Algebraic mean field theory (AMFT) for the symplectic $\mathrm{sp}\mathrm{}(3,R)\mathrm{}$ algebra is used to derive collective rotational bands in the Riemann ellipsoidal approximation. AMFT is formulated in terms of symplectic density matrices that are defined by the quantum mechanical expectations of the $\mathrm{sp}\mathrm{}(3,R)\mathrm{}$ operators. The mean field approximation restricts the densities to a coadjoint orbit of the canonical transformation group $\mathrm{Sp}\mathrm{}(3,R).$ For principal axis rotation, a system of three algebraic equations is derived from energy minimization on an orbit surface. The system is solved self-consistently for the axis lengths and the potential tensor.

Intermediate-energy Coulomb excitation is a key method to investigate collectivity in exotic nuclei far from $\beta$ stability. We report on the measurement of the absolute ${B(E2;0\mathrm{}}_1^{+}\to 2_1^{+})$ excitation strength in ${}^{46}\mathrm{Ar}$ for five different minimum impact parameters. Our findings underline the validity, feasibility, and perspective of this technique for the study of exotic nuclei also in the regime of higher beam energy.

Excited states in the neutron-deficient nucleus ${}^{167}\mathrm{Re}$ have been observed in a recoil-tagging experiment performed with the Jurosphere $\gamma$-ray spectrometer in conjunction with the RITU gas-filled recoil separator. The low-spin yrast band, based on a proton $h_{11/2}$ orbital, comprises a strongly coupled band and exhibits significant signature splitting, indicative of a triaxial shape with $\gamma <0\mathrm{}°.$ At higher spin the rotational alignment of a pair of $i_{13/2}$ neutrons induces a transition to an axial prolate shape resulting in a drastic reduction of the signature splitting. Two other strongly coupled bands have been established and their structures are discussed in terms of quasiparticle configurations.

Near-barrier excitation functions have been measured for evaporation-residue production and fission in the ${}^{12}\mathrm{C}{+}^{204,206,208}\mathrm{Pb}$ and ${}^{48}\mathrm{Ca}{+}^{168,170}\mathrm{Er}$ systems that lead to the compound nuclei ${}^{216,218,220}{\mathrm{Ra}}^{*}.$ A pronounced suppression of evaporation-residue production is observed for the more symmetric combinations, ${}^{48}\mathrm{Ca}{+}^{168,170}\mathrm{Er}.$ We relate this to the significant quasifission components already observed for these systems.

Electron-induced one-nucleon knockout observables are computed for a moderate to high momentum transfer, making use of semirelativistic expressions for the one-body and two-body meson-exchange current matrix elements. Emphasis is laid on the semirelativistic form of the $\Delta$-isobar exchange current and several prescriptions for the dynamical-equivalent form of the $\Delta$ propagator are analyzed. To this end, the inclusive transverse response function, evaluated within the context of the semi-relativistic approach and using different prescriptions for the $\Delta$ propagator, is compared with the fully relativistic calculation performed within the scheme of the relativistic Fermi gas model. It is found that the best approximation corresponds to the one using the traditional static $\Delta$ propagator. These semirelativistic approaches, which contain important aspects of relativity, are implemented in a distorted-wave analysis of quasielastic ${(e,e}^{\prime }p)$ reactions. Final state interactions are incorporated through a phenomenological optical potential model and relativistic kinematics is assumed when calculating the energy of the ejected nucleon. The results indicate that the meson-exchange currents may modify substantially the $\mathrm{TL}$ asymmetry for high missing momentum.

We use a form of the fluctuation-dissipation theorem to derive formulas giving the rate of production of spin-$\frac{1}{2}$ baryons in terms of the fluctuations of either meson or quark fields. The most general formulas do not assume thermal or chemical equilibrium. When evaluated in a thermal ensemble we find equilibration times on the order of $10\mathrm{fm}/c$ near the critical temperature in QCD.

Energy transfers in collisions between classical clusters are studied with classical N body dynamics calculations for different entrance channels. It is shown that the energy per particle transferred to thermalized classical clusters does not exceed the energy of the least bound particle in the cluster in its “ground state.” This limitation is observed during the whole time of the collision, except for the heaviest system.

In this Brief Report we present the systematics of excitation energies for even-even nuclei in two regions: the $50<Z<~66,$ $82<N<~104$ region, and the $66<Z<\mathrm{}82,$ $82<N<~104$ region. Using the $N_p{N}_n$ scheme, we obtain compact trajectories for the ground band as well as quasi-$\beta$ and quasi-$\gamma$ bands. This suggests that the $N_p{N}_n$ scheme is useful even if one extends it to nonyrast levels, and thus can serve as a general tool to disclose new types of structural evolution for higher excitations, besides the yrast states which have been investigated extensively. It is highlighted that deformations in nonyrast quasibands of nuclei with $Z\sim 80$ and $N\sim 104$ are often very different from those in the ground bands.

