Variational Monte Carlo calculations are carried out for ${}_{\Lambda \Lambda }{}^6\mathrm{He}$ using realistic $NN,NNN$, and phenomenological $\Lambda N$ and $\Lambda NN$ interactions. For the $\Lambda \Lambda$ interaction we employ the various phase equivalent Nijmegen interactions. By incorporating the various components of $\Lambda$-nuclear interactions in stages, and keeping $B_{\Lambda }\left({}_{\Lambda }{}^5\mathrm{He}\right)$ around 3.12 MeV, it is demonstrated that the incremental energy $\Delta B_{\Lambda \Lambda }$ for ${}_{\Lambda \Lambda }{}^6\mathrm{He}$ is sensitive to the three-body $\Lambda NN$ force and the exchange part of the $\Lambda N$ interaction. The $\Lambda \Lambda$ interaction obtained is only somewhat weaker than the $\Lambda N$ interaction. We also report the results for the rearrangement energy of the $\alpha$ core. We discuss the implications of our results.

Using effective field theory we prove inequalities for the correlations of two-nucleon operators in low-energy symmetric nuclear matter. For physical values of operator coefficients in the effective Lagrangian, the $S=1,I=0$ channel correlations must have the lowest energy and longest correlation length in the two-nucleon sector. This result is valid at nonzero density and temperature.

Measurements of the polarization asymmetries $\mathrm{\Sigma }\left({\theta }_{\mathrm{c.m.}}\right)$ and $\mathrm{\Sigma }\left(E_{\gamma }\right)$ of Compton scattering by ${}^{16}\mathrm{O}$ have been performed in the energy range of 25–40 MeV over a range of scattering angles between 90 and 150°. An analysis of the present data combined with previous results indicates that significant, narrow concentrations of $E2$ strength are not present below an excitation energy of 40 MeV. The existence, however, of a broad isovector giant quadrupole resonance exhausting a large percentage of the isovector energy weighted sum rule is not ruled out by the combined data. Additionally, the present data are insensitive to modifications to the free values of the nucleon polarizabilities, but cannot rule them out.

The cross sections for the stripping of two correlated nucleons from light and medium-mass nuclei are considered. Such reactions are of interest both as a means for populating and identifying low-lying excited states of very exotic nuclear species and as a potential direct spectroscopic probe of two-nucleon correlations in such systems. A calculation scheme that combines the full shell model two-nucleon spectroscopic amplitudes with eikonal reaction theory is presented. The theoretical predictions of the method, and of more approximate schemes, are compared with new data on two-proton removal from ${}^{28}\mathrm{Mg}$. The combined full shell model structure amplitudes and reaction dynamics predictions are in good agreement with the available measurements. First indications of the sensitivity of the reaction mechanism to the spatial and angular momentum structure of the stripped two-nucleon wave functions are also discussed and clarified.

This Brief Report provides simple parametrizations of the nucleon electromagnetic form factors using functions of $Q^2$ that are consistent with dimensional scaling at high $Q^2$. Good fits require only four parameters each for $G_{Ep}$, $G_{Mp}$, and $G_{Mn}$ and only two for $G_{En}$.

Details regarding the $\beta$-decay properties of ${}^{54,55,56}\mathrm{Sc}$ are reported and compared with shell model predictions. The low-energy level structures of even-even ${}^{54,56}\mathrm{Ti}$ are presented, and the systematic variation of the energy of the first excited $2_1^{+}$ state is discussed in light of proposed shell closures at $N=32,34$ for the neutron-rich $\mathrm{Ti}$ isotopes.

Gamma rays from neutron-rich nuclei in the vicinity of $Z=20$, $N=28$ have been studied at Gammasphere using deep-inelastic reactions induced by a $330\text{−}\mathrm{MeV}$ ${}^{48}\mathrm{Ca}$ beam on a thick ${}^{238}\mathrm{U}$ target. The yrast $\gamma$-ray cascade of ${}^{56}\mathrm{Ti}$ was identified for the first time and the location in energy of the $2^{+}$, $4^{+}$, and $6^{+}$ states was determined. The low-spin ${}^{56}\mathrm{Ti}$ yrast structure does not support the presence of a subshell closure at $N=34$ as suggested on the basis of other data on nuclei in the region as well as shell model calculations with a recently proposed interaction.

Proton decay from triaxially deformed nuclei is investigated. The deformation parameters corresponding to the mother nucleus are determined microscopically and the calculated decay widths are used to probe the mean-field wave function. The proton wave function in the mother nucleus is described as a resonant state in a coupled-channel formalism. The decay width, as well as the angular distribution of the decaying particle, are evaluated and their dependence upon the triaxial deformation parameters is studied in the decay of ${}^{161}\mathrm{Re}$ and ${}^{185}\mathrm{Bi}$. It is found that the decay width is very sensitive to the parameters defining the triaxial deformation while the angular distribution is a universal function which does not depend upon details of the nuclear structure.

