The Complex Energy Method [Prog. Theor. Phys. 109, 869L (2003)] is applied to the four-body Faddeev-Yakubovsky equations in the four-nucleon system. We obtain a well converged solution in all energy regions below and above the four-nucleon breakup threshold.

Background-free inelastic scattering spectra have been obtained for five Sm isotopes with $386\text{−}\text{MeV}$ $\alpha$ particles at forward angles (including $0°$) to investigate the effect of deformation on the compressional-mode giant resonances. The strength distributions for the $L⩽3$ isoscalar giant resonances have been extracted via a multipole decomposition analysis using angular distributions calculated in the framework of the density-dependent single-folding model. We observed a splitting of the giant monopole resonance because of its mixing with the giant quadrupole resonance. For the isoscalar giant dipole resonance, the observed effects of deformation are different for the low- and high-excitation-energy components. Evidence has been obtained for the theoretically predicted mixing between the isoscalar giant dipole resonance and the high energy octupole resonance.

We analyze the recent data from the BRAHMS Collaboration on the pseudorapidity dependence of nuclear modification factors in $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{NN}}=200\text{GeV}$ by using the full three dimensional hydrodynamic simulations for the density effects on parton energy loss. We first compute the transverse spectra at $\eta =0$ and 2.2, and next take a ratio $R_{\eta }=R_{AA}(\eta =2.2)∕R_{AA}(\eta =0)$, where $R_{AA}$ is a nuclear modification factor. It is shown that hydrodynamic components account for $R_{\eta }\simeq 1$ at low $p_{\mathrm{T}}$ and that quenched perturbative QCD components lead to $R_{\eta }<1$ at high $p_{\mathrm{T}}$ which are consistent with the data. Strong suppression at $\eta =2.2$ is compatible with the parton energy loss in the final state.

$\alpha$-rich freeze-outs from equilibrium occur during the core-collapse explosion of a massive star when the supernova shock wave passes through the Si-rich shell of the star. The nuclei are heated to high temperature and broken down into nucleons and $\alpha$ particles. These subsequently reassemble as the material expands and cools, thereby producing new heavy nuclei, including a number of important supernova observables. In this paper we introduce a web-based application designed to display the results of a reaction-rate sensitivity study of $\alpha$-rich freeze-out yields. This tool is intended to aid in the identification of nuclear reaction rates important for experimental study. We then analyze several iron-group isotopes $({}^{59}\mathrm{Ni},$ ${}^{57}\mathrm{Co},$ ${}^{56}\mathrm{Co},$ and ${}^{55}\mathrm{Fe})$ in terms of their roles as observables and examine the reaction rates that are important in their production.

We calculate the transition density for the overtone of the isoscalar giant monopole resonance (ISGMR) from the response to an appropriate external field $\sim {\widehat{f}}_{\xi }\left(\mathbf{r}\right)$ obtained using the semiclassical fluid dynamic approximation and the Hartree-Fock (HF) based random phase approximation (RPA). We determine the mixing parameter $\xi$ by maximizing the ratio of the energy-weighted sum for the overtone mode to the total energy-weighted sum rule and derive a simple expression for the macroscopic transition density associated with the overtone mode. This macroscopic transition density agrees well with that obtained from the HF-RPA calculations. We also point out that the ISGMR and its overtone can be clearly identified by considering the response to the electromagnetic external field $\sim j_0\left(qr\right)$.

Using the Hartree-Fock-Bogoliubov mean field theory in coordinate space, we investigate ground state properties of the sulfur isotopes from the line of stability up to the two-neutron dripline $\left({}^{34-52}\mathrm{S}\right)$. In particular, we calculate two-neutron separation energies, quadrupole moments, and rms radii for protons and neutrons. Evidence for shape coexistence is found in the very neutron-rich sulfur isotopes. We compare our calculations with results from relativistic mean field theory and with available experimental data. We also study the properties of neutron-rich zirconium $\left({}^{102,104}\mathrm{Zr}\right)$, cerium $\left({}^{152}\mathrm{Ce}\right)$, and samarium $\left({}^{158,160}\mathrm{Sm}\right)$ isotopes which exhibit very large prolate quadrupole deformations.

Recent analysis of multifragmentation data in terms of Fisher’s droplet model has led to the extraction of the nuclear liquid-vapor phase diagram. A similar analysis of Coniglio-Klein clusters of the $d=3$ Ising model shows an equivalently good Fisher’s scaling which can be used to obtain the Ising phase diagram, thus supporting the claim of the nuclear multifragmentation analysis in terms of a phase transition.

Statistical hadronization models are extremely successful in describing measured ratios of hadrons produced in heavy-ion collisions for a wide range of beam energies from SIS to RHIC. Using the idea of statistical hadronization at the phase boundary within the framework of a recently proposed dynamical model for the thermodynamics of fireballs, we establish a relation between the equation of state in the partonic phase probed at the phase transition temperature $T_C$ and the measured hadron ratios. In this way, the ratios can be predicted parameter free. We demonstrate that this framework gives a consistent description of conditions both at SPS and RHIC. As the data on dilepton emission from heavy-ion collisions give evidence for strong in-medium modifications of hadronic properties, we schematically investigate the sensitivity of our results to such modifications and qualitatively sketch a consistent scenario involving such in-medium effects.

