The problem of Coulomb breakup in the scattering of a two-body loosely bound projectile by a heavy target is addressed. A basis of transformed harmonic oscillator (THO) wave functions is used to discretize the projectile continuum and to diagonalize the Hamiltonian of the two-body system. Results for the reaction ${}^8\mathrm{B}$+${}^{58}\mathrm{Ni}$ at sub-Coulomb energies are presented. Comparison of different observables with those obtained with the standard continuum discretized coupled-channels (CDCC) method shows good agreement between both approaches.

We derive a $N\overline{N}$ interaction from a constituent quark model constrained by the $\mathit{NN}$ sector to investigate the possible baryonium resonant state $X(1835)$ recently suggested as a possible interpretation of the near-threshold enhancement found in $J/\psi \to \gamma p\overline{p}$ by the BES Collaboration. The interaction does not show bound or quasibound states but a ${}^3{P}_0$ resonance in the $I=0$ isospin channel. We analyze the shift of the antiprotonium hydrogen energy levels, finding that $p\overline{p}\text{−}n\overline{n}$ mixing can explain the abnormally big value of the $2{}^3{P}_0$ energy shift.

We describe a schematic coupled-channels transfer calculation for the reaction ${}^6\mathrm{He}+{}^{238}\mathrm{U}$ at near-barrier energies. We also present a simple semiclassical DWBA calculation of the two-neutron transfer. Both calculations are meant to supply the conditions under which the transfer cross section becomes much larger than the complete fusion one at subbarrier energies. It seems that a feasible mechanism is the incoherent contributions of two or more processes with quite different $Q$ values.

Relative populations of states in ${}^{11}\mathrm{B}$ following the ${}^{12}\mathrm{C}$($\gamma ,p$)${}^{11}\mathrm{B}$ reaction have been measured with high resolution using a 70% HpGe γ detector to observe decay γ rays from the residual nucleus. The triplet of states near 7 MeV in ${}^{11}\mathrm{B}$ are resolved and the measured populations compared to previous data. The analysis includes a consideration of γ-proton angular correlations, which was not made in the previous measurement. The new and previous results corrected for angular correlation effects agree reasonably well with calculations that include one- and two-body nuclear currents, pion exchange, and Δ currents, under the assumption that the photons are mainly absorbed on exchanged pions.

We study the production of hadrons in Au+Au collisions in the region $0.6<x_F<1.2$, which we refer to as the transfragmentation region (TFR), since it corresponds roughly to ${\eta }^{\prime }>0$, where ${\eta }^{\prime }=\eta -y_{\mathrm{beam}}$, depending on the transverse momentum $p_T$. We show how hadrons can be produced in that region when the hadronization process is parton recombination. The inclusive $x$ distributions for proton and pion production are calculated with momentum degradation taken into account. The results show that the proton yield is significantly higher than that of the pions in the TFR. Without particle identification, the existing data cannot be used for comparison with our result on the $p/\pi$ ratio. Without $p_T$ determination, it is not feasible to relate the $x$ distribution to the experimental ${\eta }^{\prime }$ distribution. Nevertheless, on theoretical grounds we have shown why the production of hadrons in the TFR is not forbidden by momentum conservation.

The isotopic dependence of the isovector Pygmy dipole response in tin is studied within the framework of the relativistic random-phase approximation. Regarded as an oscillation of the neutron skin against the isospin-symmetric core, the pygmy dipole resonance may place important constraints on the neutron skin of heavy nuclei and, as a result, on the equation of state of neutron-rich matter. The present study centers around two questions. First, is there a strong correlation between the development of a neutron skin and the emergence of low-energy isovector dipole strength? Second, could one use the recently measured Pygmy dipole resonance in ${}^{130}\mathrm{Sn}$ and ${}^{132}\mathrm{Sn}$ to discriminate among theoretical models? For the first question we found that although a strong correlation between the neutron skin and the Pygmy dipole resonance exists, a mild anticorrelation develops beyond ${}^{120}\mathrm{Sn}$. The answer to the second question suggests that models with overly large neutron skins—and thus stiff symmetry energies—are in conflict with experiment.

