Quark-model descriptions of the nucleon-nucleon interaction contain two main ingredients, a quark-exchange mechanism for the short-range repulsion and meson exchanges for the medium- and long-range parts of the interaction. We point out the special role played by higher partial waves, and in particular the ${}^1{F}_3,$ as a very sensitive probe for the meson-exchange part employed in these interaction models. In particular, we show that the presently available models fail to provide a reasonable description of higher partial waves and indicate the reasons for this shortcoming.

A new transition is reported in the β-delayed neutron decay of ${}^{16}\mathrm{C}.$ The energy of the associated neutrons is $3.29\pm 0.03\hspace{0.5em}\mathrm{MeV},$ leading to the feeding, with a branching ratio of $\sim 1\%,$ of a probable $1^{+}$ level in ${}^{16}\mathrm{N}$ at $6.00\pm 0.03\hspace{0.5em}\mathrm{MeV}.$ Such an observation is in good accordance with shell model calculations carried out within the $0p1s0d$ model space.

Analytic branching cascade is considered as a model of nuclear multifragmentation and corresponding stretched lognormal distribution of fragments size is compared with experimental data obtained in nuclear emulsion. Branching dimension of the cascade corresponding to these data is found to be equal to 3. It is also shown that the same branching dimension can be extracted from the data on the branching cascades in turbulence, while for multiparticle production at high energy heavy ion collisions the branching dimension turned out to be equal to 2.

The problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighborhood of ${}^{270}\mathrm{Hs}$ is discussed. Measurement of the energy $E_{2+}$ of the lowest $2+$ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. Branching ratio $p_{2+}{/p}_{0+}$ between $\alpha$ decay of a nucleus to this lowest $2+$ state and to the ground state $0+$ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy $E_{2+}$ for some superheavy nuclei by electron or $\alpha$ spectroscopy is a promising method for the confirmation of their deformed shapes.

The breakup of ${}^{10}\mathrm{B}$ has been studied using the ${}^7\mathrm{Li}{(}^{12}\mathrm{C}{,}^{10}{\mathrm{B}}^{*}{)}^9\mathrm{Be}$ two-nucleon transfer reaction with a 76-MeV ${}^{12}\mathrm{C}$ beam incident on a ${\mathrm{Li}}_2\mathrm{O}$ target. The ${}^{10}\mathrm{B}$ excited states were observed to break up into $\alpha {+}^6\mathrm{Li},$ $\alpha {+}^6\mathrm{Li}{(3\mathrm{}}^{+}),$ ${}^8\mathrm{Be}+d,$ and ${}^9\mathrm{Be}+p.\mathrm{}$ Evidence is found for two new states in ${}^{10}\mathrm{B}$ at excitation energies of $7.96\pm 0.07\mathrm{MeV}$ and $9.58\pm 0.06\mathrm{MeV}$ that decay strongly into the $\alpha {+}^6\mathrm{Li}{(3\mathrm{}}^{+})$ final state.

E2 transitions and quadrupole moments are studied in the recently proposed E(5) symmetry by using the intrinsic state formalism. It is shown that the values of these magnitudes can be obtained for the different bands to higher order in the boson number N by projecting the intrinsic state on γ and β variables. The formalism allows to find easily the dependence of those magnitudes on the structure parameter of the quadrupole operator, $\chi .$

Within a microscopic statistical description of heavy ion collisions, we investigate the effect of the medium on the formation of light clusters. The dominant medium effects are self-energy corrections and Pauli blocking that produce the Mott effect for composite particles and enhanced reaction rates in the collision integrals. Microscopic description of composites in the medium follows the Dyson equation approach combined with the cluster mean-field expansion. The resulting effective few-body problem is solved within a properly modified Alt-Grassberger-Sandhas formalism. The results are incorporated in a Boltzmann-Uehling-Uhlenbeck simulation for heavy ion collisions. The number and spectra of light charged particles emerging from a heavy ion collision change in a significant manner in effect of the medium modification of production and absorption processes.

Ground-state properties of $A=20\mathrm{}$ nuclei ${(}^{20}\mathrm{N},$ ${}^{20}\mathrm{O},$ ${}^{20}\mathrm{F},$ ${}^{20}\mathrm{Ne},$ ${}^{20}\mathrm{Na},$ and ${}^{20}\mathrm{Mg})$ are described in the framework of relativistic Hartree-Bogoliubov theory. The model uses the $\mathrm{NL}3\mathrm{}$ effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite-range Gogny interaction $D1S.\mathrm{}$ Binding energies, quadrupole deformations, nuclear matter radii, and differences in radii of proton and neutron distributions are compared with recent experimental data.

