The matrix equations of the random-phase approximation (RPA) are derived for the point-coupling Lagrangian of the relativistic mean-field (RMF) model. Fully consistent RMF plus (quasiparticle) RPA illustrative calculations of the isoscalar monopole, isovector dipole, and isoscalar quadrupole response of spherical medium-heavy and heavy nuclei test the phenomenological effective interactions of the point-coupling RMF model. A comparison with experiment shows that the best point-coupling effective interactions accurately reproduce not only ground-state properties but also data on excitation energies of giant resonances.

Comparisons are made among results of calculations for intermediate-energy nucleon-nucleus scattering for ${}^{12}\mathrm{C}$, ${}^{16}\mathrm{O}$, ${}^{40}\mathrm{Ca}$, ${}^{90}\mathrm{Zr}$, and ${}^{208}\mathrm{Pb}$, by use of optical potentials obtained from global Dirac phenomenology and from a microscopic Schrödinger model. Differential cross sections and spin observables for scattering from the set of five nuclei at 65 and 200 MeV have been studied to assess the relative merits of each approach. Total reaction cross sections from proton-nucleus and total cross sections from neutron-nucleus scattering have been evaluated and compared with data for those five targets in the energy range 20–800 MeV. The methods of analyses give results that compare well with experimental data in those energy regimes for which the procedures are suited.

The recent measurements by the BES Collaboration of $J/\psi$ decays into $\gamma p\overline{p}$ indicate a strong enhancement at $p\overline{p}$ threshold not observed in the decays into ${\pi }^{0}p\overline{p}$. Is this enhancement due to a $p\overline{p}$ quasibound state or a baryonium? A natural explanation follows from a traditional model of $p\overline{p}$ interactions based on the G-parity transformation. The observed $p\overline{p}$ structure is due to a strong attraction in the ${}^1{S}_0$ state and possibly to a near-threshold quasibound state in the ${}^{11}{S}_0$ wave.

The g factor of the $2_1^{+}$ state in ${}^{40}\mathrm{Ar}$ has been measured by use of Coulomb excitation in inverse kinematics and the transient magnetic-field technique. The resulting g factor, $g(2_1^{+})=-0.015(42)$, is in reasonable agreement with shell-model calculations within the (full $\mathit{sd}){}_{\pi }$(full $\mathit{fp}){}_{\nu }$ space, without including core excitations. Although highly deformed admixtures in the wave function cannot be completely ruled out, they are small, in contrast to the case of ${}^{42}\mathrm{Ca}$.

We implement for the first time the simulated annealing method to the problem of searching for the global minimum in the hypersurface of the ${\chi }^2$ function, which depends on the values of the parameters of a Skyrme-type effective nucleon-nucleon interaction. We undertake a realistic case of fitting the values of the Skyrme parameters to an extensive set of experimental data on the ground-state properties of many nuclei, ranging from normal to exotic ones. The set of experimental data used in our fitting procedure includes the radii for the valence $1d_{5/2}$ and $1f_{7/2}$ neutron orbits in the ${}^{17}\mathrm{O}$ and ${}^{41}\mathrm{Ca}$ nuclei, respectively, and the breathing-mode energies for several nuclei, in addition to the typically used data on binding energy, charge radii, and spin-orbit splitting. We also include in the fit the critical density ${\rho }_{\mathrm{cr}}$ and further constrain the values of the Skyrme parameters by requiring that (i) the quantity $P=3\rho (\mathit{dS}/d\rho )$, directly related to the slope of the symmetry energy S, must be positive for densities up to $3{\rho }_0$; (ii) the enhancement factor κ, associated with the isovector giant dipole resonance, should lie in the range of 0.1–0.5; and (iii) the Landau parameter $G_0^{\text{'}}$ is positive at $\rho ={\rho }_0$. We provide simple but consistent schemes to account for the center-of-mass corrections to the binding energy and charge radii.

Improving upon the previous treatment by Mueller and Son, we derive the Boltzmann equation that results from a classical scalar field theory. This is obtained by starting from the corresponding quantum field theory and taking the classical limit with particular emphasis on the path integral and perturbation theory. A previously overlooked Van Vleck determinant is shown to control the tadpole type of self-energy that can still appear in the classical perturbation theory. Further comments on the validity of the approximations and possible applications are also given.

Particle production of identified charged hadrons, ${\pi }^{\pm },K^{\pm },p$, and $\overline{p}$ in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=$ 200 GeV, has been studied as a function of transverse momentum and collision centrality at $y=0$ and $y~1$ by the BRAHMS experiment at Brookhaven National Laboratory's Relativistic Heavy-Ion Collider. Significant collective transverse flow at kinetic freeze-out has been observed in the collisions. The magnitude of the flow rises with the collision centrality. Proton and kaon yields relative to the pion production increase strongly as the transverse momentum increases and also increase with centrality. Particle yields per participant nucleon show a weak dependence on the centrality for all particle species. Hadron production remains relatively constant within one unit around midrapidity in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=$ 200 GeV.

