Some of the rich structure of the polarization observables recently developed for processes like $\gamma N\to \pi \pi N$ and $\gamma N\to K\overline{K}N$ are explored within the framework of a specific model for the latter process. Emphasis is placed on observables that may be accessible at existing facilities in the near future. The sensitivity of the observables to the details of the model indicate that they will be a very useful tool in differentiating among models used to describe reactions like these. Within the framework of a model for $\gamma N\to K\overline{K}N$, the sensitivity of the observables to the coupling constants of the ϕ, to the properties of the $\Lambda (1405)$, and to the existence of the ${\Theta }^{+}$ is examined.

The experimental level structure of ${}^{134}\mathrm{Sb}$ is compared with the results of a shell-model calculation in which the two-body matrix elements of the effective interaction have been derived from the CD-Bonn nucleon-nucleon potential. The experimental data, including the very low lying first-excited $1^{-}$ state, are remarkably well reproduced by the theory. The results of this paper complement those of our previous studies on ${}^{135}\mathrm{Sb}$ and ${}^{134}\mathrm{Sn}$, showing that our effective interaction is well suited to describe ${}^{132}\mathrm{Sn}$ neighbors beyond $N=82$. The various terms that contribute to the matrix elements of the proton-neutron effective interaction are examined and their relative importance is evidenced.

Solution of the momentum space Schrödinger equation in the case of deformed fields is being addressed. In particular it is shown that a complete set of single-particle states that includes bound, resonant, and complex continuum states may be obtained by the contour deformation method. This generalized basis in the complex energy plane is known as a Berggren basis. The momentum space Schrödinger equation is an integral equation that is easily solved by matrix diagonalization routines even for the case of deformed fields. The method is demonstrated for axial symmetry and a fictitious “deformed ${}^5\mathrm{He}$” but may be extended to more general deformation and applied to truly deformed halo nuclei.

We discuss the systematics of ground-state quadrupole correlations of binding energies and mean-square charge radii for all even-even nuclei, from ${}^{16}$O up to the superheavies, for which data are available. To that aim we calculate their correlated $J=0$ ground state by means of the angular-momentum and particle-number projected generator coordinate method, using the axial mass quadrupole moment as the generator coordinate and self-consistent mean-field states restricted only by axial, parity, and time-reversal symmetries. The calculation is performed within the framework of a nonrelativistic self-consistent mean-field model by use of the same Skyrme interaction SLy4 and to a density-dependent pairing force to generate the mean-field configurations and to mix them. These are the main conclusions of our study: (i) The quadrupole correlation energy varies between a few 100 keV and about 5.5 MeV. It is affected by shell closures, but varies only slightly with mass and asymmetry. (ii) Projection on angular momentum $J=0$ provides the major part of the energy gain of up to about 4 MeV; all nuclei in the study, including doubly magic ones, gain energy by deformation. (iii) The mixing of projected states with different intrinsic axial deformations adds a few 100 keV up to 1.5 MeV to the correlation energy. (iv) Typically nuclei below mass $A\le 60$ have a larger correlation energy than static deformation energy whereas the heavier deformed nuclei have larger static deformation energy than correlation energy. (v) Inclusion of the quadrupole correlation energy improves the description of mass systematics, particularly around shell closures, and of differential quantities, namely two-nucleon separation energies and two-nucleon gaps. The correlation energy provides an explanation of “mutually enhanced magicity.” (vi) The correlation energy tends to decrease the shell effect on binding energies around magic numbers, but the magnitude of the suppression is not large enough to explain the relative overbinding at $N=82$ and $N=126$ neutron-shell closures in mean-field models. (vii) Charge radii are also found to be sensitive to the quadrupole correlations. Static quadrupole deformations lead to a significant improvement of the overall systematics of charge radii. The dynamical correlations improve the local systematics of radii, in particular around shell closures. Although the dynamical correlations might reduce the charge radii for specific nuclei, they lead to an overall increase of radii when included, in particular in light nuclei.

The half-life of exohedral ${}^7\mathrm{Be}$-$C_{60}$ complex and that of ${}^7\mathrm{Be}$ implanted in a gold foil have been found to be about the same within ≈0.2%. Using a radiochemical technique, we also measured that the probability of formation of endohedral ${}^7\mathrm{Be}$@$C_{60}$ complex by nuclear implantation technique was (5.6 ± 0.45)%. We also find that the half-life of endohedral ${}^7\mathrm{Be}$@$C_{60}$ complex is shorter than that of exohedral complex by more than 1%. An analysis of these results using linear muffin-tin orbital method calculations indicates that most of the implanted ${}^7\mathrm{Be}$ ions in fullerene $C_{60}$ stay at a distance of $\approx 5.3\AA$ from the centers of nearest $C_{60}$ molecules forming exohedral compounds and those who enter the fullerene cages go to the centers of the cages forming endohedral ${}^7\mathrm{Be}$@$C_{60}$ compounds.

