Using a dynamical model based on the $\mathit{NN}\to d\pi ,\mathit{NNN}\to \mathit{dN}$, and $\mathit{NN}\pi \to d\pi$ reactions and measured proton and pion transverse momentum spectra and elliptic flows, we study the production of deuterons and their elliptic flow in heavy-ion collisions at RHIC. The results are compared with those from the coalescence model. The deviation of deuteron elliptic flow from the constituent nucleon number scaling expected from the coalescence model and the comparison with the experimental data are discussed in connection to the allowed nucleon phase space in these reactions.

A relativistic nonlocal model for the inclusive photoproduction of η mesons from complex nuclei is introduced. The model is based on the dominance of the ${\mathrm{S}}_{11}(1535)$ resonance. We compare the results of our calculations with the available data on inclusive cross sections for the nuclei C, Al, and Cu. Assuming the resonance propagates freely in the nuclear medium, we find that the calculated angular distribution and energy dependence of the cross sections reproduce the data in a reasonable fashion. The present nonlocal model allows for the inclusion of density dependent mass and width in the calculations. Including these in the calculations and comparing with presently available data leads us to conclude that if any medium modifications of the properties of the ${\mathrm{S}}_{11}(1535)$ resonance existed, they would likely be small.

A significant decay branch of ${}^8\mathrm{B}$ to the ground state of ${}^8\mathrm{Be}$ would extend the solar neutrino spectrum to higher energies than anticipated in the standard solar models. These high-energy neutrinos would affect current neutrino oscillation results and also would be a background to measurements of the hep process. We have measured the delayed α particles from the decay of ${}^8\mathrm{B}$, with the goal of observing the two 46-keV α particles arising from the ground-state decay. The ${}^8\mathrm{B}$ was produced using an in-flight radioactive beam technique. It was implanted in a silicon PIN-diode detector that was capable of identifying the α particles from the ${}^8\mathrm{Be}$ ground state. From this measurement we find an upper limit (at 90% confidence level) of $7.3\times {10}^{-5}$ for the branching ratio to the ground state. In addition to describing this measurement, we present a theoretical calculation for this branching ratio.

We discuss the geometry of the highly quantal nuclear three-body systems composed of a core plus two loosely bound particles. These Borromean nuclei have no single bound two-body subsystem. Correlation plays a prominent role. From consideration of the $B(E1)$ value extracted from electromagnetic dissociation, in conjunction with HBT-type analysis of the two valence-halo particles correlation, we show that an estimate of the over-all geometry can be deduced. In particular we find that the opening angle between the two neutrons in ${}^6\mathrm{He}$ and ${}^{11}\mathrm{Li}$ are, respectively, ${\theta }_{\mathit{nn}}={{83}^{°}}_{-10}^{+20}$ and ${{66}^{°}}_{-18}^{+22}$. These angles are reduced by about 12% to ${\theta }_{\mathit{nn}}={{78}^{°}}_{-18}^{+13}$ and ${{58}^{°}}_{-14}^{+10}$ if the laser spectroscopy values of the rms charge radii are used to obtain the rms distance between the cores and the center of mass of the two neutrons. The opening angle in the case of ${}^{11}\mathrm{Li}$ is more than 20% larger than recently reported by Nakamura et al. [Phys. Rev. Lett. 96, 252502 (2006)]. The analysis is extended to ${}^{14}\mathrm{Be}$ and the two-proton Borromean nucleus ${}^{17}\mathrm{Ne}$ where complete data are still not available. Using available experimental data and recent theoretical calculations we find ${\theta }_{\mathit{nn}}={{64}^0}_{-10}^{+9}$ and ${\theta }_{\mathit{pp}}={110}^{°}$, respectively.

We have studied U+U collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV using Monte Carlo Glauber, UrQMD, and AMPT models. We find that it is possible to separate central tip-tip events as well as central body-body events on the basis of cuts on multiplicity and magnitude of the reduced flow vector.

A three-body cluster model involving microscopic nonlocal interactions is developed and compared with a fully microscopic cluster model. The energy-independent nonlocal interactions are obtained from a renormalization of the energy-dependent kernels of the resonating-group method. Such interactions are derived for the $\alpha \alpha$ and $\alpha n$ systems. The role and importance of nonlocality are discussed. These interactions are employed in three-body studies of the $\alpha \mathit{nn},\alpha \alpha n$, and $3\alpha$ descriptions of the ${}^6\mathrm{He}$, ${}^9\mathrm{Be}$, and ${}^{12}\mathrm{C}$ nuclei. A comparison with fully microscopic calculations provides a measure of the importance of three-cluster exchanges in those states. The differences between both cluster-model calculations are in general small, except in the densities at short distances.

