We discuss how matter-enhanced active-sterile neutrino transformation in the ${\nu }_e\rightleftharpoons {\nu }_s$ and ${\overline{\nu }}_e\rightleftharpoons {\overline{\nu }}_s$ channels could enable the production of the rapid neutron capture $(r$-process) nuclei in neutrino-heated supernova ejecta. In this scheme the lightest sterile neutrino would be heavier than the ${\nu }_e$ and split from it by a vacuum mass-squared difference of $3\hspace{0.5em}{\mathrm{eV}}^2\lesssim \delta m_{\mathrm{es}}^2\lesssim 70\hspace{0.5em}{\mathrm{eV}}^2$ with vacuum mixing angle ${\sin }^{2}2{\theta }_{\mathrm{es}}>{10}^{-4}.$

An extensive study of the effects of correlations on both charged and neutral current weak interaction rates in dense matter is performed. Both strong and electromagnetic correlations are considered. The propagation of particle-hole interactions in the medium plays an important role in determining the neutrino mean free paths. The effects due to Pauli blocking and density, spin, and isospin correlations in the medium significantly reduce the neutrino cross sections. As a result of the lack of experimental information at high density, these correlations are necessarily model dependent. For example, spin correlations in nonrelativistic models are found to lead to larger suppressions of neutrino cross sections compared to those of relativistic models. This is due to the tendency of the nonrelativistic models to develop spin instabilities. Notwithstanding the above caveats, and the differences between nonrelativistic and relativistic approaches such as the spin- and isospin-dependent interactions and the nucleon effective masses, suppressions of order 2–3, relative to the case in which correlations are ignored, are obtained. Neutrino interactions in dense matter are especially important for supernova and early neutron star evolution calculations. The effects of correlations for protoneutron star evolution are calculated. Large effects on the internal thermodynamic properties of protoneutron stars, such as the temperature, are found. These translate into significant early enhancements in the emitted neutrino energies and fluxes, especially after a few seconds. At late times, beyond about 10 s, the emitted neutrino fluxes decrease more rapidly compared to simulations without the effects of correlations, due to the more rapid onset of neutrino transparency in the protoneutron star.

High-spin states in the neutron-deficient ${}^{71}\mathrm{As}$ nucleus have been studied using in-beam $\gamma$-ray spectroscopic techniques combined with mass identification. A new decay sequence of negative parity has been assigned to ${}^{71}\mathrm{As}$ and previously known sequences have been extended to higher spin and excitation. The new sequence has been identified as originating from the proton $f_{7/2}$ extruder orbital, which approaches the Fermi surface at large prolate deformations. Comparisons of experimental $B\left(M1\mathrm{}\right)/B\left(E2\mathrm{}\right)\mathrm{}$ ratios to theoretical expectations support this interpretation.

Incomplete fusion reactions at projectile energies 4–7 MeV/nucleon were studied for the system ${}^{12}\mathrm{C}{+}^{103}\mathrm{Rh}$ by excitation function and recoil range distribution measurements. The complete and incomplete fusion processes were distinguished by the linear momentum transfer from the projectile to target. Comparison of the experimental data with the predictions of Monte Carlo simulation code PACE2 for complete fusion was used to deduce the incomplete fusion component in the recoil range distributions. From the relative yields of the incomplete fusion products, the excitation energy and angular momentum of the incompletely fused composite nucleus were deduced and were found to agree with the breakup fusion model of incomplete fusion.

We determine pairing gap and binding energy of symmetric nuclear matter in a combined, self-consistent treatment of BCS gap equation and Brueckner-Hartree-Fock equations. Relative to the uncoupled scheme, we find a reduction of the gap by about 10 percent. The binding energy per nucleon is lowered by up to about 1 MeV.

The low-energy theorems for QCD are generalized to finite temperature and chemical potential, including nonzero quark masses.

Brueckner-Hartree-Fock calculations are performed for nuclear matter with an exact treatment of the Pauli exclusion operator in the Bethe-Goldstone equation. The differences in the calculated binding energy, compared to the angle-average approximation, which is commonly used, are non-negligible. These differences exhibit a specific density dependence, which shifts the calculated saturation point towards smaller densities. This effect is observed for various versions of modern models for the nucleon-nucleon interaction.

The number of hydrogenlike atoms produced when heavy nuclei collide is estimated for central collisions at the Relativistic Heavy Ion Collider using the sudden approximation of Baym et al. As first suggested by Schwartz, a simultaneous measurement of the hydrogen and hadron spectra will allow an inference of the electron or muon spectra at low momentum where a direct experimental measurement is not feasible.

The correlation between the $E1\mathrm{}$ transition strengths of the $1_1^{-}\to 0_1^{+}\gamma$ transition and the $3_1^{-}\to 2_1^{+}\gamma$ transition in heavy vibrational nuclei is investigated. For a given nucleus the $B\left(E1\mathrm{}\right)\mathrm{}$ values are equal within a factor of 2, although for different nuclei these values can differ by two orders of magnitude. This correlation points to a common origin of these $E1\mathrm{}$ strengths, which supports the quadrupole-octupole coupled two-phonon interpretation of the $1_1^{-}$ state in vibrators. The observations can be accounted for within a factor of 2 by the simple bosonic phonon picture in the collective model.

