We report an upper bound on parity-violating neutron spin rotation in ${}^4\mathrm{He}$. This experiment is the most sensitive search for neutron-weak optical activity yet performed and represents a significant advance in precision in comparison to past measurements in heavy nuclei. The experiment was performed at the NG-6 slow-neutron beamline at the National Institute of Standards and Technology (NIST) Center for Neutron Research. Our result for the neutron spin rotation angle per unit length in ${}^4\mathrm{He}$ is $d\varphi /\mathit{dz}=[+1.7\pm 9.1(\text{stat.})\pm 1.4(\text{sys.})]\times {10}^{-7}$ rad/m. The statistical uncertainty is smaller than current estimates of the range of possible values of $d\varphi /\mathit{dz}$ in $n{+}^4$He.

We study the generalized seniority properties of the low-lying states of two semimagic pseudonuclei ${}^{22}\mathrm{O}$ and ${}^{46}\mathrm{Ca}$ in the presence of one- and two-body random interactions. When the single-particle splittings are sufficiently large, $S$-pair correlation is found to be important in the low-lying states of these systems in the presence of random interactions.

$\gamma$-ray production cross sections have been measured in proton irradiations of N, Ne, and Si and $\alpha$-particle irradiations of N and Ne. In the same experiment we extracted also line shapes for strong $\gamma$-ray lines of ${}^{16}\mathrm{O}$ produced in proton and $\alpha$-particle irradiations of O. For the measurements gas targets were used for N, O, and Ne and a thick foil for Si. All targets were of natural isotopic composition. Beams in the energy range up to 26 MeV for protons and 39 MeV for $\alpha$ particles were delivered by the Institut de Physique Nucléaire–Orsay tandem accelerator. The $\gamma$ rays were detected with four high-purity Ge detectors in the angular range ${30}^{°}$ to ${135}^{°}$. We extracted 36 cross-section excitation functions for proton reactions and 14 for $\alpha$-particle reactions. For the majority of the excitation functions no other data exist to our knowledge. Where comparison with existing data was possible, usually a very good agreement was found. It is shown that these data are very interesting for constraining nuclear reaction models. In particular, the agreement of cross section calculations in the nuclear reaction code talys with the measured data could be improved by adjusting the coupling schemes of collective levels in the target nuclei ${}^{14}\mathrm{N}$, ${}^{20,22}\mathrm{Ne}$, and ${}^{28}\mathrm{Si}$. The importance of these results for the modeling of nuclear $\gamma$-ray line emission in astrophysical sites is discussed.

We study the effect of strong longitudinal color fields (SCF) in $p$ + $p$ reactions up to Large Hadron Collider (LHC) energies in the framework of the hijing/B$\overline{\mathrm{B}}$ (v2.0) model that combines (collinear factorized) perturbative quantum chromodynamics multiple minijet production with soft longitudinal string excitation and hadronization. The default vacuum string tension, ${\kappa }_0$  =  1 GeV/fm, is replaced by an effective energy-dependent string tension, $\kappa (s)={\kappa }_0(s/s_0){}^{0.06}$ that increases monotonically with center-of-mass energy. The exponent $\lambda =0.06$ is found sufficient to reproduce well the energy dependence of multiparticle observables in the Relativistic Heavy Ion Collider, Tevatron, as well as recent LHC data. This exponent is half of that predicted by the color glass saturation (CGC) model, ${\lambda }_{\mathrm{CGC}}=0.115$, where gluon fusion multiparticle production mechanisms are assumed. In hijing/B$\overline{\mathrm{B}}$ (v2.0), the rapid growth of ${\mathit{dN}}_{\mathrm{ch}}/d\eta$ with energy is due to the interplay of copious minijet production with increasing SCF contributions. The large (strange) baryon-to-meson ratios measured at Tevatron energies are well described. A significant enhancement of these ratios is predicted up to the highest LHC energy (14 TeV). The effect of $\mathcal{J}\overline{\mathcal{J}}$ loops and SCF on baryon-antibaryon asymmetry, and its relation to baryon number transport, is also discussed.

