A fully relativistic model for the description of exclusive ${(e,e}^{\prime }p)$ reactions off nuclear targets at high energies and momentum transfers is outlined. It is based on the eikonal approximation for the ejectile scattering wave function and a relativistic mean-field approximation to the Walecka model. Results for ${}^{12}\mathrm{C}{(e,e}^{\prime }p)$ and ${}^{16}\mathrm{O}{(e,e}^{\prime }p)$ differential cross sections and separated structure functions are presented for four-momenta in the range $0.8<~Q^2<~20\hspace{0.5em}(\mathrm{GeV}{/c)}^2.$ The regions of applicability of the eikonal approximation are studied and observed to be confined to proton knockout in a relatively small cone about the momentum transfer. A simple criterion defining the boundaries of this cone is determined. The $Q^2$ evolution of the effect of off-shell ambiguities on the different ${(e,e}^{\prime }p)$ structure functions is addressed. At sufficiently high values of $Q^2$ their impact on the cross sections is illustrated to become practically negligible. It is pointed out that for the whole range of $Q^2$ values studied here, the bulk of the relativistic effects arising from the coupling between the lower components in the wave functions, is manifesting itself in the longitudinal-transverse interference term.

Attenuation measurements of reaction and total cross sections have been made for ${\pi }^{-}$ beams at 410, 464, and 492 MeV on targets of ${\mathrm{CD}}_2,$ ${}^6\mathrm{Li},$ C, Al, S, Ca, Cu, Zr, Sn, and Pb. These results are assisted by and compared to predictions from a recent eikonal optical model. Calculations with this model, which does not include pion absorption, agree with recent elastic scattering data, but are significantly below our measured reaction and total cross sections.

The baryon-baryon continuum invariant mass spectrum generated from relativistic nucleus + nucleus collision data may reveal the existence of doubly strange dibaryons not stable against strong decay if they lie within a few MeV of threshold. Furthermore, since the dominant component of these states is a superposition of two color-octet clusters which can be produced intermediately in a color-deconfined quark-gluon plasma (QGP), an enhanced production of dibaryon resonances could be a signal of QGP formation. A total of eight, doubly strange dibaryon states are considered for experimental search using the STAR detector (solenoidal tracker at RHIC) at the new Relativistic Heavy Ion Collider (RHIC). These states may decay to $\Lambda \Lambda$ and/or $p{\Xi }^{-},$ depending on the resonance energy. STAR’s large acceptance, precision tracking and vertex reconstruction capabilities, and large data volume capacity, make it an ideal instrument to use for such a search. Detector performance and analysis sensitivity are studied as a function of resonance production rate and width for one particular dibaryon which can directly strong decay to $p{\Xi }^{-},$ but not $\Lambda \Lambda .$ Results indicate that such resonances may be discovered using STAR if the resonance production rates are comparable to coalescence model predictions for dibaryon bound states.

A formulation of the Skyrme model as an embedded gauge theory with the constraint deformed away from the spherical geometry is proposed. The gauge-invariant formulation is obtained by first generalizing the intrinsic geometry of the model and then converting the constraint to first class through an iterative Wess-Zumino procedure. The gauge-invariant model is quantized via the Dirac method for a first-class system. A perturbative calculation provides new free parameters related to the deformation that improve the energy spectrum obtained in earlier approaches.

We explore the $\Delta I=\frac{1}{2}$ rule and ${\epsilon }^{\prime }/\epsilon$ in $\overrightarrow{K}\pi \pi$ transitions using a Dyson-Schwinger equation model. Exploiting the feature that quantum chromodynamics penguin operators direct $K_S^0$ transitions through $0^{++}$ intermediate states, we observe an enhancement of $\overrightarrow{K}\pi {\pi }_{I=0\mathrm{}}$ transitions from the contribution of a putative light $\sigma$-meson. This mechanism also affects ${\epsilon }^{\prime }/\epsilon .$

The nucleus ${}^{69}\mathrm{As}$ was studied using the ${}^{40}\mathrm{Ca}{(}^{32}\mathrm{S}{,3p)}^{69}\mathrm{As}$ reaction at a beam energy of 105 MeV. An extension of the band built on the $g_{9/2}$ orbital was observed to exhibit a band crossing at a rotational frequency of 0.511 MeV with an associated alignment of $7ħ.$ This alignment is interpreted as being due to a pair of $g_{9/2}$ neutrons. Total Routhian surface calculations have been carried out which confirm that the shape of this nucleus changes from oblate at low spin to a triaxial prolate shape at intermediate spin.