We present covariant predictions for π and η decay modes of N and Δ resonances from relativistic constituent-quark models based on one-gluon-exchange and Goldstone-boson-exchange dynamics. The results are calculated within the point-form approach to Poincaré-invariant relativistic quantum mechanics applying a spectator-model decay operator. The direct predictions of the constituent-quark models for covariant π and η decay widths show a behavior completely different from previous ones calculated in nonrelativistic or so-called semirelativistic approaches. The present theoretical results agree with experiment only in a few cases but otherwise always remain smaller than the experimental data (as compiled by the Particle Data Group). Possible reasons for this behavior are discussed with regard to the quality of both the quark-model wave functions and the mesonic decay operator.

By use of the difference between the gauge symmetric and standard $\pi N\Delta$ couplings, a contact $\pi \pi \mathit{NN}$ term, quadratic in the $\pi N\Delta$ coupling, is explicitly constructed. In addition, contribution from the Δ excitation mechanism to the photon spectrum for the radiative muon capture in hydrogen is derived from the gauge symmetric $\pi N\Delta$ and $\gamma N\Delta$ couplings. It is shown for the photon spectrum, studied experimentally recently for photon momentum $k>60\text{MeV}$, that this contribution is smaller by 4–10% than the one obtained from the standardly used couplings for the on-shell Δ's.

Nonuniform structures of the nucleon matter at subnuclear densities are numerically studied by means of the density functional theory with relativistic mean fields coupled with the electric field. A particular role of the charge screening effects is demonstrated.

To probe the ground state and transition densities, elastic and inelastic scattering on a proton target were measured in inverse kinematics for the unstable ${}^{10}\mathrm{C}$ and ${}^{11}\mathrm{C}$ nuclei at 45.3 and 40.6 MeV/nucleon, respectively. The detection of the recoil proton was performed by the MUST telescope array, in coincidence with a wall of scintillators for the quasiprojectile. The differential cross sections for elastic and inelastic scattering to the first excited states are compared to the optical model calculations performed within the framework of the microscopic nucleon-nucleus Jeukenne-Lejeune-Mahaux potential. Elastic scattering is sensitive to the matter-root-mean square radius found to be $2.42\pm 0.1$ and $2.33\pm 0.1$ fm, for ${}^{10,11}\mathrm{C}$, respectively. The transition densities from cluster and mean-field models are tested, and the cluster model predicts the correct order of magnitude of cross sections for the transitions of both isotopes. Using the Bohr-Mottelson prescription, a profile for the ${}^{10}\mathrm{C}$ transition density from the $0^{+}$ ground to the $2_1^{+}$ state is deduced from the data. The corresponding neutron transition matrix element is extracted: $M_n=5.51\pm 1.09$ fm${}^2$.

Reactions involving weakly bound nuclei of ${}^7\mathrm{Li}$ show large yields of α particles that have their origin in elastic breakup, breakup followed by fusion, or triton transfer. The latter two processes, breakup fusion and transfer, have similar characteristics and produce the same residual fragments. We report here results of exclusive measurements of charged particles and characteristic γ rays from the heavy residues in the ${}^7\mathrm{Li}+{}^{165}\mathrm{Ho}$ system at 42 MeV ($E/V_b\simeq 1.6$) to look for experimental signatures to differentiate between transfer and breakup fusion. Such a distinction is essential for a better theoretical understanding of both the fusion process and direct reactions involving weakly bound stable and unstable beams.

We report on the first analysis of directed and elliptic flow with the new method of Lee–Yang zeros. Experimental data are presented for Ru+Ru reactions at 1.69A GeV measured with the FOPI detector at SIS/GSI. The results obtained with several methods, based on the event-plane reconstruction, on Lee–Yang zeros, and on multiparticle cumulants (up to fifth order) applied for the first time at SIS energies, are compared. They show conclusive evidence that azimuthal correlations between nucleons and composite particles at this energy are largely dominated by anisotropic flow.

The fusion-evaporation reactions ${}^{28}\mathrm{Si}({}^{32}\mathrm{S},1\alpha 2p1n){}^{53}\mathrm{Fe}$ at 125 MeV and ${}^{24}\mathrm{Mg}({}^{32}\mathrm{S},2p1n){}^{53}\mathrm{Fe}$ at a 95-MeV beam energy were used to investigate excited states in ${}^{53}\mathrm{Fe}$. The combination of the Gammasphere Ge detector array and ancillary devices led to the construction of an extensive level scheme comprising some 90 transitions connecting 40 states. The lifetime of the yrast $25/2^{-}$ state and upper limits for the lifetimes of a number of additional states were determined using the Cologne plunger device coupled to the GASP γ-ray spectrometer. The experimental results are compared to large-scale shell-model calculations using different sets of two-body matrix elements. In particular, predictions on electromagnetic decay properties such as lifetimes, branching ratios, and mixing ratios are studied in detail.

