Isospin fractionation and isoscaling are found to hold for isotopes from nuclear collisions simulated within the anitsymmetrized molecular dynamics model. The observed linear relation between the isoscaling parameter and the fragment isospin asymmetry ${(Z∕A)}^2$ of the liquid corroborates, in particular, the applicability of statistical considerations to the dynamical fragment emission. Using the derived relation, we are able to extract statistical parameters from the outcome of the dynamic evolution of collisions. The relation allows to access the symmetry energy in the equation of state. This is consistent with the previous findings that the isoscaling parameters can be used to limit the symmetry energy parameter in the nuclear equation of state.

The three-neutron transfer reaction $\left({}^{12}\mathrm{C},{}^9\mathrm{C}\right)$ has been measured on ${}^{13}\mathrm{C}$ and ${}^{12}\mathrm{C}$ targets at $230.7\text{MeV}$ incident energy. The level scheme of ${}^{16}\mathrm{C}$, which was known previously up to $6.11\text{MeV}$ excitation energy, has been extended up to $17.4\text{MeV}$ by 14 new states. The structure of these states in terms of particle-hole configurations and possible spin assignments are discussed. In ${}^{15}\mathrm{C}$ the spins of the states at $6.84\text{MeV}$ and $7.39\text{MeV}$ could be uniquely assigned as $9∕2^{-}$ and $7∕2^{-}$, respectively.

Differential cross sections and beam asymmetries of Compton scattering from ${}^4\mathrm{He}$ have been measured with linearly polarized photons in the energy range from 206 to $310\text{MeV}$. The quality of the results has the potential to provide strong constraints on the understanding of the reaction mechanism in the $\Delta$ resonance region. A phenomenological analysis of the experimental results has been performed fitting the data to a multipole expansion including dipole and quadrupole scatterings in the impulse approximation. Results indicate that quadrupole contributions should not be neglected to reproduce the general trend of the experimental results. Comparison with predictions from recent theoretical models shows that important discrepancies exist particularly at backward angles. The additional information carried by the incident photon spin increases the difficulty in achieving a comprehensive description of experimental data.

Recent data from relativistic heavy ion collider on rapidity and transverse momentum distributions of hadrons produced in ultrarelativistic reaction of both Au+Au and $p+p$ are compared to predictions of the HIJING and RQMD models. The original default minijet scale $p_0=2\text{GeV}∕c$ and energy loss, $dE∕dx=2\text{GeV}∕\text{fm}$ in HIJING lead to a too rapid growth of the multiplicity with energy. RQMD model without minijet leads on the other hand to a too slowly increasing multiplicity with energy. Therefore, we study what variations of $p_0$ and $dE∕dx$ are required in HIJING to account for the observed $N_{\mathit{part}}$ and $\sqrt{s}$ dependence of the global $d{N}_{ch}∕dy$ and $d{E}_T∕dy$ observables as well as the jet quenching pattern out to $p_T\sim 8\text{GeV}$. We show that a slight increase of $p_0$ from the default $2.0\text{GeV}∕c$ at $\sqrt{s}=130A\text{GeV}$ to $2.2\text{GeV}∕c$ at $\sqrt{s}=200A\text{GeV}$ is sufficient to account for the bulk observables. Jet quenching of ${\pi }^0$ above $p_T>4\text{GeV}∕c$ at $200A\text{GeV}$ is found to be well reproduced in central $Au+Au$ by the original HIJING default prediction. However, the effective surface emission in the HIJING model formulation of energy loss overpredicts the quenching in more peripheral collisions. Neither HIJING nor $\text{HIJING}∕\mathrm{B}\overline{\mathrm{B}}$ can account for the observed anomalous excess of moderate $p_T<4\text{GeV}∕c$ baryons. The agreement of RQMD with data in this $p_T$ region is shown to be fortuitous because, without minijets, it fails to reproduce the $p+p$ spectrum.

The impact of a $\left(I=0,J^P={\frac{1}{2}}^{+}\right)Z^{+}\left(1540\right)$ resonance with a width of $5\text{MeV}$ or more on the $K^{+}N\left(I=0\right)$ elastic cross section and on the $P_{01}$ phase shift is examined within the $KN$ meson-exchange model of the Jülich group. It is shown that the rather strong enhancement of the cross section caused by the presence of a $Z^{+}$ with the above properties is not compatible with the existing empirical information on $KN$ scattering. Only a much narrower $Z^{+}$ state could be reconciled with the existing data—or, alternatively, the $Z^{+}$ state must lie at an energy much closer to the $KN$ threshold.