We calculate in the one-loop approximation of chiral perturbation theory the temperature dependence of the S- and P-wave $\pi \pi$-scattering lengths. We find that the isospin-zero S-wave scattering length $a_0^0\mathrm{}\left(T\right)\mathrm{}$ stays constant at the level of 2% for temperatures $T<~150\mathrm{MeV}$. In contrast to this the isospin-two S-wave scattering length $a_0^2\mathrm{}\left(T\right)\mathrm{}$ decreases in magnitude by about 40% and the isospin-one P-wave scattering length $a_1^1\mathrm{}\left(T\right)\mathrm{}$ increases by about 10% for $T<~150\mathrm{MeV}.$ We also compare with the temperature dependence of the quark condensate $〈\overline{q}q〉\mathrm{}\left(T\right)\mathrm{}$ and the pion decay constant $f_{\pi }\mathrm{}\left(T\right).$

We develop an equation of state for a multicomponent hadron gas in the mean field formalism by incorporating excluded volume corrections arising due to a hard-core repulsion between a pair of baryons and meson exchange correction in the kaon sector. We use this formalism to study the kaon-condensation problem and find that the kaon-condensation phenomenon is model dependent. It occurs in our description of a hot and dense hadron gas consisting of baryons with a hard-core radius of baryons $r_N<~0.6$ fm.

A recent article by Dussel, Sofia, and Tonina studies the relation between Galilei invariance and dipole energy weighted sum rule (EWSR). The authors find that the pairing interaction, which is neither Galilei nor Lorentz invariant, produces big changes in the EWSR and in effective masses of the nucleons. They argue that these effects of the pairing force could be realistic. In this Comment we stress the validity of Galilei invariance to a very good approximation in this context of low-energy nuclear physics and show that the effective masses and the observed change in the EWSR for the electric dipole operator relative to its classical value are compatible with this symmetry.

We discuss the validity of the Galilei invariance in nuclei. The experimentally measured changes in the dipole energy weighted sum rule, due to their magnitude, cannot be explained only by the relative motion of protons and neutrons. Additionally we reemphasize that the usual mean field descriptions introduce violations of the Galilei invariance.

Calculations by Fayache et al. [Phys. Rev. C 57, 2351 (1998)] find no low-lying intruder states in ${}^8\mathrm{Be},$ in contrast with the situation in ${}^{10}\mathrm{Be}$ and ${}^{12}\mathrm{C}.$ It is argued that the models they used are not sufficiently realistic for their results to settle the question of whether or not such states exist in ${}^8\mathrm{Be}.$

In the preceding Comment, our calculations based on the shell model and on the anisotropic harmonic oscillator model for ${}^8\mathrm{Be}$ are criticized. In this Reply we argue that our calculations and remarks on intruder states are relevant.

New $8^{+}$ isomers in ${}^{82}\mathrm{Se}$ and ${}^{80}\mathrm{Ge}$ and their decays were studied by observing $\gamma$ rays from the projectilelike fragments produced by the deep-inelastic collision ${}^{198}\mathrm{Pt}+743\mathrm{}\hspace{0.5em}\mathrm{MeV}{}^{82}\mathrm{Se}$. The lifetimes of the $8^{+}$ isomers have been measured to be $T_{1/2}=6.6\mathrm{}\left(4\right)\mathrm{}\hspace{0.5em}\mathrm{ns}$ and $T_{1/2}>0.4\mathrm{}\hspace{0.5em}\mathrm{ns}$ ${\mathrm{for}\mathrm{}}^{82}\mathrm{Se}$ and ${}^{80}\mathrm{Ge}$, respectively. The $N=48\mathrm{}$ isotones from ${}_{32}^{80}\mathrm{Ge}$ to ${}_{46}^{94}\mathrm{Pd}$ turned out to show quite different energy spectra of the yrast states up to $I^{\pi }{=8\mathrm{}}^{+}$, depending on the orbital occupied by valence protons.

High-angular-momentum states in the deformed nucleus ${}^{186}\mathrm{Os}$ have been studied following fusion-evaporation reactions with a radioactive ${}^{14}\mathrm{C}$ beam. A high-$Kt$-band has been observed and its role in the first crossing of the ground-state band established. The lack of isomerism of the identified $I>~18$ multi-quasiparticle yrast states is presented as new evidence for triaxial shapes.

Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results for spontaneous proton-emission half-life values in excellent agreement with the existing experimental data. Predictions of half-life values for other possible proton-emission cases are presented for null orbital angular momentum.

The effect of particle emission of the intermediate giant dipole resonance on the excitation of the double giant dipole resonance in heavy ion reactions is calculated. General assessment of the time scales involved in such excitation and subsequent decay is given. Both the direct as well as the nondirect, Brink-Axel, paths are considered.

The monopole Hamiltonian $H_m$ is defined as the part of the interaction that reproduces the average energies of configurations. After separating the bulk contributions, we propose a minimal form for $H_m$ containing six parameters adjusted to reproduce the spectra of particle and hole states on doubly magic cores. The mechanism of shell formation is then explained. The reliability of the parametrization is checked by showing that the predicted particle-hole gaps are consistent with experimental data, and that the monopole matrix elements obtained provide the phenomenological cure made necessary by the bad saturation and shell properties of the realistic $\mathrm{NN}$ interaction. Predictions are made for the yet unobserved levels around ${}^{132}\mathrm{Sn},$ ${}^{22}\mathrm{O},$ ${}^{34,42}\mathrm{Si},$ ${}^{68,78}\mathrm{N}\mathrm{i},$ and ${}^{100}\mathrm{Sn}$ and for the particle-hole gaps in these nuclei.