Symmetry energy terms from macroscopic mass formulas are investigated as generalized polarizabilities of nuclear matter. Besides the neutron-proton ($n\text{−}p$) symmetry energy, the spin-dependent symmetry energies and a scalar one are also defined. They depend on the nuclear densities (ρ), neutron-proton asymmetry (b), temperature (T), and exchanged energy and momentum (q). Based on a standard expression for the generalized polarizabilities, a differential equation is proposed to constrain the dependence of the symmetry energy on the $n\text{−}p$ asymmetry and on the density. Some solutions are discussed. The q dependence (zero frequency) of the symmetry energy coefficients with Skyrme-type forces is investigated in the four channels of the particle-hole interaction. Spin-dependent symmetry energies are also investigated indicating much stronger differences in behavior with q for each Skyrme force than the results for the neutron-proton one.

We study dissipative properties of the motion of a slow nuclear collective variable weakly coupled to a complex quantum environment formed by the fast nucleonic degrees of freedom. The fast quantum mechanical subsystem is treated within the random matrix approach, where the complexity of the nucleonic degrees of freedom's motion can be changed by a parameter from regular to fully chaotic. Classical dynamics is assumed for the slow variable, and the equation of motion is determined from conservation of the total energy of the nuclear many-body system. We show that the macroscopic equation of motion for the collective variable is subject to a memory-dependent friction force, with a retardation defined by the chaoticity of the fast nucleonic environment.

It has been suggested recently [N. K. Timofeyuk, R. C. Johnson, and A. M. Mukhamedzhanov, Phys. Rev. Lett. 91, 232501 (2003)] that charge symmetry of nucleon-nucleon interactions relates the asymptotic normalization coefficients (ANCs) of proton and neutron virtual decays of mirror nuclei. This relation is given by a simple analytical formula that involves proton and neutron separation energies, charges of residual nuclei, and the range of their strong interaction with the last nucleon. The relation between mirror ANCs, if understood properly, can be used to predict astrophysically relevant direct proton capture cross sections using neutron ANCs measured with stable beams. In this work, we calculate one-nucleon ANCs for several light mirror pairs, using microscopic two-, three-, and four-cluster models and compare the ratio of mirror ANCs to the predictions of the simple analytic formula. We also investigate mirror symmetry between other characteristics of mirror one-nucleon overlap integrals, namely, spectroscopic factors and single-particle ANCs.

We study self-consistently the finite T broadening of the ρ meson and its implications for dilepton emission in heavy-ion collisions. For this purpose finite width effects at finite temperature due to the $\rho \text{−}\pi$ interaction are investigated in a self-consistent Φ-functional approach. The temperature dependence of the ρ meson and pion spectral functions and self-energies is discussed. The spectral functions show considerable broadening in comparison with a perturbative calculation on the one-loop level. Using these spectral functions, we make a comparison to dilepton emission data from the CERES NA49 Collaboration employing a parametrized fireball evolution model of collision. We demonstrate that these nonperturbative finite width effects are in-medium modifications relevant to the understanding of the enhancement of the low invariant mass spectrum of dileptons emitted in A-A collisions.

The short-lived $K(892){}^{*}$ resonance provides an efficient tool to probe properties of the hot and dense medium produced in relativistic heavy-ion collisions. We report measurements of $K^{*}$ in $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ Au+Au and $p+p$ collisions reconstructed via its hadronic decay channels $K(892){}^{*0}\to K\pi$ and $K(892){}^{*\pm }\to K_S^0{\pi }^{\pm }$ using the STAR detector at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. The $K^{*0}$ mass has been studied as a function of $p_T$ in minimum bias $p+p$ and central Au+Au collisions. The $K^{*}{p}_T$ spectra for minimum bias $p+p$ interactions and for Au+Au collisions in different centralities are presented. The $K^{*}/K$ yield ratios for all centralities in Au+Au collisions are found to be significantly lower than the ratio in minimum bias $p+p$ collisions, indicating the importance of hadronic interactions between chemical and kinetic freeze-outs. A significant nonzero $K^{*0}$ elliptic flow ($v_2$) is observed in Au+Au collisions and is compared to the $K_S^0$ and Λ $v_2$. The nuclear modification factor of $K^{*}$ at intermediate $p_T$ is similar to that of $K_S^0$ but different from Λ. This establishes a baryon-meson effect over a mass effect in the particle production at intermediate $p_T$ ($2<p_T\le 4\mathrm{GeV}/c$).

