The first calculation of triangular flow $v_3$ in Au$+$Au collisions at $\sqrt{s_{\mathrm{NN}}}=200A$ GeV from an event-by-event $(3+1)d$ transport$+$hydrodynamics hybrid approach is presented. As a response to the initial triangularity ${\epsilon }_3$ of the collision zone, $v_3$ is computed in a similar way to the standard event-plane analysis for elliptic flow $v_2$. It is found that the triangular flow exhibits weak centrality dependence and is roughly equal to elliptic flow in most central collisions. We also explore the transverse momentum and rapidity dependence of $v_2$ and $v_3$ for charged particles as well as identified particles. We conclude that an event-by-event treatment of the ideal hydrodynamic evolution starting with realistic initial conditions generates the main features expected for triangular flow.

${}^8\mathrm{C}$ is found to decay to four protons and an $\alpha$ particle in two $2p$ emission steps. The correlations between the protons in the first step (${}^8\mathrm{C}$ to ${}^6\mathrm{Be}$) exhibit a significant enhancement in the region of the decay phase space where the two protons have small relative energy, a region sometimes called the diproton region. The decay of the isobaric analog of ${}^8\mathrm{C}$ in ${}^8\mathrm{B}$ is also found to decay by $2p$ emission. This is the first case of isospin-allowed $2p$ decay between isobaric analog states.

We study the properties of the neutron-nucleus total and reaction cross sections for several nuclei. We have applied an analytical model, the nuclear Ramsauer model, justified it from the nuclear reaction theory approach, and extracted the values of 12 parameters used in the model. The given parametrization has an advantage as phenomenological optical model potentials are limited up to $150-200$ MeV. The present model provides good estimates of the total cross sections for several nuclei particularly at high energies.

Within the framework of a dinuclear system model, a new master equation is constructed and solved, which includes the relative distance of nuclei as a new dynamical variable in addition to the mass asymmetry variable so that the nucleon transfer, which leads to fusion and the evolution of the relative distance, which leads to quasifission (QF) are treated simultaneously in a consistent way. The QF mass yields and evaporation residual cross sections to produce superheavy nuclei are systematically investigated under this framework. The results fit the experimental data well. It is shown that the Kramers formula gives results of QF, which agree with those by our diffusion treatment, only if the QF barrier is high enough. Otherwise some large discrepancies occur.

The recently published [A. A. Aguilar-Arevalo (MiniBooNE Collaboration), Phys. Rev. D 81, 092005 (2010)] MiniBooNE charge current quasielastic double differential cross-section data are analyzed and compared with simulations based on two nuclear models: Fermi gas model and spectral function model. In both cases the axial mass parametr $M_A$ is obtained from a fitting procedure which takes into account the multiplicative factor in the uncertainty of the flux. Bins with large ($>50\%$) contribution from events with small momentum transfer ($q<q_{\mathrm{cut}}$) are eliminated from the analysis. More restrictive cuts result in smaller fitted $M_A$ values. The $q_{\mathrm{cut}}=500$ MeV/$c$ leads to the value of $M_A=1350\pm 66$ MeV in the Fermi gas model and $M_A=1343\pm 60$ MeV in the spectral function model. In both cases the value of $M_A=1030$ MeV is excluded at the confidence level greater than $5\sigma$.

The longitudinal asymmetry induced by parity-violating (PV) components in the nucleon-nucleon potential is studied in the charge-exchange reaction ${}^3\mathrm{He}$($\mathrm{n⃗},p$)${}^3\mathrm{H}$ at vanishing incident neutron energies. An expression for the PV observable is derived in terms of $T$-matrix elements for transitions from the ${}^{2S+1}{L}_J={}^1{S}_0$ and ${}^3{S}_1$ states in the incoming $n$-${}^3\mathrm{He}$ channel to states with $J=0$ and 1 in the outgoing $p$-${}^3\mathrm{H}$ channel. The $T$-matrix elements involving PV transitions are obtained in first-order perturbation theory in the hadronic weak-interaction potential, while those connecting states of the same parity are derived from solutions of the strong-interaction Hamiltonian with the hyperspherical-harmonics method. The coupled-channel nature of the scattering problem is fully accounted for. Results are obtained corresponding to realistic or chiral two- and three-nucleon strong-interaction potentials in combination with either the DDH or pionless EFT model for the weak-interaction potential. The asymmetries, predicted with PV pion and vector-meson coupling constants corresponding (essentially) to the DDH “best values” set, range from –9.44 to –2.48 in units of ${10}^{-8}$, depending on the input strong-interaction Hamiltonian. This large model dependence is a consequence of cancellations between long-range (pion) and short-range (vector-meson) contributions and is of course sensitive to the assumed values for the PV coupling constants.

