High spin states have been studied in the nucleus ${}^{100}\mathrm{Pd}$ with the aim of investigating the novel phenomenon of “antimagnetic rotation.” A cascade of four “rotational-band-like” transitions is proposed as corresponding to antimagnetic rotation, based on the observed spectroscopic properties and a comparison with calculations in the configuration-dependent cranked Nilsson-Strutinsky formalism.

We present experimental data on directed flow in semicentral Au+Au collisions at incident energies from 90 to $400A\hspace{0.5em}\mathrm{MeV}.$ For the first time for this energy domain, the data are presented in a transverse momentum differential way. We study the first order Fourier coefficient $v_1$ for different particle species and establish a gradual change of its patterns as function of incident energy and for different regions in rapidity.

We perform continuous-choice Brueckner-Hartree-Fock calculations of hypernuclear matter, using the recent Nijmegen potentials for hyperon-nucleon and hyperon-hyperon interactions. Single-particle observables of the various hyperons in bulk matter, as well as properties of single- and double-lambda hypernuclei, employing an extended Skyrme-Hartree-Fock scheme, are presented. We find that the potentials tend to overbind the single hypernuclei and strongly underbind the double hypernuclei.

The equation of state (EOS) for asymmetric nuclear matter is discussed starting from a phenomenological hadronic field theory of Serot-Walecka type including exchange terms. In a model with self-interactions of the scalar sigma meson we show that the Fock terms naturally lead to isospin effects in the nuclear EOS. These effects are quite large and lead to a density dependence of the isovector couplings. We obtain a potential symmetry term of “stiff” type, i.e., increasing with baryon density and an interesting behavior of neutron-proton effective masses of relevance for transport properties of asymmetric dense matter.

We report on a microscopic calculation of $n{-}^3\mathrm{H}$ and $p{-}^3\mathrm{He}$ scattering employing the Argonne $v_{18}$ and $v_8^{\prime }$ nucleon-nucleon potentials with and without additional three-nucleon force. An R-matrix analysis of the $p{-}^3\mathrm{He}$ and $n{-}^3\mathrm{H}$ scattering data is presented. Comparisons are made for the phase shifts and a selection of measurements in both scattering systems. Differences between our calculation and the R-matrix results or the experimental data can be attributed to only two partial waves ${(}^3{P}_0$ and ${}^3{P}_2).\mathrm{}$ We find the effect of the Urbana IX and the Texas-Los Alamos three-nucleon forces on the phase shifts to be negligible.

We investigate the problem of quantum back reactions due to particle production by the parametric resonance mechanism in an environment of nonequilibrium chiral phase transition. We work with the linear sigma model and employ Boyanovsky et al.’s formalism [D. Boyanovsky, H. J. de Vega, and R. Holman, Phys. Rev. D 51, 734 (1995)] to take account of back reactions under the Hartree-Fock approximation. We calculate the single-pion momentum distributions and two-pion correlations under the initial condition of thermal equilibrium and small amplitude sigma oscillations around a potential minimum. We observe that the resonance peak survives under the back reaction, which is remarkable considering the strong coupling of the sigma model.

The polarization transfer coefficient $K_y^{y^{\prime }}$ has been measured for the ${}^2\mathrm{H}{\mathrm{}(d,p)\mathrm{}}^3\mathrm{H}$ reaction at a scattering angle of 0° at very low energies (⩽90 keV). The polarization of the emitted protons from the reaction was measured with a proton polarimeter using $p-{}^{28}\mathrm{Si}$ elastic scattering. A value of $0.09\pm 0.10$ was obtained for $K_y^{y^{\prime }}.$ This value was compared with the value for $K_y^{y^{\prime }}$ that we have calculated from the transition amplitudes determined by Lemaître and Schieck for the ${}^2\mathrm{H}{\mathrm{}(d,p)\mathrm{}}^3\mathrm{H}$ reaction [Ann. Physik 2, 503 (1993)].