Using an isospin-dependent transport model for heavy-ion collisions induced by neutron-rich nuclei at intermediate energies, we study the production of light clusters such as deuteron, triton, and ${}^3\mathrm{He}$ via coalescence of nucleons. We find that both the yields and the energy spectra of these light clusters are affected significantly by the density dependence of nuclear symmetry energy, with a stiffer symmetry energy giving a larger yield.

The transverse mass spectra of $\Omega$ hyperons and $\phi$ mesons measured recently by STAR Collaboration in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathrm{NN}}}=130\mathrm{}\mathrm{GeV}$ are described within a hydrodynamic model of the quark-gluon plasma expansion and hadronization. The flow parameters at the plasma hadronization extracted by fitting these data are used to predict the transverse mass spectra of $J/\psi$ and ${\psi }^{\prime }$ mesons.

Virtual photon theory (VPT) has long been suggested as a means of extracting photoreaction cross sections from measurements of cross sections for equivalent electron-induced reactions. Experimental information on the validity of VPT is, however, extremely limited. A test of VPT is reported in this paper. Measurements of the cross section for the ${d(e,p)e}^{\prime }n$ reaction at energies between 165 and 365 MeV have been performed for outgoing proton angles of $40°,$ $90°,$ and $120°.$ From these results, cross sections for the $d(\gamma ,p)n$ reaction have been extracted using VPT, and are compared with $d(\gamma ,p)n$ cross sections measured concurrently using a bremsstrahlung beam.

The mechanism of $p{}^3\mathrm{He}$ backward elastic scattering is studied. It is found that the triangle diagrams with the subprocesses $p{d}^3\mathrm{He}{\pi }^0,$ ${\overrightarrow{{\mathrm{pd}}^{*}}}^3\mathrm{He}{\pi }^0,$ and ${p\left(\mathrm{pp}\right)\mathrm{}}^3\mathrm{He}{\pi }^{+},$ where $d^{*}$ and $\mathrm{pp}$ denote the singlet deuteron and diproton pair in the ${}^1{S}_0$ state, respectively, dominate in the cross section at 0.3–0.8 GeV, and their contribution is comparable with that for a sequential transfer of a $\mathrm{np}$ pair at 1–1.5 GeV. The contribution of the $d^{*}+pp,$ estimated on the basis of the spectator mechanism of the ${p\left(\mathrm{NN}\right)\mathrm{}}^3\mathrm{He}\pi$ reaction, increases the $p{}^3{\overrightarrow{\mathrm{He}}}^3\mathrm{He}p$ cross section by one order of magnitude as compared to the contribution of the deuteron alone. Effects of the initial and final states’ interaction are taken into account.

Characteristics of the primary fragments produced in central collisions of ${}^{129}\mathrm{Xe}{+}^{\mathrm{nat}}\mathrm{Sn}$ from 32 to 50 A MeV have been obtained. By using the correlation technique for the relative velocity between light charged particles (LCP) and fragments, we were able to extract the multiplicities and average kinetic energy of secondary evaporated LCP. We then reconstructed the size and excitation energy of the primary fragments. For each bombarding energy a constant value of the excitation energy per nucleon over the whole range of fragment charge has been found. This value saturates at 3A MeV for beam energies 39A MeV and above. The corresponding secondary evaporated LCP represent less than 40% of all produced particles and decreases down to 23% for 50A MeV. The experimental characteristics of the primary fragments are compared to the predictions of statistical multifragmentation model (SMM) calculations. Reasonable agreement between the data and the calculation has been found for any given incident energy. However SMM fails to reproduce the trend of the excitation function of the primary fragment excitation energy and the amount of secondary evaporated LCP’s.

A continuum expression for the trace of the massive dressed-quark propagator is used to explicate a connection between the infrared limit of the QCD Dirac operator’s spectrum and the quark condensate appearing in the operator product expansion. This connection is verified via comparison with a lattice-QCD simulation. The pseudoscalar vacuum polarization provides a good approximation to the condensate over a larger range of current-quark masses.

A scalar field $\eta \left(\mathbf{r}\right)$ is coupled to the Skyrmion. Its classical value in the vacuum (“condensate”) reduces to the pion decay constant $f_{\pi },$ being thus proportional to the chiral condensate $〈\overline{q}q〉.$ A quadratic coupling of the scalar field to the pion kinetic Lagrangian term, reminiscent from the linear $\sigma$ model, is considered. Its mass is an additional free parameter in the model associated to the lightest scalar-isoscalar meson. Solutions for the two resulting coupled differential equations are found in several cases. The nucleon, as a topological soliton, “digs a hole” in the vacuum, making the value of the scalar condensate to be close to zero inside the Skyrmion. Some of the observables, as for example the baryon masses, may have their values closer to the experimental ones. Derrick’s stability analysis is applied to the model.

