We study the one-neutron removal strength of the ${}^7\mathrm{He}$ ground state, which provides us with the ${}^6\mathrm{He}\text{−}n$ component in ${}^7\mathrm{He}$. The He isotopes are described on the basis of the ${}^4\mathrm{He}+\mathit{Xn}$ cluster model ($X=1,2,3$). The complex scaling method is applied to describe not only the Gamow resonances but also the nonresonant continuum states of valence neutrons, with the correct boundary condition of particle decays. The one-neutron removal strength of ${}^7\mathrm{He}$ into the unbound states of ${}^6\mathrm{He}$ is calculated using the complex-scaled Green's function, in which a complex-scaled complete set of ${}^4\mathrm{He}+n+n$ states is adopted. Using this framework, we investigate resonant and nonresonant contributions of the strength, which individually produce specific structures in the distributions. In addition, we propose a method to obtain the real-value strength using the complex values of spectroscopic factors of Gamow states. As a result, the ${}^6\mathrm{He}$($2^{+}$) resonance is found to give the largest contribution.

Multiplicity fluctuations and correlations are calculated within thermalized relativistic ideal quantum gases. These are shown to be sensitive to the choice of statistical ensemble as well as to the choice of acceptance window in momentum space. It is furthermore shown that global conservation laws introduce nontrivial correlations between disconnected regions in momentum space, even in the absence of any dynamics.

The differential and total cross sections for the $\mathit{dp}\to {}^3\mathrm{He}\eta$ reaction have been measured at COSY–ANKE at excess energies of 19.5, 39.4, and 59.4 MeV over the full angular range. The results are in line with trends apparent from the detailed near-threshold studies and also largely agree with those from CELSIUS, though the present data have much better angular coverage near the forward and backward directions, thus allowing firmer conclusions to be drawn. While at 19.5 MeV the results can be described in terms of $s$- and $p$-wave production, by 59.4 MeV higher partial waves are required. Including the 19.5 MeV point together with the near-threshold data in a global $s$- and $p$-wave fit gives a poorer overall description of the data though the position of the pole in the $\eta {}^3\mathrm{He}$ scattering amplitude, corresponding to the quasibound or virtual state, is hardly changed.

The ${}^{64}\mathrm{Zn}$($t$,${}^3\mathrm{He}$) reaction has been studied by using a secondary triton beam of 115 MeV/nucleon to extract the Gamow-Teller transition-strength distribution to ${}^{64}\mathrm{Cu}$. The results were compared with shell-model calculations with the $\mathit{pf}$-shell effective interactions KB3G and GXPF1A and with existing data from the ${}^{64}\mathrm{Zn}$($d$,${}^2\mathrm{He}$) reaction. Whereas the experimental results exhibited good consistency, neither of the theoretical predictions managed to reproduce the data. The implications for electron-capture rates during late stellar evolution were investigated. The rates based on the theoretical strength distributions are lower by factors of 3.5–5 compared to the rates based on experimental strength distributions.

The differential cross section for the process $p(e,e^{\text{'}}p)\eta$ has been measured at $Q^2~5.7$ and $7.0(\mathrm{GeV}/c){}^2$ for center-of-mass energies from threshold to 1.8 GeV, encompassing the $S_{11}(1535)$ resonance, which dominates the channel. This is the highest momentum-transfer measurement of this exclusive process to date. The helicity-conserving transition amplitude $A_{1/2}$, for the production of the $S_{11}(1535)$ resonance, is extracted from the data. Within the limited $Q^2$ now measured, this quantity appears to begin scaling as $Q^{-3}$—a predicted, but not definitive, signal of the dominance of perturbative QCD at $Q^2~5\hspace{0.5em}(\mathrm{GeV}/c){}^2$.

In astrophysical environments, the long-lived ($T_{1/2}=37.6$ Gyr) ground state of ${}^{176}\mathrm{Lu}$ can communicate with a short-lived ($T_{1/2}=3.664$ h) isomeric level through thermal excitations. Thus, the lifetime of ${}^{176}\mathrm{Lu}$ in an astrophysical environment can be quite different than in the laboratory. We examine the possibility that the rate of equilibration can be enhanced via $K$ mixing of two levels near $E_x=725$ keV and estimate the relevant $\gamma$-decay rates. We use this result to illustrate the effect of $K$ mixing on the effective stellar half-life. We also present a network calculation that includes the equilibrating transitions allowed by $K$ mixing. Even a small amount of $K$ mixing will decrease the timescale for equilibration during an $s$-process triggered by the ${}^{22}\mathrm{Ne}$ neutron source.

