Azimuthal anisotropy is studied by taking into account the ridges created by semihard scattering, which is sensitive to the initial spatial configuration in noncentral heavy-ion collisions. No rapid thermalization is required. Although hydrodynamics is not used in this study, the validity of hydrodynamical expansion is not excluded at later time after equilibration is achieved. Phenomenological properties of the bulk and ridge behaviors are used as inputs to determine the elliptic flow of pion and proton at low $p_T$. At intermediate $p_T$ the recombination of shower partons with thermal partons becomes more important. The ϕ dependence arises from the variation of the in-medium path length of the hard parton that generates the shower. The $p_T$ dependence of $v_2$ is therefore very different at intermediate $p_T$ compared to that at low $p_T$. Quark number scaling of $v_2$ is shown to be only approximately valid at low $p_T$, but is broken at intermediate $p_T$, even though recombination is the mechanism of hadronization in all $p_T$ regions considered.

The exclusive channel $\overrightarrow{p}(\overrightarrow{e},e^{\text{'}}p){\pi }^0$ was studied in the first and second nucleon resonance regions in the $Q^2$ range from $0.187$ to $0.770\hspace{0.5em}{\mathrm{GeV}}^2$ at Jefferson Lab using the CEBAF Large Acceptance Spectrometer. Longitudinal target and beam-target asymmetries were extracted over a large range of center-of-mass angles of the ${\pi }^0$ and compared to the unitary isobar model MAID, the dynamic model by Sato and Lee, and the dynamic model DMT. A strong sensitivity to individual models was observed, in particular for the target asymmetry and in the higher invariant mass region. This data set, once included in the global fits of the above models, is expected to place strong constraints on the electrocoupling amplitudes $A_{1/2}$ and $S_{1/2}$ for the Roper resonance $N(1400)P_{11}$ and the $N(1535)S_{11}$ and $N(1520)D_{13}$ states.

The ${}^{96}\mathrm{Mo}(d,{}^2\mathrm{He}){}^{96}\mathrm{Nb}$ charge-exchange reaction was investigated at an incident energy of $E_d=183.5$ MeV. An excitation-energy resolution of 110 keV was achieved. The experiment was performed at KVI, Groningen, using the magnetic spectrometer BBS at three angular positions: $0^{°},2.5^{°}$, and $6^{°}$. We found that below 6 MeV almost the entire Gamow-Teller (${\mathrm{GT}}^{+}$) strength is concentrated in a single state at 0.69 MeV excitation energy. As ${}^{96}\mathrm{Mo}$ is the daughter of the $\beta \beta$ decay nucleus ${}^{96}\mathrm{Zr}$, the present result provides information about the nuclear matrix elements active in the $2\nu \beta \beta$ decay of ${}^{96}\mathrm{Zr}$.

In view of the fact that $\alpha$ decay and cluster radioactivity are physically analogical processes, we propose a general formula of half-lives and decay energies for $\alpha$ decay and cluster radioactivity. This new formula is directly deduced from the WKB barrier penetration probability with some approximations. It is not only simple in form and easy to see the physical meanings but also shows excellent agreement with the experimental values. Moreover, the difference between two sets of parameters to separately describe $\alpha$ decay and cluster radioactivity is small. Therefore, we use only one set of adjustable parameters to simultaneously describe the $\alpha$ decay and cluster radioactivity data for even-even nuclei. The results are also satisfactory. This indicates that this formula successfully combines the phenomenological laws of $\alpha$ decay and cluster radioactivity. We expect it to be a significant step toward a unified phenomenological law of $\alpha$ decay and cluster radioactivity.

Cross sections for the reaction ${}^1\mathrm{H}(e,e^{\text{'}}{\pi }^{+})n$ were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from $Q^2=0.60$ to 2.45 ${\mathrm{GeV}}^2$ at an invariant mass of the virtual photon-nucleon system of $W=1.95$ and 2.22 GeV. The measured cross sections were separated into the four structure functions ${\sigma }_{\mathrm{L}},{\sigma }_{\mathrm{T}},{\sigma }_{\mathrm{LT}}$, and ${\sigma }_{\mathrm{TT}}$. The various parts of the experimental setup and the analysis steps are described in detail, including the calibrations and systematic studies, which were needed to obtain high-precision results. The different types of systematic uncertainties are also discussed. The results for the separated cross sections as a function of the Mandelstam variable $t$ at the different values of $Q^2$ are presented. Some global features of the data are discussed, and the data are compared with the results of some model calculations for the reaction ${}^1\mathrm{H}(e,e^{\text{'}}{\pi }^{+})n$.

