We present a phenomenological discussion of spin-independent, generalized dipole polarizabilities of hadrons entering the virtual Compton scattering process ${\gamma }^{*}\overrightarrow{h}\gamma h.\mathrm{}$ We introduce a new method of obtaining a tensor basis with appropriate Lorentz-invariant amplitudes which are free from kinematical singularities and constraints. The result is summarized in terms of a compact effective Lagrangian. We then motivate a gauge-invariant separation into a generalized Born term containing ground-state properties only and a residual contribution describing the model-dependent internal structure. The generalized dipole polarizabilities are defined in terms of Lorentz-invariant residual amplitudes. Particular emphasis is laid on a physical interpretation of these quantities as characterizing the spatial distributions of the induced electric polarization and magnetization of hadrons. It is argued that three dipole polarizabilities—namely, the longitudinal electric ${\alpha }_L{(q}^2),$ the transverse electric ${\alpha }_T{(q}^2),$ and the magnetic $\beta {(q}^2)$ ones—are required in order to fully reconstruct local polarizations induced by soft external fields in a hadron. One of these polarizabilities, ${\alpha }_T{(q}^2),$ describes an effect of higher order in the soft final-photon momentum $q^{\prime }.$ We argue that the associated spatial distributions obtained via Fourier transforms in the Breit frame are meaningful even for such a light particle as the pion. The spatial distributions are determined at large distances $r\sim {1/m}_{\pi }$ for pions, kaons, and octet baryons by the use of chiral perturbation theory.

Effective astrophysical factors for nonresonant astrophysical nuclear reaction are usually calculated with respect to a zero-energy limit. In the present work that limit is shown to be very disadvantageous compared to the more natural effective-energy limit. The latter is used in order to modify the thermonuclear reaction rate formula in stellar evolution codes so that it takes into account both plasma and laboratory screening effects.

Parity violation in p-wave neutron resonances of ${}^{121}\mathrm{Sb},$ ${}^{123}\mathrm{Sb},$ and ${}^{127}\mathrm{I}$ has been measured by transmission of a longitudinally polarized neutron beam through natural antimony and iodine targets. The measurements were performed at the pulsed spallation neutron source of the Los Alamos Neutron Science Center. Five statistically significant parity violation effects were observed in ${}^{121}\mathrm{Sb},$ one effect in ${}^{123}\mathrm{Sb},$ and seven effects in ${}^{127}\mathrm{I}.$ The weak interaction rms matrix elements and the corresponding spreading widths were determined.

The single and multinucleon transfer cross sections in ${}^{16}\mathrm{O},$ ${}^{18}\mathrm{O}{+}^{174}\mathrm{Yb}$ reactions were measured at $E_{\mathrm{lab}}=83\mathrm{}\hspace{0.5em}\mathrm{MeV}$ bombarding energy. The data were analyzed to obtain the variation of transfer cross sections with the number of nucleons transferred from the projectile to the target nucleus, and with respect to the ground state Q value ${(Q}_{\mathrm{gg}})$ of the transfer reaction. In ${}^{18}\mathrm{O}{+}^{174}\mathrm{Yb}$ reaction, the two-neutron stripping and the two-neutron correlated cluster transfer cross sections are strongly enhanced as compared to the ${}^{16}\mathrm{O}$ ${+}^{174}\mathrm{Yb}$ reaction. The results have been discussed on the basis of the possible influence of the valence neutrons in the ${}^{18}\mathrm{O}$ nucleus on multiparticle transfer cross sections. The transfer probabilities of multinucleon transfers have been analyzed as a function of distance of closest approach and the results for two-neutron transfer is consistent with the supposition of correlated pair transfer of valence nucleons in the ${}^{18}\mathrm{O}{+}^{174}\mathrm{Yb}$ reaction.

Extending previous work we study the constraints of QCD sum rules on mass and width of light vector and axial-vector mesons in vacuum and in a medium with finite nuclear density. For the latter case especially the effect of nuclear pions leading to vector–axial-vector mixing is included in the analysis. We examine the consequences of the mixing effect for positions and shapes of the peaks which show up in the current-current correlators. We also discuss the model dependences in the amount of mixing, in the evaluation of the four-quark condensate, and in the width parametrizations for the meson spectral functions.