The yrast structure of the neutron-rich nucleus ${}^{97}\mathrm{Zr}$ has been studied using fission of targetlike products in the reaction of a ${}^{48}\mathrm{Ca}$ beam on a thick ${}^{238}\mathrm{U}$ target. The level scheme, known from previous studies up to an excitation energy and spin-parity of approximately 4619 keV and $23/2^{-}$, has been extended by about 3 MeV and a few units of angular momentum. Two states fed in the $\beta$ decay of the $27/2^{-}$ high-spin isomer in ${}^{97}\mathrm{Y}$ were identified at 5570 and 5606 keV. The located level structure can be discussed in terms of shell-model configurations.

Excited states in ${}^{219}\mathrm{Th}$ have been observed for the first time in an experiment using the ${}^{26}\mathrm{Mg}+{}^{198}\mathrm{Pt}$ reaction and evaporation-residue-gated $\gamma$-ray spectroscopy. Two structures of interlinked alternating-parity levels with simplex quantum numbers $s=\pm i$ are observed, reminiscent of similar sequences in heavier odd-mass isotopes, but only three mass units away from the $N=126$ neutron closed shell. The emergence of quadrupole-octupole collectivity in this mass region and the trend for parity-doublet bands are discussed.

Patterns of shape-phase transition in the proton-neutron coupled systems are studied within the $\mathit{SD}$-pair shell model. The results show that some transitional patterns in the $\mathit{SD}$-pair shell model are similar to the U(5)-SU(3) and U(5)-SO(6) transitions with signatures of the critical point symmetry of the interacting boson model.

Elastic and inelastic scattering of 240 MeV ${}^6\mathrm{Li}$ particles from ${}^{24}\mathrm{Mg}$ and ${}^{28}\mathrm{Si}$ were measured with the MDM spectrometer. Optical potential parameters for ${}^6\mathrm{Li}+{}^{24}\mathrm{Mg}$ and ${}^6\mathrm{Li}+{}^{28}\mathrm{Si}$ scattering systems were obtained by fitting elastic scattering with two different folding model potentials as well as $W\text{−}S$ potentials. $E0\text{−}E3$ giant resonance strength distributions for ${}^{28}\mathrm{Si}$ and ${}^{24}\mathrm{Mg}$ were obtained. $E0$ strength corresponding to ${106}_{-24}^{+34}\%$ of the EWSR was identified in ${}^{24}\mathrm{Mg}$ and ${80}_{-20}^{+35}\%$ was found for ${}^{28}\mathrm{Si}$ between $E_x=8.0$ to 40.0 MeV.

We present a new formulation of effective field theory for nucleon-nucleon ($\mathit{NN}$) interactions that treats pion interactions perturbatively, and we offer evidence that the expansion converges satisfactorily to third order in the expansion, which we have computed analytically for $s$- and $d$-wave $\mathit{NN}$ scattering. Starting with the Kaplan-Savage-Wise (KSW) expansion about the nontrivial fixed point corresponding to infinite $\mathit{NN}$ scattering length, we cure the convergence problems with that theory by modifying the short distance pion interaction, essentially resumming those contributions in the contact interactions. This method appears to make possible a host of high precision analytic few-body calculations in nuclear physics.

Quasi-elastic scattering measurements at large backward angles have been carried out for the ${}^6\mathrm{Li}+{}^{232}\mathrm{Th}$ system at energies around the Coulomb barrier. Barrier distribution has been obtained from the excitation function data. Coupled channel calculations using a double-folding potential as the bare potential have been performed. The disagreement between data and theoretical predictions shows a large breakup effect in the quasi-elastic scattering of a weakly bound projectile on a deformed target.

The cross sections for formation of ${}^{92}\mathrm{Nb}{}^m$ in the ${}^{93}\mathrm{Nb}(n,2n){}^{92}\mathrm{Nb}{}^m$ reaction induced by 9 to 24 MeV neutrons have been theoretically estimated using the TALYS-1.0 computer program. The variations of the cross sections with the level densities and effective imaginary potential were also studied to obtain the best fit of the excitation function. It is observed that the theoretical cross sections match fairly well with the experimental cross sections reported in literature only when both contributions from negative and positive parity levels of ${}^{92}\mathrm{Nb}$ are considered. The results of the present study reveal that the approach of the earlier worker to neglect the contributions of the low-lying negative parity energy levels in the formation of ${}^{92}\mathrm{Nb}{}^m$, in order to match the theoretical cross sections with the experimental cross sections cannot be an obvious solution, particularly when the gamma rays emitted by ${}^{92}\mathrm{Nb}$ nuclei in the transition from negative parity levels have been measured.