The cross section for exclusive heavy-quark and heavy-antiquark pair ($Q\mathrm{Q̄}$) production in peripheral ultrarelativistic heavy-ion collisions is calculated at an energy available at the CERN Large Hadron Collider, i.e., $\sqrt{s_{\mathit{NN}}}$ = 5.5 TeV. Here we consider only processes with photon-photon interactions and omit diffractive contributions. We present results in the impact parameter equivalent photon approximation and compare some of them with results obtained by exact calculations of the Feynman diagrams in the momentum space. We include $Q\mathrm{Q̄}$, $Q\mathrm{Q̄}g$, and $Q\mathrm{Q̄}q\mathrm{q̄}$ final states as well as photon single-resolved components. Realistic charge densities in nuclei were taken in the calculation. The different components give contributions of the same order of magnitude to the nuclear cross section. The cross sections found here are smaller than those for the diffractive photon-Pomeron mechanism and larger than the diffractive Pomeron-Pomeron discussed in the literature.

We calculate the two-photon exchange amplitude for elastic electron-pion scattering in the dispersion-relation-inspired approach, including both elastic and inelastic contributions. The latter was modeled as a sum of $\rho$- and $b_1(1235)$-meson contributions. We find that at $Q^2\lesssim 2\mathrm{\hspace{0.5em}}{\mathrm{GeV}}^2$ the elastic contribution is dominant, similarly to the electron-proton scattering case. At higher $Q^2$ the inelastic contribution is not negligible, but still smaller than the elastic one. We also explain the observed rapid amplitude growth at backward angles.

Excited states of the ${}^{146}\mathrm{Tb}$ nucleus have been studied using $\gamma$-ray and electron spectroscopy in off-beam and in-beam modes following ${}^{112}\mathrm{Sn}$(${}^{40}\mathrm{Ar}$,$3n3p$) reaction with the use of the OSIRIS-II, HPGe detector array and the conversion electron spectrometer. The multipolarity of the 343 keV transition deexciting the $(7^{-})$ level in ${}^{146}\mathrm{Tb}$ shows mainly an $E2$ nature and the first excited state above the 23 s isomer is assigned as a $(5^{-},6^{-})$ state. The log $\mathit{ft}$ values have been deduced for 11 ${\beta }^{+}/$EC transitions populating excited states in ${}^{146}\mathrm{Gd}$. The systematic behavior of spins and parities of the long-lived levels at $0+x$ keV and the first excited states above them in the $N=81$ isotones ${}^{146}\mathrm{Tb}$, ${}^{148}\mathrm{Ho}$, and ${}^{150}\mathrm{Tm}$ is discussed.

We present results on strange and multistrange particle production in Au + Au collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ GeV as measured with the STAR detector at RHIC. Midrapidity transverse momentum spectra and integrated yields of $K_S^0$, $\Lambda$, $\Xi$, and $\Omega$ and their antiparticles are presented for different centrality classes. The particle yields and ratios follow a smooth energy dependence. Chemical freeze-out parameters, temperature, baryon chemical potential, and strangeness saturation factor obtained from the particle yields are presented. Intermediate transverse momentum ($p_T$) phenomena are discussed based on the ratio of the measured baryon-to-meson spectra and nuclear modification factor. The centrality dependence of various measurements presented show a similar behavior as seen in Au + Au collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV.

A general formalism is developed to calculate the cross section and the polarization observables for the reaction $\mathrm{N̄}+N\to \pi +{\ell }^{+}+{\ell }^{-}$. The matrix element and the observables are expressed in terms of six scalar amplitudes (complex functions of three kinematical variables) that determine the reaction dynamics. The numerical predictions are given in the frame of a particular model in the kinematical range accessible in the antiproton annihilation at Darmstadt (PANDA) experiment at the Facility for Antiproton and Ion Research (FAIR).