For single-$j$ shells with $j=7/2,$ 9/2, and $11/2,$ we relate the large probability of $I^{+}$ ground states to the largest (smallest) coefficients ${\alpha }_{I\left(v\beta \right)}^J=〈\mathrm{nv}\beta I|A^{J†}\cdot A^J|\mathrm{nv}\beta I〉,$ where n is the particle number, $v$ is the seniority, β is an additional quantum number, and I is the angular momentum of the state. Interesting regularities of the probabilities of $I^{+}$ ground states are noticed and discussed for four-particle systems. Several counter examples of the $0^{+}$ ground state (0g.s.) predominance are noticed for the first time.

Fission fragment angular distributions have been measured for ${}^{11}\mathrm{B}\mathrm{}{+}^{235}\mathrm{U}$ and ${}^{14}\mathrm{N}\mathrm{}{+}^{232}\mathrm{Th},$ both leading to the same compound nucleus ${}^{246}\mathrm{Bk}$ and lying on either side of the Businaro-Gallone critical asymmetry parameter. At comparable excitation energies, even though $〈l^2〉$ of the compound nucleus for ${}^{14}\mathrm{N}\mathrm{}{+}^{232}\mathrm{Th}$ are smaller than that of ${}^{11}\mathrm{B}\mathrm{}{+}^{235}\mathrm{U},$ the anisotropies measured for the former are found to be significantly larger than that from the latter. Further, while the measured anisotropies in the case of ${}^{11}\mathrm{B}\mathrm{}{+}^{235}\mathrm{U}$ are found to be consistent with the statistical saddle-point model, the corresponding data for ${}^{14}\mathrm{N}{+}^{232}\mathrm{Th}$ are found to be “anomalous” indicating the presence of entrance channel dependent noncompound nuclear contributions.

Isoscaling, where ratios of isotopes emitted from two reactions exhibit an exponential dependence on the neutron and proton number of the isotope, has been observed over a variety of reactions including evaporation, strongly damped binary collision, and multifragmentation. The conditions for isoscaling to occur as well as the conditions when isoscaling fails are investigated.

The weak interaction rates in ${}^{16,18}\mathrm{O}$ are investigated in detail in a large shell-model space. Special attention is given to the muon capture process, which populates the states in ${}^{16,18}\mathrm{N}.$ The best agreement with experimental rate is obtained when unquenched weak-coupling constants are used. The roles of different multipoles are discussed, along with their strength distributions. The extracted mean excitation energy in muon capture is 10.6 MeV in ${}^{16}\mathrm{O}$ and 9.9 MeV in ${}^{18}\mathrm{O},$ close to the dipole resonance. The isotope effect is also discussed.

The rate for the fusion process $p+\overrightarrow{p}{d+e}^{+}+{\nu }_e$ is calculated using nonrelativistic effective field theory. Including the four-nucleon derivative interaction, results are obtained in next-to-leading order in the momentum expansion. This reproduces the effects of the effective range parameter. Coulomb interactions between the incoming protons are included nonperturbatively in a systematic way. The resulting fusion rate is independent of specific models and wave functions for the interacting nucleons. At this order in the effective Lagrangian there is an unknown counterterm which limits the numerical accuracy. Assuming the counterterm to have a natural magnitude, the result is consistent with previous nuclear physics calculations.

The reaction $e\overrightarrow{p}{e}^{\prime }{K}^{+}\Lambda \mathrm{}\left(1520\right)\mathrm{}$ with $\Lambda \mathrm{}\left(1520\right)\mathrm{}\to p^{\prime }{K}^{-}$ was studied at electron beam energies of 4.05, 4.25, and 4.46 GeV, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The $\cos {\theta }_{K^{+}},$ ${\phi }_{K^{+}},$ $Q^2,$ and W dependencies of $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ electroproduction are presented for the kinematic region $0.9<\mathrm{}{Q}^2<2.4\mathrm{}\hspace{0.5em}{\mathrm{GeV}}^2$ and $1.95<W<\mathrm{}2.65\mathrm{}\hspace{0.5em}\mathrm{GeV}.$ Also, the $Q^2$ dependence of the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ decay angular distribution is presented for the first time. The $\cos {\theta }_{K^{+}}$ angular distributions suggest t-channel diagrams dominate the production process. Fits to the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ t-channel helicity frame decay angular distributions indicate the $m_z=\pm \frac{1}{2}$ parentage accounts for about 60% of the total yield, which suggests this reaction has a significant contribution from t-channel processes with either ${\mathit{K}}^{+}$ exchange or longitudinal coupling to an exchanged ${\mathit{K}}^{*}.$ The $Q^2$ dependence of the $\Lambda \mathrm{}\left(1520\right)\mathrm{}$ production cross section is the same as that observed for $\Lambda \mathrm{}\left(1116\right)\mathrm{}$ photo- and electroproduction.

