The polarization transfer coefficient $K_y^{y^{\prime }}\left(0\mathrm{}°\right)$ has been measured for the ${}^3\mathrm{He}{\mathrm{}(d,p)\mathrm{}}^4\mathrm{He}$ reaction at energies of 520, 890, and 1490 keV. The measured values are $\approx -2/3,$ consistent with expectations based on the presence of a broad $J^{\pi }={\frac{3}{2}}^{+}$ resonance at $E_d=430\mathrm{}\mathrm{keV}.$ A comparison with data taken at somewhat higher energies reveals a large change in this observable as the reaction becomes dominated by direct neutron transfer.

Neutron inner hole responses in ${}^{115}\mathrm{Sn}$ and ${}^{119}\mathrm{Sn}$ nuclei have been studied via the $(\overrightarrow{d},t)$ reaction at $E_d=200\mathrm{}\mathrm{MeV}$ using a polarized beam with both vector and tensor components. One-step pickup observables corresponding to the overlapping ${1g}_{9/2},$ ${1f}_{5/2},$ and ${1f}_{7/2}$ responses were analyzed between $3°$ and $15°$ via a least square fit procedure up to $E_X=21.5\mathrm{}\mathrm{MeV}$ and 20 MeV in ${}^{115}\mathrm{Sn}$ and ${}^{119}\mathrm{Sn},$ respectively. The relative enhancement of transitions with high total angular momentum j and the strongly characteristic angular distributions of $j_{-}=l-1/2$ versus $j_{+}=l+1/2\mathrm{}$ vector and tensor analyzing powers allow the extraction for the first time of ${1f}_{5/2}$ and ${1f}_{7/2}$ strength distributions and of new ${1g}_{9/2}$ strength in addition to its previously known main component. The standard DWBA analysis is complemented by a refined analysis taking into account the form factor dependence on excitation energy due to the hole coupling with surface vibrations calculated in the framework of the quasiparticle-phonon coupling model (QPMFF). Residual nucleus spectra were measured, mainly in ${}^{115}\mathrm{Sn},$ up to $E_X\sim 45\mathrm{MeV}$ where the underlying background of multistep reactions is dominant and can be calibrated. The background of multistep pickup cross section is calculated for the first time in the forward angle region, assuming a dominant role of collective excitations in inelastic steps. Coupled channel calculations for two-step pickup observables involving low multipole collective excitations are performed for comparison. Integrated strengths deduced in the present work are compared with previous data on the ${1g}_{9/2}$ structure and tail, and with the very limited previous information existing on the $1f$ strengths. The ${1g}_{9/2},$ ${1f}_{5/2},$ and ${1f}_{7/2}$ QPMFF and standard strength distributions are compared with available theoretical predictions. In particular, we find that the ${1f}_{5/2}$ and ${1f}_{7/2}$ strength distributions are not well reproduced by the QPM model. The QPMFF spreading widths are found much narrower than the standard ones, but nevertheless much wider than predicted by theoretical calculations.

Transverse mass spectra of protons emitted in Au+Au collisions at beam energies of 6, 8, and 10.8 GeV/nucleon have been measured as a function of collision centrality over a rapidity range $0.5<\mathrm{}{y}_{\mathrm{lab}}<\mathrm{1.5.}\mathrm{}$ The spectra are well reproduced by Boltzmann distributions over the measured transverse mass region, which allows for extrapolation of the data to derive the rapidity density and apparent temperature of the emitting source. The shapes of the rapidity distributions suggest significant transparency or substantial longitudinal expansion in even the most central collisions at all three beam energies. The data are analyzed within a simple thermal source plus longitudinal expansion model.

