A model-independent irreducible tensor formalism that was developed earlier to analyze measurements of $\overrightarrow{p}\overrightarrow{p}\to \mathit{pp}{\pi }^{°}$ is extended to present a theoretical discussion of $\overrightarrow{p}\overrightarrow{p}\to pp\omega$ and of ω polarization in $\mathit{pp}\to \mathit{pp}\overrightarrow{\omega }$ and in $p\overrightarrow{p}\to pp\overrightarrow{\omega }$. The recent measurement of an unpolarized differential cross section for $pp\to pp\omega$ is analyzed by use of this theoretical formalism.

Excited states in ${}^{31}\mathrm{S}$ and ${}^{31}\mathrm{P}$ were populated in the ${}^{12}\mathrm{C}$(${}^{20}\mathrm{Ne}$,n) and ${}^{12}\mathrm{C}$(${}^{20}\mathrm{Ne}$,p) reactions, respectively, at a beam energy of 32 MeV. High spin states of positive and negative parity have been observed in ${}^{31}\mathrm{S}$ for the first time, and the yrast scheme of ${}^{31}\mathrm{P}$ has been extended. Large mirror energy differences between the first $9/2^{-}$ and $13/2^{-}$ states were observed, but only small differences for the first $7/2^{-}$ and $11/2^{-}$ levels. The significance of these observations is discussed in relation to the electromagnetic spin-orbit effect and the relative binding energy of the levels.

The mean lifetimes of the ${25/2}^{+}$, ${21/2}^{+}$, and ${17/2}^{+}$ states in the highly deformed (HD) band of ${}^{133}\mathrm{Nd}$, excited via the reaction ${}^{104}\mathrm{Pd}$(${}^{32}\mathrm{S}$,2$\mathit{pn}$)${}^{133}\mathrm{Nd}$, have been measured using a recoil distance Doppler-shift method. The decay out of the HD band occurs as a result of an admixture of normally deformed (ND) components into the HD states’ wave function. The consistency in the mixing amplitude was assessed from the measured lifetimes, branching ratios, and quadrupole moments of the HD and the ND bands. This analysis unequivocally confirms the earlier approach to explain the decay-out mechanism.

X (5) is a paradigm for the structure at the critical point of a particular first-order phase transition for which the intrinsic energy surface has two degenerate minima separated by a low barrier. For a finite system, we show that the dynamics at such a critical point can be described by an effective deformation determined by minimizing the energy surface after projection onto angular momentum zero and combined with two-level mixing. Wave functions of a particular analytic form are used to derive estimates for energies and quadrupole rates at the critical point.

The binding energy of three identical bosons is estimated by coupled differential equations that generalize the Feshbach–Rubinow approximation. This method turns out to be rather efficient, especially in the limit of vanishing binding.

The question of nuclear response functions in a homogeneous medium is examined. A general method for calculating response functions in the random-phase approximation with exchange is presented. The method is applicable for finite-range nuclear interactions. Examples are shown in the case of symmetric nuclear matter described by a Gogny interaction. It is found that the convergence of the results with respect to the multipole truncation is quite fast. Various approximation schemes such as the Landau approximation, or the Landau approximation for the exchange terms only, are discussed in comparison with the exact results.

The energy levels of ${}^{15}\mathrm{F}$ have been measured by the $p($${}^{14}\mathrm{O}$,$p)$${}^{14}\mathrm{O}$ reaction. The 120 MeV ${}^{14}\mathrm{O}$ radioactive ion beam was produced by the BEARS coupled cyclotron system at an intensity averaging $1\times {10}^4$ particles/second on target. Energy calibration was obtained using resonances from the $p({}^{14}\mathrm{N}$,$p){}^{14}\mathrm{N}$ reaction. The two lowest resonances in ${}^{15}\mathrm{F}$ were fitted with an R-matrix calculation. The fit to the ground state had $J^{\pi }=1/2^{+}$ at 1.23 ± 0.05 MeV (width 0.5 − 0.84 MeV), and the first excited state was $J^{\pi }=5/2^{+}$ at 2.81 ± 0.02 MeV (width 0.30 ± 0.06 MeV), both relative to the mass-energy of the proton and ${}^{14}\mathrm{O}$. The ${}^{15}\mathrm{F}$ ground state energy supports the disappearance of the Z = 8 proton magic number for odd $Z,T_z=-3/2$ nuclei.

