We reexamine several issues related to the physics of scaling in electron scattering from nuclei. A basic model is presented in which an assumed form for the momentum distribution having both long- and short-range contributions is incorporated in the single-particle Green’s function. From this one can obtain saturation of nuclear matter for an $NN$ interaction with medium-range attraction and short-range repulsion and obtain the density-density polarization propagator and, hence, the electromagnetic response and scaling function. For the latter, the shape of the scaling function and how it approaches scaling as a function of momentum transfer are both explored.

An interacting-boson-model Hamiltonian determined from Hartree-Fock-Bogoliubov calculations with the microscopic Gogny energy density functional D1M is applied to the spectroscopic analysis of neutron-rich Yb, Hf, W, Os, and Pt isotopes with mass $A\sim 180$–200. Excitation energies and transition rates for the relevant low-lying quadrupole collective states are calculated by this method. Transitions from prolate to oblate ground-state shapes are analyzed as a function of neutron number $N$ in a given isotopic chain by calculating excitation energies, $B\left(E2\right)$ ratios, and correlation energies in the ground state. It is shown that such transitions tend to occur more rapidly for the isotopes with lower proton number $Z$ when departing from the proton shell closure $Z=82$. The triaxial degrees of freedom turn out to play an important role in describing the considered mass region. Predicted low-lying spectra for the neutron-rich exotic Hf and Yb isotopes are presented. The approximations used in the model and the possibilities to refine its predictive power are addressed.

We extract the two-photon exchange (TPE) contributions to electron-proton elastic scattering using two parametrizations and compare the results to different phenomenological extractions and direct calculations of the TPE effects. We find that many of the extractions give similar results and highlight the common assumptions and the impact of not including these assumptions. We provide a simple parametrization of the TPE contribution to the unpolarized cross section, along with an estimate of the fit uncertainties and the uncertainties associated with the model dependence of the extractions. We look at the contributions as extracted from various $e$-$p$ elastic-scattering observables and make predictions for ratio of positron-proton to electron-proton elastic-scattering cross sections.

A new dynamical symmetry limit of the two-fluid interacting vector boson model (IVBM), defined through the chain $\text{Sp}(12,R)\supset \text{U}(3,3)\supset {\text{U}}^{*}\left(3\right)\otimes \text{SU}(1,1)\supset {\text{SU}}^{*}\left(3\right)\supset \text{SO}\left(3\right)$, is introduced. The SU${}^{*}$(3) algebra considered in the present paper closely resembles many properties of the SU${}^{*}$(3) limit of the interacting boson model-2, which have been shown by many authors geometrically to correspond to the rigid triaxial model. The influence of different types of perturbations on the SU${}^{*}$(3) energy surface, in particular the addition of a Majorana interaction and an O(6) term to the model Hamiltonian, is studied. The effect of these perturbations results in the formation of a stable triaxial minimum in the energy surface of the IVBM Hamiltonian under consideration. Using a schematic Hamiltonian that possesses a perturbed SU${}^{*}$(3) dynamical symmetry, the theory is applied for the calculation of the low-lying energy spectrum of the nucleus ${}^{192}$Os. The theoretical results obtained agree reasonably with the experimental data and show a very shallow triaxial minimum in the energy surface for the ground state in ${}^{192}$Os, suggesting that the proposed dynamical symmetry might be appropriate for the description of the collective properties of different nuclei, exhibiting triaxial features.

In the framework of the classical Glauber approach, the analytical expressions for the variance of the number of wounded nucleons and binary collisions in $AA$ interactions at a given centrality are presented. Along with the optical approximation term, they contain additional contact terms arising only in the case of nucleus-nucleus collisions. The magnitude of the additional contributions, e.g., for PbPb collisions at Super Proton Synchrotron (SPS) energies, is larger than the contribution of the optical approximation at some values of the impact parameter. The sum of the additional contributions is in good agreement with the results of independent Monte Carlo simulations of this process. Due to these additional terms, the variance of the total number of participants for peripheral PbPb collisions and the variance of the number of collisions at all values of the impact parameter exceed several multiples of the Poisson variances. The correlator between the numbers of participants in colliding nuclei at fixed centrality is also analytically calculated.