Thermalization and collective flow of charm (c) and bottom (b) quarks in ultrarelativistic heavy-ion collisions are evaluated based on elastic parton rescattering in an expanding quark-gluon plasma (QGP). We show that resonant interactions in a strongly interacting QGP (sQGP), as well as parton coalescence, can play an essential role in the interpretation of recent data from the BNL Relativistic Heavy-Ion Collider (RHIC), and thus illuminate the nature of the sQGP and its hadronization. Our main assumption, motivated by recent findings in lattice quantum chromodynamics, is the existence of D- and B-meson states in the sQGP, providing resonant cross sections for heavy quarks. Pertinent drag and diffusion coefficients are implemented into a relativistic Langevin simulation to compute transverse-momentum spectra and azimuthal asymmetries ($v_2$) of b- and c-quarks in Au-Au collisions at RHIC. After hadronization into D- and B-mesons using quark coalescence and fragmentation, associated electron-decay spectra and $v_2$ are compared to recent RHIC data. Our results suggest a reevaluation of radiative and elastic quark energy-loss mechanisms in the sQGP.

The superscaling approach is applied to studies of neutral current neutrino reactions in the quasielastic regime. Using input from scaling analyses of electron scattering data, predictions for high-energy neutrino and antineutrino cross sections are given and compared with results obtained using the relativistic Fermi gas model. The influence of strangeness content inside the nucleons in the nucleus is also explored.

Supernovae are rare nearby, but they are not rare in the Universe, and all past core-collapse supernovae contributed to the diffuse supernova neutrino background (DSNB), for which the near-term detection prospects are very good. The Super-Kamiokande limit on the DSNB electron antineutrino flux, $\varphi (E_{\nu }>19.3\mathrm{MeV})<1.2$ cm${}^{-2}$ s${}^{-1}$, is just above the range of recent theoretical predictions based on the measured star formation rate history. We show that the Sudbury Neutrino Observatory should be able to test the corresponding DSNB electron-neutrino flux with a sensitivity as low as $\varphi (22.5<E_{\nu }<32.5\mathrm{MeV})\simeq 6$ cm${}^{-2}$ s${}^{-1}$, improving the existing Mont Blanc limit by about 3 orders of magnitude. While conventional supernova models predict comparable electron-neutrino and antineutrino fluxes, it is often considered that the first (and forward-directed) SN 1987A event in the Kamiokande-II detector should be attributed to electron-neutrino scattering with an electron, which would require a substantially enhanced electron-neutrino flux. We show that, with the required enhancements in either the burst or thermal phase ${\nu }_e$ fluxes, the DSNB electron-neutrino flux would generally be detectable in the Sudbury Neutrino Observatory. A direct experimental test could then resolve one of the enduring mysteries of SN 1987A: whether the first Kamiokande-II event reveals a serious misunderstanding of supernova physics or was simply an unlikely statistical fluctuation. Thus the electron-neutrino sensitivity of the Sudbury Neutrino Observatory is an important complement to the electron antineutrino sensitivity of Super-Kamiokande in the quest to understand the DSNB.

Prescriptions for computation of Coulomb displacement energies for ${1/2}^{+}$ analog levels in light nuclei using Woods-Saxon wells are discussed. Behavior at high energy sets a limit to their applicability.

We study nuclear matter, at the mean-field approximation, by considering as equal the values of the scalar and the vector density in the Walecka model, which is a very reasonable approximation up to the nuclear matter saturation density. It turns out that the model has an analytical solution for the scalar and vector couplings as functions only of the nuclear matter density and binding energy. The nuclear matter properties are very close to the original version of the model. This solution allows us to show that the correlation between the binding energy and the saturation density is Coester line like. The liquid-gas phase transition is also studied and the critical and flash temperatures are again very similar to the original ones.