The charged pion form factor, $F_{\pi }(Q^2)$, is an important quantity that can be used to advance our knowledge of hadronic structure. However, the extraction of $F_{\pi }$ from data requires a model of the ${}^1\mathrm{H}(e,e^{\text{'}}{\pi }^{+})n$ reaction and thus is inherently model dependent. Therefore, a detailed description of the extraction of the charged pion form factor from electroproduction data obtained recently at Jefferson Lab is presented, with particular focus given to the dominant uncertainties in this procedure. Results for $F_{\pi }$ are presented for $Q^2=0.60\text{−}2.45\hspace{0.5em}{\mathrm{GeV}}^2$. Above $Q^2=1.5\hspace{0.5em}{\mathrm{GeV}}^2$, the $F_{\pi }$ values are systematically below the monopole parametrization that describes the low $Q^2$ data used to determine the pion charge radius. The pion form factor can be calculated in a wide variety of theoretical approaches, and the experimental results are compared to a number of calculations. This comparison is helpful in understanding the role of soft versus hard contributions to hadronic structure in the intermediate $Q^2$ regime.

A systematic study is made of the Cd isotopes ${}^{110\text{−}116}\mathrm{Cd}$ by making use of available experimental data and interacting boson model calculations incorporating both normal vibrational levels and intruder excitations. At the two-phonon level, the calculations appear to reproduce the data reasonably well in ${}^{110\text{−}114}\mathrm{Cd}$, whereas they break down completely for the $0^{+}$ states in ${}^{116}\mathrm{Cd}$. At the three-phonon level, systematic deviations occur across the Cd isotopic chain, revealing the breakdown of vibrational motion in low-spin states. Combined with the failure to reproduce ${}^{116}\mathrm{Cd}$ at the two-phonon level, it is possible that the Cd isotopes may not represent vibrational systems and that the essential physics of their motion has been missing.

Parameters of isobaric analog resonance (IAR) are calculated in the framework of the Lane model using different methods. In the standard method, the direct numerical solution of the coupled channel (CC) Lane equations served as a reference for checking two complex energy methods, namely the complex energy shell model (CXSM) and the complex scaling (CS) approaches. The IAR parameters calculated by the CXSM and the CS methods agree with that of the CC results within 1 keV for all partial waves considered. Although the CXSM and the CS methods have similarities, an important difference is that only the CXSM method offers a direct way for studying the configurations of the IAR wave function.

Parity quantum numbers of $J=1$ states up to 7 MeV in the region of the Pygmy Dipole Resonance in ${}^{140}\mathrm{Ce}$ were determined model independently by combining the methods of Nuclear Resonance Fluorescence and Compton polarimetry. For the first time the well-established method of Compton polarimetry was applied at such high energies. The experiment was performed using a fourfold segmented HPGe clover detector for the detection of the scattered photons. For all investigated dipole transitions asymmetries are found which correspond to negative parity of the excited states.