The low-lying structure of ${}^{112}\mathrm{Sn}$ has been studied by use of the ($n,n^{\text{'}}\gamma$) reaction. Excitation functions and angular distributions of γ rays have been used to characterize the decays of the excited levels, and level lifetimes have been measured with the Doppler-shift attenuation method. A $\gamma \text{−}\gamma$ coincidence experiment has also been performed to confirm γ-ray placements. Low-lying $1^{-}$, $2^{(-)},3^{-}$, and $5^{-}$ states are suggested as members of a heterogeneous quadrupole-octupole quintuplet. Their excitation energies and decay properties are consistent with a structure formed by the coupling of the lowest quadrupole $2_1^{+}$ and octupole $3_1^{-}$ excitations.

Calculations of the spectra of various even-even nuclei in the fp shell (${}^{44}\mathrm{Ti}$, ${}^{46}\mathrm{Ti}$, ${}^{48}\mathrm{Ti}$, ${}^{48}\mathrm{Cr}$, and ${}^{50}\mathrm{Cr}$) are performed with two sets of two-body interaction matrix elements. The first set consists of the matrix elements of the FPD6 interaction. The second set has the same $T=1$ two-body matrix elements as the FPD6 interaction, but all the $T=0$ two-body matrix elements are set equal to zero (T0FPD6). Surprisingly, the T0FPD6 interaction gives a semireasonable spectrum when compared to FPD6 (or else this method would make no sense). A consistent feature for even-even nuclei, e.g., ${}^{44,46,48}\mathrm{Ti}$ and ${}^{48,50}\mathrm{Cr}$, is that the reintroduction of $T=0$ matrix elements makes the spectrum look more rotational than when the $T=0$ matrix elements are set equal to zero. The odd-odd nucleus ${}^{46}\mathrm{V}$ is also discussed. In general, but not always, the inclusion of $T=0$ two-body matrix elements enhances the $B(E2)$ rates.

A detailed study of two-photon exchange in unpolarized and polarized elastic electron-nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio, $G_E/G_M$. The two-photon exchange contribution to the longitudinal polarization transfer $P_L$ is small, whereas the contribution to the transverse polarization transfer $P_T$ is enhanced at backward angles by several percent, increasing with $Q^2$. This gives rise to a small, $\lesssim 3\%$ suppression of $G_E/G_M$ obtained from the polarization transfer ratio $P_T/P_L$ at large $Q^2$. We also compare the two-photon exchange effects with data on the ratio of $e^{+}p$ to $e^{-}p$ cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron and estimate the elastic intermediate state contribution to the ${}^3\mathrm{He}$ form factors.

We have investigated the influence of different forms of symmetry energies on various observables proposed to be sensitive to the symmetry energy at subnormal and supranormal densities for reactions ${}^{208}\mathrm{Pb}$ +${}^{208}\mathrm{Pb}$, ${}^{132}\mathrm{Sn}$ +${}^{124}\mathrm{Sn}$, and ${}^{96}\mathrm{Zr}$ $+{}^{96}\mathrm{zR}$ at $E_b=0.4A\mathrm{GeV}$ within the microscopic transport model—ultrarelativistic quantum molecular dynamics model. The same systems are adopted for testing the probes of the symmetry potential at both subnormal and supranormal densities. It is shown that the differences between the predicted values of investigated quantities by different symmetry potentials have a close correspondence with the different behavior of the density dependence of the interaction part of the different symmetry energies. We also find that the comprehensive study with multiple probes provides a possibility for gaining the density dependence of the symmetry potential in a broad density region, which allows us to extract the information of the isospin-dependent part of the effective interaction.

The triangular enhancement of the rapidity distribution of hadrons produced in $p+A$ reactions relative to $p+p$ is a leading order in ($A^{1/3}/\log s$) violation of longitudinal boost invariance at high energies. In $A+A$ reactions this leads to a trapezoidal enhancement of the local rapidity density of produced gluons. The local rapidity gradient is proportional to the local participant number asymmetry and leads to an effective rotation in the reaction plane. We propose that three-dimensional jet tomography, correlating the long-range rapidity and azimuthal dependences of the nuclear modification factor $R_{\mathit{AA}}(\eta ,\varphi ,p_{\perp };b>0)$, can be used to look for this intrinsic longitudinal boost violating structure of $A+A$ collisions to image the produced twisted strongly coupled quark gluon plasma. In addition to dipole and elliptic azimuthal moments of $R_{\mathit{AA}}$, a significant high $p_{\perp }$ octupole moment is predicted away from midrapidity. The azimuthal angles of maximal opacity and hence minima of $R_{\mathit{AA}}$ are rotated away from the normal to the reaction plane by an octupole twist angle ${\theta }_3(\eta )$ at forward rapidities.