The isospin-breaking effects due to the Coulomb interaction in weakly bound nuclei are studied using the Gamow shell model, a complex-energy configuration-interaction approach which simultaneously takes into account many-body correlations between valence nucleons and continuum effects. We investigate the near-threshold behavior of one-nucleon spectroscopic factors and the structure of wave functions along an isomultiplet. Illustrative calculations are carried out for the $T=1$ isobaric triplet. By using a shell-model Hamiltonian consisting of an isoscalar nuclear interaction and the Coulomb term, we demonstrate that for weakly bound or unbound systems the structure of isobaric analog states varies within the isotriplet and impacts the energy dependence of spectroscopic factors. We discuss the partial dynamical isospin symmetry present in isospin-stretched systems, despite the Coulomb interaction that gives rise to large mirror symmetry-breaking effects.

The thermodynamic properties of hot nuclei are described within the canonical and microcanonical ensemble approaches. These approaches are derived based on the solutions of the BCS and self-consistent quasiparticle random-phase approximation at zero temperature embedded into the canonical and microcanonical ensembles. The results obtained agree well with the recent data extracted from experimental level densities by the Oslo group for ${}^{94}\mathrm{Mo}$, ${}^{98}\mathrm{Mo}$, ${}^{162}\mathrm{Dy}$, and ${}^{172}\mathrm{Yb}$ nuclei.

A comprehensive level scheme of ${}^{93}\mathrm{Nb}$ below 2 MeV has been constructed from information obtained with the ${}^{93}\mathrm{Nb}$($n,n^{\prime }\gamma$) and the ${}^{94}\mathrm{Zr}$($p,2n\gamma \gamma$)${}^{93}\mathrm{Nb}$ reactions. Branching ratios, lifetimes, transition multipolarities, and spin assignments have been determined. From $M1$ and $E2$ strengths, fermionic-bosonic excitations of isoscalar and isovector characters have been identified from the weak couplings of the $\pi 1g_{9/2}\otimes {}_{40}^{92}\mathrm{Zr}$ and $\pi 2p_{1/2}^{-1}\otimes {}_{42}^{94}\mathrm{Mo}$ configurations. A microscopic interpretation of such excitations is obtained from shell-model calculations, which use low-momentum effective interactions.

The recent works by the present authors predicted that the real part of heavy-ion optical potentials changes its character from attraction to repulsion around the incident energy per nucleon $E/A=200–300\hspace{0.5em}\mathrm{MeV}$ on the basis of the complex $G$-matrix interaction and the double-folding model (DFM) and revealed that the three-body force plays an important role there. In the present paper, we have precisely analyzed the energy dependence of the calculated DFM potentials and its relation to the elastic-scattering angular distributions in detail in the case of the ${}^{12}\mathrm{C}$$+$${}^{12}\mathrm{C}$ system in the energy range of $E/A=100–400\hspace{0.5em}\mathrm{MeV}$. The tensor force contributes substantially to the energy dependence of the real part of the DFM potentials and plays an important role to lower the attractive-to-repulsive transition energy. The nearside and farside ($N/F$) decompositions of the elastic-scattering amplitudes clarify the close relation between the attractive-to-repulsive transition of the potentials and the characteristic evolution of the calculated angular distributions with the increase of the incident energy. Based on the present analysis, we propose experimental measurements for the predicted strong diffraction phenomena of the elastic-scattering angular distribution caused by the $N/F$ interference around the attractive-to-repulsive transition energy together with the reduced diffractions below and above the transition energy.

