We present shell-model calculations of electron capture strength distributions in $A=28$ nuclei and computations of the corresponding capture rates in supernova core conditions. We find that in these nuclei the Brink-Axel hypothesis for the distribution of Gamow-Teller strength fails at low and moderate initial excitation energy but may be a valid tool at high excitation. The redistribution of GT strength at high initial excitation may affect capture rates during collapse. If these trends which we have found in lighter nuclei also apply for the heavier nuclei which provide the principal channels for neutronization during stellar collapse, then there could be two implications for supernova core electron capture physics. First, a modified Brink-Axel hypothesis could be a valid approximation for use in collapse codes. Second, the electron capture strength may be moved down significantly in transition energy, which would likely have the effect of increasing the overall electron capture rate during stellar collapse.

High-spin states in neutron-rich ${}^{158}\mathrm{Sm}$ have been reinvestigated by measuring the prompt $\gamma$ rays emitted in the spontaneous fission of ${}^{252}\mathrm{Cf}$. A new negative-parity band has been established up to spin 12. By comparison with the theoretical calculations, a two-quasiparticle state with $\pi 5/2\left[532\right]$ $\otimes$ $\pi 5/2\left[413\right]$ configuration has been proposed for the band head. The systematics of the two-quasiparticle states and bands in this region are discussed.

The angular distributions of the ${}^{12}\mathrm{C}{{(}^{11}\mathrm{B},{}^{11}\mathrm{B})}^{12}\mathrm{C}$ and ${}^{12}\mathrm{C}{{(}^{11}\mathrm{B},{}^{12}\mathrm{C})}^{11}\mathrm{B}$ reactions have been measured at an incident energy of 50 MeV by using the high resolution Q3D magnetic spectrometer of the HI-13 tandem accelerator at China Institute of Atomic Energy, Beijing. The optical potential parameters of the ${}^{11}\mathrm{B}+{}^{12}\mathrm{C}$ system are determined by fitting the angular distribution of the elastic scattering and then used to predict the cross sections of the elastic transfer reaction leading to the ground state in ${}^{12}\mathrm{C}$ based on distorted-wave Born approximation (DWBA) analysis. Taking into account the interference between the elastic scattering and the elastic transfer processes, the proton spectroscopic factor of the ${}^{12}\mathrm{C}$ ground state is extracted to be 2.15 $\pm$ 0.23 by constraining the geometrical parameters $r_0$ and $a$ using the rms radius of the valence proton in the ${}^{12}\mathrm{C}$ ground state.

Assuming the statistical hadronization model and charm flavor conservation, one can quantify the deviation of charm and anticharm quarks from chemical equilibrium both in the hadronic phase and in the quark-gluon plasma. By linking the hadronic fireball volume and the corresponding plasma source volume via entropy conservation as proposed earlier [L. Grandchamp, R. Rapp, and G. E. Brown, Phys. Rev. Lett. 92, 212301 (2004)], a direct comparison between the $J/\psi$ yields in both pictures can be used to obtain limits for the charm quark mass in the deconfined medium.

In this paper we study low-lying states of $sd$ bosons under random interactions. We find that the yrast states are highly correlated, regardless of whether the ground state spin is zero or not. Many of the random samplings in the random ensemble well overlap with predictions of the U(5) limit in the interacting boson model.

High-spin states in the doubly-odd ${}^{198}\mathrm{Bi}$ nucleus have been studied by using the ${}^{185,187}\mathrm{Re}({}^{16}\mathrm{O},xn)$ reactions at a beam energy of 112.5 MeV. $\gamma \text{−}\gamma$ coincidences, directional correlation ratio, and integrated polarization asymmetry ratio were measured by using the INGA array with 15 Compton-suppressed clover high-purity germanium (HPGe) detectors. Definite spins and parities were assigned to the observed levels. The high-spin structure is grouped into three bands (B1, B2, and B3), of which two (B1 and B2) exhibit the properties of magnetic rotation (MR). Tilted axis cranking calculations were carried out to explain the MR bands having large multiquasiparticle (qp) configurations. The calculated results explain the bands B1 and B2 very nicely, confirming the shears mechanism and suggest a crossing of two MR bands in both the cases. The crossing is from 6-qp to 8-qp in band B1 and from 4-qp to 6-qp in band B2, a very rare finding. A semiclassical model has also been used to obtain the particle-hole interaction strengths below the band crossing for the bands B1 and B2.

The ${}^9\mathrm{Be}\left({}^{28}\mathrm{Mg},{}^{27}\mathrm{Na}\right)$ one-proton removal reaction with a large proton separation energy of $S_p\left({}^{28}\mathrm{Mg}\right)=16.79$ MeV is studied at intermediate beam energy. Coincidences of the bound ${}^{27}\mathrm{Na}$ residues with protons and other light charged particles are measured. These data are analyzed to determine the percentage contributions to the proton removal cross section from the elastic and inelastic nucleon removal mechanisms. These deduced contributions are compared with the eikonal reaction model predictions and with the previously measured data for reactions involving the removal of more weakly bound protons from lighter nuclei. The role of transitions of the proton between different bound single-particle configurations upon the elastic breakup cross section is also quantified in this well-bound case. The measured and calculated elastic breakup fractions are found to be in good agreement.