We investigate the condensation of $K^0$ mesons along with $K^{-}$ condensation in neutrino-trapped matter with and without hyperons. Calculations are performed in the relativistic mean field models in which both the baryon-baryon and (anti)kaon-baryon interactions are mediated by meson exchange. In the neutrino-trapped matter relevant to protoneutron stars, the critical density of $K^{-}$ condensation is shifted considerably to higher density whereas that of $K^0$ condensation is shifted slightly to higher density with respect to that of the neutrino-free case. The onset of $K^{-}$ condensation always occurs earlier than that of $K^0$ condensation. A significant region of maximum mass protoneutron stars is found to contain $K^0$ condensate for larger values of the antikaon potential. With the appearance of $K^0$ condensation, there is a region of symmetric nuclear matter in the inner core of a protoneutron star. We note that the gross properties of the protoneutron stars are significantly affected by the antikaon condensation for larger values of the antikaon potential. It is found that the maximum mass of a protoneutron star containing $K^{-}$ and $K^0$ condensate is greater than that of the corresponding neutron star. We reexamine the implication of this scenario in the context of the metastability of protoneutron stars and their evolution to low mass black holes.

An irreducible tensor formalism to analyze inelastic scattering of nucleons on nuclei with arbitrary spins is outlined and the nature of noncentral interactions involved therein is studied. In the particular case of inelastic scattering of nucleons on ${}^{12}\mathrm{C}$ leading to the ${(1\mathrm{}}^{+})$ excited state at 15.11 MeV, the relative importance of vector and tensor amplitudes is examined using the DW81 and DREX codes.

A consistent generalization of the random phase approximation (RPA) for odd nuclei is suggested. The derivation is based on the Green function method using the equation for the three-particle Green function. The model developed combines properties of both the standard RPA, and the particle-vibration coupling model. This gives a possibility to describe both the single-particle and collective parts of the excitation spectrum including giant resonances in the continuum and splitting of discrete collective states [particle (hole) $\otimes$ phonon multiplets] on a common basis. In the framework of this model, where the single-particle continuum is taken into account exactly, the $E1\mathrm{}$ photoabsorption cross section and the isoscalar $E1\mathrm{}$ resonance in ${}^{17}\mathrm{O}$ are calculated. The comparative RPA calculations of the same $E1\mathrm{}$ modes in ${}^{16}\mathrm{O}$ nucleus are presented. The results obtained are compared with experiment for the $E1\mathrm{}$ resonance in ${}^{16}\mathrm{O}$ and ${}^{17}\mathrm{O}.$ For the isoscalar $E1\mathrm{}$ strength in ${}^{17}\mathrm{O}$ we obtained an additional and noticeable low-lying contribution below 12.5 MeV caused by the odd neutron only.

Four $\gamma$-ray transitions belonging to the ground state band of the $N=Z$ nucleus ${}^{88}\mathrm{Ru}$ are reported for the first time. The reaction ${}^{58}\mathrm{Ni}{(}^{32}\mathrm{S},2n\gamma )$ at 105 MeV has been used, and the prompt $\gamma$ rays were detected with the GASP array. The assignment of $\gamma$ rays to ${}^{88}\mathrm{Ru}$ was made by combining information from GASP, the ISIS silicon ball, and the n-Ring neutron detector. The ${}^{88}\mathrm{Ru}$ nucleus is weakly deformed, with an ${E(2\mathrm{}}^{+})$ energy of 0.616 MeV and ${E(4\mathrm{}}^{+}{)/E(2\mathrm{}}^{+})$ ratio of 2.30. The evolution of the nuclear structure along the $N=Z,$ $N=44,$ and $Z=44\mathrm{}$ lines is discussed. Unlike in other nuclei from the region, no sign of backbending is seen in ${}^{88}\mathrm{Ru}$ at a rotational frequency of $\approx 0.5\hspace{0.5em}\mathrm{MeV},$ which might be a signature of the $T=0\mathrm{}$ neutron-proton pairing in the $N=Z$ nuclei.

The decay of ${}^9\mathrm{C}$ ${(T}_{1/2}=126.5\mathrm{}$ ms) has been observed in two experiments at the TISOL facility at TRIUMF employing different detector configurations for each run. In the first of two papers [E. Gete et al., Phys. Rev. C 61, 064310 (2000)], the experimental technique and data analysis were described. Phenomenological branching ratios and Gamow-Teller strengths were then deduced. In this paper, the data are analyzed using a multichannel, multistate $R-\mathrm{m}\mathrm{a}\mathrm{t}\mathrm{r}\mathrm{i}\mathrm{x}$ approach which leads to a different interpretation of the spectra and therefore modified state energies, widths, branching ratios, and Gamow-Teller strengths. Difficulties in fitting the second excited state of ${}^9\mathrm{B}$ at 2.34 MeV and possible modifications to the penetrability are described. The existence of a $J^{\pi }{=1/2\mathrm{}}^{-}$ state at about 5 MeV excitation energy is suggested from the fits, as well as a considerable decay strength from the ${}^9\mathrm{B}$ ground state at high energies. Consequences for the properties of the $A=9,$ $T=1/2\mathrm{}$ nuclear system are then discussed; in particular, it is shown that the data agree qualitatively with shell model predictions without unusual Gamow-Teller strength present at high excitation energies. Finally, an estimate of the ${}^4\mathrm{He}(\alpha n,\gamma {)}^9\mathrm{Be}$ stellar reaction rate is given.