The structure of neutron-rich ${}^{40,42,44}\mathrm{S}$ nuclei has been investigated through in-beam $\gamma$-ray spectroscopy using the fragmentation reaction of a 60 MeV A ${}^{48}\mathrm{Ca}$ beam on a thin Be target. $E_{\gamma },$ $I_{\gamma },$ $\gamma \gamma$-coincidence, and $\gamma$-ray angular distributions were measured for each produced fragment. The level schemes previously containing only a single $\gamma$ transition were extended, and spin values were proposed for the new states. The experimental results were interpreted by use of microscopic collective-model and large-scale shell-model calculations. The results of the model calculations are consistent with each other, and give a reasonable description of the experimental results. Both models predict an erosion of the $N=28\mathrm{}$ shell closure at $Z=16\mathrm{}$ and suggest a deformed ground state for ${}^{40,42}\mathrm{S}$ and a spherical-deformed mixed configuration for ${}^{44}\mathrm{S}.$

We present new data on $2{\pi }^0$ production by $750\mathrm{MeV}/c$ ${\pi }^{-}$ on hydrogen and the complex nuclei C, Al, and Cu, in search of the proposed medium modifications of the $f_0\left(400\mathrm{}-1200\right),$ or $\sigma ,$ state. We have found that the ${\pi }^0{\pi }^0$ invariant mass spectra for the four targets are different. The data indicate that nuclear absorption is mainly responsible for the change in the shape of the $2{\pi }^0$ invariant mass spectra for the complex targets. There is no hint of a narrow peak in the $\pi \pi$ invariant mass around ${2m}_{\pi }.$ We have also measured single ${\pi }^0$ and $\eta$ production on the above nuclei, in support of our investigation of nuclear final-state interaction processes. We observed strong $\eta$ absorption in nuclei.

Semihard and hard pion-pion scattering is of special interest because of its potential impact via final state interactions on the $\gamma +\overrightarrow{\gamma }{\pi }^{+}+{\pi }^{-}$ reaction in which perturbed QCD (PQCD) quark-exchange contribution is known to be short of strength. At moderate energies one can model large-angle pion-pion scattering by the PQCD two-gluon $\mathrm{}\left(2g\right)\mathrm{}$ exchange contribution. We discuss the onset of the dominance of the Glauber-Gribov-Landshoff (GGL) component of hard $2g$ exchange, which in the nonrelativistic approximation is free of suppression by the pion form factor, whereas in the relativistic light-cone approach it acquires a residual, albeit a weak, suppression and is free of the end-point contributions. Evaluation of the GGL amplitude with a model light-cone wave function consistent with the pion electromagnetic form factor data suggests that PQCD $2g$ exchange becomes substantial already at $|t|\gtrsim 1{\mathrm{GeV}}^{-2},$ but the PQCD exchange dominance is deferred to $|t|\gtrsim 3{\mathrm{GeV}}^{-2}$ because of competing multiple soft rescattering effects. Based on the NN and $\pi N$ total cross section data and Regge factorization, we evaluate the dominant soft contribution to the $\pi \pi$ total cross section and find the results consistent with the ones deduced earlier from the absorption model analysis of the $\pi \overrightarrow{N}XN,$ $X\Delta$ data.

We derive the equation of state of nuclear matter for the quark-meson coupling model taking into account quantum fluctuations of the $\sigma$ meson as well as vacuum polarization effects for the nucleons. This model incorporates explicitly quark degrees of freedom with quarks coupled to the scalar and vector mesons. Quantum fluctuations lead to a softer equation of state for nuclear matter giving a lower value of incompressibility than would be reached without quantum effects. The in-medium nucleon and $\sigma$-meson masses are also calculated in a self-consistent manner. The spectral function of the $\sigma$ meson is calculated and the $\sigma$ mass has the value increased with respect to the purely classical approximation at high densities.

Shell-model calculations in a large model space are performed for ${}_{\Lambda }^{16}\mathrm{O}$ and ${}_{\Lambda }^{17}\mathrm{O}.$ Effective interactions with degrees of freedom of $\Sigma$ in addition to $\Lambda$ and nucleons are derived from hyperon-nucleon and nucleon-nucleon interactions within the framework of the unitary-model-operator approach. Effects of the $\Sigma$ degrees of freedom and the parity-mixing intershell coupling on the $\Lambda$ hypernuclear structure are investigated, employing the Nijmegen $\mathrm{NSC}97a-f$ and NSC89 hyperon-nucleon potentials.

We study the spectra of mesons and baryons, composed of light quarks, in the framework of a semirelativistic potential model including instanton induced forces. We show how a simple modification of the instanton interaction in the baryon sector allows a good description of the meson and the baryon spectra using an interaction characterized by a unique set of parameters.