We study the chiral phase transition at nonzero temperature T and baryon chemical potential ${\mu }_B$ within the framework of the linear sigma model and the Nambu–Jona-Lasinio (NJL) model. For small bare quark masses we find in both models a smooth crossover transition for nonzero T and ${\mu }_B=0\mathrm{}$ and a first order transition for $T=0\mathrm{}$ and nonzero ${\mu }_B.$ We calculate explicitly the first order phase transition line and spinodal lines in the $(T,{\mu }_B)$ plane. As expected they all end at a critical point. We find that, in the linear sigma model, the sigma mass goes to zero at the critical point. This is in contrast to the NJL model, where the sigma mass, as defined in the random phase approximation, does not vanish. We also compute the adiabatic lines in the $(T,{\mu }_B)$ plane. Within the models studied here, the critical point does not serve as a “focusing” point in the adiabatic expansion.

Updated stellar rates for the reactions ${}^{56}\mathrm{Ni}(p,\gamma {)}^{57}\mathrm{Cu}$ and ${}^{57}\mathrm{Cu}(p,\gamma {)}^{58}\mathrm{Zn}$ are calculated by using all available experimental information as well as input data from the nuclear shell model. We calculated Coulomb and Thomas-Ehrmann shifts to obtain the unknown excitation energies and the spin/parity assignments of ${}^{58}\mathrm{Zn}.$ The astrophysical consequences are discussed.

We consider extensions of the lattice gas model to incorporate radial flow. Experimental data are used to set the magnitude of radial flow. This flow is then included in the lattice gas model in a microcanonical formalism. For magnitudes of flow seen in experiments, the main effect of the flow on observables is a shift along the $E^{*}/A$ axis.

We show that ${\omega }_B$ or ${\omega }_{\overline{B}},$ the squared baryon or antibaryon number fluctuation per baryon or antibaryon, is a possible signature for the quark-gluon plasma that is expected to be created in relativistic heavy ion collisions, as it is a factor of 3 smaller than in an equilibrated hadronic matter due to the fractional baryon number of quarks. Using kinetic equations with exact baryon number conservation, we find that their values in an equilibrated matter are half of those expected from a Poisson distribution. Effects due to finite acceptance and nonzero net baryon number are also studied.

In the past, several efficient methods have been developed to solve the Schrödinger equation for four-nucleon bound states accurately. These are the Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis variational, the stochastic variational, the hyperspherical variational, the Green’s function Monte Carlo, the no-core shell model, and the effective interaction hyperspherical harmonic methods. In this article we compare the energy eigenvalue results and some wave function properties using the realistic $\mathrm{AV}{8}^{\prime }$ NN interaction. The results of all schemes agree very well showing the high accuracy of our present ability to calculate the four-nucleon bound state.

We explore how nuclear modifications to the nucleon structure functions, shadowing, affect massive gauge boson production in heavy ion collisions at different impact parameters. We calculate the dependence of $Z^0,$ $W^{+},$ and $W^{-}$ production on rapidity and impact parameter to next-to-leading order in Pb+Pb collisions at 5.5 TeV/nucleon to study quark shadowing at high $Q^2.$ We also compare our Pb+Pb results to the $\mathrm{pp}$ rapidity distributions at 14 TeV.

We consider the effect of nuclear shadowing in polarized deep inelastic scattering (DIS) on ${}^6\mathrm{Li}\mathrm{}\mathrm{D}$ at small Bjorken x and its relevance for the extraction of the deuteron spin structure function $g_1^d{(x,Q}^2).\mathrm{}$ Using models, which describe nuclear shadowing in unpolarized DIS, we demonstrate that the nuclear shadowing correction to $g_1^d{(x,Q}^2)$ is significant.