An analysis is performed of the liquid-gas phase transition of nuclear matter obtained from different versions of scalar derivate coupling suggested by Zimanyi and Moszkowski (ZM) and the results are compared with those obtained from the Walecka model. We present the phase diagram for the models and one of them, the ZM3 model, has the lowest critical temperature $T_c=13.6\mathrm{}\mathrm{MeV}$ with the lowest critical density ${\rho }_c=0.037\mathrm{}{\mathrm{fm}}^{\mathrm{-}3}$ and pressure $p_c=0.157\mathrm{}{\mathrm{MeV}\mathrm{}\mathrm{fm}}^{\mathrm{-}3}.$ These results are in accordance with recent observations from energetic heavy-ion collisions, which suggest a small liquid-gas phase region.

The nonlinear effect of gluon depletion in the collision of large nuclei can be large. It is due to multiple scatterings among comoving partons initiated by primary scattering of partons in the colliding nuclei. The effect can give rise to substantial suppression of $J/\psi$ production in very large nuclei, even if the linear depletion effect is insignificant for the collisions of nuclei of smaller sizes. This mechanism offers a natural explanation of the enhanced suppression in the Pb-Pb data recently observed by NA50.

A mean-field formalism with excluded volume correction arising due to a hard-core repulsion between a pair of baryons has been extended for a multicomponent hadron gas involving nonstrange as well as strange hadrons. We incorporate the effects of chiral attraction as well as repulsion between the kaons. The resulting equation of state is used to study the problem of kaon condensation as well as the medium modification of the properties of kaons. We find that the kaon condensation is model dependent and depends upon the hard-core radius of baryons in our excluded volume model, and it can occur in the dense hadron gas when the radius is $<~0.6\mathrm{fm}.$

Dielectron mass spectra are examined for various nuclear reactions recently measured by the DLS Collaboration. A detailed description is given of all dilepton channels included in the transport model UrQMD 1.0, i.e., Dalitz decays of ${\pi }^0,\eta ,\omega ,{\eta }^{\prime }$ mesons and of the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ resonance, direct decays of vector mesons and $\mathrm{pn}$ bremsstrahlung. The microscopic calculations reproduce data for light systems fairly well, but tend to underestimate the data in $\mathrm{pp}$ at high energies and in $\mathrm{pd}$ at low energies. These conventional sources, however, cannot explain the recently reported enhancement for nucleus-nucleus collisions in the mass region $0.15\mathrm{\hspace{0.5em}}\mathrm{GeV}<~M_{e^{+}{e}^{-}}<~0.6\mathrm{\hspace{0.5em}}\mathrm{GeV}.$ Chiral scaling and $\omega$ meson broadening in the medium are investigated as a source of this mass excess. They also cannot explain the recent DLS data.

We extract nucleon resonance parameters from an effective Lagrangian model employing the $K$-matrix approximation. To this end we analyze simultaneously all available data for reactions involving the final states $\pi N,$ $\pi \pi N,$ $\eta N,$ and $K\Lambda$ in the energy range $m_N{+m}_{\pi }<~\sqrt{s}<~1.9$ GeV. The background contributions are generated consistently from the relevant Feynman amplitudes, which significantly reduces the number of free parameters. The sensitivity of the parameters upon the $\pi N$–partial-wave analysis and the details of the Lagrangians and form factors used are discussed.

A method is described to precisely predict the relative intensities and degrees of linear polarization of coherent bremsstrahlung from diamond crystals, taking into account the collimation of the photon beam and the lateral distribution and angular divergence of the electron beam in addition to the properties of the crystal. It is confirmed that the increase of the degree of linear polarization through collimation of the photon beam is a sizable effect. Compared to previous approaches considerable progress has been made in reproducing the experimentally observed relative intensities of collimated coherent bremsstrahlung, by taking into account the angular distribution of coherent bremsstrahlung in full detail. For the predicted degree of linear polarization agreement with experimental data from MAMI (Mainz) is obtained on a $\gtrsim 3\%$ level of precision.

Calculations of the ${}^3\mathrm{H}$ bound state wave function obtained with the pair-correlated hyperspherical harmonic method are presented for a variety of three-body force models. In each calculation the strength of the three-body force is adjusted to reproduce the observed binding energy. Wave functions obtained with different three-body forces are compared, and results are presented in graphical form for both coordinate and momentum space. For these binding-energy equivalent calculations, the $S$- and $D$-state components of the wave function are largely insensitive to the details of the three-body force. However, significant sensitivity is observed for the very small $P$-state components.