Quarks produced in the early stage of noncentral heavy-ion collisions could develop a global spin polarization along the opposite direction of the reaction plane due to the spin-orbital coupling via parton interaction in a medium that has finite longitudinal flow shear along the direction of the impact parameter. We study how such polarization evolves via multiple scattering in a viscous quark-gluon plasma with an initial laminar flow. The final polarization is found to be sensitive to the viscosity and the initial shear of local longitudinal flow.

The shear viscosity of a gluon gas is calculated using the Green-Kubo relation. Time correlations of the energy-momentum tensor in thermal equilibrium are extracted from microscopic simulations using a parton cascade solving various Boltzmann collision processes. We find that the perturbation-QCD- (pQCD-) based gluon bremsstrahlung described by Gunion-Bertsch processes significantly lowers the shear viscosity by a factor of 3 to 8 compared to elastic scatterings. The shear viscosity scales with the coupling as $\eta \sim 1/\left[{\alpha }_s^2\log (1/{\alpha }_s)\right]$. For constant ${\alpha }_s$ the shear viscosity to entropy density ratio $\eta /s$ has no dependence on temperature. Replacing the pQCD-based collision angle distribution of binary scatterings by an isotropic form decreases the shear viscosity by a factor of 3.

Heavy quarkonia are observed to be suppressed in relativistic heavy-ion collisions relative to their production in $p+p$ collisions scaled by the number of binary collisions. In order to determine if this suppression is related to color screening of these states in the produced medium, one needs to account for other nuclear modifications including those in cold nuclear matter. In this paper, we present new measurements from the PHENIX 2007 data set of $J/\psi$ yields at forward rapidity ($1.2<\left|y\right|<2.2$) in $\text{Au}+\text{Au}$ collisions at $\sqrt{s_{{}_{NN}}}=200$ GeV. The data confirm the earlier finding that the suppression of $J/\psi$ at forward rapidity is stronger than at midrapidity, while also extending the measurement to finer bins in collision centrality and higher transverse momentum ($p_T$). We compare the experimental data to the most recent theoretical calculations that incorporate a variety of physics mechanisms including gluon saturation, gluon shadowing, initial-state parton energy loss, cold nuclear matter breakup, color screening, and charm recombination. We find $J/\psi$ suppression beyond cold-nuclear-matter effects. However, the current level of disagreement between models and $d+\text{Au}$ data precludes using these models to quantify the hot-nuclear-matter suppression.

We present an updated extraction of the proton electromagnetic form factor ratio, ${\mu }_p{G}_E/G_M$, at low $Q^2$. The form factors are sensitive to the spatial distribution of the proton, and precise measurements can be used to constrain models of the proton. An improved selection of the elastic events and reduced background contributions yielded a small systematic reduction in the ratio ${\mu }_p{G}_E/G_M$ compared to the original analysis.

Using the isospin-dependent quantum molecular dynamics model, we study the effect of charge asymmetry and isospin-dependent cross section on nuclear stopping and multiplicity of free nucleons and light mass fragments. Simulations were carried out for the reactions ${}^{124}{X}_m+{}^{124}{X}_m$, where $m$ varies from 47 to 59 and for ${}^{40}{Y}_n+{}^{40}{Y}_n$, where $n$ varies from 14 to 23. Our study shows that nuclear stopping depends strongly on the isospin of the cross section.

We study the structure of the neutron-rich ${}^{44}$S isotope with modern configuration mixing methods based on the Gogny interaction, including beyond-mean-field effects. Restoration of particle number and rotational symmetries are taken into account as well as shape mixing in the whole triaxial $({\beta }_2,\gamma )$ plane. We obtain a qualitative agreement between the calculated spectrum and the experimental data reported recently. Very extended collective wave functions in the $({\beta }_2,\gamma )$ plane are found for the lowest states, corresponding to very flat potentials, which indicate wide configuration mixing and support the weakening of the $N=28$ magic number.

Deviations from the isobaric multiplet mass equation are presented and discussed for the $A=7$, $T=3/2$ quartet and the $A=8$, $T=2$ quintet.