A hybrid version the deformed nuclear potential is suggested, which combines a spherical Woods-Saxon potential with a deformed Nilsson potential. It removes the problems of the conventional Nilsson potential in the mass 130 region. Based on the hybrid potential, tilted axis cranking calculations are carried out for the magnetic dipole band in ${}^{128}\mathrm{Ba}.$

High angular momentum states in odd-odd ${}^{86}\mathrm{Nb}$ were populated through the ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},3pn)$ reaction at 135 MeV. Recoiling ${}^{86}\mathrm{Nb}$ nuclei were stopped in a thick Ta backing. Prompt multi-$\gamma$ coincidences with evaporated charged particles were detected using the full array of Gammasphere and the Microball. Mean lifetimes of 51 levels in ${}^{86}\mathrm{Nb}$ were measured using the Doppler-shift attenuation method. Strongly alternating magnetic dipole transition strengths were observed in the yrast positive-parity bands. Most of the transition quadrupole moments inferred from the lifetimes lie in the range of 1 to $2.7\hspace{0.5em}e\mathrm{b},$ which would correspond to quadrupole deformations ${\beta }_2$ of 0.10 to 0.27 in a rotational model. Comparison with Hartree-Fock-Bogoliubov cranking calculations suggests triaxial to oblate shapes.

The high spin states in the $N=82\mathrm{}$ odd-A ${}^{143}\mathrm{Pm}$ have been investigated by in-beam $\gamma$-spectroscopic techniques following the reactions ${}^{135}\mathrm{Ba}{(}^{11}\mathrm{B}{,3n)}^{143}\mathrm{Pm}$ at $E=47\mathrm{}$ MeV and ${}^{133}\mathrm{Cs}{(}^{13}\mathrm{C}{,3n)}^{143}\mathrm{Pm}$ at $E=63\mathrm{}$ MeV, respectively, using a gamma detector array, consisting of 12 Compton-supressed high purity germanium detectors and a multiplicity ball of 14 bismuth germanate elements. 28 new $\gamma$ rays have been assigned to ${}^{143}\mathrm{Pm}$ on the basis of the $\gamma$-ray singles and $\gamma -\gamma$ coincidence data. The level scheme of ${}^{143}\mathrm{Pm}$ has been extended up to an excitation energy of 8.4 MeV and spin $47/2ħ$ and 24 new levels have been proposed. Spin-parity assignments for most of the newly proposed levels have been made using the measured directional correlation orientation ratios for strong transitions. The observed level structure is discussed in the light of available experimental data and a modest shell model calculation done by us, using the OXBASH code.

Within the framework of the relativistic plane wave impulse approximation (RPWIA), complete sets of quasielastic $(\overrightarrow{p},p^{\prime })$ and $(\overrightarrow{p},\overrightarrow{n})$ spin observables are calculated employing a general and complete Lorentz invariant representation of the $\mathrm{NN}$ scattering matrix (referred to as the IA2 representation). The use of a complete representation eliminates the arbitrariness of a previously used five-term parametrization (commonly called the IA1 representation) and allows for the correct incorporation of effective-mass-type medium effects within the RPWIA framework and within the context of the Walecka model. For quasielastic scattering from a ${}^{40}\mathrm{Ca}$ target at incident proton energies between 200 and 500 MeV, we investigate the sensitivity of complete sets of spin observables to effective nucleon masses for both IA1 and IA2 representations. In general it is seen that the IA1 representation may overestimate the importance of nuclear medium effects, whereas the IA2-based predictions nearly correspond to values for free nucleon-nucleon scattering.

The ultrarelativistic quantum molecular dynamics model (UrQMD) is used to study global observables in central reactions of Au+Au at $\sqrt{s}=200A$ GeV at the Relativistic Heavy Ion Collider (RHIC). Strong stopping governed by massive particle production is predicted if secondary interactions are taken into account. The underlying string dynamics and the early hadronic decoupling implies only small transverse expansion rates. However, rescattering with mesons is found to act as a source of pressure leading to additional flow of baryons and kaons, while cooling down pions.

