We studied two-photon exchange for elastic electron-proton scattering at low $Q^2$. Compact approximate formulas for the amplitudes were obtained. Numerical calculations were done for $Q^2⩽0.1{\mathrm{GeV}}^2$ with several realistic form factor parametrizations, yielding similar results. They indicate that the corrections to the magnetic form factor can visibly affect the cross-section and proton radii. For low-$Q^2$ electron-neutron scattering two-photon exchange corrections were shown to be negligibly small.

We study the radiative energy loss of hard partons in a soft medium in the multiple soft scattering approximation. The soft medium is described by a 3D hydrodynamical model and we treat the averaging over all possible parton paths through the medium without approximation. While the nuclear suppression factor $R_{AA}$ does not reflect the high quality of the medium description (except in a reduced systematic uncertainty in extracting the quenching power of the medium), the hydrodynamical model also allows to study different centralities and in particular the angular variation of $R_{AA}$ with respect to the reaction plane, allowing for a controlled variation of the in-medium path-length. We study the angular dependence of $R_{AA}$ for different centralities, discuss the influence of hydrodynamical expansion and flow and comment on the comparison with preliminary data.

We calculate the static nucleon-antinucleon interaction potential from the modified Skyrme model with an additional $B^{\mu }{B}_{\mu }$ term using the product ansatz. The static properties of the single baryon are improved in the modified Skyrme model. State mixing is taken into account by perturbation theory, which substantially increases the strength of the central attraction. We obtain a long- and mid-range potential which is in qualitative agreement with some phenomenological potentials.

Focusing on α clustering, the structure of ${}^{22}\mathrm{Ne}$ was studied. We predict the presence of the molecular orbital bands that have an $\alpha +$ ${}^{16}\mathrm{O}$ cluster core surrounded by two neutrons occupying the molecular orbitals, together with $\alpha +$ ${}^{18}\mathrm{O}$ molecular bands. The formation of the $\alpha +$ ${}^{16}\mathrm{O}$ cluster core and its close relation to the configuration of two valence neutrons are discussed.

The excited states of the neutron-rich nucleus ${}_{15}^{37}{\mathrm{P}}_{22}$ have been populated in grazing reactions, using a beam of ${}^{36}\mathrm{S}$ ions (at 215 MeV) delivered onto a thin ${}^{208}\mathrm{Pb}$ target. Emitted γ rays from excited projectile-like nuclei were detected using the CLARA array of 25 escape-suppressed Ge clover detectors in coincidence with reaction products detected and identified with the PRISMA magnetic spectrometer. A level scheme is presented for ${}^{37}\mathrm{P}$ together with proposed spin assignments. The level structure of ${}^{37}\mathrm{P}$ is discussed within the context of shell-model calculations by using an improved $\mathit{sdpf}$ effective interaction.

The asymmetry term effects for the cross sections of ($n$, charged particle) and ($n,2n$) reactions at 14–15 MeV neutron incident energy have been investigated. The effects of pairing and odd-even nucleon numbers in new data and in the formula of Tel et al. [J. Phys. G. 29, 2169 (2003)] are discussed. We have determined three different parameters groups by the classification of nuclei into even-even, even-odd, and odd-even ($n,d$) reactions. In addition, since there are not enough experimental data available, we have considered two different parameters groups by the classification of nuclei into odd-$A$ and even-$A$ ($n,t$) reaction cross sections. The empirical formulas with two parameters for the evaluation of the ($n,d$) and ($n,t$) reactions cross sections are discussed in the present study.

In-medium nucleon-nucleon scattering cross sections are explored by comparing results of quantum molecular dynamics simulations to data on stopping and on elliptic and directed flow in intermediate-energy heavy-ion collisions. The comparison points to in-medium cross sections which are suppressed at low energies but not at higher energies. Positive correlations are found between the degree of stopping and the magnitudes of elliptic and directed flows.

Recently, the first nuclei to lie along an arc of regularity in the collective symmetry triangle were identified. These nuclei are predicted to display significantly more ordered spectra than their neighbors. The nuclei identified all lie in the rare earth region from $A=156–180$. Here we present the results of a search of all known nuclei from $A=90–208$ and have identified an additional set of such candidates for regular nuclei using a particular degeneracy condition as a signature.

A comparative study of the microscopic optical potentials viz., semimicroscopic with extended Jeukenne-Lejeune-Mahaux interaction and microscopic Brueckner theory using Hamada-Johnston as well as Urbana V14 soft-core internucleon interactions, has been carried out. These microscopic optical potentials are compared with that of Dirac phenomenology (DP) for the polarized proton-${}^{40}\mathrm{Ca}$ elastic scattering at 35 MeV and 200 MeV. These potentials have different shapes for 200 MeV below 4 fm. In particular, for the real part of the central potential, only the Dirac phenomenology and the microscopic optical potential calculated with the Hamada-Johnston interaction exhibit the well known wine-bottle-bottom shape. It is found that the calculated observables (cross section, analyzing power and spin rotation function) using these potentials having different shapes, compare well with the experiment.