Lifetimes of excited states in ${}^{229}\mathrm{Th}$, populated in the β decay of ${}^{229}\mathrm{Ac}$, have been measured using the advanced time-delayed $\beta \gamma \gamma$(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new γ lines have been introduced into the β-decay scheme of ${}^{229}\mathrm{Ac}$ based on results of $\gamma \gamma$ coincidence measurements. Reduced transition probabilities have been determined for more than 70 γ transitions in ${}^{229}\mathrm{Th}$. Average $\left|D_0\right|$ values of 0.029(1), 0.077(3), and 0.024(5) $e$ fm have been deduced for the lowest $K^{\pi }=1/2^{\pm },3/2^{\pm }$, and $5/2^{\pm }$ parity partner bands, respectively. Excited states in ${}^{229}\mathrm{Th}$ and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, $3/2^{+}$ isomeric state is predicted to be about 10 h. Potential energy surfaces on the (${\beta }_2,{\beta }_3$) plane for the lowest single quasiparticle configurations in ${}^{229}\mathrm{Th}$ have been calculated using the Strutinsky method.

The new neutron-deficient isotope ${}^{187}\mathrm{Po}$ has been identified in the complete fusion reaction ${}^{46}\mathrm{Ti}$+${}^{144}\mathrm{Sm}$→${}^{187}\mathrm{Po}$+$3n$ at the velocity filter SHIP. Striking features of the ${}^{187}\mathrm{Po}$ α decay are the strongly-hindered decay to the spherical ground state and unhindered decay to a surprisingly low-lying deformed excited state at 286 keV in the daughter nucleus ${}^{183}\mathrm{Pb}$. Based on the potential energy surface calculations, the ${}^{187}\mathrm{Po}$ ground state and the 286 keV excited state in ${}^{183}\mathrm{Pb}$ were interpreted as being of prolate origin. The systematic deviation of the α-decay properties in the lightest odd-A Po isotopes relative to the smooth behavior in the even-A neighbors is discussed. Improved data for the decay of ${}^{187}{\mathrm{Bi}}^{m,g}$ were also obtained.

It is pointed out that the usual threshold anomaly, found operative in the energy behavior of the imaginary and real parts of the optical potential representing the elastic scattering of tightly bound nuclei at near- and below-barrier energies, suffers a drastic qualitative change in the case of the elastic scattering of weakly bound nuclei. Owing to the strong coupling to the breakup channel even at sub-barrier energies, the imaginary potential strength seems to increase as the energy is lowered to below the natural barrier threshold; this is accompanied by a decrease in the real potential strength. This feature is consistent with the dispersion relation. The system ${}^6\mathrm{Li}$+${}^{208}\mathrm{Pb}$ is analyzed to illustrate this new phenomenon.

Average energy loss of light quarks has been calculated in a two stage equilibrium scenario where the quarks are executing Brownian motion in a gluonic heat bath. The evolution of the quark $p_T$ spectra is studied by solving Fokker-Planck equation in an expanding plasma. Results are finally compared with experimentally measured pion $p_T$ spectrum at RHIC.

In ultrarelativistic heavy-ion collisions a finite-size QCD medium is created. In this paper the radiative energy loss is computed to zeroth order in opacity by taking into account finite-size effects. Transition radiation occurs on the boundary between the finite-size medium and the vacuum, and we show that it lowers the difference between medium and vacuum zeroth-order radiative energy loss relative to the infinite-size medium case. Further, in all previous computations of light parton radiation to zeroth order in opacity, there was a divergence caused by the fact that the energy loss is infinite in the vacuum and finite in the QCD medium. By including the transition radiation, we show that this infinite discontinuity is naturally regulated.

The ($n,\gamma$) cross sections of ${}^{176}\mathrm{Hf}$, ${}^{177}\mathrm{Hf}$, ${}^{178}\mathrm{Hf}$, ${}^{179}\mathrm{Hf}$, and ${}^{180}\mathrm{Hf}$ have been measured in the energy range from 3 to 225 keV relative to the gold standard. Neutrons were produced via the ${}^7\mathrm{Li}$($p,n$)${}^7\mathrm{Be}$ reaction and capture events were registered with the Karlsruhe 4π barium fluoride detector. The overall uncertainties are between 0.9 and 2.6%, about 5 times smaller than in previous experiments. Partial cross sections to ground and isomeric states could be experimentally identified for neutron capture on ${}^{176,177,178,179}\mathrm{Hf}$, indicating a strong population of yet-unknown isomeric states in ${}^{177}\mathrm{Hf}$ and ${}^{180}\mathrm{Hf}$. This feature was confirmed by extensive GEANT simulations based on calculated capture cascades. The deduced Maxwellian-averaged ($n,\gamma$) cross sections for thermal energies between $\mathit{kT}=8$ and 100 keV contribute to the analysis of the s-process branchings at $A=176$ and $A=179/180$ and have significant consequences for the separation of the solar s- and r-process components.