The ${}^{18}\mathrm{Ne}(\alpha ,p){}^{21}\mathrm{Na}$ reaction impacts the break-out from the hot CNO cycles to the $rp$ process in type-I x-ray bursts. We present a revised thermonuclear reaction rate, which is based on the latest experimental data. The new rate is derived from Monte Carlo calculations, taking into account the uncertainties of all nuclear physics input quantities. In addition, we present the reaction rate uncertainty and probability density versus temperature. Our results are also consistent with estimates obtained using different indirect approaches.

We report on $J/\psi$ production from asymmetric Cu + Au heavy-ion collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of $J/\psi$ yields in Cu + Au collisions in the Au-going direction is found to be comparable to that in Au + Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, $J/\psi$ production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-$x$ gluon suppression in the larger Au nucleus.

We present results on deep sub-threshold hyperon production in nuclear collisions, with the UrQMD transport model. Introducing anti-$\text{kaon}+\text{baryon}$ and hyperon + hyperon strangeness exchange reactions we obtain a good description of experimental data on single strange hadron production in $\text{Ar}+\text{KCl}$ reactions at $E_{\mathrm{lab}}=1.76A$ GeV. We find that the hyperon strangeness exchange is the dominant process contributing to the ${\Xi }^{-}$ yield; however, our study remains short of explaining the ${\Xi }^{-}/\Lambda$ ratio measured with the HADES experiment. We also discuss possible reasons for the discrepancy with previous studies and the experimental results, finding that many details of the transport simulation may have significant effects on the final ${\Xi }^{-}$ yield.

When neutrinos travel through matter with a periodic density profile, the neutrino oscillation probability can be enhanced if certain conditions are satisfied. In a two-neutrino framework, the condition for parametric resonance is known. Herein, we consider the analogous parametric resonance condition within the context of a full three-neutrino framework with two oscillation scales. For energies in the range of hundreds of MeV to a few GeV, we find that neutrino oscillation can be parametrically enhanced if two approximate relations are satisfied. The first is similar to the two-neutrino parametric resonance condition while the second involves the other oscillation scale. Treating the Earth's density as piecewise constant, we show that oscillations in this energy range can be enhanced between two- and threefold.

Short-range correlations in nuclear and neutron matter are examined through the properties of the correlated wave function obtained by solving the Bethe–Goldstone equation. Tensor correlations are explored through the dominant tensor-driven transition and central correlations through the singlet and triplet $S$ waves. Predictions from a popular meson-theoretic nucleon-nucleon potential employed in the Dirac–Brueckner–Hartree–Fock approach are compared with those from two- and three-body high-quality chiral interactions in Brueckner $G$-matrix calculations. Short-range correlations in symmetric matter are remarkably stronger than in neutron matter. It is found that short-range correlations are very model dependent and have a large impact on the symmetry energy above normal density.

To help guide our intuition, summarize important features, and point out essential elements, we review the analytical solutions of Landau (1+1)-dimensional hydrodynamics and discuss the full evolution of the dynamics from the very beginning. Special emphasis is placed on the matching and the interplay between the Khalatnikov solution and the Riemann simple wave solution, at the earliest times and in the edge regions at later times. These analytical solutions collected and developed here serve well as a useful guide and cross-check in the development of complicated numerically intensive relativistic hydrodynamical Monte Carlo simulations.

We study collective excitations in a superfluid neutron gas at zero temperature within the quasiparticle random-phase approximation. The particle-hole residual interaction is obtained from a Skyrme functional, while a separable interaction is used in the pairing channel, which gives a BCS gap that is very similar to the one obtained with a realistic nucleon-nucleon interaction. In accordance with the Goldstone theorem, we find an ungapped collective mode (analogous to the Bogoliubov-Anderson mode). At low momentum, its dispersion relation is approximately linear and its slope coincides with the hydrodynamic speed of sound calculated with the Skyrme equation of state. The response functions are compared with those obtained within the Landau approximation. We also compute the contribution of the collective mode to the specific heat of the neutron gas.

Recent experimental results related to the quadrupole collectivity in neutron-rich carbon isotopes are analyzed in a phenomenological approach. $B(E2;2_1^{+}\to 0_1^{+})$ transitions rates derived from lifetime measurements are interpreted in terms of the mixing of basic neutron and proton $2^{+}$ excitations. A seniority inspired scheme is used to describe the neutron component. The observed increase in collectivity can be explained with a corresponding increased role of proton excitations. This is likely due to the reduction of the proton $p_{3/2}-p_{1/2}$ spin-orbit splitting caused by the tensor and two-body spin-orbit components of the force between the protons and the added neutrons in the ($d_{5/2}+s_{1/2}$) shells.

We analyze the $\alpha$-decay fine structure to excited $0_2^{+}$ states in Hg and Rn isotopes. These states are described as minima in the potential energy surface (PES) provided by the standard deformed Woods-Saxon plus pairing approach. We also investigate $\alpha$ decay from the excited state $P\left(0_2^{+}\right)$ in the parent nucleus by evaluating the corresponding hindrance factor (HF). By analyzing the experimental HF's we find the remarkable property that the ground and excited states $D\left(0_1^{+}\right)$ and $D\left(0_2^{+}\right)$ in the daughter nuclei are occupied with almost equal probabilities if there is no excited $P\left(0^{+}\right)$ states in the parent nucleus. Moreover, if there exists an excited state $P\left(0_2^{+}\right)$ then the occupation probability of this state is 25%.