Background: Two soft-photon amplitudes, the two-u-two-t special (TuTts) amplitude and the Low amplitude, are known to produce quantitatively similar $\mathit{np}\gamma$ cross sections, but they predict quite different $\mathit{pp}\gamma$ cross sections for those kinematic conditions in which the nucleon scattering angles are small (less than ${25}^{°}$). Purpose: These two amplitudes have been applied to systematically investigate three different nucleon-nucleon bremsstrahlung ($NN\gamma$) processes: $\mathit{pp}\gamma ,\mathit{np}\gamma$, and $\mathit{nn}\gamma$. The $\mathit{nn}\gamma$ process is explored for the first time. The primary focus of this work is to investigate the contribution of the proton and the neutron anomalous magnetic moments to all three $NN\gamma$ processes for projectile energies above 150 MeV and for laboratory scattering angles (${\theta }_1$ and ${\theta }_2$) lying between $8^{°}$ and ${40}^{°}$. Method: A special soft-photon expansion in which the TuTts amplitude is expanded in terms of the Low amplitude plus additional amplitudes is utilized to explore the relationship between the TuTts and Low amplitudes and the reasons why they agree and disagree. We also used the TuTts amplitude to calculate the $NN\gamma$ cross section with and without the anomalous magnetic moment contributions to explore the importance of that element of the electromagnetic current. Results: The TuTts amplitude describes well the available $\mathit{pp}\gamma$ cross-section data. The anomalous magnetic moment contribution is (i) significant in the $\mathit{pp}\gamma$ process when each scattering angle is less than ${25}^{°}$ but insignificant when each scattering angle is ${40}^{°}$ or greater and (ii) insignificant in the $\mathit{np}\gamma$ process for all scattering angles. The $\mathit{nn}\gamma$ cross sections for the TuTts and Low amplitudes differ substantially for the kinematics investigated. Conclusions: In general, the Low amplitude agrees well with the TuTts amplitude when anomalous magnetic moment effects are not significant, but the two amplitudes can yield quite different predictions when such effects are significant. These findings have enhanced our understanding of the fundamental emission mechanism governing $NN\gamma$ processes, and they explain why the TuTts amplitude should be used to describe all three $NN\gamma$ processes.

We attempt to obtain a unified description of the bound and unbound states of multivalence nucleons of a core system in the framework of the cluster-orbital shell model (COSM). In this framework, the interaction between the core and a valence nucleon (the core-N interaction) is treated microscopically, and the changes in both the core structure and the core-N interaction are discussed on the same basis. Furthermore, the center-of-mass motion of every nucleon is completely eliminated, and higher shell configurations, including unbound continuum components, are appropriately taken into account by applying a stochastic variational approach. To examine the reliability of this approach and to discuss how the dynamics of the core reflects to the total system, we study oxygen isotopes and $N=8$ isotones, which are described by ${}^{16}\mathrm{O}$ + Xn and ${}^{16}\mathrm{O}$ + Xp models, respectively.

We parametrize the recently proposed generalized Skyrme effective force (GSEF) containing extended density dependence. The parameters of the GSEF are determined by the fit to several properties of the normal and isospin-rich nuclei. We also include in our fit a realistic equation of state for the pure neutron matter up to high densities so that the resulting Skyrme parameters can be suitably used to model the neutron star with the “canonical” mass ($~1.4M_{\odot }$). For the appropriate comparison, we generate a parameter set for the standard Skyrme effective force (SSEF) using exactly the same set data as employed to determine the parameters of the GSEF. We find that the GSEF yields larger values for the neutron skin thickness which are closer to the recent predictions based on the isospin diffusion data. The Skyrme parameters so obtained are employed to compute the strength function for the isoscalar giant monopole, dipole, and quadrupole resonances. It is found that in the case of GSEF, because of the larger value of the nucleon effective mass, the values of centroid energies for the isoscalar giant resonances are in better agreement with the corresponding experimental data than those obtained using the SSEF. We also present results for some of the key properties associated with the neutron star of canonical mass and for the one with the maximum mass.

Resonant elastic scattering of a radioactive ${}^{20}\mathrm{Na}$ beam incident upon protons in a polyethylene target has been used to probe the level structure of ${}^{21}\mathrm{Mg}$ above the proton decay threshold. Three states have been observed, and their properties deduced through analysis based on the R-matrix formalism. The results improve and extend previous studies of this nucleus. An estimate of the ${}^{20}\mathrm{Na}$(p,γ)${}^{21}\mathrm{Mg}$ reaction rate, including these new data, suggests this reaction will not play a significant role in explosive hydrogen burning in astrophysical sites such as novae and x-ray bursts.