We study quantitatively the formation and evolution of $\overline{b}c,b\overline{c}$ bound states in a space-time domain of deconfined quarks and gluons (quark-gluon plasma, QGP). At the Relativistic Heavy Ion Collider (RHIC), one expects for the first time that typical central collisions will result in multiple pairs of heavy (in this case charmed) quarks. This provides a new mechanism for the formation of heavy quarkonia which depends on the properties of the deconfined region. We find typical enhancements of about 500-fold for the $\overline{b}c,b\overline{c}$ production yields over expectations from the elementary coherent hadronic $B_c$-meson production scenario. The final population of bound states may serve as a probe of the plasma phase parameters.

We improve our previous QCD sum rule calculation on $g_{\mathrm{KN}\Lambda }$ and $g_{\mathrm{KN}\Sigma }$ coupling constants by including the contributions from higher dimensional condensates, $〈\overline{q}{g}_s\sigma \cdot \mathrm{Gq}〉$ and $〈\overline{q}q〉〈({\alpha }_s/\pi {)G}^2〉,$ in the OPE. It is found that the contribution of these condensates is non-negligible compared to that of the quark condensates. Using a best-fit analysis we find $|g_{\mathrm{KN}\Lambda }|=2.49\mathrm{}\pm 1.25$ and $|g_{\mathrm{KN}\Sigma }|=0.395\mathrm{}\pm \mathrm{0.377.}$

Excited states in the nucleus ${}^{133}\mathrm{Sb},$ populated in spontaneous fission of ${}^{248}\mathrm{Cm},$ were studied with EUROGAM2. Medium-spin structure, described as the $\nu {(f}_{7/2}{h}_{11/2}^{-1})$ multiplet of the ${}^{132}\mathrm{Sn}$ core coupled to the odd proton in the $g_{7/2}$ orbital, has been identified in this nucleus. Levels corresponding to the octupole excitations of the ${}^{132}\mathrm{Sn}$ core were also identified. Some uncertainities concerning isomeric decays in ${}^{133}\mathrm{Sb},$ observed in previous works, have been resolved.

The $\pi h_{11/2}\otimes \nu h_{11/2}$ yrast band in the odd-odd nucleus ${}^{140}\mathrm{Tb}$ has been populated by the ${}^{92}\mathrm{Mo}$ ${(}^{54}\mathrm{Fe},$ $\alpha pn)$ reaction at 240-MeV incident beam energy. No previous spectroscopic information was known in this nucleus. The present data fit nicely in the systematics of the $N=75\mathrm{}$ isotones of La, Pr, Pm, Eu, and Tb $(Z=57\mathrm{}$ to 65).

Some commonly used level density compilations are compared with one another and with data in the mass range $20<~A<~41.$ A new formula is proposed which appears to be consistent with both low energy $(U<\mathrm{}5\mathrm{}\hspace{0.5em}\mathrm{MeV})$ and high energy $(U>~20\hspace{0.5em}\mathrm{MeV})$ data. This new compilation is used as a benchmark for testing theoretical calculations of level densities utilizing the two-body interaction with moment methods.

A ten-parameter Skyrme force, along with a four-parameter $\delta$-function pairing force, have been fitted, using the Hartree-Fock-BCS method, to the masses of 1719 nuclei, both spherical and deformed, with an rms error of 0.754 MeV. The corresponding value of the symmetry coefficient J is 28.0 MeV, and that of the effective nucleon mass $M^{*}$ is $1.05M.$

The interacting boson-fermion model (IBFM) Hamiltonian is derived microscopically based on the generalized seniority scheme starting from the shell-model interaction. Employing many nondegenerate levels and identical nucleon systems, systematic studies of singly magic nuclei are given in comparison with experiments. The resulting energy spectra in the IBFM are found to be in good agreement with those of the shell model and the $\mathrm{SD}$ pair plus one-particle model.

The thermal random phase approximation (TRPA) equation is derived from the variational principle applied to the grand potential with an entropy term. This form of the TRPA equation is exact within the framework of the random phase approximation at finite temperature, whose matrix representation coincides with the stability matrix for the solution to the thermal Hartree-Fock-Bogoliubov equation. It is, however, shown that the $\gamma$-ray energy-dependence of the response function for a giant resonance built on a heated nucleus is not altered within a perturbation treatment of the entropy effect based on a simple microscopic model. Thus, an application of the TRPA formalism neglecting the entropy effect is justifiable as for giant resonance shape. The calculation employing a simple microscopic model shows that the increase of the Landau splitting of giant resonance levels with temperature is mainly attributed to the contributions of $\mathrm{pp}$ and $\mathrm{hh}$ configurations.