Measurement of fusion cross sections for the ${}^7\mathrm{Li}+{}^{16}\mathrm{O}$ reaction by the $\gamma$-ray method has been done in the energy interval $E_{\text{c.m.}}=12.5–23.6\text{MeV}$ (where c.m. means center-of-mass). The $\gamma$-ray data obtained at high bombarding energies are found to be in agreement with those obtained by the evaporation residue method. The present data, together with the previous $\gamma$-ray data, show that there is no fusion suppression at energies below and near the Coulomb barrier.

Theoretical studies of prospective $2p$ emitters are performed in a three-body $\text{core}+p+p$ model. Lifetime dependencies on the decay energy are calculated for ${}^{45}\mathrm{Fe}$, ${}^{48}\mathrm{Ni}$, ${}^{54}\mathrm{Zn}$, ${}^{58}\mathrm{Ge}$, ${}^{62}\mathrm{Se}$, ${}^{66}\mathrm{Kr}$, and compared to the quasiclassical estimates. The observation of products from the in-flight decays is discussed as an important technique supplementing a standard implantation method for a broad range of lifetimes of prospective two-proton emitters. The sensitivity of the model to various aspects of nuclear dynamics is demonstrated on the ${}^{45}\mathrm{Fe}$ example. Possible momentum correlations for emitted protons are discussed with the emphasis on ${}^{19}\mathrm{Mg}$ and ${}^{45}\mathrm{Fe}$. We study convergence and stability of theoretical momentum distributions with respect to different physical and numerical aspects of the model. Opportunities to extract valuable information on $2p$ emission from incomplete kinematics decay data are discussed.

We investigate different choices for the quadratic momentum dependence required in nucleon-nucleon potentials to fit phase shifts in high partial waves. In the Argonne $v_{18}$ potential ${\mathbf{L}}^2$ and ${\left(\mathbf{L}·\mathbf{S}\right)}^2$ operators are used to represent this dependence. The $v_{18}$ potential is simple to use in many-body calculations since it has no quadratic momentum-dependent terms in $S$ waves. However, ${\mathbf{p}}^2$ rather than ${\mathbf{L}}^2$ dependence occurs naturally in meson-exchange models of nuclear forces. We construct an alternate version of the Argonne potential, designated Argonne $v_{18pq}$, in which the ${\mathbf{L}}^2$ and ${\left(\mathbf{L}·\mathbf{S}\right)}^2$ operators are replaced by ${\mathbf{p}}^2$ and $Q_{ij}$ operators, respectively. The quadratic momentum-dependent terms are smaller in the $v_{18pq}$ than in the $v_{18}$ interaction. Results for the ground-state binding energies of ${}^3\text{H}$, ${}^3\text{He}$, and ${}^4\text{He}$, obtained with the variational Monte Carlo method, are presented for both the models with and without three-nucleon interactions. We find that the nuclear wave functions obtained with $v_{18pq}$ are slightly larger than those with $v_{18}$ at interparticle distances $<1\text{fm}$. The two models provide essentially the same binding in the light nuclei, although $v_{18pq}$ gains less attraction when a fixed three-nucleon potential is added.

Level densities up close to the neutron binding energy have been extracted from primary $\gamma$ spectra for ${}^{56,57}\mathrm{Fe}$ and ${}^{96,97}\mathrm{Mo}$ nuclei using $\left({}^3\mathrm{He},\alpha \gamma \right)$ and $({}^3\mathrm{He},{}^3\mathrm{He}\prime \gamma )$ reactions on ${}^{57}\mathrm{Fe}$ and ${}^{97}\mathrm{Mo}$ targets. It is shown that statistical spectroscopy provides a useful tool in this mass region. Apparent step structures in the level-density curves are tentatively explained by a schematic microscopic model comprising single-particle level spacings and seniority-conserving and seniority-nonconserving interactions.

We review the basics of the coupled-cluster expansion formalism for numerical solutions of the many-body problem, and we outline the principles of an approach directed towards an adequate inclusion of continuum effects in the associated single-energy spectrum. We illustrate our findings by considering the simple case of a single-particle quantum mechanics problem.