Lifetimes of excited states in ${}^{68}\mathrm{Cu}$ were measured by the $\gamma \text{−}\gamma \text{−}t$ coincidence using two ${\text{BaF}}_2$ detectors through the decay of ${}^{68}{\mathrm{Cu}}^m$ produced by the $\left(n,p\right)$ reaction. The half-life of the $2^{+}$ state at $84\text{keV}$ was obtained as $7.84\left(8\right)\text{ns}$, corresponding to the $B(M1;2^{+}\to 1^{+})$ value of $0.00777\left(8\right){\mu }_N^2$. A shell model calculation with a minimum model space of $\pi p_{3∕2}\nu p_{1∕2}^{-1}$ gives a good prediction of this $B\left(M1\right)$ value by using experimental $g$ factors of neighboring nuclei. This small $B\left(M1\right)$ value can also be explained by a shell model calculation in the $f_{7∕2}^{-r}{\left(p_{3∕2}{f}_{5∕2}{p}_{1∕2}\right)}^{n+r}(r=0,1)$ model space.

Intermediate mass fragment $\left(Z>2\right)$ emission in ${}^{124}\mathrm{Sn},{}^{124}\mathrm{Xe}+{}^{124}\mathrm{Sn},{}^{112}\mathrm{Sn}$ reactions at $28\text{MeV}∕\text{nucleon}$ were studied using neutron ion multidetector for reaction oriented dynamics, a $4\pi$ charged particle detection system. A number of observables, such as isotopic yield distributions, energy spectra of light charged particles and intermediate mass fragments, isotopic and isobaric yield ratios, and average neutron to proton ratios are investigated. These observables show significant dependence on the isospin $N∕Z$ of the reacting system. It is observed that the formation of neutron-rich clusters are correlated with the excess neutrons in the composite system and depends on the temperature of the emitting source. The origin of light particles and fragments was studied through observations of rapidity distribution as a function of collision violence. With increasing centrality, the heavier ${}^6\mathrm{He}$ isotope is found to be emitted closer to the midrapidity region than the lighter ${}^3\mathrm{He}$ isotope. The emission of heavy fragments from the midrapidity region becomes increasingly favorable for fragments with higher charge $Z$. The results suggest that the midrapidity region is not only neutron rich but also a rich source of heavy fragment (cluster) formation.

Using chiral perturbation theory, we calculate the density-dependent spin-orbit coupling generated by the two-pion exchange three-nucleon interaction involving virtual $\Delta$-isobar excitation. From the corresponding three-loop Hartree and Fock diagrams we obtain an isoscalar spin-orbit strength $F_{\text{so}}\left(k_f\right)$ which amounts at nuclear matter saturation density to about half of the empirical value of $90\text{MeV}{\text{fm}}^5$. The associated isovector spin-orbit strength $G_{\text{so}}\left(k_f\right)$ comes out to be about a factor of 20 smaller. Interestingly, this three-body spin-orbit coupling is not a relativistic effect but independent of the nucleon mass $M$. Furthermore, we calculate the three-body spin-orbit coupling generated by two-pion exchange on the basis of the most general chiral $\pi \pi NN$-contact interaction. We find similar (numerical) results for the isoscalar and isovector spin-orbit strengths $F_{\text{so}}\left(k_f\right)$ and $G_{\text{so}}\left(k_f\right)$ with a strong dominance of the $p$-wave part of the $\pi \pi NN$-contact interaction and the Hartree contribution.

Previous nonrelativistic calculations have demonstrated a high sensitivity of hard bremsstrahlung $pp\to pp\gamma$ at the beam energies of $350–500\text{MeV}$ to the kind of nucleon-nucleon potential (meson exchange potentials versus the Moscow one). Here, bremsstrahlung calculations are generalized by means of relativistic considerations (point form dynamics). The necessary formal technique is presented. Resulting cross sections become smaller in comparison with nonrelativistic theory and their angular dependence changes. However, the high sensitivity to the kind of potential continues to exist and is characteristic of the differential cross section even at a relatively low beam energy of $E_0=280\text{MeV}$ where corresponding experimental data do exist. Our calculations give some preliminary indication that one of the versions of the Moscow potential may be valid here.

Recent progress in experimental techniques have made possible accurate measurements of fusion cross sections far below the Coulomb barrier, revealing an unexpected behavior of these quantities as a function of the bombarding energy. Besides providing a plausible cause for the observed energy dependence we profit from the nature of this explanation and the high sensitivity of the experimental data to show how one can use these measurements to investigate the radial dependence of the nuclear ion-ion potential at extremely close distances.

We present predictions for energies, proton and neutron rms radii, and neutron skins of some closed-shell nuclei based upon a microscopic model of the equation of state for asymmetric nuclear matter which is used as input for a mass formula. We employ realistic two-body forces and the Dirac-Brueckner-Hartree-Fock approach to nuclear matter. We compare with experimental information, when available, and point out the need for accurate determinations of neutron densities and skins.