The α decay of the trans-lead isotopes ${}^{212}\mathrm{At}$, ${}^{216}\mathrm{Fr}$, and ${}^{220}\mathrm{Ac}$ was investigated by using mass-separated sources and analog as well as digital signal processing. By measuring $\alpha \text{−}\alpha$ time correlations evidence was obtained for the occurrence of an α-decaying ($9^{-}$) isomer in ${}^{216}\mathrm{Fr}$. The α-decay energy and half-life amount to 9000(5) keV and 850(30) ns, respectively. The excitation energy of the isomer is compared with shell-model predictions for the high-spin members of the $\pi (h_{9/2})\nu (g_{9/2})$ multiplet, and the relevance of the new data concerning the search for reflection asymmetry is presented.

In the $\Delta \varphi \text{−}\Delta \eta$ correlation associated with a near-side jet observed by the STAR Collaboration in heavy-ion collisions at the BNL Relativistic Heavy Ion Collider (RHIC), the ridge structure can be explained by the momentum kick model in which the ridge particles are identified as medium partons which suffer a collision with the jet and acquire a momentum kick along the jet direction. If this is indeed the correct mechanism, the ridge structure associated with the near-side jet may be used to probe the parton momentum distribution at the moment of the jet-parton collision, leading to the result that at that instant the parton temperature is slightly higher and the rapidity width substantially greater than corresponding quantities of their evolution product inclusive particles at the end point of the nucleus-nucleus collision.

We present the formalism for the decay of dynamically generated scalar mesons with open- or hidden charm and give results for the decay of $D_{s0}^{*}(2317)$ to $\gamma D_s^{*}$ plus that of a hidden charm scalar meson state predicted by the theory around 3700 MeV decaying into $\gamma J/\psi$.

It is widely discussed in the literature that the wave function of the nucleon bound in a nucleus is modified by the interaction with the surrounding medium. We argue that the modification should strongly depend on the momentum of the nucleon. We study such an effect in the case of the pointlike configuration component of the wave function of a nucleon bound in a nucleus $A$, considering the case of arbitrary final states of the spectator $A-1$ system. We show that for nonrelativistic values of the nucleon momentum, the momentum dependence of the nucleon deformation appears to follow from rather general considerations and discuss the implications of our theoretical observation for two different phenomena: (i) the search for medium-induced modifications of the nucleon radius of a bound nucleon through the measurement of the electromagnetic nucleon form factors via the $A(e,e^{\text{'}}p)X$ process and (ii) the $A$ dependence of the EMC effect.

The Advanced-Time-Delayed method was used to measure lifetimes of the states in ${}^{41}\mathrm{Ar}$ populated in the β decay of ${}^{41}\mathrm{Cl}$. The nuclei ${}^{41}\mathrm{Cl}$ were produced at ISOLDE by 1.4-GeV proton bombardment of a thick UC${}_x$ target and mass-separated as molecular ions, ${\mathrm{XeCl}}^{+}$. Our measured half-life of the 167.1-keV state, $T_{1/2}=315(15)$ ps, is significantly lower than the previously measured value of 410(30) ps. We have also determined $T_{1/2}=260(80)$ ps and $T_{1/2}⩽46$ ps for the 515.9- and 1867.7-keV states, respectively. These are the shortest lifetimes measured so far with the ultrafast timing method using the new ${\mathrm{LaBr}}_3$(Ce) crystals for γ-ray detection.

We report the results of an experiment in which we studied the near-yrast states in selenium isotopes approaching $N=50$ following their population in multinucleon transfer reactions between a ${}^{82}\mathrm{Se}$ beam and a ${}^{192}\mathrm{Os}$ target. The level schemes for ${}^{80,82}\mathrm{Se}$ derived from the current work are compared with restricted-basis shell-model calculations and pair-truncated shell-model calculations. These provide a good description of the yrast sequences in these nuclei using a basis space limited to excitations in the $\nu (p_{\frac{3}{2}},p_{\frac{1}{2}},g_{\frac{9}{2}}$) and $\pi (f_{\frac{5}{2}},p_{\frac{3}{2}},p_{\frac{1}{2}}$) orbitals.

In this article we study the behavior of collectivity under random two-body interactions in the framework of the fermion dynamical symmetry model (FDSM). We found that a Hamiltonian with the SO(8) symmetry of the FDSM does not give vibrational and rotational modes under random interactions while a Hamiltonian with the SP(6) symmetry does. It is suggested that collective motions such as vibration and rotation are closely related not only to the quadruple-quadruple correlation in the Hamiltonian but also to the dynamical symmetries of the Hamiltonian.

Using Woods-Saxon potentials and the eigenphase formalism for one-particle resonances, one-particle bound and resonant levels for neutrons as a function of quadrupole deformation are presented, which are supposed to be useful for the interpretation of spectroscopic properties of some light neutron-rich nuclei with weakly bound neutrons. Compared with Nilsson diagrams in textbooks that are constructed using modified oscillator potentials, we point out a systematic change of the shell structure in connection with both weakly bound and resonant one-particle levels related to small orbital angular momenta $\ell$. Then, it is seen that weakly bound neutrons in nuclei such as ${}^{15-19}\mathrm{C}$ and ${}^{33-37}\mathrm{Mg}$ may prefer being deformed as a result of the Jahn-Teller effect, due to the near degeneracy of the $1d_{5/2}\text{−}2s_{1/2}$ levels and the $1f_{7/2}\text{−}2p_{3/2}$ levels in the spherical potential, respectively. Furthermore, the absence of some one-particle resonant levels compared with the Nilsson diagrams in textbooks is illustrated.