The strength of the neutron-neutron correlation function from the $E=45\mathrm{}\mathit{A}\mathrm{MeV}{\hspace{0.5em}}^{58}\mathrm{Ni}{+}^{27}\mathrm{Al},$ ${}^{\mathrm{nat}}\mathrm{Ni},$ and ${}^{197}\mathrm{Au}$ reactions depends on the neutron parallel velocity. This indicates the presence of multiple sources of neutron emission. We find these sources consistent with a dissipative, binary reaction mechanism as it is described by, e.g., Boltzmann-Uehling-Uhlenbeck calculations.

Projectile fragmentation reactions are well suited to structure studies of weakly bound nuclei, but an accurate reaction theory is necessary to extract quantitative spectroscopic properties. We examine here the accuracy of the commonly used eikonal approximation for the nuclear-induced breakup of halo nuclei. Comparing to numerical solutions of the full time-dependent Schrödinger equation, we find that the eikonal remains fairly accurate for calculating breakup probabilities of halo nuclei even down to 20 MeV/nucleon, reproducing relative spectroscopic strengths to within a few percent. Absolute reaction probabilities tend to be underpredicted by the eikonal, which would make extracted spectroscopic strengths somewhat too high. We discuss other features that are seen in the full calculation but are missing in the eikonal approximation such as the “towing” mode.

Lifetimes in the neutron-rich nuclei ${}^{104}\mathrm{Mo},$ ${}^{110}\mathrm{Ru},$ and ${}^{144}\mathrm{Ba}$ were measured using the differential recoil distance method. The experiment was performed with a ${}^{252}\mathrm{Cf}$ fission source inside the New Yale Plunger Device. $\gamma$ rays were detected by the SPEctrometer for Experiments with Doppler shifts at Yale (SPEEDY) while fission fragments with the appropriate kinematics were detected by an array of photocells.

Temperature-dependent fission barriers and fission-fragment mass distributions are calculated in the framework of the multimodal random neck-rupture model (MM-RNRM). It is shown how the distinction between the different fission modes disappears at higher excitation energies, due to the melting of shell effects. The fission-fragment mass yield calculations are coupled to the nuclear reaction code ALICE-91, which takes into account the competition between the other reaction channels and fission. With the combination of the temperature-dependent MM-RNRM and ALICE-91 nucleon-induced fission is investigated at energies between 10 and 200 MeV for nuclei varying from Au to Am.

The problem of one pair of identical nucleons sitting in $\mathcal{N}$ single particle levels of a potential well and interacting through the pairing force is treated introducing even Grassmann variables. The eigenvectors are analytically expressed solely in terms of these with coefficients fixed by the eigenvalues and the single particle energies. When the latter are those of a harmonic oscillator well an accurate expression is derived for both the collective eigenvalue and for those trapped in between the single particle levels, for any strength of the pairing interaction and any number of levels. Notably the trapped solutions are labeled through an index upon which they depend parabolically.

$\Delta$ isobar components in the nuclear many-body wave function are investigated for the deuteron, light nuclei ${(}^{16}\mathrm{O}),$ and infinite nuclear matter within the framework of the coupled-cluster theory. The predictions derived for various realistic models of the baryon-baryon interaction are compared to each other. These include local (V28) and nonlocal meson exchange potentials $\left({\mathrm{Bonn}}_{2000}\right)$ but also a model recently derived by the Salamanca group accounting for quark degrees of freedom. The characteristic differences which are obtained for the $N\Delta$ and $\Delta \Delta$ correlation functions are related to the approximation made in deriving the matrix elements for the baryon-baryon interaction.

α-nucleus single-folding cluster optical potentials based upon the α-cluster model and an α-α interaction were generated for $m\alpha$-cluster structure targets $(m=3,$ 4, 6, 7, and 8). Angular distributions of the differential cross section of α elastic scattering by ${}^{12}\mathrm{C},$ ${}^{16}\mathrm{O},$ and ${}^{28}\mathrm{Si}$ have been analyzed for various incident energies using the derived potentials. Also, single-folding optical model potentials were constructed using an α-nucleon effective interaction to analyze the same data. Both models produced reasonable success in predicting scattering data, particularly at higher energies. The effect of uncertainties in the projectile and target nuclear densities on the results was investigated. The energy dependence of the calculated potentials is also discussed.