The branching ratio ${\Gamma }_{\alpha }/{\Gamma }_{\gamma }$ of the 4.033 MeV ${3/2}^{+}$ state in ${}^{19}\mathrm{Ne}$ plays a crucial role in the breakout from the hot CNO cycle into the rapid proton capture process. This ratio has been studied by making use of the advantages of inverse kinematics. The state was populated via the ${}^3\mathrm{He}{(}^{20}\mathrm{Ne},\alpha {)}^{19}{\mathrm{Ne}}^{*}$ reaction and its decay via $\gamma$ or $\alpha$ emission was measured by detecting the heavy reaction products ${(}^{19}\mathrm{Ne}$ or ${}^{15}\mathrm{O})$ in coincidence in a magnetic spectrograph. An upper limit ${\Gamma }_{\alpha }/{\Gamma }_{\gamma }<~6\times {10}^{-4}$ has been obtained. With these results, the astrophysical reaction rate for the ${}^{15}\mathrm{O}$ $(\alpha ,\gamma )$ ${}^{19}\mathrm{Ne}$ reaction has been calculated. Its influence on the breakout at various astrophysical sites, novas, x-ray bursts, and supermassive stars, is discussed.

Excited states of ${}^{34}\mathrm{Si}$ were studied in the ${}^2\mathrm{H}{(}^{34}\mathrm{Si}{,}^{34}\mathrm{Si}\gamma )$ reaction using a radioactive ${}^{34}\mathrm{Si}$ beam at $38.4A\mathrm{MeV}$ and a liquid deuterium target. Deexcitation $\gamma$ rays were measured using a NaI(Tl)-scintillator array in coincidence with scattered ${}^{34}\mathrm{Si}$ particles. From $\gamma -\gamma$ coincidence analyses, the $\gamma$ lines at 1.193, 1.715, and 2.696 MeV, which were reported previously but unplaced in the level diagram, were found to be associated with the 3.326-MeV $\gamma$ line corresponding to the transition from the first $2^{+}$ state to the ground state. This excludes the 1.193-MeV line as a candidate for the transition from the $2^{+}$ state to the second $0^{+}$ state, as suggested by Nummela et al. [Phys. Rev. C 63, 044316 (2001)].

Recent modifications to the “Manitoba II” high resolution mass spectrometer are described. Mass differences among the members of the triplet ${}^{199}\mathrm{Hg}{-}^{183}{\mathrm{W}}^{16}\mathrm{O}{-}^{12}{\mathrm{C}}_2^{35}{\mathrm{Cl}}_5$ have been measured. These self-consistent mass differences give masses for ${}^{183}\mathrm{W}$ and ${}^{199}\mathrm{Hg},$ as well as the mass difference across the W to Hg region of the mass table. These masses and the mass difference provide important constraints for the least squares atomic mass evaluation.

The two neutrino double $\beta$ decay of ${}^{100}\mathrm{Mo}$ for $0^{+}\to 2^{+}$ transition is studied in the projected Hartree-Fock-Bogoliubov framework. In our earlier work, the reliability of the intrinsic wave functions has been established for ${}^{100}\mathrm{Mo}$ and ${}^{100}\mathrm{Ru}$ by obtaining an overall agreement between the available experimental data and theoretically calculated results for yrast spectra, reduced transition probabilities ${B(E2:0\mathrm{}}^{+}\to 2^{+}),$ quadrupole moments ${Q(2\mathrm{}}^{+}),$ gyromagnetic factors ${g(2\mathrm{}}^{+}),$ and double Gamow-Teller matrix element for $0^{+}\to 0^{+}$ transition. In the present work, the half-life for $0^{+}\to 2^{+}$ transition $T_{1/2}^{2\nu }{(0\mathrm{}}^{+}\to 2^{+})$ has been calculated using the same set of intrinsic wave functions.

High-spin band crossings in $N=Z$ nuclei have been suggested to contain information on $T=0\mathrm{}$ neutron-proton pairing correlations. Several experiments that produced high angular momentum states in the $N=Z$ nuclei ${}_{34}^{68}\mathrm{Se}$ and ${}_{36}^{72}\mathrm{Kr}$ have been carried out. Levels in these neutron deficient nuclei were populated through heavy-ion fusion reactions and their subsequent $\gamma$ decay was measured with Gammasphere. The combination of these data allowed the level sequence in yrast and near yrast bands to be firmly established, extended to higher spin, and has resolved some previously published discrepancies. The yrast sequence in ${}^{68}\mathrm{Se}$ was extended to spin $J=26\mathrm{}$ and a new band crossing observed. In ${}^{72}\mathrm{Kr},$ the ground state band was found to fork into three bands, each of which has irregularities in its moment of inertia. Differential Doppler shift measurements indicate that the two high-spin bands have very different shapes. Similar, sharp band crossings were established in both nuclei. A comparison of these data with recent measurements of $N=Z+2\mathrm{}$ nuclei ${}^{70}\mathrm{Se}$ and ${}^{74}\mathrm{Kr}$ allowed the issue of “delayed alignments” to be addressed in detail. No clear-cut evidence for any delay was found.