High-spin states in ${}^{79}\mathrm{Sr}$ were studied using the ${}^{54}\mathrm{Fe}$(${}^{28}\mathrm{Si}$,$2p$$n$) reaction at 90 MeV, with a thick 14-mg/${\mathrm{cm}}^2$ ${}^{54}\mathrm{Fe}$ target used to stop all recoils. Prompt $\gamma \text{−}\gamma$ coincidences were detected using the Florida State University Compton-suppressed Ge array consisting of three Clover detectors and seven single-crystal detectors. The most recent ${}^{79}\mathrm{Sr}$ level scheme has been confirmed in three separate band structures up to a spin as high as the $({\frac{37}{2}}^{+})$ yrast state based on γ-ray coincidence relations, intensity and effective lifetime measurements, and directional correlation of oriented nuclei ratios. Lifetimes of 33 excited states were measured using the Doppler-shift attenuation method, with the experimental line shapes obtained at two separate observation angles and by gating from above the transitions of interest whenever possible. Transition quadrupole moments $Q_t$ inferred from the lifetimes indicate a high degree of collectivity and deformation over a rather wide range of spins in all three observed bands, with evidence for modest reductions in the values with increasing spin. The changes in $Q_t$ are attributed to the onset of quasiproton alignment and are supported qualitatively by the predictions of the projected shell model and cranked Woods-Saxon calculations in conjunction with the cranked shell model. Lifetimes measured in a band based on the [431]${\frac{1}{2}}^{+}$ intrinsic Nilsson configuration suggest a large quadrupole deformation (${\beta }_2\approx 0.41$) associated with this band, providing another example of the strong deformation-driving properties of the $d_{5/2}$ intruder orbital in the mass 80 region.

Using the quantum molecular dynamics approach, we analyzed the results of the recent INDRA Collaboration Au+Au experiments at GSI in the energy range between $60A$ and $150A$ MeV. It turns out that in this energy region, the transition toward a participant-spectator scenario takes place. The large Au+Au system displays, in the simulations as in the experiment, simultaneously dynamical and statistical behavior, which we analyze in detail. The composition of fragments close to midrapidity follows statistical laws, and the system shows bimodality, i.e., a sudden transition between different fragmentation patterns, as a function of centrality, as expected for a phase transition. The fragment spectra at small and large rapidities, on the other hand, are determined by dynamics, and the system as a whole does not come to equilibrium—an observation that is confirmed by FOPI Collaboration experiments for the same system.

The semi-relativistic approach to electron and neutrino quasielastic scattering from nuclei is extended to include final-state interactions. Starting with the usual nonrelativistic continuum shell model, the problem is relativized by using the semi-relativistic expansion of the current in powers of the initial nucleon momentum and relativistic kinematics. Two different approaches are considered for the final-state interactions: the Smith-Wambach 2p-2h damping model and the Dirac-equation-based potential extracted from a relativistic mean-field plus the Darwin factor. Using the latter, the scaling properties of $(e,e^{\prime })$ and $({\nu }_{\mu },{\mu }^{-})$ cross sections for intermediate momentum transfers are investigated.

We present a new formalism for the theory of relativistic dissipative hydrodynamics. Here, we look for the minimal structure of such a theory which satisfies the covariance and causality by introducing the memory effect in irreversible currents. Our theory has a much simpler structure and thus has several advantages for practical purposes compared to the Israel-Stewart theory (IS). It can readily be applied to the full three-dimensional hydrodynamical calculations. We apply our formalism to the Bjorken model and the results are shown to be analogous to the IS.

We take the Δ-isobar degrees of freedom into account in neutron star matter and evaluate their contributions to neutrino scattering cross sections and mean free paths. The neutron star matter is described by means of an effective hadronic model in the relativistic mean-field approximation. It is found that Δ isobars may be present in neutron stars. The electron chemical potential does not decrease and the neutrino abundance does not increase with the increase of the density when neutrinos are trapped in the matter with Δ isobars. The large vector coupling constant between the ${\Delta }^{-}$ and neutrino and the high spin of the Δ influence significantly the neutrino scattering cross section and lead the contribution of the ${\Delta }^{-}$ to the dominance of the scattering rates. In neutrino-trapped case, the presence of Δs causes the neutrino mean free path to decrease drastically compared to that in the matter in which baryons are only nucleons.

The Canadian Penning Trap mass spectrometer has been used to determine the mass excesses of ${}^{64}\mathrm{Ge}$ and ${}^{64}\mathrm{Ga}$ as −54344(30) keV and −58832.5(39) keV, respectively. Under typical conditions used for modeling x-ray bursts, ${}^{64}\mathrm{Ge}$ is confirmed as a waiting-point nuclide and can contribute up to 35.5 s to the timescale of the $\mathit{rp}$ process at a peak x-ray burst temperature of 1.5 GK.