Using SU(3) chiral perturbation theory, we calculate the density-dependent complex mean field $U_{\Sigma }(k_f)+i\hspace{1em}{W}_{\Sigma }(k_f)$ of a Σ hyperon in isospin-symmetric nuclear matter. The leading long-range $\Sigma N$ interaction arises from one-kaon exchange and from two-pion exchange with a Σ or a Λ hyperon in the intermediate state. We find from the $\Sigma N\to \Lambda N$ conversion process at nuclear matter saturation density ${\rho }_0=0.16{\mathrm{fm}}^{-3}$ an imaginary single-particle potential of $W_{\Sigma }(k_{f0})=-21.5$ MeV, in fair agreement with existing empirical determinations. The genuine long-range contributions from iterated (second order) one-pion exchange with an intermediate Σ or Λ hyperon sum to a moderately repulsive real single-particle potential of $U_{\Sigma }(k_{f0})=59$ MeV. Recently measured $({\pi }^{-},K^{+}$) inclusive spectra related to ${\Sigma }^{-}$ formation in heavy nuclei give evidence for a Σ-nucleus repulsion of similar size. Our results suggest that the net effect of the short-range $\Sigma N$ interaction on the Σ nuclear mean field could be small.

We analyze two types of spin observables in the reaction $\pi \overrightarrow{D}\to \overrightarrow{\Sigma }{\Theta }^{+}$ near the threshold. One concerns the spin-transfer coefficients $K_x^x$ and $K_z^z$. The second is the deuteron spin anisotropy. These observables are sensitive to the ${\Theta }^{+}$ parity and can be used as a tool for the ${\Theta }^{+}$ parity determination.

The Lagrangian density of standard relativistic mean-field models with density-dependent meson-nucleon coupling vertices is modified by introducing couplings of the meson fields to derivative nucleon densities. As a consequence, the nucleon self-energies that describe the effective in-medium interaction become momentum dependent. In this approach it is possible to increase the effective (Landau) mass of the nucleons, that is related to the density of states at the Fermi energy, as compared to conventional relativistic models. At the same time the relativistic effective (Dirac) mass is kept small to obtain a realistic strength of the spin-orbit interaction. Additionally, the empirical Schrödinger-equivalent central optical potential from Dirac phenomenology is reasonably well described. A parametrization of the model is obtained by a fit to properties of doubly magic atomic nuclei. Results for symmetric nuclear matter, neutron matter, and finite nuclei are discussed.

High-spin states in the nucleus ${}^{102}\mathrm{Ru}$ have been investigated via the ${}^{96}\mathrm{Zr}$(${}^{13}\mathrm{C}$,α3n) reaction at beam energies of 51 and 58 MeV, using the euroball IV γ-ray spectrometer and the diamant charged particle array. Several new high-spin bands have been established. The ground-state band has been extended up to $E_x~12$ MeV with $I^{\pi }=({26}^{+}$); the previously published negative-parity bands have been extended up to $E_x~11$ and ∼ 9 MeV with $I^{\pi }=({23}^{-}$) and $({20}^{-})$, respectively. The deduced high-spin structure has been compared with Woods-Saxon total Routhian surface calculations and, on the basis of the measured Routhians, aligned angular momenta, and $B(M1)/B(E2)$ ratios, $\nu h_{11/2}(g_{7/2},d_{5/2}$) configurations are suggested for the negative-parity structures.

We develop a new 3 + 1 dimensional Monte Carlo cascade solving the kinetic on-shell Boltzmann equations for partons including the inelastic $gg\leftrightarrow ggg$ pQCD processes. The back reaction channel is treated—for the first time—fully consistently within this scheme. An extended stochastic method is used to solve the collision integral. The frame dependence and convergency are studied for a fixed tube with thermal initial conditions. The detailed numerical analysis shows that the stochastic method is fully covariant and that convergency is achieved more efficiently than within a standard geometrical formulation of the collision term, especially for high gluon interaction rates. The cascade is then applied to simulate parton evolution and to investigate thermalization of gluons for a central Au+Au collision at RHIC energy. For this study the initial conditions are assumed to be generated by independent minijets with $p_T>p_0=2$ GeV. With that choice it is demonstrated that overall kinetic equilibration is driven mainly by the inelastic processes and is achieved on a scale of 1 fm/c. The further evolution of the expanding gluonic matter in the central region then shows almost an ideal hydrodynamical behavior. In addition, full chemical equilibration of the gluons follows on a longer time scale of about 3 fm/c.