Oscillations of mainly surface character ($S=0$ modes) give rise, in atomic nuclei, to an attractive (induced) pairing interaction, while spin ($S=1$) modes of mainly volume character generate a repulsive interaction, the net effect being an attraction which accounts for a sizeable fraction of the experimental pairing gap. Suppressing the particle-vibration coupling mediated by the proton degrees of freedom, i.e., mimicking neutron matter, the total surface plus spin-induced pairing interaction becomes repulsive.

We present model results for the two-halo-neutron correlation functions, $C_{\mathit{nn}}$, for the dissociation process of light exotic nuclei modelled as two neutrons and a core. A minimum is predicted for $C_{\mathit{nn}}$ as a function of the relative momentum of the two neutrons, $p_{\mathit{nn}}$, due to the coherence of the neutrons in the halo and final state interaction. Studying the systems ${}^{14}\mathrm{Be}$, ${}^{11}\mathrm{Li}$, and ${}^6\mathrm{He}$ within this model, we show that the numerical asymptotic limit, $C_{\mathit{nn}}\to 1$, occurs only for $p_{\mathit{nn}}\gtrsim 400\mathrm{MeV}/c$, while such limit is reached for much lower values of $p_{\mathit{nn}}$ in an independent particle model as the one used in the analysis of recent experimental data. Our model is consistent with data once the experimental correlation function is appropriately normalized.

In considering the collisional energy loss rates of heavy quarks from hard light parton interactions, we computed the total energy loss of a charm quark for a static medium. For the energy range $E~5$–10 GeV of charm quark, it proved to be almost the same order as that of radiative ones estimated to a first-order opacity expansion. The collisional energy loss becomes much more important for lower energy charm quarks, and this feature could be very interesting for the phenomenology of hadrons spectra. Using such collisional energy loss rates, we estimate the momentum loss distribution employing a Fokker-Planck equation and the total energy loss of a charm quark for an expanding quark-gluon plasma under conditions resembling the energies presently available at the BNL Relativistic Heavy Ion Collider. The fractional collisional energy loss is found to be suppressed by a factor of 5 as compared to the static case and does not depend linearly on the system size. We also investigate the heavy to light hadrons $D/\pi$ ratio at moderately large (5–10 GeV/c) transverse momenta and comment on its enhancement.

We calculate the nuclear modification factor of neutral pions and the photon yield at high $p_T$ in central Au-Au collisions at the Relativistic Heavy-Ion Collider (RHIC) ($\sqrt{s}=200\text{GeV}$) and Pb-Pb collisions at the Large Hadron Collider (LHC) ($\sqrt{s}=5500\text{GeV}$). A leading-order accurate treatment of jet energy loss in the medium has been convolved with a physical description of the initial spatial distribution of jets and a one dimensional hydrodynamic expansion. We reproduce the nuclear modification factor for pions $R_{\mathit{AA}}$ at RHIC, assuming an initial temperature $T_i=370\text{MeV}$ and a formation time ${\tau }_i=0.26$ fm/c, corresponding to $\mathit{dN}/\mathit{dy}=1260$. The resulting suppression depends on the particle rapidity density $\mathit{dN}/\mathit{dy}$ but weakly on the initial temperature. The jet energy loss treatment is also included in the calculation of high $p_T$ photons. Photons coming from primordial hard N-N scattering are the dominant contribution at RHIC for $p_T>5\text{GeV}$, whereas at the LHC, the range $8<p_T<14\text{GeV}$ is dominated by jet-photon conversion in the plasma.

We report a new measurement of the differential cross section for ${\pi }^{-}p\to {\pi }^{0}n$ from $p_{\pi }=649$ to 752 MeV/c, which is around the opening of the η channel (685 MeV/c). Our data support the main features of the ${\pi }^{-}p$ charge-exchange differential cross sections generated by the SAID $\pi N$ partial-wave analysis. The opening of the η channel has a clear effect on the shape of the excitation function for $d\sigma ({\pi }^{-}p\to {\pi }^{0}n)$, which is most noticeable in the backward direction.

We study the $\Lambda (1520)D_{03}$ in a chiral coupled channel approach. This resonance appears to be dynamically generated from the interaction of the decuplet of baryons and the octet of mesons in s wave, and its treatment is improved here with the phenomenological inclusion of the $\overline{K}N$ and $\pi \Sigma$ channels in d wave. Since the most important building block in $\Lambda (1520)$ is the $\pi {\Sigma }^{*}(1385)P_{13}$ channel, we study the $K^{-}p\to \pi {\Sigma }^{*}(1385)({\pi }^0\Lambda )$ reaction in the region of $\Lambda (1520)$ and above, and compare the results with recent experimental data. With the coupling of $\Lambda (1520)$ to the $\pi {\Sigma }^{*}$ channel predicted by the theory, we find a cross section in good agreement with the data. There is also agreement for the invariant mass distributions which show a neat peak for ${\Sigma }^{*}(1385)$ in the $({\pi }^0\Lambda )$ spectrum. Predictions are made of a strong $\Lambda (1520)$ resonant peak of the cross section, as a function of the $K^{-}$ momentum, in the region below the measured data, which, if confirmed experimentally, would give stronger support to the idea of $\Lambda (1520)$ as a dynamically generated resonance.