The role of the Pauli principle in the formation of both the discrete spectrum and multichannel states of the two-cluster nuclear systems is studied in the algebraic version of the resonating-group method. Solutions of the Hill-Wheeler equations in the discrete representation of a complete basis of the Pauli-allowed states are discussed for the ${}^4\mathrm{He}+n$, ${}^3\mathrm{H}+{}^3\mathrm{H}$, and ${}^4\mathrm{He}+{}^4\mathrm{He}$ binary systems. An exact treatment of the antisymmetrization effects related to the kinetic energy exclusively is shown to result in either an effective repulsion or attraction of the clusters. It also yields a change in the intensity of the centrifugal potential. Both factors significantly affect the scattering phase behavior. Special attention is paid to the ${}^6\mathrm{He}+{}^6\mathrm{He}$ multichannel two-cluster system as well as to the coupled-channel calculation of the ${}^{12}\mathrm{Be}$ nucleus (provided that ${}^6\mathrm{He}+{}^6\mathrm{He}$ and ${}^4\mathrm{He}+{}^8\mathrm{He}$ clusterings are taken into account). In the latter case, the cluster-cluster interaction derived from the kinetic-energy operator modified by the Pauli principle leads to inelastic processes and ensures the existence of both the bound state and a resonance in the ${}^{12}\mathrm{Be}$ compound nucleus.

A previous microscopic three-cluster calculation, applied to the ${}^7\mathrm{Be}(p,\gamma ){}^8\mathrm{B}$ reaction, is updated in several ways: the ${}^7\mathrm{Be}$ description is improved, two nucleon-nucleon interactions are considered, and new experimental information about the scattering lengths is taken into account. Weak changes in the energy dependence of the $S$ factor are obtained. A “theoretical” uncertainty is estimated. It amounts to 5% near $1\mathrm{MeV}$ but reaches more than 10% when energy increases. We suggest that reducing the current uncertainty on the experimental scattering length would significantly reduce the error bar on $S_{17}\left(0\right)$. Elastic ${}^7\mathrm{Be}+p$ phase shifts are briefly discussed and analyzed for different ${}^7\mathrm{Be}$ deformations. We show that the differences with the potential model are due to shortcomings of that model, such as the lack of ${}^7\mathrm{Be}$ deformation, included in the present approach. We also investigate the ${}^8\mathrm{Li}$ and ${}^8\mathrm{B}$ spectroscopy, electromagnetic transition probabilities, and spectroscopic factors. The ${}^5\mathrm{He}+{}^3\mathrm{H}$ configuration (or mirror) is shown to be important in the ground-state structure.

In this work we discuss two methods of calculation of quark propagation in the quark-gluon plasma. Both methods make use of the Nambu-Jona-Lasinio model. The essential difference of these calculations is the treatment of deconfinement. A model of confinement is not included in the work of Gastineau, Blanquier, and Aichelin (e-print hep-ph/0404207), however, the meson states they consider are still bound for temperatures greater than the deconfinement temperature $T_c$. On the other hand, our model deals with unconfined quarks and includes a description of the $q\overline{q}$ resonances found in lattice QCD studies that make use of the maximum entropy method. We compare the $q\overline{q}$ cross sections calculated in these models.

We have measured the transverse momentum distributions of charged hadrons in $d+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$ in the range of $0.5<p_T<4.0\mathrm{GeV}∕c$. The total range of pseudorapidity, $\eta$, is $0.2<\eta <1.4$, where positive $\eta$ is in the deuteron direction. The data has been divided into three regions of pseudorapidity, covering $0.2<\eta <0.6$, $0.6<\eta <1.0$, and $1.0<\eta <1.4$, and has been compared to charged hadron spectra from $p+\overline{p}$ collisions at the same energy. There is a significant change in the spectral shape as a function of pseudorapidity. As $\eta$ increases we see a decrease in the nuclear modification factor $R_{dAu}$.

Angular distributions of differential cross sections for elastic and inelastic deuteron scattering from ${}^6\mathrm{Li}$, ${}^{16}\mathrm{O}$, ${}^{32}\mathrm{S}$, ${}^{50,51}\mathrm{V}$, and ${}^{70,72}\mathrm{Ge}$ at an incident energy of $171\mathrm{MeV}$ and from ${}^{90}\mathrm{Zr}$ and ${}^{116}\mathrm{Sn}$ at an incident energy of $183\mathrm{MeV}$ are presented. Phenomenological optical-model parameters for elastic scattering are extracted from the data and compared to existing deuteron-nucleus global optical potentials.

