The ${}^{118,124}\mathrm{Sn}$($p$,$t$)${}^{116,122}\mathrm{Sn}$ reactions have been investigated in high-resolution experiments at incident proton energies of 24.6 and 25 MeV, respectively. Angular distributions for 55 transitions to levels of ${}^{116}\mathrm{Sn}$ and 63 transitions to levels of ${}^{122}\mathrm{Sn}$, up to excitation energies of $~3.850$ and $~4.000$ MeV, respectively, have been measured. The spin and parity identification was carried out by means of a distorted-wave Born approximation (DWBA) analysis, performed by using conventional Woods-Saxon potentials. A shell-model study of ${}^{116}\mathrm{Sn}$ and ${}^{122}\mathrm{Sn}$ nuclei was performed using a realistic two-body effective interaction derived from the CD-Bonn nucleon-nucleon potential. The doubly magic nucleus ${}^{132}\mathrm{Sn}$ was assumed as a closed core, with the 16 and 10 valence neutron holes occupying the five levels of the 50-82 shell. The energy spectra have been calculated and compared with the experimental ones, and the theoretical two-nucleon spectroscopic amplitudes, evaluated in a truncated seniority space, have been used in the microscopic DWBA calculation of some cross-section angular distributions of both reactions.

The expansion of the fireball created in Au-Au collisions at $\sqrt{s}=200$ GeV and Pb-Pb collisions at $2.76$ TeV is modelled using relativistic viscous hydrodynamics. The experimentally observed interferometry radii are well reproduced. Additional pre-equilibrium flow slightly improves the results for the lower energies studied.

The Skyrme model is applied to the study of the $\pi N$ scattering amplitude. The useful expression of amplitude given by the chiral reduction formula is employed. The calculation is performed in the lowest order of $1/N_c$: a source of interaction is a classical soliton taking a hedgehog configuration. It is important to consider the zero modes both for the translation invariance and for the isospin symmetry simultaneously. Despite the former negative impression, the Skyrme model correctly produces the Born term in the scattering amplitude.

The rate of the carbon-nitrogen-oxygen (CNO) cycle of hydrogen burning is controlled by the ${}^{14}\mathrm{N}$($p$,$\gamma$)${}^{15}\mathrm{O}$ reaction. The reaction proceeds by capture to the ground states and several excited states in ${}^{15}\mathrm{O}$. In order to obtain a reliable extrapolation of the excitation curve to astrophysical energy, fits in the $R$-matrix framework are needed. In an energy range that sensitively tests such fits, new cross-section data are reported here for the four major transitions in the ${}^{14}\mathrm{N}$($p$,$\gamma$)${}^{15}\mathrm{O}$ reaction. The experiment has been performed at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400-kV accelerator placed deep underground in the Gran Sasso facility in Italy. Using a composite germanium detector, summing corrections have been considerably reduced with respect to previous studies. The cross sections for capture to the ground state and to the 5181, 6172, and 6792 keV excited states in ${}^{15}\mathrm{O}$ have been determined at 359, 380, and 399 keV beam energy. In addition, the branching ratios for the decay of the 278-keV resonance have been remeasured.

The question of how the scattering cross section changes when the spectra of the colliding nuclei have low-excitation particle-emitting resonances is explored using a multichannel algebraic scattering method. As a test case, the particle-unstable nucleus ${}^8\mathrm{Be}$ has been considered as a target. Nucleon-nucleus scattering cross sections, as well as the spectra of the compound nuclei formed, have been determined from calculations that consider, as well as those that disregard, particle-emission widths of the target nuclear states. The resonant character of the unstable excited states introduces a problem because the low-energy tails of these resonances can intrude into the subthreshold, bound-state region. This unphysical behavior needs to be corrected by modifying, in an energy-dependent way, the shape of the target resonances from the usual Lorentzian form. The resonance function must smoothly reach zero at the elastic threshold. We explore herein a way of achieving this condition.

Using a Langevin equation coupled with a statistical decay model, we calculate the excess of evaporation-residue cross sections over its standard statistical-model value as a function of nuclear dissipation strength for ${}^{200}\mathrm{Hg}$ compound nuclei (CNs) under two distinct types of initial conditions for populated CNs: (i) high excitation energy but low angular momentum (produced via proton-induced spallation reactions at GeV energies and via peripheral heavy-ion collisions at relativistic energies) and (ii) high angular momentum but low excitation energy (produced through fusion mechanisms). We find that the conditions of case (ii) not only amplify the effect of dissipation on the evaporation residues, but also substantially increase the sensitivity of this excess to nuclear dissipation. These results suggest that, in experiments, to obtain accurate information of presaddle nuclear dissipation strength by measuring evaporation-residue cross sections, it is best to choose the heavy-ion-induced fusion reaction approach to yield excited compound nuclei.