We have measured the ${}^{28}\mathrm{Si}$$(e,e^{\text{'}}n)$ reaction in the excitation energy range 21.5–40.5 MeV at three effective momentum transfers, 0.38, 0.49, and 0.60 fm${}^{-1}$. The $E1$ and $E2\text{−}E0$ components were separated based on their different momentum-transfer dependences. The $E1$ strength obtained was found to agree with that of photoreactions in shape and strength. The strength of the $E2\text{−}E0$ component at low excitation energies was very small when compared with that of the $(e,e^{\text{'}}p)$ reaction. At higher excitation energies, the $E2\text{−}E0$ component has a bump structure at about 26–30 MeV and it is suggested that it has an isovector character by comparison with $(\alpha ,{\alpha }^{\text{'}})$ reaction data. This is supported by results of a ${}^{28}\mathrm{Si}$(${}^7\mathrm{Li}$,${}^7\mathrm{Be}$)${}^{28}\mathrm{Al}$ experiment. The $E2\text{−}E0$ strength of 37.9(±4.7)% in the isovector $E2$ energy-weighted sum rule is exhausted in the excitation energy range 22.5–40.5 MeV.

Collisions of deformed uranium nuclei are studied in a Monte Carlo Glauber model. For U+U at zero impact parameter ($b=0$) in the most favorable orientation (tip-to-tip), the transverse particle density (charged-particle rapidity density per weighted transverse area of the initial participant zone) increases by about 35% compared to Au+Au at $b=0$. To estimate the advantage of U+U over Au+Au in the context of real experiments at the Relativistic Heavy Ion Collider, we examine the effect of a range of centrality cuts on the event sample. In terms of the transverse particle density, the predicted advantage of U+U is about 16%.

The relation between Renyi entropies and moments of the Wigner function, representing the quantum mechanical description of the M-particle semi-inclusive distribution at freeze-out, is investigated. It is shown that in the limit of infinite volume of the system, the classical and quantum descriptions are equivalent. Finite volume corrections are derived and shown to be small for systems encountered in relativistic heavy ion collisions.

The ${}^{20}\mathrm{Ne}$$(p,\gamma )$${}^{21}\mathrm{Na}$ reaction rate at stellar energies is dominated by capture to the ground state through the tail of a subthreshold resonance state at an excitation energy of 2425 keV in ${}^{21}\mathrm{Na}$. Both resonant and direct capture contribute to the reaction rate while direct captures to other bound states are negligible. The overall normalization of direct capture to the subthreshold state is determined by the asymptotic normalization coefficient (ANC). Simultaneously this ANC determines the proton partial width of the subthreshold resonance state. To determine the ANC, the ${}^{20}\mathrm{Ne}$(${}^3\mathrm{He}$$,d)$${}^{21}\mathrm{Na}$ proton transfer reaction has been measured, at an incident energy of 25.83 MeV. Angular distributions for proton transfer to the ground and first three excited states were measured, and ANCs were then extracted from comparison with distorted-wave Born approximation calculations. Using these ANCs, we calculated the astrophysical factor for ${}^{20}\mathrm{Ne}$$(p,\gamma )$${}^{21}\mathrm{Na}$. Our total astrophysical factor is $S(0)=5900\pm 1200$ keV b. Our analysis confirms that only nonresonant and resonant captures through the subthreshold state are important.

An interesting physical process has been unveiled: Dynamical core excitation during a breakup reaction of loosely bound $\mathrm{core}+N$ systems. These reactions are typically used to extract spectroscopic information and/or astrophysical information. A new method, the eXtended Continuum Discretized Coupled Channel (XCDCC) method, was developed to incorporate, in a consistent way and to all orders, core excitation in the bound and scattering states of the projectile, as well as dynamical excitation of the core as it interacts with the target. The model predicts cross sections to specific states of the core. It is applied to the breakup of ${}^{11}\mathrm{Be}$ on ${}^9\mathrm{Be}$ at 60 MeV/nucleon, and the calculated cross sections are in improved agreement with the data. The distribution of the cross section amongst the various core states is shown to depend on the reaction model used, and not simply on the ground state spectroscopic factors.

Two-particle correlations of identical charged pion pairs from Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ and 200 GeV were measured by the PHOBOS experiment at BNL Relativistic Heavy Ion Collider (RHIC). Data for the 15% most central events were analyzed with Bertsch-Pratt and Yano-Koonin-Podgoretskii parametrizations using pairs with rapidities of $0.4<y_{\pi \pi }<1.3$ and transverse momenta $0.1<k_T<1.4$ GeV/c. The Bertsch-Pratt radii $R_o$ and $R_{\ell }$ decrease as a function of pair transverse momentum. $R_o$ and $R_s$ are independent of collision energy, while $R_{\ell }$ shows a slight increase. The source rapidity $y_{\mathrm{YKP}}$ scales roughly with the pair rapidity $y_{\pi \pi }$, indicating strong dynamical correlations.