We used a novel radiochemical technique to search for the decay of the 3.5-eV level ${(}^{229}{\mathrm{Th}}^m)\mathrm{in}{}^{229}\mathrm{Th}$ to the ground state ${(}^{229}{\mathrm{Th}}^g)$ by separating “fresh” ${}^{229}\mathrm{Th}$ from approximately 25 g of ${}^{233}\mathrm{U}.$ We then measured its γ-ray decay as a function of time seeking evidence of ${}^{229}{\mathrm{Th}}^g$ growth from ${}^{229}{\mathrm{Th}}^m$ isomeric decay. No evidence of such growth was observed. From this experiment we have concluded that the ${}^{229}{\mathrm{Th}}^m$ half-life must be either <6 h or >20 days.

The structures of neutron-rich isotones $N=82\mathrm{}–84$ of nuclei near ${}^{132}\mathrm{Sn}$ have been studied within the shell model formalism using available interactions obtained from the well-studied ${}^{208}\mathrm{Pb}$ region after proper scaling. The theoretically calculated binding energies, excitation energies, transition probabilities, magnetic moments have been compared with the experimental results. For $N=82,83\mathrm{}$ isotones, the results agree reasonably well with the experimental data. But for $N=84\mathrm{}$ isotones, the agreement between theoretical and experimental energies and transition probabilities is not satisfactory.

An approach to the generator coordinate method (GCM) using Skyrme-type effective forces and Woods-Saxon construction potential is applied to calculate the single-particle proton and neutron overlap functions in ${}^{40}\mathrm{Ca}.$ The relationship between the bound-state overlap functions and the one-body density matrix has been used. These overlap functions are applied to calculate the cross sections of one-nucleon removal reactions such as ${(e,e}^{\prime }p),$ $(\gamma ,p),$ and $\mathrm{}(p,d)\mathrm{}$ on ${}^{40}\mathrm{Ca}$ on the same theoretical footing. A consistent description of data for the different reactions is achieved. The shapes of the experimental cross sections for transitions to the ${3/2}^{+}$ ground state and the first ${1/2}^{+}$ excited state of the residual nuclei are well reproduced by the overlap functions obtained within the GCM. An additional spectroscopic factor accounting for correlations not included in the overlap function must be applied to the calculated results to reproduce the size of the experimental cross sections.

A complete set of analyzing powers has been obtained for ${}^{12}\mathrm{C}{(}^7\mathrm{Li}\to {,}^7\mathrm{Li}{)}^{12}\mathrm{C}$ elastic scattering at a bombarding energy of 34 MeV. Optical model calculations using standard forms for the spin-orbit and tensor potentials are unable to simultaneously describe all the available data. However, coupled-discretized-continuum-channels (CDCC) calculations using cluster-folding model form factors provide a reasonable overall description of the data with only two adjustable parameters. Reorientation effects are extremely important in obtaining a good description of the analyzing powers, with the reorientation coupling of the ${}^7\mathrm{Li}$ ground state being a major contributor to all the analyzing powers and the main source of the second-rank tensor analyzing powers $T_{20},$ $T_{21},$ and $T_{22}.$ The failure of optical model calculations to describe the second rank data implies that the effect of this reorientation coupling cannot be described accurately by means of a dynamic polarization potential constrained to be of the standard forms. The CDCC calculations also demonstrate the effect of coupling to the $\alpha -t$ continuum on the analyzing powers.

We examine the possibility of extracting non-Gaussian sources from two-particle correlations in heavy-ion reactions. Non-Gaussian sources have been predicted in a variety of model calculations and may have been seen in various like-meson pair correlations. As a tool for this investigation, we have developed an improved imaging method that relies on a basis spline expansion of the source functions with an improved implementation of constraints. We examine under what conditions this improved method can distinguish between Gaussian and non-Gaussian sources. Finally, we investigate pion, kaon, and proton sources from the $p-\mathrm{Pb}$ reaction at $450$ GeV/nucleon and from the $S-\mathrm{Pb}$ reaction at $200$ GeV/nucleon studied by the NA44 experiment. Both the pion and kaon sources from the $S-\mathrm{P}\mathrm{b}$ correlations seem to exhibit a Gaussian core with an extended, non-Gaussian halo. We also find evidence for a scaling of the source widths with particle mass in the sources from the $p-\mathrm{P}\mathrm{b}$ reaction.