Intermediate-energy heavy-ion collisions can produce a spin polarization of the projectile-like species. Spin polarization has been observed for both nucleon removal and nucleon pickup processes. Qualitative agreement with measured spin polarization as a function of the momentum of the projectile-like fragment is found in a kinematic model that considers conservation of linear and angular momentum and assumes peripheral interactions between the fast projectile and target. Better quantitative agreement was reached by including more realistic angular distributions and deorientation caused by γ-ray emission and by correcting for the out-of-plane acceptance. The newly introduced corrections were found to apply to both nucleon removal and nucleon pickup processes.

We analyze the fusion data for ${}^{16}\mathrm{O}+{}^{208}\mathrm{Pb}$ using coupled-channels calculations. We include couplings to the low-lying surface excitations of the projectile and target and study the effect of the (${}^{16}\mathrm{O}$,${}^{17}\mathrm{O}$) one-neutron pickup. The hindrance of the fusion data that is observed at energies far below the Coulomb barrier cannot be explained by a conventional ion-ion potential and defining the fusion in terms of ingoing-wave boundary conditions (IWBC). We show that the hindrance can be explained fairly well by applying the M3Y double-folding potential which has been corrected with a calibrated, repulsive term that simulates the effect of nuclear incompressibility. We show that the coupling to one-neutron transfer channels plays a crucial role in improving the fit to the data. The best fit is achieved by increasing the transfer strength by 25% relative to the strength that is required to reproduce the one-neutron transfer data. The larger strength is not unrealistic because the calculated inelastic plus transfer cross section is in good agreement with the measured quasielastic cross section. We finally discuss the problem of reproducing the fusion data at energies far above the Coulomb barrier. Here we do not account for the data when we apply the IWBC but the discrepancy is essentially eliminated by applying the M3Y+repulsion potential and a weak, short-ranged imaginary potential.

Testing the constancy of the gravitational constant $G$ is a longstanding fundamental question in natural science. As first suggested by Jofré, Reisenegger, and Fernández (2006, Phys. Rev. Lett. 97, 131102), Dirac's hypothesis of a decreasing gravitational constant $G$ with time caused by the expansion of the Universe would induce changes in the composition of neutron stars, causing dissipation and internal heating. Eventually, neutron stars reach their quasistationary states where cooling, as a result of neutrino and photon emissions, balances the internal heating. The correlation of surface temperatures and radii of some old neutron stars may thus carry useful information about the rate of change of $G$. Using the density dependence of the nuclear symmetry energy, constrained by recent terrestrial laboratory data on isospin diffusion in heavy-ion reactions at intermediate energies, and the size of neutron skin in ${}^{208}\mathrm{Pb}$, within the gravitochemical heating formalism developed by Jofré et al. (2006, Phys. Rev. Lett. 97, 131102), we obtain an upper limit for the relative time variation $|\stackrel{·}{G}/G|$ in the range ($4.5\text{−}21)\times {10}^{-12}$ yr${}^{-1}$.

Below the critical temperature of superfluid phase transition baryonic matter emits neutrinos by breaking and recombination of Cooper pairs formed in the condensate. The weak vector and axial-vector vertices and the neutrino loss rates via pair breaking are modified by strong interactions in nuclear medium. We study these modifications nonperturbatively by summing infinite series of particle-hole loops in $S$-wave superfluid neutron matter. The interactions in the particle-hole channel are described within the Landau Fermi-liquid framework with the Landau parameters derived from the microscopic theory. The $S$-wave superfluid is described within the BCS theory. We derive the renormalized three-point vector and axial-vector vertices and the complete polarization tensor of matter and its low momentum transfer expansion. The leading-order term in this expansion and the associated neutrino losses arise at $O(q^2)$, consistent with the $f$-sum rule. The neutrino emission rate due to the pair breaking is parametrically suppressed compared to its one-loop counterpart by the ratio of the neutron recoil energy to the temperature, which is of order $5\times {10}^{-3}$. The approximations to the normal and anomalous self-energies that guarantee the conformity of the theory with the generalized Ward identities are established.

The cross section and decay angular distributions for the coherent ϕ-meson photoproduction on the deuteron have been measured for the first time up to a squared four-momentum transfer $t=(p_{\gamma }-p_{\varphi }){}^2=-2$ GeV${}^2/c^2$, using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The cross sections are compared with predictions from a rescattering model. In a framework of vector meson dominance, the data are consistent with the total ϕ-N cross section ${\sigma }_{\varphi N}$ at about 10 mb. If vector meson dominance is violated, a larger ${\sigma }_{\varphi N}$ is possible by introducing a larger $t$ slope for the $\varphi N\to \varphi N$ process than that for the $\gamma N\to \varphi N$ process. The decay angular distributions of the ϕ are consistent with helicity conservation.