We perform an evaluation of the p-wave amplitudes of meson-baryon scattering in the strangeness $S=-1$ sector starting from the lowest order chiral Lagrangians and introducing explicitly the ${\Sigma }^{*}$ field with couplings to the meson-baryon states obtained using SU(6) symmetry. The $N/D$ method of unitarization is used, equivalent, in practice, to the use of the Bethe-Salpeter equation with a cutoff. The procedure leaves no freedom for the p-waves once the s-waves are fixed and thus one obtains genuine predictions for the p-wave scattering amplitudes, which are in good agreement with experimental results for differential cross sections, as well as for the width and partial decay widths of the ${\Sigma }^{*}\mathrm{}\left(1385\right).$

We apply the perturbative chiral quark model at one loop to calculate the strange form factors of the nucleon. A detailed numerical analysis of the strange magnetic moments and radii of the nucleon, and also the momentum dependence of the form factors is presented.

We discuss the effect of electromagnetic environment on laboratory measurements of the nuclear fusion reactions of astrophysical interest. The radiation field is eliminated using the path integral formalism in order to obtain the influence functional, which we evaluate in the semiclassical approximation. We show that enhancement of the tunneling probability due to the radiation correction is extremely small and does not resolve the longstanding problem that the observed electron screening effect is significantly larger than theoretical predictions.

We report on the first calculation of the scattering length $A_{K^{-}d}$ based on a relativistic three-body approach where the $\overline{K}N$ coupled channel two-body input amplitudes have been obtained with the chiral $\mathrm{SU}\mathrm{}\left(3\right)\mathrm{}$ constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes, based on the fixed center approximation, and for which we find significant deviations from the three-body results. Effects of the deuteron D-wave component, pion-nucleon, and hyperon-nucleon interactions are also evaluated.

Spin-polarized ${}^{27}\mathrm{Na}$ and ${}^{31}\mathrm{Al}$ secondary beams have been produced at GANIL by the fragmentation of a 77.5 MeV/nucleon ${}^{36}{\mathrm{S}}^{16+}$ primary beam onto a ${}^9\mathrm{Be}$ target. The primary beam was deflected at an angle of $-2\left(1\right)\mathrm{}°$ with respect to the entrance of the LISE3 spectrometer, where the target was placed. For linear momenta higher than that of the ${}^{36}\mathrm{S}$ projectiles, a deduced spin polarization $P=-6.2\left(9\right)\%$ and $P=-1.5\left(4\right)\%$ was obtained for ${}^{27}\mathrm{Na}$ and ${}^{31}\mathrm{Al}$ projectile fragments. These results demonstrate for the first time that fragments far from the projectile mass can be substantially polarized.

We study the temperature evolution of the $\rho$ and $\sigma$ mass and width, using a unitary chiral approach. The one-loop $\pi \pi$ scattering amplitude in chiral perturbation theory at $T\ne 0$ is unitarized via the inverse amplitude method. Our results predict a clear increase with T of both the $\rho$ and $\sigma$ widths. The masses decrease slightly for high T, while the $\rho \pi \pi$ coupling increases. The $\rho$ behavior seems to be favored by experimental results. In the $\sigma$ case, it signals chiral symmetry restoration.

We present continuum random phase approximation (CRPA) calculations for neutral-current neutrino scattering off ${}^{208}\mathrm{Pb}.$ These reactions are of interest for the terrestrial detection of supernova neutrinos. We fold the computed cross sections with a Fermi-Dirac distribution to obtain information about these processes and examine the dependence of the response on the spectrum parameters. The experimental interest in neutron knockout induced by neutrino interactions on ${}^{208}\mathrm{Pb}$ motivated an analysis of the CRPA branching ratios and single-particle knockout channels. We investigate the role of the single-particle wave functions and the residual interaction for the response. We compare our cross sections with previous work.