The transition amplitude for $\pi K$ scattering is evaluated within the SU(3) Nambu–Jona-Lasinio model. Ordering terms according to the expansion in ${1/N}_c$ leads to a boxlike diagram, $t$ channel diagrams that admit scalar isoscalar $(\sigma ,{\sigma }^{\prime })$ exchanges, and a $u$ channel exchange of a scalar isodoublet ${\sigma }_K$ that has quantum numbers corresponding to the $K_0^{*}\mathrm{}\left(1430\right)\mathrm{}$. Both the Pauli-Villars and $O\left(3\right)\mathrm{}$ regularization procedures are used to evaluate the $T=0\mathrm{}$ values of the $l=0\mathrm{}$ scattering lengths $a_0^{3/2}$ and $a_0^{1/2}.$ The finite temperature dependence is studied. We find that the variation in the $t$ channel in the calculation of $a_0^{3/2}$ leads to a change in $a_0^{3/2}$ of a factor of about two over the temperature range of $T=150\mathrm{}$ MeV.

Analyzing powers for the ${}^9\mathrm{Be}(\overrightarrow{p},\gamma {)}^{10}\mathrm{B}$ reaction were measured by stopping a 100 keV polarized proton beam in a ${}^9\mathrm{Be}$ target. The measured vector analyzing power is $A_y\left(90\mathrm{}°\right)=0.18\mathrm{}\pm 0.03$ for capture to the ground state, with smaller values at $90°$ for the first three excited states. Astrophysical $S$ factors were calculated for each of the final states using a direct capture plus resonance model which fit both the present analyzing power data and the previously reported cross section data. The calculated $S$ factors at $E_p=0\mathrm{}\hspace{0.5em}\mathrm{keV}$ for capture to the ground state and first three excited states were 0.25, 0.34, 0.27, and 0.10 keV b, respectively, which are considerably smaller than previously reported. The observed analyzing powers are explained, within experimental uncertainty, as arising from the interference of the $E1\mathrm{}$ direct capture amplitude with the tails of nearby $p$-wave and $s$-wave resonances.

The proton capture cross sections of the stable ruthenium isotopes 96, 98, 99, and 104 have been measured by means of the activation method in the proton energy range between 1.5 and 3 MeV. Thin layers of natural ruthenium were irradiated at the Karlsruhe 3.75 MV Van de Graaff accelerator with proton beams of 20–50 μA. The activity induced by $(p,\gamma )$ reactions was measured with a calibrated HPGe detector. In this way, six $(p,\gamma )$ cross sections for populating ground states and isomers in four different Rh isotopes could be determined simultaneously with systematic uncertainties of typically 4–5 %. The fact that experimental data are almost completely missing in the $A>\mathrm{}70\mathrm{}$ region illustrates the need of checking and complementing the statistical model calculations which are so far the only data used in $p$ process studies.

We present Gamow-Teller strength distributions from shell model Monte Carlo studies of $\mathrm{fp}$-shell nuclei that may play an important role in the precollapse evolution of supernovas. We then use these strength distributions to calculate the electron-capture cross sections and rates in the zero-momentum transfer limit. We also discuss the thermal behavior of the cross sections. We find large differences in these cross sections and rates when compared to the naive single-particle estimates. These differences need to be taken into account for improved modeling of the early stages of type-II supernova evolution.

Starting from a fully microscopic calculation, the ${}^{16}\mathrm{O}(p,\gamma {)}^{17}\mathrm{F}$ radiative-capture reaction is discussed in detail. The generator-coordinate and microscopic $R$-matrix methods are applied to the determination of the bound states and phase shifts of the ${}^{16}\mathrm{O}+p$ system, where ${}^{16}\mathrm{O}$ is described by a closed $p$ shell cluster. The astrophysical $S$ factor is then calculated and compared with experiment. A study of its behavior at very low energies leads to general quantal formulas for the $S$ factor and for its logarithmic derivative at zero energy, which are valid for all cases where capture dominantly occurs when both nuclei are far from each other. The larger capture to the ${1/2}^{+}$ excited state is then explained by its lower binding energy without need for a special halo effect. The logarithmic derivative at zero energy is shown to depend on a slowly varying function of the bound-state Sommerfeld parameter and its different values for capture to the ${5/2}^{+}$ and ${1/2}^{+}$ states are explained. The same expressions are applied to the ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction.