An algebraic $\mathit{s}\mathit{p}\left(4\right)$ shell model is introduced to achieve a deeper understanding and interpretation of the properties of pairing-governed $0^{+}$ states in medium mass atomic nuclei. The theory, which embodies the simplicity of a dynamical symmetry approach to nuclear structure, is shown to reproduce the excitation spectra and fine structure effects driven by proton-neutron interactions and isovector pairing correlations across a broad range of nuclei.

We study the ${}^{1}S_0$ proton pairing gap in neutron star matter putting emphasis on influence of the Dirac effective mass and the proton fraction on the gap within the relativistic Hartree-Bogoliubov model. The gap equation is solved using the Bonn-$B$ potential as a particle-particle channel interaction. It is found that the maximal pairing gap ${\Delta }_{\max }$ is $1–2\mathrm{MeV}$, which has a strong correlation with the Dirac effective mass. Hence we suggest that it serves as a guide to narrow down parameter sets of the relativistic effective field theory. Furthermore, the more slowly protons increase with density in the core region of neutron stars, the wider the superfluid range and the slightly lower the peak of the gap become.

The $\gamma$-cascades following the Gamow Teller beta decay of ${}^{148}\mathrm{Dy}$ $0^{+}$ have been investigated with the total absorption gamma spectrometer at GSI. Our measurements confirm that the Gamow-Teller resonant state is populated with a $\log \mathit{ft}=3.9$ and that there is very little mixing of this state with the background $J=1$ states. In contrast to previous measurements, the experimental method presented here is sensitive to very small admixtures at high excitation energy. Previously unobserved, weak beta-branches to levels in ${}^{148}\mathrm{Tb}$ are also reported.

New measurements of the analyzing powers $A_y$ and $T_{20}$ have been obtained for the ${}^2\mathrm{H}\left(d,\gamma \right){}^4\mathrm{H}\mathrm{e}$ reaction at a laboratory beam energy of $115\mathrm{keV}$. A transition matrix element analysis results in a unique solution which indicates that the reaction proceeds by 55% $E2$, 29% $E1$, and 16% $M2$ radiation. These results are shown to be in good agreement with the results of a new refined resonating group model calculation. The impact of these results on the extrapolated value of the astrophysical $S$ factor for this reaction is discussed.

We derive expressions for cluster overlap integrals or channel cluster form factors for ab initio no-core shell model (NCSM) wave functions. These are used to obtain the spectroscopic factors and can serve as a starting point for the description of low-energy nuclear reactions. We consider the composite system and the target nucleus to be described in the Slater determinant (SD) harmonic oscillator (HO) basis while the projectile eigenstate to be expanded in the Jacobi coordinate HO basis. This is the most practical case. The spurious center of mass components present in the SD bases are removed exactly. The calculated cluster overlap integrals are translationally invariant. As an illustration, we present results of cluster form factor calculations for $⟨{}^5\mathrm{He}\mid {}^4\mathrm{He}+n⟩$, $⟨{}^5\mathrm{He}\mid {}^3\mathrm{H}+d⟩$, $⟨{}^6\mathrm{Li}\mid {}^4\mathrm{He}+d⟩$, $⟨{}^6\mathrm{Be}\mid {}^3\mathrm{He}+{}^3\mathrm{He}⟩$, $⟨{}^7\mathrm{Li}\mid {}^4\mathrm{He}+{}^3\mathrm{H}⟩$, $⟨{}^7\mathrm{Li}\mid {}^6\mathrm{Li}+n⟩$, $⟨{}^8\mathrm{Be}\mid {}^6\mathrm{Li}+d⟩$, $⟨{}^8\mathrm{Be}\mid {}^7\mathrm{Li}+p⟩$, $⟨{}^9\mathrm{Li}\mid {}^8\mathrm{Li}+n⟩$, and $⟨{}^{13}\mathrm{C}\mid {}^{12}\mathrm{C}+n⟩$, with all the nuclei described by multi-$\hslash \Omega$ NCSM wave functions.

A variational Monte Carlo method is used to generate sets of orthogonal trial functions, ${\Psi }_T(J^{\pi };T)$, for given quantum numbers in various light $p$-shell nuclei. These ${\Psi }_T$ are then used as input to Green’s function Monte Carlo (GFMC) calculations of first, second, and higher excited $(J^{\pi };T)$ states. Realistic two- and three-nucleon interactions are used. We find that if the physical excited state is reasonably narrow, the GFMC energy converges to a stable result. With the combined Argonne ${\mathrm{v}}_{18}$ two-nucleon and Illinois-2 three-nucleon interactions, the results for many second and higher states in $A=6–8$ nuclei are close to the experimental values.

We propose a new procedure for constructing projected three-pion correlation functions which reduces undesirable artificial momentum dependences resulting from the commonly used procedure and facilitates comparison of three-pion correlation data with theoretical models.