Using an $\alpha$ decay single-particle level scheme, the fine structure in odd nuclei is explained by taking into account the radial and rotational couplings between the unpaired valence nucleon and the core of the decaying system. It is shown that the experimental behavior of the $\alpha$ decay fine structure phenomenon is governed by the dynamical characteristics of the system.

Broadening of the transverse momentum of a parton propagating through a medium is treated using the color dipole formalism, which has the advantage of being a well developed phenomenology in deep-inelastic scattering and soft processes. Within this approach, nuclear broadening should be treated as color filtering, i.e., absorption of large-size dipoles leading to diminishing (enlarged) transverse separation (momentum). We also present a more intuitive derivation based on the classic scattering theory of Molière. This derivation helps one to understand the origin of the dipole cross section, part of which comes from attenuation of the quark, while another part is due to multiple interactions of the quark. It also demonstrates that the lowest-order rescattering term provides an $A$ dependence very different from the generally accepted $A^{1/3}$ behavior. The effect of broadening increases with energy, and we evaluate it using different phenomenological models for the unintegrated gluon density. Although the process is dominated by soft interactions, the phenomenology we use is tested using hadronic cross section data.

A semiclassical analysis of an optical potential cross section is presented. The cross section considered is characterized by the appearance of an Airy-like pattern. This pattern is similar to that which is present in many cross sections, which fit the recent measurements of light heavy ion elastic scattering, and is considered as a manifestation of a rainbow phenomenon. The semiclassical analysis shows that, in the case considered, the oscillations arise from the interference between the contributions from two different terms of a multireflection expansion of the scattering function, and, therefore, cannot be associated with the rainbow phenomenon.

It has been suggested recently [K. Buckley, T. Fugleberg, and A. Zhitnitsky, Phys. Rev. Lett. 84, 4814 (2000)] that an arbitrary, induced $\theta -\mathrm{v}\mathrm{a}\mathrm{c}\mathrm{u}\mathrm{u}\mathrm{m}$ state $\left({\theta }^{\mathrm{ind}}\right)$ could be created in heavy-ion collisions. If such a state can be created, it would decay by various mechanisms to the ${\theta }^{\mathrm{fund}}=0\mathrm{}$ state which is the true ground state of our world. In the following we will discuss the possibility of studying this unusual state through the emission of pions, $\eta$ mesons, and ${\eta }^{\prime }$ mesons. We will also present the spectrum of the produced particles in this nonzero $\theta$ background. We use the instantaneous perturbation theory for our estimates.

We propose a method to introduce Fock term contributions in relativistic models of fermions coupled to mesons, including self-interactions for the mesonic fields. We show that effects on equilibrium properties and on the dynamical response of the fermionic system can be consistently accounted for. Some implications on equilibrium properties of asymmetric nuclear matter are discussed. In particular an indication is emerging for a reduced contribution of charged mesons to the symmetry term of the nuclear equation of state around normal density.

Strength functions for isoscalar dipole excitations in ${}^{90}\mathrm{Zr},$ ${}^{116}\mathrm{Sn},$ and ${}^{208}\mathrm{Pb}$ have been measured with inelastic scattering of 240 MeV α particles at small angles. The isoscalar $E1\mathrm{}$ strength distribution in each nucleus is found to consist of a broad component at $E_x\sim {114/A}^{1/3}\mathrm{MeV}$ containing approximately 100% of the $E1\mathrm{}$ EWSR and a narrower one at $E_x\sim {72/A}^{1/3}\mathrm{MeV}$ containing 15–28 % of the total isoscalar $E1\mathrm{}$ strength. The higher component is the compression mode $E1\mathrm{}$ strength previously reported only in ${}^{208}\mathrm{Pb},$ whereas the lower component may be a new mode not reported previously, but suggested by recent RPA-HF and relativistic mean field calculations.

A binomial reducibility and thermal scaling analysis is performed on well-chacracterized thermal-like sources formed in $8\mathrm{GeV}/c{\pi }^{-}{+}^{197}\mathrm{Au}$ reactions. The fragment probability distributions are shown to be binomial when plotted as a function of the measured excitation energy $E^{*}$ and the binomial elementary probability p is shown to follow the expected Boltzmann factor: $\ln \mathrm{}\left(p\right)\mathrm{}\propto \exp (-B/\sqrt{E^{*}/A}).\mathrm{}$ Binomial reducibility and thermal scaling are explored also using global variables other than $E^{*},$ and the effect of source size on the binomial parameter p and m is shown. Finally, the extracted probability p is found to be correlated with the experimentally deduced fragment emission time up to about $6A\mathrm{MeV}\mathrm{}$ of excitation energy, hinting at a possible transition in decay mechanism above that excitation energy.