The negative parity states and some electromagnetic transition properties of even-odd erbium isotopes (${}^{159,161,163,165}\mathrm{Er}$) were studied within the framework of the interacting boson-fermion model. The single fermion is assumed to be in one of the ${\mathit{lh}}_{9/2},3p_{3/2},2f_{5/2}$, and $3p_{1/2}$ single-particle orbits. It was found that the calculated negative parity state energy spectra of the even-odd erbium isotopes agree quite well with the experimental data. The $B(E2)$ values were also calculated and compared with the experimental data.

Isospin is a good quantum number under the assumption that the nuclear interaction is charge independent. An analogous structure of excited states is expected for nuclei with the same mass number $A$ but with different $z$ components $T_z$ of the isospin $T$, where $T_z=(N-Z)/2$. The analogous structure has been studied for the isobaric nuclei ${}^{58}\mathrm{Ni}$ and ${}^{58}\mathrm{Cu}$ by comparing the transitions from the ${}^{58}\mathrm{Ni}$ ground state (initial isospin $T_i=1$ and $J^{\pi }=0^{+}$) to the $M1$ and the Gamow-Teller (GT) states ($J^{\pi }=1^{+}$) in ${}^{58}\mathrm{Ni}$ and ${}^{58}\mathrm{Cu}$, respectively. For this purpose, proton inelastic scattering ($p,p^{\text{'}}$) at $E_p=160$ MeV and the charge-exchange (${}^3\mathrm{He}$,$t$) reaction at 140 MeV/nucleon were both measured at $0^{°}$, exciting final states with isospin $T_f=1$ and 2 and $T_f=0$, 1, and 2, respectively. High energy and scattering-angle resolutions were achieved by applying complete beam matching techniques. On the basis of the correspondence between excitation energies and transition strengths, isospin values $T_f=1$ and 2 of analog GT and $M1$ states were identified. The distribution of $T_f=2$ states was also compared with results of ${}^{58}\mathrm{Ni}$($d,$${}^2\mathrm{He}$), ${}^{58}\mathrm{Ni}$($t,$${}^3\mathrm{He}$), and ${}^{58}\mathrm{Ni}$($n,p$) experiments, in which only $T_f=2$ states are excited. The obtained GT strength distribution is compared with the results of shell-model calculations.

We report differential cross section measurements for the stretched transition from the ${}^{10}\mathrm{B}$ ground state ($J^{\pi }=3^{+}$) to the ${}^{10}\mathrm{Be}$ ground state ($J^{\pi }=0^{+}$) in the ${}^{10}\mathrm{B}$($n,p$)${}^{10}\mathrm{Be}$ (g.s.) reaction. These data were obtained over the energy range from 70 to 240 MeV, covering momentum transfer values from 0.6 to 2.5 fm${}^{-1}$. In this momentum transfer range, the isovector tensor effective interaction dominates the transition. Cross sections are compared to zero- and finite-range distorted wave impulse approximation calculations using modern free and density-dependent effective interactions and a transition density consistent with ($e,e^{\text{'}}$) data. Good agreement is observed at energies above 120 MeV, but below this energy the cross sections are larger than the calculated values by more than 40%. The implications for DWIA calculations are discussed.

Spin transfer from circularly polarized real photons to recoiling hyperons has been measured for the reactions $\overrightarrow{\gamma }+p\to K^{+}+\overrightarrow{\Lambda }$ and $\overrightarrow{\gamma }+p\to K^{+}+{\overrightarrow{\Sigma }}^0$. The data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS) detector at the Jefferson Lab for center-of-mass energies $W$ between 1.6 and 2.53 GeV, and for $-0.85<\cos {\theta }_{K^{+}}^{c.m.}<+0.95$. For the Λ, the polarization transfer coefficient along the photon momentum axis, $C_z$, was found to be near unity for a wide range of energy and kaon production angles. The associated transverse polarization coefficient $C_x$ is smaller than $C_z$ by a roughly constant difference of unity. Most significantly, the total $\Lambda$ polarization vector, including the induced polarization $P$, has magnitude consistent with unity at all measured energies and production angles when the beam is fully polarized. For the ${\Sigma }^0$ this simple phenomenology does not hold. All existing hadrodynamic models are in poor agreement with these results.

A neutron-α-particle coincidence experiment was performed to study breakup of ${}^6\mathrm{He}$ on a ${}^{209}\mathrm{Bi}$ target at an incident energy of 22.5 MeV. Direct breakup, as well as breakup through the $2^{+}$ excited state of ${}^6\mathrm{He}$ and also the ${}^5\mathrm{He}$$+n$ channel, could be distinguished. A total breakup cross section of $205\pm 65$ mb was measured. The data compare well with a coupled-channels calculation that assumes a 50% reduction in the B(E1) computed from a pure ${}^4\mathrm{He}$$+2n$ cluster configuration, in agreement with results obtained at much higher energies. A value of $\mathrm{B}(\mathrm{E}2\Uparrow )=5.4\pm 0.7e^2{\mathrm{fm}}^4$ is deduced for the $2^{+}$ state in ${}^6\mathrm{He}$.