The fragment production cross sections of secondary neutron-rich beams of ${}^{68}\mathrm{Ni}$, ${}^{69}\mathrm{Cu}$, and ${}^{72}\mathrm{Zn}$ isotopes at energies of about $95A$ MeV have been measured. We compare the measured cross sections to EPAX, an empirical parametrization of fragmentation cross sections. A reasonable agreement of the experimental data and EPAX predictions suggests that an EPAX parametrization used for stable beams seems to be valid for unstable neutron-rich ion beams. EPAX tends to overestimate the yields of neutron-rich isotopes. This problem is amplified when neutron-rich radioactive beams are employed, leading to overly optimistic estimates of the production of neutron-rich isotopes.

We construct an equation of state of the classical quark-gluon plasma (cQGP) valid for all values of $\Gamma =V/K$, the ratio of the mean Coulomb to kinetic energy. By enforcing the Gibbs relations, we derive the pertinent pressure and entropy densities for all $\Gamma$. For the case of an SU(2) classical gluonic plasma our results compare well with lattice simulations. We show that the strongly coupled component of the cQGP contributes significantly to the bulk thermodynamics across $T_c$. Alternatively, a direct fit of $\Gamma$ using a lattice extracted running coupling constant implies a sharp drop in $\Gamma$ and a rapid rise in the bulk thermodynamics across $T_c$ in the cQGP, a behavior usually identified with a phase change.

We present new improved $R$ matrix fits of direct data and indirect Trojan Horse data for the ${}^{15}\mathrm{N}(p,\alpha ){}^{12}\mathrm{C}$ reaction and provide a more accurate recommended value of $S(0)=73.0\pm 5.0$ MeV b from direct Redder data [A. Redder et al., Z. Phys. A 305, 325 (1982)] and $S(0)=70.0\pm 13.5$ MeV b from the Trojan Horse data [M. La Cognata et al., Phys. Rev. C 76, 065804 (2007)]. We also analyze a recent fit by Barker [F. C. Barker, Phys. Rev. C 78, 044611 (2008)] and demonstrate that when all the uncertainties are taken into account, our results overlap with his. We also provide a fit of the Trojan Horse data that properly takes into account finite residual energy resolution of the data.

An experiment of a ${}^{29}\mathrm{S}$ beam bombarding a ${}^{197}\mathrm{Au}$ target at an energy of 49.2 MeV/u has been performed to study the two-proton correlated emission from ${}^{29}\mathrm{S}$ excited states. Complete-kinematics measurements were carried out in the experiment. The relative momentum, opening angle, and relative energy of two protons, as well as the invariant mass of the final system, were deduced by relativistic-kinematics reconstruction. The ${}^{27}\mathrm{Si}$-$p\text{−}p$ coincident events were picked out under strict conditions and the phenomenon of $p\text{−}p$ correlations was observed among these events. The mechanisms of two-proton emission were analyzed in a simple schematic model, in which the extreme decay modes like ${}^2\mathrm{He}$ cluster emission, three-body phase-space decay, and two-body sequential emission were taken into account. Associated with the Monte Carlo simulations, the present results show that two protons emitted from the excited states between 9.6 MeV and 10.4 MeV exhibit the features of ${}^2\mathrm{He}$ cluster decay with a branching ratio of ${29}_{-11}^{+10}\%$.

The characteristics of the ${}^{12}\mathrm{O}$ resonant ground state are investigated through the analysis of the experimental data for the two-proton decay process. The sequential and simultaneous two-proton emission decay modes have been considered in a statistical calculation of the decay energy distribution. The resonant structures of ${}^{11}\mathrm{N}$ have been employed as intermediate states for the sequential mode, having their parameters determined by considering the structure of single particle resonance in quantum scattering problem. The width of the ${}^{12}\mathrm{O}$ resonant ground state has been extracted from a best fit to the experimental data. The contributions from the different channels to the decay energy distribution have been evaluated, and width and peak location parameters of the ${}^{12}\mathrm{O}$ resonant ground state are compared with results of other works for the sequential and simultaneous two-proton decay modes.

Quark-meson coupling (QMC) models can be successfully applied to the description of compact star properties in nuclear astrophysics as well as to nuclear matter. In the regime of hot hadronic matter very few calculations exist using the QMC model, in particular when applied to particle yields in heavy ion collisions. In the present work, we identify the free energy of the bag with the effective mass of the baryons and we calculate the particle production yields on a $\mathrm{Au}+\mathrm{Au}$ collision at the BNL Relativistic Heavy Ion Collider (RHIC) with the QMC model and compare them with results obtained previously with other relativistic models. A smaller temperature for the fireball, $T=132$ MeV, is obtained because of the smaller effective baryon masses predicted by QMC. QMC was also applied to the description of particle yields at the CERN Super Proton Synchrotron (SPS) in $\mathrm{Pb}+\mathrm{Pb}$ collisions.