\odot }$, as follows from our EoS, one could not appropriately describe the neutron star cooling data existing today. We discuss a “$2\mathrm{SC}+X$” phase as a possibility for having all quarks paired in two-flavor quark matter under neutron star constraints, where the $X$ gap is of the order of $10\text{keV}–1\text{MeV}$. Density-independent gaps do not allow us to fit the cooling data. Only the presence of an $X$ gap that decreases with increasing density would allow us to appropriately fit the data in a similar compact star mass interval to that following from a purely hadronic model. This scenario is suggested as an alternative explanation of the cooling data in the framework of a hybrid star model.

The structure of the $N\approx Z$ nuclei ${}^{66}\mathrm{Ge}$ and ${}^{68}\mathrm{Ge}$ is studied by the shell model with an extended $P+\mathrm{QQ}$ Hamiltonian in the configuration space ($2p_{3/2},1f_{5/2},2p_{1/2},1g_{9/2}$). This framework can be shown to give a consistent and good description of energy levels, moments of inertia, and Q moments in Ge isotopes. We also investigate particle alignments and nuclear shapes in ${}^{66}\mathrm{Ge}$ and ${}^{68}\mathrm{Ge}$. It is shown that structural changes in the four sequences of the positive- and negative-parity yrast states with even J and odd J are caused by various types of particle alignments in the $g_{9/2}$ orbit. The nuclear shape is also investigated by calculating spectroscopic Q moments of the first and second $2^{+}$ states, and the triaxiality is examined by potential energy surface.

The droplet model theory of the difference between the rms radii of the neutron and proton distributions in nuclei is compared with measurements obtained with the aid of antiprotonic atoms.

We consider the spin-isospin–independent central part of the residual nucleon-nucleon potential in finite spherical nuclei taking into account the deformation effects of the nucleons within the surrounding nuclear environment. It is shown that inside the nucleus the short-range repulsive contribution of the potential is increased and the intermediate-range attraction is decreased. We identify the growth of the radial component of the spin-isospin–independent short-range part of the in-medium nucleon-nucleon interaction as the responsible agent that prevents the radial collapse of the nucleus.

We study the behavior of the fusion, breakup, reaction, and elastic scattering of different projectiles on ${}^{64}\mathrm{Zn}$, at near and above barrier energies. We present fusion and elastic scattering data with the tightly bound ${}^{16}\mathrm{O}$ and the stable weakly bound ${}^6\mathrm{Li}$, ${}^7\mathrm{Li}$, and ${}^9\mathrm{Be}$ projectiles. The data are analyzed by coupled channel calculations. The total fusion cross sections for these systems are not affected by the breakup process at energies above the barrier. The elastic (noncapture) breakup cross section is important at energies close to and above the Coulomb barrier and increases the reaction cross sections. In addition, we show that the breakup process at near and below barrier energies is responsible for the vanishing of the usual threshold anomaly of the optical potential and gives rise to a new type of anomaly.

The Boltzmann-Uehling-Uhlenbeck (BUU) transport model is applied to study strangeness and pion production in nucleus-nucleus collisions. Starting from proton induced reactions, we further investigate $\mathrm{Si}+\mathrm{Au},\mathrm{Au}+\mathrm{Au}$, and $\mathrm{Pb}+\mathrm{Pb}$ collisions in the energy range between 2 and $40A\mathrm{GeV}$ and compare the results with data and other transport calculations. The $q\overline{q}$-annihilation, or resonance, channel simulated by the string model in meson-nucleon collisions at $\sqrt{s}>2\mathrm{GeV}$ is introduced. The importance of this channel for a good description of the proton-nucleus data on $K^{+}$ production is demonstrated. We further show that meson-meson collisions contribute significantly to the $K\stackrel{̲}{K}$ production in heavy-ion collisions above $5A\mathrm{GeV}$ and improve the agreement with data on the $K^{+}/{\pi }^{+}$ ratio. Finally, we study the influence of in-medium modifications of the FRITIOF model on pion and kaon production.

We analyze the problem of how to determine the parity of the ${\Theta }^{+}$ pentaquark in the reaction $\gamma N\to K\Theta \to \mathrm{NK}\overline{K}$, where $N=n,p$. Our model calculations indicate that the contribution of the nonresonant background of the reaction $\gamma N\to \mathrm{NK}\overline{K}$ cannot be neglected and that suggestions to determine the parity based solely on the initial-stage process $\gamma N\to K\Theta$ cannot be implemented cleanly. We discuss the various mechanisms that contribute to the background. Among the observables considered in this work, the triple spin asymmetry shows a kinematical “window” where the predictions are sensitive to the ${\Theta }^{+}$ parity and insensitive to the various reaction mechanisms considered, and thus, this observable offers a possibility of determining the parity of the ${\Theta }^{+}$.

We report a measurement of the longitudinal alignment $A_L$ of the recoil nucleus in the ${\mu }^{-}+{}^{14}\mathrm{N}(1^{+},0)\to {\nu }_{\mu }+{}^{14}\mathrm{C}(2^{+},7012)$ transition. The experiment was performed on the M9B beamline at the TRIUMF cyclotron via the measurement of the Doppler line shape of the subsequent ${}^{14}\mathrm{C}(2^{+},7012)\to {}^{14}\mathrm{C}(0^{+},0)\gamma$ rays. We compare our result, $A_L=0.60\pm 0.11$, to various model calculations and discuss the sensitivity to the induced pseudoscalar coupling, second-forbidden effects, and $2\hslash \omega$ wave-function admixtures.