We solve the Hartree-Fock-Bogoliubov (HFB) equations for deformed, axially symmetric even-even nuclei in coordinate space on a two-dimensional (2-D) lattice utilizing the basis-spline expansion method. Results are presented for the neutron-rich zirconium isotopes up to the two-neutron drip line. In particular, we calculate binding energies, two-neutron separation energies, normal and pairing densities, mean square radii, quadrupole moments, and pairing gaps. Very large prolate quadrupole deformations $({\beta }_2=0.42,0.43,0.470)$ are found for the ${}^{102,104,112}\mathrm{Zr}$ isotopes, in agreement with recent experimental data. We compare 2-D basis-spline lattice results with the results from a 2-D HFB code that uses a transformed harmonic oscillator basis.

The cross sections for radiative neutron capture by ${}^{102}\mathrm{Pd}$ have been deduced from a measurement of the γ rays emitted by 17.0-d ${}^{103}\mathrm{Pd}$. The thermal cross section has been determined to be $\sigma =1.82\pm 0.20$ b, and the effective resonance integral is $I=23\pm 4$ b. We also report thermal and resonance capture cross sections for ${}^{108}\mathrm{Pd}$ and note possible inconsistencies with the presently accepted values of the ${}^{110}\mathrm{Pd}$ cross sections.

We systematically investigate the elastic electron scattering on both stable and unstable nuclei with the relativistic eikonal approximation, where the charge density distributions of nuclei are from the self-consistent relativistic mean field model. Calculations show that the relativistic eikonal approximation can reproduce the experimental data of electron scattering on nuclei ranging from the light region, such as ${}^{12}\mathrm{C}$, to the heavy region, such as ${}^{208}\mathrm{Pb}$. This is the systematic test of the relativistic eikonal approximation for elastic electron scattering for both light and heavy nuclei. With this method, further studies are made of the variation of charge form factors along isotopic chains and the sensitivity of charge form factors to the changes of charge distribution. For isotopic chains with Z = 20 and 28, we find that the charge form factors vary significantly with neutron number. The charge form factors shift outward and downward when the target nucleus moves from the neutron-rich region to the proton-rich region along the isotopic chain. The significant shift shows that the charge form factor is very sensitive to a change of neutron number. If the isotopic shifts of the charge form factor are measured on the next-generation electron-nucleus collider (at RIKEN and GSI), the charge size and charge distribution can be determined for unstable nuclei. The calculations will provide a reference for future experiments.

The lifetime measurements are done for different quasiparticle bands in neutron-deficient ${}^{187}\mathrm{Tl}$ nucleus through the recoil distance Doppler shift technique. A sudden change in the transition quadrupole moment is observed for both positive and negative parity prolate bands as one moves from lower spins to higher spins, indicating a major shape transitions in this nucleus. The prolate-oblate shape coexistence picture of this nucleus is discussed in the light of the extracted transition quadrupole moments. For the negative parity $\pi h_{9/2}$ band the transition quadrupole moment for the low K (3/2) prolate sequence is found to be higher than that of the high K (9/2) oblate sequence. The total Routhian surface calculations are done within the framework of the cranked Hartree-Fock-Bogoliubov model to analyze the shape coexistence picture theoretically. The theoretical predictions are found to be in close agreement with the experimental observations. The existence of a superdeformed band is also predicted for the nucleus.

Calorimetric and coalescence techniques have been employed to probe equilibration for hot nuclei produced in heavy-ion collisions of 35 to 55 MeV/nucleon projectiles with medium mass targets. Entrance channel mass asymmetries and energies were selected so that very hot composite nuclei of similar mass and excitation would remain after early stage preequilibrium particle emission. Intercomparison of the properties and deexcitation patterns for these different systems provides evidence for the production of hot nuclei with decay patterns relatively independent of the specific entrance channel.

The electromagnetic decays of the ${\Sigma }^0(1385)$ and $\Lambda (1520)$ hyperons were studied in photon-induced reactions $\gamma p\to K^{+}\Lambda (1116)\gamma$ in the Large Acceptance Spectrometer detector at the Thomas Jefferson National Accelerator Facility. We report the first observation of the radiative decay of the ${\Sigma }^0(1385)$ and a measurement of the $\Lambda (1520)$ radiative decay width. For the ${\Sigma }^0(1385)\to \Lambda (1116)\gamma$ transition, we measured a partial width of $479\pm 120(\mathrm{stat}){}_{-100}^{+81}(\mathrm{sys})\mathrm{keV}$, larger than all of the existing model predictions. For the $\Lambda (1520)\to \Lambda (1116)\gamma$ transition, we obtained a partial width of $167\pm 43(\mathrm{stat}){}_{-12}^{+26}(\mathrm{sys})\mathrm{keV}$.