A value of $0.28\pm 0.02$ s has been deduced for the half-life of the ground state of ${}^{60}\mathrm{Mn}$, in sharp contrast to the previously adopted value of $51\pm 6$ s. Access to the low-spin ${}^{60}\mathrm{Mn}$ ground state was accomplished via β decay of the $0^{+}$ ${}^{60}\mathrm{Cr}$ parent nuclide. New low-energy states in ${}^{60}\mathrm{Mn}$ have been identified from β-delayed γ-ray spectroscopy. The new, shorter half-life of ${}^{60}{\mathrm{Mn}}^g$ is not suggestive of isospin-forbidden β decay, and new spin and parity assignments of $1^{+}$ and $4^{+}$ have been adopted for the ground and isomeric β-decaying states, respectively, of ${}^{60}\mathrm{Mn}$.

Patterns of the vibrational to rotational phase transition in the SD-pair shell model are studied. The results show that the U(5)-SU(3) transitional patterns of the interacting boson model can be reproduced well in the SD-pair shell model.

The inability of otherwise successful dynamical models to reproduce the Hanbury-Brown–Twiss (HBT) radii extracted from two-particle correlations measured at the Relativistic Heavy Ion Collider (RHIC) is known as the RHIC HBT Puzzle. Most comparisons between models and experiment exploit the fact that for Gaussian sources the HBT radii agree with certain combinations of the space-time widths of the source that can be directly computed from the emission function without having to evaluate, at significant expense, the two-particle correlation function. We here study the validity of this approach for realistic emission function models, some of which exhibit significant deviations from simple Gaussian behavior. By Fourier transforming the emission function, we compute the two-particle correlation function, and fit it with a Gaussian to partially mimic the procedure used for measured correlation functions. We describe a novel algorithm to perform this Gaussian fit analytically. We find that for realistic hydrodynamic models the HBT radii extracted from this procedure agree better with the data than the values previously extracted from the space-time widths of the emission function. Although serious discrepancies between the calculated and the measured HBT radii remain, we show that a more apples-to-apples comparison of models with data can play an important role in any eventually successful theoretical description of RHIC HBT data.

The numerical solutions of the nonrelativistic and relativistic Boltzmann equations have been studied at various initial conditions. Particularly, the known analytical solution of the nonrelativistic Boltzmann equation at spherically symmetric Gaussian initial conditions has been recovered and the corresponding conservation of particle spectra and correlation functions have been confirmed. Similar conservation properties have also been found for a more general class of solutions describing the nonrelativistic and relativistic systems at anisotropic initial conditions.

The transverse mass $m_t$ distributions for antiprotons are measured at midrapidity for minimum bias Pb+Pb collisions at 158A GeV and for central Pb+Pb collisions at 20A, 30A, 40A, and 80A GeV beam energies in the fixed target experiment NA49 at the CERN SPS. The rapidity density $\mathit{dn}/\mathit{dy}$, inverse slope parameter T, and mean transverse mass $\langle m_t\rangle$ derived from the $m_t$ distributions are studied as a function of the incident energy and the collision centrality and compared to the relevant data on proton production. The shapes of the $m_t$ distributions of $\overline{p}$ and p are very similar. The ratios of the particle yields, $\overline{p}$/p and $\overline{\Lambda }$/$\overline{p}$, are also analyzed. The $\overline{p}$/p ratio exhibits an increase with decreasing centrality and a steep rise with increasing beam energy. The $\overline{\Lambda }$/$\overline{p}$ ratio increases beyond unity with decreasing beam energy.

A significant improvement has been made in the identification of γ rays from muon capture in natural Ca, and to a lesser extent for Fe and Ni. For calcium, capture was observed in ${}^{44}\mathrm{Ca}$ and even ${}^{42}\mathrm{Ca}$, as well as the dominant ${}^{40}\mathrm{Ca}$. The (${\mu }^{-},\nu )$ reaction was clearly observed in ${}^{40}\mathrm{Ca}$, but, as in the past, no clear identification was made in Fe and Ni. The (${\mu }^{-},\nu n$) reaction was clearly observed in all nuclei, and the γ rays observed correspond better to the ($\gamma ,p$) reaction than to spectroscopic factors from the ($d,$${}^3\mathrm{He}$) or ($t,\alpha )$ reactions. Some (${\mu }^{-},\nu 2n$) and other reactions have been observed at a lower yield.

The external-field QCD sum rules method is used to evaluate the coupling constants of the light isoscalar-scalar meson (“σ” or ɛ) to the $\Lambda ,\Sigma$, and Ξ baryons. It is shown that these coupling constants as calculated from QCD sum rules are consistent with SU(3) flavor relations, which leads to a determination of the $F/(F+D)$ ratio of the scalar octet assuming ideal mixing: we find ${\alpha }_s\equiv F/(F+D)=0.55$. The coupling constants with SU(3) breaking effects are also discussed.