We study the in-medium masses of the charmonium states $J/\psi$ and ${\eta }_c$ in the nuclear medium using the QCD sum rule approach. These mass modifications arise owing to modifications of the scalar and the twist-2 gluon condensates in the hot hadronic matter. The scalar gluon condensate $\langle \frac{{\alpha }_s}{\pi }{G}_{\mu \nu }^a{G^a}^{\mu \nu }\rangle$ and the twist-2 tensorial gluon operator $\langle \frac{{\alpha }_s}{\pi }{G}_{\mu \sigma }^a{{G^a}_{\nu }}^{\sigma }\rangle$ in the nuclear medium are calculated from the medium modification of a scalar dilaton field introduced to incorporate trace anomalies of QCD within the chiral SU(3) model used in the present investigation. The effects of isospin asymmetry, density, and temperature of the nuclear medium on the in-medium masses of the lowest charmonium states $J/\psi$ and ${\eta }_c$ mesons are investigated in the present work. The results of the present investigation are compared with the existing results on the masses of these states. The medium modifications of the masses of these charmonium states ($J/\psi$ and ${\eta }_c$) seem to be appreciable at high densities and should modify the experimental observables arising from the compressed baryonic matter produced in asymmetric heavy-ion collision experiments at the future facility of Facility for Antiproton and Ion Research, GSI.

Several resonances in ${}^{25}\mathrm{Al}$($p,\gamma$)${}^{26}\mathrm{Si}$ have been studied via the ${}^{28}\mathrm{Si}$($p,t$)${}^{26}\mathrm{Si}$ reaction. Triton energies and angular distributions were measured using a segmented annular detector array. An additional silicon detector array was used to simultaneously detect the coincident protons emitted from the decay of states in ${}^{26}\mathrm{Si}$ above the proton threshold in order to determine branching ratios. A resonance at $5927\pm 4$ keV has been experimentally confirmed as the first $\ell =0$ state above the proton threshold, with a proton branching ratio consistent with one.

Cross sections and analyzing powers for polarized proton elastic scattering from ${}^{58}\mathrm{Ni}$, and ${}^{204,206,208}\mathrm{Pb}$ were measured at intermediate energy $E_p=295$ MeV. An effective relativistic Love-Franey interaction is tuned to reproduce ${}^{58}\mathrm{Ni}$ scattering data within the framework of the relativistic impulse approximation. The neutron densities of the lead isotopes are deduced using model-independent sum-of-Gaussians distributions. Their error envelopes are estimated by a new ${\chi }^2$ criterion including uncertainties associated with the reaction model. The systematic behaviors of extracted error envelopes of the neutron density distributions in ${}^{204,206,208}\mathrm{Pb}$ are presented. The extracted neutron and proton density distribution of ${}^{208}\mathrm{Pb}$ gives a neutron skin thickness of $\Delta r_{\mathit{np}}={0.211}_{-0.063}^{+0.054}$ fm.

We present a sophisticated treatment of the hydrodynamic evolution of ultrarelativistic heavy ion collisions, based on the following features: initial conditions obtained from a flux tube approach, compatible with the string model and the color glass condensate picture; an event-by-event procedure, taking into the account the highly irregular space structure of single events, being experimentally visible via so-called ridge structures in two-particle correlations; the use of an efficient code for solving the hydrodynamic equations in $3+1$ dimensions, including the conservation of baryon number, strangeness, and electric charge; the employment of a realistic equation of state, compatible with lattice gauge results; the use of a complete hadron resonance table, making our calculations compatible with the results from statistical models; and a hadronic cascade procedure after hadronization from the thermal matter at an early time.

We explain the application of a recently developed analytic continuation method to extract the electromagnetic transition form factors for the nucleon resonances ($N^{*}$) within a dynamical coupled-channel model of meson-baryon reactions. Illustrative results of the obtained $N^{*}\to \gamma N$ transition form factors, defined at the resonance pole positions on the complex energy plane, for the well-isolated $P_{33}$ and $D_{13}$ and the complicated $P_{11}$ resonances are presented. A formula was developed to give a unified representation of the effects due to the first two $P_{11}$ poles, which are near the $\pi \Delta$ threshold, but are on different Riemann sheets. We also find that a simple formula, with its parameters determined in the Laurent expansions of the $\pi N\to \pi N$ and $\gamma N\to \pi N$ amplitudes, can reproduce to a very large extent the exact solutions of the considered model at energies near the real parts of the extracted resonance positions. We discuss the important differences between our approach, which is consistent with the earlier formulations of resonances, and the phenomenological approaches using the Breit-Wigner parametrization of resonant amplitudes to fit the data.

Multi-quasiparticle high-$K$ states in neutron-deficient mercury, lead, and polonium isotopes have been investigated systematically by means of configuration-constrained potential-energy-surface calculations. An abundance of high-$K$ states is predicted with both prolate and oblate shapes, which extends the shape coexistence of the mass region. Well-deformed shapes provide good conditions for the formation of isomers, as exemplified in ${}^{188}\mathrm{Pb}$. Of particular interest is the prediction of low-lying ${10}^{-}$ states in polonium isotopes, which indicate long-lived isomers.