The (${}^8\mathrm{Li}$, α) reaction has been studied at E(${}^8\mathrm{Li})=27.7$ MeV on targets of ${}^{\mathrm{nat}}$C, ${}^{27}\mathrm{Al}$, and ${}^{208}\mathrm{Pb}$ using a secondary ${}^8\mathrm{Li}$ beam. The α-energy spectra for ${}^{27}\mathrm{Al}$ and ${}^{208}\mathrm{Pb}$ are generally nondistinct and resemble fragmentation spectra. In contrast, data for the ${}^{\mathrm{nat}}$C target exhibit enhanced (${}^8\mathrm{Li}$, α) cross sections in the region corresponding to population of low-lying levels in ${}^{16}\mathrm{N}$. Angular distributions were determined over a large angular range and exhibit a strong forward peaking for ${}^{27}\mathrm{Al}$ and some forward peaking for the ${}^{\mathrm{nat}}$C data. They are otherwise rather featureless but distinct from spectra expected from fusion evaporation. The data for ${}^{27}\mathrm{Al}$ are indicative of either direct or sequential fragmentation processes. Similar analysis of limited data obtained at $E({}^8\mathrm{Li})=27.7$ MeV for the ${}^{208}\mathrm{Pb}$ target, along with data previously obtained at higher ${}^8\mathrm{Li}$ energies, is suggestive of a sequential breakup mechanism. In the case of the ${}^{\mathrm{nat}}$C target, the data corresponding to low excitation energies in ${}^{16}\mathrm{N}$ exhibit (${}^8\mathrm{Li}$, α) angular distributions that appear to be most consistent with a ${}^4\mathrm{H}$ transfer mechanism. However, we cannot distinguish between a one-step ${}^4\mathrm{H}$ cluster transfer and a multistep ${}^4\mathrm{H}$ transfer (such as $n+{}^3\mathrm{H})$.

To describe the fusion of two very heavy nuclei at near barrier energies, a generalized Langevin approach is proposed. The approach incorporates the quantum statistical fluctuations in accordance with the fluctuation and dissipation theorem. It is illustrated that the quantum statistical effects introduce an enhancement of the formation of a compound nucleus, though the quantum enhancement is somewhat less pronounced as indicated in the previous calculations.

Fusion barriers have been determined for light nuclei isotopic-isobaric and isobaric and heavy nuclei isotopic-isobaric reactions leading to ${}^{104}\mathrm{Pd}$, $A=110$ and ${}^{292}118$ compound nuclei, in head-on type configurations of two intersected spheroids. Deformation energy is calculated with the macroscopic-microscopic method. The final static fusion barrier is obtained by minimizing this energy against different partner deformation paths. The results show an influence of the shell corrections especially in the last part of the overlapping region, when protons and neutrons interchange within the same mass number. Penetrability calculations show that the trend given by the outer barrier could be reversed by the shape of the inner barrier for some isotopic-isobaric channels.

The pseudorapidity behavior of the azimuthal anisotropy parameters $v_1$ and $v_2$ of inclusive charged ($h^{\pm }$) hadrons and their dependence on centrality has been studied in Au+Au collisions at full relativistic-heavy-ion-collider energy of $\sqrt{s_{\mathit{NN}}}=200\mathrm{GeV}$ within the microscopic quark-gluon string model (QGSM). The QGSM simulation results for the directed flow $v_1$ show antiflow alignment within the pseudorapidity range $\left|\eta \right|\le 2$ in fair agreement with the experimental $v_1(\eta )$ data, but it cannot reproduce the further development of the antiflow up to $\left|\eta \right|\simeq 3.5$. The η dependence of the elliptic flow $v_2$ extracted from the simulations agrees well with the experimental data in the whole pseudorapidity range for different centrality classes. The centrality dependence of the integrated elliptic flow of charged hadrons in the QGSM almost coincides with the PHOBOS experimental distribution. The transverse momentum dependence of the elliptic flow of identified (${\pi }^{\pm },K^{\pm },p,\overline{p}$) and inclusive charged hadrons is studied also. The model reproduces quantitatively the low-$p_T$ part of the distributions rather well, but it underestimates the measured elliptic flow for transverse momenta $p_T>1\mathrm{GeV}/c$. Qualitatively, however, the model can reproduce the saturation of the $v_2(p_T)$ spectra with rising $p_T$ as well as the crossing of the elliptic flow for mesons and baryons.