Central and mid-central collisions which lead to the formation of a heavy residue in the 37A MeV ${}^{36}\mathrm{Ar}{+}^{98}$Mo reaction have been studied with the MEDEA multidetector array coupled to a Parallel Plate Avalanche Counter. The dependence of the high energy gamma ray and light charged particle production as a function of the linear momentum transferred to the fused system has been studied. The unique potentialities of the MEDEA detector have made it possible to follow the evolution of the reaction dynamics from the pre-equilibrium stage to the formation of a heavy compound nucleus. The analysis of the correlation between the most energetic photons and protons shows how both of them are mainly produced in the most energetic primary nucleon-nucleon collisions. The multiplicity of high energy ${(E}_{\gamma }>30\mathrm{}\mathrm{MeV})$ $\gamma$ rays has been found to increase with the linear momentum transfer, showing the dominance of two-body dissipation in the transfer mechanism and giving a tool to correlate the momentum transfer with the centrality of the collision. Light charged particle kinetic energy spectra show how in these collisions, compound systems with excitation energies of more than $3A\mathrm{MeV}$ and temperature up to 7 MeV are formed. The experimental findings are compared with Boltzmann-Nordheim-Vlasov calculations. A scenario is found where the nucleus-nucleus interaction starts with two-body nucleon-nucleon collisions in the overlap region of nuclear densities. These collisions give rise to the production of high energy nucleons and $\gamma$ rays, and play a fundamental role in the energy transfer from the relative motion to internal excitation of the quasiprojectile and the target.

$R$-matrix formulas are used to calculate the two-proton decay widths of the ${}^6\mathrm{Be}$ and ${}^8\mathrm{C}$ ground states and of the ${}^6\mathrm{Be}$ first excited state. The calculated widths for the ${}^6\mathrm{Be}$ states depend strongly on the values taken for the energy and width of the ${}^5\mathrm{Li}$ ground state; agreement for the ${}^6\mathrm{Be}$ ground-state width can be obtained for a reasonable choice $\mathrm{of}{\hspace{0.5em}}^5\mathrm{Li}$ parameter values, and the same choice gives good agreement for $\mathrm{the}{\hspace{0.5em}}^6\mathrm{Be}$ excited-state width and branching ratio for ${}^2\mathrm{He}$ decay. For ${}^8\mathrm{C},$ contributions from two of the possible decay channels give an appreciable fraction of the experimental width.

Excitation functions have been measured for the fusion of the weakly bound nuclei ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li}$ with ${}^{209}\mathrm{Bi}.$ The complete-fusion cross sections are lower than those predicted by fusion models, being only 65% and 75% for ${}^6\mathrm{Li}$ and ${}^7\mathrm{Li},$ respectively. Within the uncertainties, this suppression is independent of beam energy. Distinguishing complete fusion from incomplete fusion, both experimentally and in theoretical models, is essential to understand the fusion process of weakly bound nuclei. A simple classical trajectory model which makes this distinction is presented. Further developments of the concepts of this model could be used for realistic predictions for the fusion of unstable weakly bound nuclei.

The β decay of ${}^{100}\mathrm{In},$ the one proton hole and one neutron particle neighbor to ${}^{100}\mathrm{Sn},$ was investigated at the GSI on-line mass separator by using germanium detectors and a NaI total-absorption spectrometer. On the basis of βγγ coincidences, the ${}^{100}\mathrm{In}$ decay scheme was established for the first time. The ground-state spin and parity for ${}^{100}\mathrm{In}$ are discussed by investigating β feeding of levels in ${}^{100}\mathrm{Cd}$ and $\beta$-delayed proton emission to ${}^{99}\mathrm{Ag}.$ The half-life was remeasured and found to be 5.9(2) s. The $Q_{\mathrm{EC}}$ value was determined from the measured $EC/{\beta }^{+}$ ratio for the β-delayed protons to be 10.08(23) MeV. The main fraction of the β feeding was established to populate the region of 6 MeV excitation energy, which corresponds to a total Gamow-Teller (GT) strength of 3.9(9) and a centroid at 6.4 MeV. Large-scale shell-model calculations employing a realistic interaction are used to assign configurations to states in ${}^{100}\mathrm{In}$ and ${}^{100}\mathrm{Cd}.$ The GT β-decay strength distribution measured in the total absorption experiment is compared to shell-model predictions. The deduced overall hindrance of the GT strength agrees with the values predicted for the ${}^{100}\mathrm{Sn}$ GT decay.