Including nucleon-nucleon correlations due to both Fermi statistics and nuclear forces, we have developed a general formalism for calculating the neutral-current neutrino-nucleon scattering rates in nuclear matter. We derive corrections to the dynamic structure factors due to both density and spin correlations and find that neutrino-nucleon scattering rates are suppressed by large factors around and above nuclear density. Hence, in particular for the ${\nu }_{\mu }$ and ${\nu }_{\tau }$ neutrinos, but also for the ${\nu }_e$ neutrinos, supernova cores are more “transparent” than previously thought. The many-body corrections increase with density, decrease with temperature, and are roughly independent of incident neutrino energy. In addition, we find that the spectrum of energy transfers in neutrino scattering is considerably broadened by the interactions in the medium. An identifiable component of this broadening comes from the absorption and emission of quanta of collective modes akin to the Gamow-Teller and giant dipole resonances in nuclei (zero sound; spin sound), with Čerenkov kinematics. Under the assumption that both the charged-current and the neutral-current cross sections are decreased by many-body effects, we calculate a set of ad hoc protoneutron star cooling models to gauge the potential importance of the new opacities to the supernova itself. While the early luminosities are not altered, the luminosities after many hundreds of milliseconds to seconds can be increased by factors that range from 10 to 100 %. Such enhancements may have a bearing on the efficacy of the neutrino-driven supernova mechanism, the delay to explosion, the energy of the explosion, and the strength and relative role of convective overturn at late times. However, the actual consequences, if any, of these new neutrino opacities remain to be determined.

A phenomenological formula for in-medium nucleon-nucleon cross section is presented, in which nuclear matter density and incident energy dependencies are included. This formula is used to study total nuclear reaction cross section based on Coulomb-modified Glauber model. The calculated results can reproduce experimental total reaction cross section induced by the stable nuclei and the exotic nuclei over a wide energy range.

Elastic and inelastic scattering cross sections of the system ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ at several bombarding energies are calculated within a parameterfree model using the recently developed nonlocal energy-independent bare potential. Comparison with the data indicates that such a calculation gives accurately the average values of the cross sections. The system ${}^{12}\mathrm{C}{+}^{11}\mathrm{Li}$ is also discussed.

We investigate the energy dependence of the astrophysical $S$ factors for the reactions ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B},$ the primary source of high-energy solar neutrinos in the solar $\mathrm{pp}$ chain, and ${}^{16}\mathrm{O}(p,\gamma {)}^{17}\mathrm{F},$ an important reaction in the CNO cycle. Both of these reactions have predicted $S$ factors which rise at low energies; we find the source of this behavior to be a pole in the $S$ factor at a center-of-mass energy $E=-E_{\mathrm{B}},$ the point where the energy of the emitted photon vanishes. The pole arises from a divergence of the radial integrals.

The Faddeev-Yakubowsky equations in configuration space have been solved for the four nucleon system. The results with an $S$-wave interaction model in the isospin approximation are presented. They concern the bound and scattering states below the first three-body threshold. The elastic phase shifts for the $N+NNN$ reaction in different $\mathrm{}(S,T)\mathrm{}$ channels are given and the corresponding low-energy expansions are discussed. Particular attention is paid to the $n+t$ elastic cross section. Its resonant structure is well described in terms of a simple $\mathrm{NN}$ interaction. First results concerning the $S$ matrix for the coupled $N+NNN-NN+NN$ channels and the strong deuteron-deuteron scattering length are obtained.

The spectral function of ${}^4\mathrm{He}$ is calculated with the Lorentz integral transform method in a large energy and momentum range. The excitation spectrum of the residual $3N$ system is fully taken into account. The obtained spectral function is used to calculate the quasielastic longitudinal ${(e,e}^{\prime })$ response $R_L$ of ${}^4\mathrm{He}$ for $q=300\mathrm{}$, 400, and $500\hspace{0.5em}\mathrm{MeV}/c$. Comparison with the exact $R_L$ shows a rather sizable disagreement except in the quasielastic peak, where the differences reduce to about 10% at $q=500\mathrm{}\hspace{0.5em}\mathrm{MeV}/c$. It is shown as well that very simple momentum distribution approximations for the spectral function provide almost the same results for $R_L$ as the exact spectral function.

Calculations for the excitation functions of ${}^{63}\mathrm{Cu}(\alpha {,n)}^{66}\mathrm{Ga},$ ${}^{63}\mathrm{Cu}(\alpha {,2n)}^{65}\mathrm{Ga},$ ${}^{63}\mathrm{Cu}(\alpha {,np)}^{65}\mathrm{Zn},$ ${}^{65}\mathrm{Cu}(\alpha {,n)}^{68}\mathrm{Ga},$ and ${}^{65}\mathrm{Cu}(\alpha {,2n)}^{67}\mathrm{Ga}$ reactions have been carried out in the 8–27 MeV energy range using statistical and preequilibrium nuclear reaction models. The results have been compared with reported measurements and are discussed.

The nucleon-pair shell model truncated to the $S-D$ subspace is applied to the barium isotopes ${}^{130}{\mathrm{Ba}–}^{136}\mathrm{Ba}.$ The effects of the single-particle energy splitting on collectivities are examined. The main features of the low-lying collective states of the nuclei, especially for nuclei with a larger number of pairs, are well reproduced by a shell model Hamiltonian with three parameters.