A stochastic approach to fission dynamics based on one- and three-dimensional Langevin equations was applied to calculate the fission probability and the pre-scission particle multiplicity. Evaporation of pre-scission light particles along Langevin fission trajectories from the ground state of the compound nucleus to its scission and fission probability have been calculated using a Monte Carlo simulation technique. To examine this approach we used ${}^{19}\mathrm{F}+{}^{181}\mathrm{Ta}$ and ${}^{16}\mathrm{O}+{}^{197}\mathrm{Au}$ systems. Our results show that the fission probability and pre-scission particle multiplicity in three dimensions is different from the one-dimensional Langevin approach. The theoretical results of pre-scission neutron, proton, and $\alpha$-particle multiplicities and the fission probability for given systems based on this model are compared with available experimental data. The obtained results using three-dimensional calculations are in better agreement with experimental data.

Multiparticle-multihole states around ${}^{16}\mathrm{O}$ such as the famous $0_2^{+}$ state in ${}^{16}\mathrm{O}$ are investigated with a shell-model calculation in the full $p$-$\mathit{sd}$ model space. It is found that the modification of the $N=Z=8$ shell gap due to correlation energy is unexpectedly large, which plays an essential role in accounting for those states. We point out that correlation energy affects the shell gap in the opposite way between ${}^{16}\mathrm{O}$ and ${}^{56}\mathrm{Ni}$, giving its mechanism in terms of the difference of the $L$-$S$ and $j$-$j$ closures.

Distinct maxima and minima in neutron total and absorption cross-section uncertainties when optical-model parameters are varied have been observed in large-scale covariance calculations. These features were seen over a wide mass range (20–210) and for energies up to 20 MeV. Here we investigate the physical origin of the observed patterns over an extended energy range (1 keV to 200 MeV). We have calculated the sensitivity of the cross sections for a specific nucleus (${}^{56}\mathrm{Fe}$) to variations of the 15 parameters of a standard global optical potential parametrization, and have also carried out calculations for alternative global optical potentials over the original wide mass and energy ranges. We find that simple physical descriptions can be found in two energy ranges. Below approximately 100 keV, the patterns arise from the interplay of the $s$- and $p$-wave single-particle resonances. Above approximately 4 MeV, a single-phase-shift approximation (the Ramsauer model) describes the observed behavior. We discuss the potential importance of such sensitivity studies for further development of optical potentials.

We present measurements of the $\mathit{ep}\to \mathit{ep}{\pi }^0$ cross section extracted at two values of four-momentum transfer $Q^2=1.9\hspace{0.5em}{\mathrm{GeV}}^2$ and $Q^2=2.3\hspace{0.5em}{\mathrm{GeV}}^2$ at Jefferson Lab Hall A. The kinematic range allows one to study the evolution of the extracted cross section as a function of $Q^2$ and $W$. Results are confronted with Regge-inspired calculations and GPD predictions. An intepretation of our data within the framework of semi-inclusive deep inelastic scattering is also discussed.

Weak decay rates under stellar density and temperature conditions holding at the rapid proton-capture process are studied in neutron-deficient medium-mass waiting-point nuclei extending from Ni up to Sn. Neighboring isotopes to these waiting-point nuclei are also included in the analysis. The nuclear structure part of the problem is described within a deformed Skyrme Hartree-Fock$+$BCS$+$quasiparticle random-phase-approximation approach, which reproduces not only the $\beta$-decay half-lives but also the available Gamow-Teller strength distributions, measured under terrestrial conditions. The various sensitivities of the decay rates to both density and temperature are discussed. In particular, we study the impact of contributions coming from thermally populated excited states in the parent nucleus and the competition between $\beta$ decays and continuum electron captures.

The relation between the monopole transition strength and existence of cluster structure in the excited states is discussed based on an algebraic cluster model. The structure of ${}^{12}\mathrm{C}$ is studied with a 3$\alpha$ model, and the wave function for the relative motions between $\alpha$ clusters are described by the symplectic algebra Sp(2, $R$)${}_z$, which corresponds to the linear combinations of SU(3) states with different multiplicities. Introducing Sp$(2,R){}_z$ algebra works well for reducing the number of the basis states, and it is also shown that states connected by the strong monopole transition are classified by a quantum number $\Lambda$ of the Sp$(2,R){}_z$ algebra.