The isospin effects in proton-induced reactions on isotopes of ${}^{112-132}\mathrm{Sn}$ and the corresponding $\beta$-stable isobars are studied by means of the improved quantum molecular dynamics model and some sensitive probes for the density dependence of the symmetry energy at subnormal densities are proposed. The beam energy range is chosen to be 100–300 MeV. Our study shows that the system size dependence of the reaction cross sections for $p+{}^{112-132}\mathrm{Sn}$ deviates from the Carlson's empirical expression obtained by fitting the reaction cross sections for proton on nuclei along the $\beta$-stability line and sensitively depends on the stiffness of the symmetry energy. We also find that the angular distribution of elastic scattering for $p+{}^{132}\mathrm{Sn}$ at large impact parameters is very sensitive to the density dependence of the symmetry energy, which is uniquely due to the effect of the symmetry potential with no mixture of the effect from the isospin dependence of the nucleon-nucleon cross sections. The isospin effects in neutron-induced reactions are also studied and it is found that the effects are just opposite to that in proton-induced reactions. We find that the difference between the peaks of the angular distributions of elastic scattering for $p+{}^{132}\mathrm{Sn}$ and $n+{}^{132}\mathrm{Sn}$ at $E_{p,n}=100$ MeV and $b=7.5$ fm is positive for soft symmetry energy $U_{\mathrm{sym}}^{\mathrm{sf}}$ and negative for super-stiff symmetry energy $U_{\mathrm{sym}}^{\mathrm{nlin}}$ and close to zero for linear density dependent symmetry energy $U_{\mathrm{sym}}^{\mathrm{lin}}$, which seems very useful for constraining the density dependence of the symmetry energy at subnormal densities.

A new type of complex $G$-matrix interactions including the effect of three-body nucleon-nucleon ($\mathit{NN}$) force is proposed and applied to the folding-model calculation of proton-nucleus elastic scattering at $E_p=65~200$ MeV for ${}^{12}\mathrm{C},{}^{40}\mathrm{Ca},{}^{90}\mathrm{Zr}$, and ${}^{208}\mathrm{Pb}$ target nuclei. All the measured cross sections and analyzing powers are well reproduced by the folding potentials with the new complex $G$-matrix interaction when the effect of three-body force (TBF) is included so as to give the reasonable saturation property. The inclusion of TBF largely reduces the strength of real-central component of folding potential at middle and short distances. The TBF effect is clearly observed in drastic improvements of analyzing powers at forward angles, which is, however, due to the TBF effect on the real-central potentials, not to the direct effects on the spin-orbit potentials. The calculated folding potential is shown to be very sensitive to the difference of neutron-density profile of the target nucleus.

We derive the space-time distribution of energy and momentum deposited by a fast parton traversing a weakly coupled quark-gluon plasma by treating the fast parton as the source of an external color field perturbing the medium. We then use our result as a source term for the linearized hydrodynamical equations of the medium. We show that the solution contains a sonic Mach cone and a dissipative wake if the parton moves at a supersonic speed.

The ground state energy and width of ${}^7\mathrm{He}$ has been measured with the Modular Neutron Array (MoNA) and superconducting dipole Sweeper magnet experimental setup at the National Superconducting Cyclotron Laboratory. ${}^7\mathrm{He}$ was produced by proton knockout from a secondary ${}^8\mathrm{Li}$ beam. The measured decay energy spectrum is compared to simulations based on Breit-Wigner line shape with an energy-dependent width for the resonant state. The energy of the ground state is found to be 400(10) keV with a full-width at half-maximum of $125({}_{-15}^{+40})$ keV.

A new theoretical approach is presented that combines the Hartree-Fock variational scheme with the exact solution of the pairing problem in the finite orbital space. Using this formulation in the $\mathit{sd}$-space as an example, we show that the exact pairing significantly improves the results for the ground state energy.

We investigate eigenvalues of many-body systems interacting by two-body forces as well as those of random matrices. For two-body random ensemble, we find a strong linear correlation between eigenvalues and diagonal matrix elements if both of them are sorted from the smaller values to larger ones. By using this linear correlation we are able to predict reasonably all eigenvalues of a given Hamiltonian matrix without complicated iterations. For Gaussian orthogonal ensemble matrices, the hyperbolic tangent function improves the accuracy of predicted eigenvalues near the minimum and maximum.

Within the framework of fermionic molecular dynamics a method is developed to better account for long-range tensor correlations in nuclei when working with a single Slater determinant. Single-particle states with mixed isospin and broken parity build up an intrinsic Slater determinant, which is then charge and parity projected. By minimizing the energy of this many-body state with respect to the parameters of the single-particle states and projecting afterward on angular momentum, ground-state energies are obtained that are systematically lower than corresponding Hartree-Fock results. The realistic Argonne V18 potential is used and short-range correlations are treated with the unitary correlation operator method. Comparison with exact few-body calculations shows that in ${}^4\mathrm{He}$ about one-fifth of the correlation energy from long-range correlations are accounted for. These correlations, which extend over the whole nucleus, are visualized with the isospin and spin-isospin density of the intrinsic state. The divergence of the spin-isospin density, the source for pion fields, turns out to be of dipole nature.