A new upper limit is presented for the branching ratio (BR) of $\eta \to 3\gamma$. This decay is not allowed by charge-conjugation invariance. We have determined that $\mathit{BR}(\eta \to 3\gamma )<4\times {10}^{-5}$. We also obtained $\mathit{BR}(\eta \to {\pi }^0\gamma \to 3\gamma )<9\times {10}^{-5}$; this decay mode is absolutely forbidden, as it violates conservation of angular momentum. Finally, we have established that $\mathit{BR}(\eta \to {\pi }^0{\pi }^0\gamma \gamma )<1.2\times {10}^{-3}$ in a restricted diphoton-energy region. All three upper limits are at the 90% confidence level. They were obtained by using the Crystal Ball multiphoton spectrometer at the AGS and are based on the analysis of 28 million η mesons produced in the ${\pi }^{-}p\to \eta n$ reaction close to threshold.

The cross section of the ${}^{16}\mathrm{O}$($\alpha ,\gamma$)${}^{20}\mathrm{Ne}$ capture reaction is analyzed at low energies where the direct capture mechanism is dominant. For temperatures below $T_9=0.2$ the resulting astrophysical reaction rate is about a factor of 2 higher than in a recent compilation whereas the energy dependence of the astrophysical S factor and the branching ratios to the ${}^{20}\mathrm{Ne}$ bound states are very similar to previous calculations. The validity of the widely used detailed balance theorem for the inverse ${}^{20}\mathrm{Ne}$($\gamma ,\alpha$)${}^{16}\mathrm{O}$ photodisintegration rate is confirmed for the special case of high-lying first excited states.

Cross sections for ${}^{71}\mathrm{Ga}$(n, 2n)${}^{70}\mathrm{Ga}$ reaction have been measured in the neutron energies of 13.5–14.7 MeV using the activation technique, with the gallium sample irradiated under low neutron fluxes and short irradiation time. The data for ${}^{71}\mathrm{Ga}$(n, 2n)${}^{70}\mathrm{Ga}$ reaction cross sections are reported to be 782 ± 80, 896 ± 91, and 1169 ± 120 mb at 13.5 ± 0.2, 14.1 ± 0.1, and 14.7 ± 0.2 MeV incident neutron energies, respectively. The results are discussed and compared with the literature. From the comparison we see that the values show well agreement with the theoretical results calculated from the code STAPRE.

We present a full Monte Carlo simulation of the multiplicity and eccentricity distributions in $U+U$ collisions at $\sqrt{s}=200A\mathrm{GeV}$. Although unavoidable trigger inefficiencies in selecting full-overlap $U+U$ collisions cause significant modifications of the multiplicity distribution shown in Heinz and Kuhlman [Phys. Rev. Lett. 94, 132301 (2005)], a selection of source eccentricities by cutting the multiplicity distribution is still possible.

The measured pseudorapidity distributions of primary charged particles over a wide pseudorapidity range of $\left|\eta \right|\le 5.4$ and integrated charged particle multiplicities in $d+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ are presented as a function of collision centrality. The longitudinal features of $d+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ are found to be very similar to those seen in $p+A$ collisions at lower energies. The total multiplicity of charged particles is found to scale with the total number of participants according to $N_{\mathrm{ch}}^{d\mathrm{Au}}=\frac{1}{2}$$\langle N_{\mathrm{part}}\rangle N_{\mathrm{ch}}^{\mathit{pp}}$, and the energy dependence of the density of charged particles produced in the fragmentation region exhibits extended longitudinal scaling.

A recently suggested modified BCS (MBCS) model has been studied at finite temperatures. We show that this approach does not allow the existence of the normal (nonsuperfluid) phase at any finite temperature (FT). Other MBCS predictions, such as a negative pairing gap, pairing induced by heating in closed-shell nuclei, and superfluid to super-superfluid phase transition are discussed also. The MBCS model is tested by comparing it with exact solutions for the picket fence model. Severe violation of the internal symmetry of the problem is detected. The MBCS equations are found to be inconsistent. The limit of the MBCS applicability has been determined to be far below the superfluid–normal phase transition of the conventional FT-BCS, where the model performs worse than the FT-BCS.

The synthesis and identification of superheavy nuclei have taken a dramatic turn recently with the emergence of hot fusion reactions. Such new methods have enabled the synthesis and identification of superheavy elements with $Z=114\text{−}116$ and 118. The identification of such elements is mainly done by observing their α-decay chains terminating with spontaneous fission events. In such studies, the role played by the shapes of superheavy elements has assumed great significance. In this work, we use the Shanmugam-Kamalaharan model for α decay, which is versatile in accounting for the shapes and deformations of the parent and the daughter nuclei as well as the charge redistribution (also termed charge equilibration) process during the decay. Our calculations turn out to be very useful for the identification of superheavy elements.