The isotope shifts and hyperfine-structure-splitting constants of the $6s^2{}^{1}S_0-5d6p{}^{3}D_1(\lambda =538.2\text{nm})$ and $5d^2{}^{3}P_2-5d6p{}^{1}D_2(\lambda =548.4\text{nm})$ transitions of $\text{La}\mathrm{II}$ have been measured by collinear laser-ion-beam spectroscopy for the accelerator-produced isotopes ${}^{135}\text{La}$ and ${}^{137}\text{La}$, and for the naturally occurring isotopes ${}^{138}\text{La}$ and ${}^{139}\text{La}$. The magnetic moments of the ground states of the isotopes ${}^{135}\text{La}$ and ${}^{137}\text{La}$ have been determined to be $\mu \left(135\right)=+3.70\left(9\right){\mu }_N$ and $\mu \left(137\right)=+2.700\left(15\right){\mu }_N$, respectively, and the quadrupole moments to be $Q\left(135\right)=-0.4\left(4\right)e\mathrm{b}$ and $Q\left(137\right)=+0.21\left(3\right)e\mathrm{b}$. The ratio of the magnetic dipole coupling constants $A\left(138\right)∕A\left(139\right)$ of the level $5d6p{}^{3}D_1$ has shown a $-0.35\left(23\right)\%$ hyperfine anomaly with respect to the NMR ratio of the nuclear $g$ factors. The change in the mean-square nuclear charge radius determined from the isotope shift between ${}^{139}\text{La}$ and ${}^{135}\text{La}$ is $\delta {⟨r^2⟩}^{135,139}=0.08\left(3\right){\text{fm}}^2$. This value is smaller than the predictions made by the finite-range droplet model or by the Hartree-Fock plus BCS calculation.

We investigate the influence of the neutron halo and the breakup channel on the total ${}^6\mathrm{He}+{}^{238}\mathrm{U}$ fusion cross section at near-barrier energies. To include static effects of the $2n$-halo in ${}^6\mathrm{He}$ nuclei, we use a single-folding potential obtained from an appropriate nucleon-${}^{238}\mathrm{U}$ interaction and a realistic ${}^6\mathrm{He}$ density. Dynamical effects arising from the breakup process are then included through coupled-channel calculations. These calculations suggest that static effects dominate the cross section at energies above the Coulomb barrier, while the coupling to the breakup channel is more important at sub-barrier energies. The comparison of our calculations with recent data suggests that the coupling to other channels may be influencing the cross section at very low energies.

An attempt to extract critical exponents $\gamma$, $\beta$, and $\tau$ from data on gold nuclei fragmentation due to interactions with nuclear emulsion at energies $4.0A\text{GeV}$ and $10.6A\text{GeV}$ is presented. Based on analysis of Campi’s second charge moments, two subsets of data at each energy are selected from the inclusive data, corresponding to “liquid” and “gas” phases. The extracted values of critical exponents for the selected datasets are in agreement with predictions of the three-dimensional Ising universality.

Using a multiphase transport model, we study pseudorapidity distributions and transverse momentum spectra in deuteron-gold collisions at RHIC. We find that final-state partonic and hadronic interactions affect the transverse momentum spectrum of protons more than those of kaons or pions. Relative to $p+p$ collisions at same center-of-mass energy per nucleon pair, the effect of final-state interactions on the charged particle transverse momentum spectra in $\mathrm{d}+\text{Au}$ collisions is much smaller than observed in experimental data, indicating that initial-state effects such as the Cronin effect are important.

Momentum spectra of charged pions over nearly full rapidity coverage from target to beam rapidity have been extracted from $0-5\%$ most central $\text{Au}+\text{Au}$ collisions in the beam energy range from $2A$ to $8A\text{GeV}$ by the E895 experiment. Using a thermal parametrization to fit the transverse mass spectra, rapidity density distributions are extracted. The observed spectra are compared with predictions from the RQMD version 2.3 cascade model and also to a thermal model including longitudinal flow. The total $4\pi$ yields of the charged pions are used to infer an initial-state entropy produced in the collisions.

The $KN$ and $\overline{K}N$ low-energy elastic scattering is consistently studied in the framework of the QCD-inspired quark potential model. The model is composed of the $t$-channel one-gluon exchange potential, the $s$-channel one-gluon exchange potential, and the harmonic oscillator confinement potential. By means of the resonating group method, nonlocal effective interaction potentials for the $KN$ and $\overline{K}N$ systems are derived and used to calculate the $KN$ and $\overline{K}N$ elastic scattering phase shifts. By considering the effect of QCD renormalization, the contribution of the color octet of the clusters $\left(q\overline{q}\right)$ and $\left(qqq\right)$, and the suppression of the spin-orbital coupling, the numerical results are in fairly good agreement with the experimental data.

Model-independent effects of $\Delta \left(1232\right)$ excitation on nucleon polarizabilities are computed in a Lorentz-invariant fashion. We find a large effect of relative order $(M_{\Delta }-M)∕M$ in some of the spin polarizabilities, with the backward spin polarizability receiving the largest contribution. Similar subleading effects are found to be important in the fourth-order spin-independent polarizabilities ${\alpha }_{E\nu }$ , ${\alpha }_{E2}$, ${\beta }_{M\nu }$, and ${\beta }_{M2}$. Combining our results with those for the model-independent effects of pion loops we obtain predictions for spin and fourth-order polarizabilities which compare favorably with the results of a recent dispersion-relation analysis of data.