The recently observed high-spin rotational bands in odd-$A$ nuclei ${}^{247,249}\mathrm{Cm}$ and ${}^{249}\mathrm{Cf}$ [Tandel et al., Phys. Rev. C 82, 041301(R) (2010)] are investigated by using the cranked-shell model (CSM) with the pairing correlations treated by a particle-number conserving (PNC) method in which the blocking effects are taken into account exactly. The experimental moments of inertia and alignments and their variations with the rotational frequency $\omega$ are reproduced very well by the PNC-CSM calculations. By examining the $\omega$ dependence of the occupation probability of each cranked Nilsson orbital near the Fermi surface and the contributions of valence orbitals to the angular momentum alignment in each major shell, the level crossing and upbending mechanism in each nucleus is understood clearly.

We report results of fully nonperturbative, path integral Monte Carlo calculations for dilute neutron matter. The neutron-neutron interaction in the $s$ channel is parameterized by the scattering length and the effective range. We calculate the energy and the chemical potential as a function of temperature at density $\rho =0.003\hspace{0.5em}{\text{fm}}^{-3}$. The critical temperature $T_c$ for the superfluid-normal phase transition is estimated from the finite size scaling of the condensate fraction. At low temperatures we extract the spectral weight function $A(\mathbf{p},\omega )$ from the imaginary time propagator using the methods of maximum entropy and singular value decomposition. We determine the quasiparticle spectrum, which can be accurately parameterized by three parameters: an effective mass $m^{*}$, a mean-field potential $U$, and a gap $\Delta$. Large values of $\Delta /T_c$ indicate that the system is not a BCS-type superfluid at low temperatures.

Pseudorapidity distributions of charged particles produced in $p-\mathrm{p̄}$ or $p-p$ collisions at different energies were reported by the UA5, UA1, P238, CDF, and ALICE collaborations. A multisource ideal gas model is used to fit the experimental data in this paper. According to the parameter values obtained from fitting the data, we find different linear relationships between different parameters and logarithmic center-of-mass energy. A prediction for the pseudorapidity distributions of charged particles produced in $p-\mathrm{p̄}$ or $p-p$ collisions at the higher Large Hadron Collider energies is given.

The muon-capture reactions ${}^2\mathrm{H}$(${\mu }^{-},{\nu }_{\mu }$)$\mathit{nn}$ and ${}^3\mathrm{He}$(${\mu }^{-},{\nu }_{\mu }$)${}^3\mathrm{H}$ are studied with conventional or chiral realistic potentials and consistent weak currents. The initial and final $A=2$ and $A=3$ nuclear wave functions are obtained from the Argonne $v_{18}$ or chiral next-to-next-to-next-to leading order (N3LO) two-nucleon potential, in combination with, respectively, the Urbana IX or chiral next-to-next-to leading order (N2LO) three-nucleon potential in the case of $A=3$. The weak current consists of polar- and axial-vector components. The former are related to the isovector piece of the electromagnetic current via the conserved-vector-current hypothesis. These and the axial currents are derived either in a meson-exchange or in a chiral effective field theory ($\chi$EFT) framework. There is one parameter (either the $N$-to-$\Delta$ axial coupling constant in the meson-exchange model, or the strength of a contact term in the $\chi$EFT model) that is fixed by reproducing the Gamow-Teller matrix element in tritium $\beta$ decay. The model dependence relative to the adopted interactions and currents (and cutoff sensitivity in the $\chi$EFT currents) is weak, resulting in total rates of $392.0\pm 2.3$ ${\mathrm{s}}^{-1}$ for $A=2$, and $1484\pm 13$ ${\mathrm{s}}^{-1}$ for $A=3$, where the spread accounts for this model dependence.