For projectile fragmentation, we work out details of a model whose origin can be traced back to the Bevalac era. The model positions itself between the phenomenological empirical parametrization of fragmentation cross sections (EPAX) and microscopic transport models like the heavy ion phase-space exploration (HIPSE) model and antisymmetrized molecular dynamics (AMD) model. We apply the model to some recent data of projectile fragmentation of Ni on Ta and Be at beam energy 140 MeV/nucleon and some older data of Xe on Al at beam energy 790 MeV/nucleon. Reasonable values of cross sections for various composites populated in the reactions are obtained.

We have measured the distributions of protons and deuterons produced in the 20% most central $\mathrm{Au}+\mathrm{Au}$ collisions at the Relativistic Heavy-Ion Collider (RHIC) ($\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV) over a very wide range of transverse and longitudinal momentum. Near midrapidity we have also measured the distribution of antiprotons and antideuterons. We present our results in the context of coalescence models. In particular, we extract the “homogeneity volume” and the average phase-space density for protons and antiprotons. Near central rapidity the coalescence parameter $B_2(p_T)$ and the space-averaged phase-space density $\langle f\rangle (p_T)$ are very similar for both protons and antiprotons. For protons we see little variation of either $B_2(p_T)$ or the space-averaged phase-space density as the rapidity increases from 0 to 3. However, these quantities depend strongly on $p_T$ at all rapidities. These results are in contrast to data from lower-energy collisions where the proton and antiproton phase-space densities are different at $y=0$, and both $B_2$ and $\langle f\rangle$ depend strongly on rapidity.

We present results from a hybrid description of Cu + Cu collisions using (3 + 1)-dimensional hydrodynamics (music) for the bulk evolution and a Monte Carlo simulation (martini) for the evolution of high-momentum partons in the hydrodynamical background. We explore the limits of this description by going to small system sizes and determine the dependence on different fractions of wounded nucleon and binary collisions scaling of the initial energy density. We find that Cu + Cu collisions are well described by the hybrid description at least up to 20% central collisions.

Fluctuations in the initial conditions for relativistic heavy ion collisions are proving to be crucial to understanding final state flow and jet quenching observables. The initial geometry has been parametrized in terms of moments in the spatial anisotropy (i.e., ${\epsilon }_2,{\epsilon }_3,{\epsilon }_4,{\epsilon }_5,\dots$), and it has been stated in multiple published articles that the vector directions of odd moments are uncorrelated with the even moments and the reaction place angle. In this article, we demonstrate that this is incorrect and that a substantial nonzero correlation exists between the even and odd moments in peripheral $\mathrm{Au}+\mathrm{Au}$ collisions. These correlations persist for all centralities, though at a very small level for the 0–$55\%$ most central collisions.

Using the (2$+$1)-dimensional viscous hydrodynamic code vish2+1 with a temperature-dependent specific shear viscosity $(\eta /s)(T)$, we present a detailed study of the influence of a large hadronic shear viscosity and its corresponding relaxation time ${\tau }_{\pi }$ on the transverse momentum spectra and elliptic flow of hadrons produced in $200A$ GeV Au$+$Au collisions. Although theory, in principle, predicts a well-defined relation ${\tau }_{\pi }T=\kappa (T)\times (\eta /s)(T)$, the precise form of $\kappa (T)$ for the matter created in relativistic heavy-ion collisions is not known. For the popular choice $\kappa =3$ the hadron spectra are found to be insensitive to a significant rise of $\eta /s$ in the hadronic stage, whereas their differential elliptic flow $v_2(p_T)$ is strongly suppressed by large hadronic viscosity. The large viscous effects on $v_2$ are strongly reduced if (as theoretically expected) $\kappa (T)$ is allowed to grow with decreasing temperature in the hadronic stage. This implies that, until reliable calculations of $\kappa (T)$ become available, an extraction of the hadronic shear viscosity from a comparison between vish2+1 and a microscopic hadron cascade or experimental data requires a simultaneous fit of $(\eta /s)(T)$ and $\kappa (T)$.