We present a formalism to describe proton emission from odd-odd nuclei based on a scatteringlike approach. Special emphasis is given to the case of transitions between states with different deformations. As an example we estimate the proton half-life of the odd-odd nucleus ${}^{58}\mathrm{Cu}$. Our calculations show that the change of deformation in the decay process has a significant influence on the half life. In addition, the angular momentum coupling of proton and neutron orbitals can result in an additional $K$ hindrance of the decay. To fully account for the observed half life in ${}^{58}\mathrm{Cu}$, we propose shape mixing of the final state.

The neutrino propagation in neutron stars is studied in the framework of the linear response method. The medium effects are treated in the nonrelativistic Brueckner-Hartree-Fock approach either in the mean-field approximation or in the random phase approximation. The residual interaction is expressed in terms of the Landau parameters extracted from the equation of state of spin- and isospin-polarized nuclear matter. The Brueckner theory including three-body forces is used for determining the equation of state. Numerical predictions for the response function of nuclear matter in $\beta$ equilibrium and the neutrino mean free path are presented in a range of baryonic densities and temperatures. The main results are a dominance of the charge-exchange component over the scattering component and an enhancement of the neutrino mean free path induced by nuclear correlations.

The absolute branching ratio of the $\beta$-delayed $\gamma$-ray emission of ${}^{18}\mathrm{N}$ was measured, providing absolute normalization of the previous work by Olness et al. [Nucl. Phys. A373, 13 (1982)] who measured the relative branching ratios for the individual $\gamma$-rays. We find the total absolute branching ratio for $\beta$-delayed $\gamma$-ray emission of ${}^{18}\mathrm{N}$ to be $76.7\pm 7.2\left(\text{stat}\right)\pm 5.8\left(\text{norm}\right)\%$. A combination of other results suggests a value consistent with our result, but smaller than that calculated by Millener as quoted in Olness et al.

We briefly review recent calculations of neutrino-deuteron cross sections within the effective field theory and traditional potential model approaches. We summarize recent efforts to determine the counter term describing axial two-body currents, $L_{1A}$, in the effective field theory approach. We determine the counterterm directly from the solar neutrino data and find several, slightly different, ranges of $L_{1A}$ under different sets of assumptions. Our most conservative fit value with the largest uncertainty is $L_{1A}={4.5}_{-12}^{+18}{\text{fm}}^3$. We show that the contribution of the uncertainty of $L_{1A}$ to the analysis and interpretation of the solar neutrino data measured at the Sudbury Neutrino Observatory is significantly less than the uncertainty coming from the lack of having a better knowledge of ${\theta }_{13}$.

The systematics of the first $2^{+}$ state $g$ factors in the mass 80 region are investigated in terms of an IBM-II analysis, a pairing-corrected geometrical model, and a shell-model approach. Subshell closure effects at $N=38$ and overall trends were examined using IBM-II. A large-space shell-model calculation was successful in describing the behavior for $N=48$ and $N=50$ nuclei, where single-particle features are prominent. A schematic truncated-space calculation was applied to the lighter isotopes. The variations of the effective boson $g$ factors are discussed in connection with the role of $F$-spin breaking, and comparisons are made between the mass 80 and mass 180 regions.

We reinvestigate Adler’s partially conserved axial-vector current relation in the presence of an external electromagnetic field within the framework of QCD coupled to external fields. We discuss pion electroproduction within a tree-level approximation to chiral perturbation theory and explicitly verify a chiral Ward identity referred to as the Adler-Gilman relation. We critically examine soft-momentum techniques and point out how inadmissable approximations may lead to results incompatible with chiral symmetry. As a result we confirm that threshold pion electroproduction is indeed a tool to obtain information on the axial form factor of the nucleon.

The predictions of the geometric collective model (GCM) for different sets of Hamiltonian parameter values are related by analytic scaling relations. For the quartic truncated form of the GCM—which describes harmonic oscillator, rotor, deformed $\gamma$-soft, and intermediate transitional structures—these relations are applied to reduce the effective number of model parameters from four to two. Analytic estimates of the dependence of the model predictions upon these parameters are derived. Numerical predictions over the entire parameter space are compactly summarized in two-dimensional contour plots. The results considerably simplify the application of the GCM, allowing the parameters relevant to a given nucleus to be deduced essentially by inspection. A precomputed mesh of calculations covering this parameter space and an associated computer code for extracting observable values are made available through the Electronic Physics Auxiliary Publication Service. For illustration, the nucleus ${}^{102}\mathrm{Pd}$ is considered.

In view of the numerous experimental results recently released, we provide in this paper an update on the performance of our simple Regge model for strangeness electroproduction on the nucleon. Without refitting any parameters, a decent description of all measured observables and channels is achieved. We also give predictions for spin transfer observables, recently measured at Jefferson Lab, which have high sensitivity to discriminate between different theoretical approaches.