An analytically solvable composite potential that can closely reproduce the combined potential of an $\alpha +\mathrm{nucleus}$ system consisting of attractive nuclear and repulsive electrostatic potentials is developed. The exact $s$-wave solution of the Schrödinger equation with this potential in the interior region and the outside Coulomb wave function are used to give a heuristic expression for the width or half-life of the quasibound state at the accurately determined resonance energy, called the $Q$ value of the decaying system. By using the fact that for a relatively low resonance energy, the quasibound state wave function is quite similar to the bound state wave function where the amplitude of the wave function in the interaction region is very large as compared to the amplitude outside, the resonance energy could easily be calculated from the variation of relative probability densities of inside and outside waves as a function of energy. By considering recent $\alpha$-decay systems, the applicability of the model is demonstrated with excellent explanations being found for the experimental data of $Q$ values and half-lives of a vast range of masses including superheavy nuclei and nuclei with very long lifetimes (of order ${10}^{22}$ s). Throughout the application, by simply varying the value of a single potential parameter describing the flatness of the barrier, we obtain successful results in cases with as many as 70 pairs of $\alpha +\mathrm{daughter}$ nucleus systems.

We report on a study of the structure of the unbound nucleus ${}^7\mathrm{He}$ utilizing the proton-removal reaction ${}^2\mathrm{H}({}^8\mathrm{Li},{}^3\mathrm{He}){}^7\mathrm{He}$. Combining the present results with those of our prior measurements of the neutron-adding reaction ${}^2\mathrm{H}({}^6\mathrm{He},p){}^7\mathrm{He}$, a consistent picture emerges for the low-lying excitations in ${}^7\mathrm{He}$. Specifically, the negative-parity sequence of resonances, in order of excitation energies, is consistent with $3/2^{-},1/2^{-}$, and $5/2^{-}$. The stable-beam reactions ${}^2\mathrm{H}({}^7\mathrm{Li},t){}^6\mathrm{Li}$ and ${}^2\mathrm{H}({}^7\mathrm{Li},{}^3\mathrm{He}){}^6\mathrm{He}$ were also measured. The results are compared with the predictions of nuclear structure models, including those of ab initio quantum Monte Carlo calculations.

The ${}^7\mathrm{H}$ and ${}^6\mathrm{H}$ nuclear systems were investigated via transfer reactions with a ${}^8\mathrm{He}$ beam at $15.4A$ MeV impinging in a ${}^{12}\mathrm{C}$ target. The experimental setup allowed a complete reconstruction of the reaction kinematics with the MAYA gas detector, based on the active-target concept, where the carbon atoms of the filling isobutane played also the role of reaction target. The ${}^7\mathrm{H}$ resonance was observed at $0.{57}_{-0.21}^{+0.42}$ MeV above the ${}^3\mathrm{H}+4n$ threshold with a width of $0.{09}_{-0.06}^{+0.94}$ MeV. The ${}^6\mathrm{H}$ system was formed at $2.{91}_{-0.95}^{+0.85}$ MeV with a resonance width of $1.{52}_{-0.35}^{+1.77}$ MeV. These results show the availability of nuclear structure information well outside the bounding limits, resulting in an extraordinary input to improve the present models and understanding of nuclear matter.

Using the instant form dynamics of Poincaré invariant quantum mechanics and the modified relativistic impulse approximation proposed previously, we calculate asymptotic behavior of electromagnetic form factors for the deuteron considered as a two-nucleon system. We show that today, experimentation on elastic $\mathit{ed}$ scattering has reached the asymptotic regime. We also estimate the possible range of momentum transfer in which the quark degrees of freedom will possibly be seen in future JLab experiments. The explicit relation between the behavior of the deuteron wave function at $r=0$ and the form factors asymptotic behavior is obtained, and the conditions of wave functions that give the asymptotic behavior predicted by QCD and quark counting rules are formulated.