In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, the effect of the momentum dependence of the nuclear symmetry potential on the ${\pi }^{-}/{\pi }^{+}$ ratio in the neutron-rich reaction ${}^{132}\mathrm{Sn}$ $+$ ${}^{124}\mathrm{Sn}$ at a beam energy of $400$ MeV/nucleon is studied. We find that the momentum dependence of the nuclear symmetry potential affects the compressed density of colliding nuclei, the numbers of produced ${\pi }^{-}$ and ${\pi }^{+}$, as well as the value of the ${\pi }^{-}/{\pi }^{+}$ ratio. The momentum-dependent nuclear symmetry potential increases the compressed density of colliding nuclei, the number of produced resonances $\Delta (1232)$, $N^{*}(1440)$, ${\pi }^{-}$, and ${\pi }^{+}$, as well as the value of the ${\pi }^{-}/{\pi }^{+}$ ratio.

A potential experimental probe, the forward-backward elliptic anisotropy correlation ($C_{\mathrm{FB}}$), has been proposed by Liao and Koch to distinguish the jet and true elliptic flow contribution to the measured elliptic flow ($v_2$) in relativistic heavy-ion collisions. The jet and flow fluctuation contribution to elliptic flow is investigated within the framework of a multiphase transport model using the $C_{\mathit{FB}}$ probe. We find that the $C_{\mathit{FB}}$ correlation is remarkably different from, and about two times that, proposed by Liao and Koch. It originates from the correlation between fluctuation of forward and that of backward elliptic flow at a low transverse momentum, which is mainly caused by the initial correlation between fluctuation of forward and that of backward eccentricity. This results in an amendment of the $C_{\mathit{FB}}$ by a term related to the correlation between fluctuation of forward and that of backward elliptic flow. Our results suggest that a suitable rapidity gap for $C_{\mathrm{FB}}$ correlation studies is about $\pm$3.5.

We use the continuum shell model approach to explore the resonance width distribution in unstable many-body systems. The single-particle nature of a decay, the few-body character of the interaction Hamiltonian, and the collectivity that emerges in nonstationary systems due to the coupling to the continuum of reaction states are discussed. Correlations between the structures of the parent and daughter nuclear systems in the common Fock space are found to result in deviations of decay width statistics from the Porter-Thomas distribution.

Describing the hyperonic and quark phases of neutron stars with an isospin- and momentum-dependent effective interaction for the baryon octet and the MIT bag model, respectively, and using the Gibbs conditions to construct the mixed phase, we study the energy release from a neutron star owing to the hadron-quark phase transition. Moreover, the frequency and damping time of the first axial $w$ mode of gravitational waves are studied for both hyperonic and hybrid stars. We find that the energy release is much more sensitive to the bag constant than the density dependence of the nuclear symmetry energy. Also, the frequency of the $w$ mode is found to be significantly different with or without the hadron-quark phase transition and depends strongly on the value of the bag constant. Effects of the density dependence of the nuclear symmetry energy become, however, important for large values of the bag constant that lead to higher hadron-quark transition densities.

We study the impact on the primordial abundances of light elements created by a variation of the quark masses at the time of Big Bang nucleosynthesis (BBN). In order to navigate through the particle and nuclear physics required to connect quark masses to binding energies and reaction rates in a model-independent way, we use lattice QCD data and a hierarchy of effective field theories. We find that the measured ${}^4\mathrm{He}$ abundances put a bound of $-1\%\lesssim \delta m_q/m_q\lesssim 0.7\%$ on a possible variation of quark masses. The effect of quark mass variations on the deuterium abundances can be largely compensated by changes of the baryon-to-photon ratio $\eta$. Including bounds on the variation of $\eta$ coming from WMAP results and adding some additional assumptions further narrows the range of allowed values of $\delta m_q/m_q$.

We present dynamic polarization potentials (DPPs) arising from neutron pickup coupled reaction channels, contributing to the proton-nucleus interaction for 71 MeV/nucleon protons scattering from ${}^6\mathrm{He}$. The DPPs do not represent a uniform renormalization of the potential and result in a change in the rms radius of the real part. The inclusion of breakup of the deuteron somewhat reduces the repulsive effect of the coupling and enhances the absorption. The linearity of the coupling effect suggests a method of incorporating it into a computationally feasible phenomenological scheme.

We extend the ab initio no-core shell model/resonating-group method (NCSM/RGM) to projectile-target binary-cluster states where the projectile is a deuteron. We discuss the formalism in detail and give algebraic expressions for the integration kernels. Using a soft similarity-renormalization-group evolved chiral nucleon-nucleon potential, we calculate deuteron-${}^4\mathrm{He}$ scattering and investigate ${}^6\mathrm{Li}$ bound and unbound states. Virtual three-body breakup effects are obtained in an approximated way by including excited pseudostates of the deuteron in the calculation. We compare our results to experiment and to a standard NCSM calculation for ${}^6\mathrm{Li}$.