Evidence of strong coupling of quasiparticle excitations with $\gamma$ vibration is shown to occur in transitional nuclei. High-spin band structures in ${}^{166,168,170,172}$Er are studied by employing the recently developed multiquasiparticle triaxial projected shell model approach. It is demonstrated that a low-lying $K=3$ band observed in these nuclei, the nature of which has remained unresolved, originates from the angular-momentum projection of triaxially deformed two-quasiparticle (qp) configurations. Furthermore, it is predicted that the structure of this band depends critically on the shell filling: in ${}^{166}$Er the lowest $K=3$ 2-qp band is formed from proton configuration, in ${}^{168}$Er the $K=3$ neutron and proton 2-qp bands are almost degenerate, and for ${}^{170}$Er and ${}^{172}$Er the neutron $K=3$ 2-qp band becomes favored and can cross the $\gamma$-vibrational band at high rotational frequencies. We consider that these are a few examples in even-even nuclei, where the three basic modes of rotational, vibrational, and quasiparticle excitations coexist close to the yrast line.

Electromagnetic interactions of the ground and first radial excited states of $\eta$ and ${\eta }^{\prime }$ mesons in the framework of the extended U$\left(3\right)\times \text{U}\left(3\right)$ Nambu–Jona-Lasinio model are considered. The radial excitations are described with the help of polynomial form factor of the second order over the inner quark momentum. The solution of the U${}_A\left(1\right)$ problem by means of 't Hooft interaction is taken into account. For diagonalization of the free Lagrangian, the $4\times 4$ mixing matrix is used. Two-photon decay widths of the ground $\eta$ and ${\eta }^{\prime }$ mesons are found to be in a satisfactory agreement with the experiment. Predictions for the two-photon decay widths of $\eta \left(1295\right)$ and $\eta \left(1475\right)$ are given. The probabilities of $\eta$-meson production by a two-photon mechanism in $e^{+}{e}^{-}$ collisions and of their photoproduction on electrons are calculated.

One-nucleon overlap functions required for various nucleon-removal calculations must be solutions of the inhomogeneous equation with a source term whose shape and strength are determined by nuclear wave functions and the effective interaction of the removed nucleon with the nucleons in the remainder nucleus. A number of previous works has reported calculations of the source term and the overlap functions for a range of $A⩽16$ nuclei. It was shown that the source-term approach gives reasonable results for spectroscopic factors and asymptotic normalization coefficients and, in particular, it explains the phenomenon of reduction of spectroscopic factors observed in knockout reactions. In the present article, the source-term approach has been extended to $A⩾16$ nuclei. To achieve this, a new technique has been developed which excludes the spurious center-of-mass motion within the translation-invariant oscillator shell model. Applications using this technique are performed for double-closed-shell nuclei, both stable and away from $\beta$ stability, such as ${}^{16,24}$O, ${}^{40,48,60}$Ca, ${}^{56,78}$Ni, ${}^{100,132}$Sn, and ${}^{208}$Pb. The spectroscopic factors and asymptotic normalization coefficients for one-nucleon removal and addition have been calculated. They are compared to experimental values and results from other microscopic models when available.

Simultaneous measurement of the proton-transfer ${}^{18}\mathrm{F}{(d,n)}^{19}\mathrm{Ne}$ and neutron-transfer ${}^{18}\mathrm{F}{(d,p)}^{19}\mathrm{F}$ reactions were performed with a ${}^{18}\mathrm{F}$ radioactive beam at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. The experiments clarify the nuclear structure of ${}^{19}\mathrm{Ne}$ near the proton threshold, which is relevant for understanding the rates of proton-induced reactions on ${}^{18}\mathrm{F}$ in novae. Analogs for several states in the mirror nucleus ${}^{19}\mathrm{F}$ have not yet been identified in ${}^{19}\mathrm{Ne}$, indicating that the level structure of ${}^{19}\mathrm{Ne}$ in this region is incomplete. We observed 15 levels in ${}^{19}\mathrm{Ne}$ from the ${}^{18}\mathrm{F}{(d,n)}^{19}\mathrm{Ne}$ measurement and 18 levels in ${}^{19}\mathrm{F}$ from the ${}^{18}\mathrm{F}{(d,p)}^{19}\mathrm{F}$ measurement. Angular distributions were extracted for all strongly populated states and compared to distorted-wave Born approximation calculations. The angular distributions for all the known states in the two nuclei determined in this work are consistent with their previously assigned spins and parities. The spectroscopic factors determined for these levels in the two nuclei are reported.