We propose a physically transparent analytic model of astrophysical $S$ factors as a function of a center-of-mass energy $E$ of colliding nuclei (below and above the Coulomb barrier) for nonresonant fusion reactions. For any given reaction, the $S(E)$ model contains four parameters [two of which approximate the barrier potential, $U(r)$]. They are easily interpolated along many reactions involving isotopes of the same elements; they give accurate practical expressions for $S(E)$ with only several input parameters for many reactions. The model reproduces the suppression of $S(E)$ at low energies (of astrophysical importance) due to the shape of the low-$r$ wing of $U(r)$. The model can be used to reconstruct $U(r)$ from computed or measured $S(E)$. For illustration, we parametrize our recent calculations of $S(E)$ (using the São Paulo potential and the barrier penetration formalism) for 946 reactions involving stable and unstable isotopes of C, O, Ne, and Mg (with nine parameters for all reactions involving many isotopes of the same elements, e.g., $\mathrm{C}+$O). In addition, we analyze astrophysically important ${}^{12}\mathrm{C}$${+}^{12}$C reaction, compare theoretical models with experimental data, and discuss the problem of interpolating reliably known $S(E)$ values to low energies ($E\lesssim 2–3$ MeV).

We present a statistical-model description of fission, in the framework of compound-nucleus decay, which is found to simultaneously reproduce data from both heavy-ion-induced fusion reactions and proton-induced spallation reactions at around $1$ GeV. For the spallation reactions, the initial compound-nucleus population is predicted by the Liège intranuclear cascade model. We are able to reproduce experimental fission probabilities and fission-fragment mass distributions in both reactions types with the same parameter sets. However, no unique parameter set was obtained for the fission probability. The introduction of fission transients can be offset by an increase of the ratio of level-density parameters for the saddle-point and ground-state configurations. Changes to the finite-range fission barriers could be offset by a scaling of the Bohr-Wheeler decay width as predicted by Kramers. The parameter sets presented allow accurate prediction of fission probabilities for excitation energies up to $300$ MeV and spins up to $60$ $\hslash$.

We study the equation of state (EOS) of nuclear matter at subnuclear density in a virial expansion for a nonideal gas. The gas consists of neutrons, protons, alpha particles, and 8980 species of nuclei with $A⩾12$ and masses from the finite-range droplet model. At very low density, the virial expansion reduces to nuclear statistical equilibrium. At higher density, the virial results match smoothly to the relativistic mean field results discussed in our previous paper. We tabulate the resulting EOS at over 73 000 grid points in the temperature range $T=0.158$ to 15.8 MeV, the density range $n_B={10}^{-8}$ to 0.1 fm${}^{-3}$, and the proton fraction range $Y_P=0.05$ to 0.56. In the future we plan to match these low-density results to our earlier high-density mean field results, and generate a full EOS table for use in supernova and neutron star merger simulations. This virial EOS is exact in the low-density limit.

The discrete $\gamma$ radiation in the interaction of 14.9-MeV neutrons and a natural silicon sample is investigated with a total $\gamma$-radiation measurement (TGRM) technique. Fifty prompt $\gamma$ lines, one delayed $\gamma$ line, and seven final nuclei are identified. Forty-one possible transitions are designated. Differential production cross sections of 40 $\gamma$ lines at ${40}^{°}$, ${55}^{°}$, ${90}^{°}$, ${125}^{°}$, and ${140}^{°}$ are determined. Using relative differential production cross sections, accurate integral isotopic cross sections of the ${}^{28}\mathrm{Si}$($n$,$p$)${}^{28}\mathrm{Al}$ reaction are determined, and partial integral isotopic cross sections of the ${}^{28}\mathrm{Si}$($n$,$n$′)${}^{28}\mathrm{Si}$, ${}^{28}\mathrm{Si}$($n$,$\alpha$)${}^{25}\mathrm{Mg}$, ${}^{29}\mathrm{Si}$($n$,$n$′)${}^{29}\mathrm{Si}$, and ${}^{30}\mathrm{Si}$($n$,$n$′)${}^{30}\mathrm{Si}$ reaction channels are also estimated. The present results are in good agreement with some recent experimental and evaluated results.