In a recent paper [Phys. Rev. C 83, 044612 (2011)] we proposed a model for calculating cross sections of various reaction products which arise from disintegration of projectile-like fragments resulting from heavy-ion collisions at intermediate or higher energy. The model has three parts: (1) abrasion, (2) disintegration of the hot abraded projectile-like fragment (PLF) into nucleons and primary composites using a model of equilibrium statistical mechanics, and (3) possible evaporation of hot primary composites. It was assumed that the PLF resulting from abrasion has one temperature $T$. Data suggested that, while just one value of $T$ seemed adequate for most cross-section calculations, a single value failed when dealing with very peripheral collisions. We have now introduced a variable $T=T\left(b\right)$ where $b$ is the impact parameter of the collision. We argue that there are data which not only show that $T$ must be a function of $b$ but, in addition, also point to an approximate value of $T$ for a given $b$. We propose a very simple formula: $T\left(b\right)=D_0+D_1[A_s\left(b\right)/A_0]$ where $A_s\left(b\right)$ is the mass of the abraded PLF and $A_0$ is the mass of the projectile; $D_0$ and $D_1$ are constants. Using this model we compute cross sections for several collisions and compare with data.

Elastic, inelastic, and one-nucleon transfer channels in the ${}^{48}$Ca + ${}^{64}$Ni reaction have been measured at $\approx 6$ MeV/nucleon with the PRISMA-CLARA setup, at Legnaro National Laboratory, consisting of the coupling of a large solid angle magnetic spectrometer with a germanium array. By trajectory reconstruction the reaction products have been fully identified in mass, nuclear charge, and kinetic energy, while coincident $\gamma$ spectra of binary partners have been constructed after Doppler correction. Absolute differential cross sections have been extracted for the inelastic excitation and one-nucleon transfer, also for specific excited states. The data are in good agreement with semiclassical calculations and distorted wave Born approximation predictions. The work outlines an experimental method which can become valuable to extract structural information from heavy-ion reaction studies.

Particle decay of ${}^{69}$Br and ${}^{65}$As was observed through $\beta$-delayed proton emission of ${}^{69}$Kr and ${}^{65}$Se, respectively. Decay spectroscopy was performed through $\beta$-$p$ correlations using a position-sensitive silicon-implantation detector surrounded by a $\gamma$-ray detector array. A $\beta$-decay half-life of 27(3) ms was measured for ${}^{69}$Kr and 33(4) ms for ${}^{65}$Se. The ${}^{69}$Kr ground state decays by a superallowed transition to its unbound isobaric analog state in ${}^{69}$Br which immediately decays by a 2.97(5)-MeV proton group to the first excited state in ${}^{68}$Se at 854.2 keV. This chain of decays constrains both the mass and spin of the ${}^{69}$Kr ground state. We observed no evidence of ground-state proton decay from ${}^{69}$Br.

The high-spin structure above the previously known 10${}^{+}$ isomers of the ${}^{118,120,122,124}$Sn isotopes was studied via prompt $\gamma$-ray spectroscopy. All isotopes were populated as fragments following the fission of much heavier compound nuclei formed in three fusion-fission reactions. The ${}^{118,120,122}$Sn isotopes were also independently populated and studied as evaporation residues in the ${}^{124}$Sn$(n,xn\gamma )$ reactions, with $x=3,5,7$. Transitions above the previously known 10${}^{+}$ isomers were observed for the first time and the corresponding level schemes above these isomers were established up to 6646-, 5673-, 5386-, and 5952-keV excitation energy for ${}^{118,120,122,124}$Sn, respectively. The experimental results are compared with predictions from shell-model calculations.