Hard high-energy pion-nucleus bremsstrahlung, ${\pi }^{-}+A\to {\pi }^{-}+\gamma +A$, is studied in the Coulomb region, i.e., the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. Special attention is focussed on the possibility of measuring the pion polarizability in such reactions. We study the sensitivity to the structure of the underlying pion-Compton amplitude through a model with $\sigma ,\rho$, and $a_1$ exchanges. It is found that the effective energy in the virtual pion-Compton scattering is often so large that the threshold approximation does not apply.

The high-spin structures of ${}^{125}\mathrm{Xe}$ were studied by using in-beam γ-ray spectroscopy with the ${}^{116}\mathrm{Cd}$ (${}^{13}\mathrm{C}$, 4n) ${}^{125}\mathrm{Xe}$ reaction at E${}_{\mathrm{lab}}=62$ MeV. The level scheme of ${}^{125}\mathrm{Xe}$ was constructed through the $\gamma \text{−}\gamma$ coincidences and $\gamma \text{−}\gamma$ angular directional correlation ratios. Several negative parity bands built on the neutron $h_{11/2}$ orbital were identified. In contrast to the yrast $h_{11/2}$ band with a large signature splitting, the second (yrare) $h_{11/2}$ band exhibits a small signature splitting, showing signature inversion below $I^{\pi }=23/2^{-}$. In addition, a band built on the $27/2^{-}$ level at 3619 keV was newly observed and found to be associated with a three quasiparticle alignment based on a neutron in the $h_{11/2}$ orbital coupled to a pair of protons in the $h_{11/2}$ orbital, namely, the $\nu [h_{11/2}]\pi [(h_{11/2}){}^2]$ configuration.

We have observed an intense high-energy component in an inclusive ${}^4\mathrm{He}$(stopped $K^{-},d$) spectrum. For back-to-back $\Lambda d$ pairs a prominent event cluster has been found just below the $m_{{}^4\mathrm{He}}+m_{K^{-}}-m_n$ mass threshold in the $\Lambda d$ invariant mass spectrum of $\Lambda \mathit{dn}$ events, which is evidence for a three-nucleon absorption process of $K^{-}$ in ${}^4\mathrm{He}$. In addition, an appreciable strength is revealed below $~3220$ MeV/$c^2$. Well separated ${\Sigma }^0\mathit{dn}$ events show a peak similar to the case of $\Lambda \mathit{dn}$.

The unexpectedly strong suppression of high $p_T$ heavy quarks in heavy-ion collisions has given rise to the idea that partons propagating through a medium in addition to energy loss by induced radiation also undergo substantial energy loss due to elastic collisions. However, the precise magnitude of this elastic energy-loss component is highly controversial. Although for a parton inside a medium it is surprisingly difficult to define the difference between elastic and radiative processes rigorously, the main phenomenological difference is in the dependence of energy loss on in-medium path length: in a constant medium radiative energy loss is expected to grow quadratically with path length, elastic energy loss linearly. In this article, we investigate a class of energy-loss models with such a linear path-length dependence and demonstrate that they are incompatible with measured data on hard hadronic back-to-back correlations where a substantial variation of path length is probed. This indicates that any elastic energy-loss component has to be small.

Nuclear parton distribution functions (NPDFs) are determined by global analyses of experimental data on structure-function ratios $F_2^A/F_2^{A^{\text{'}}}$ and Drell-Yan cross-section ratios ${\sigma }_{\mathit{DY}}^A/{\sigma }_{\mathit{DY}}^{A^{\text{'}}}$. The analyses are done in the leading order (LO) and next-to-leading order (NLO) of running coupling constant ${\alpha }_s$. Uncertainties of the NPDFs are estimated in both LO and NLO for finding possible NLO improvement. Valence-quark distributions are well determined, and antiquark distributions are also determined at $x<0.1$. However, the antiquark distributions have large uncertainties at $x>0.2$. Gluon modifications cannot be fixed at this stage. Although the advantage of the NLO analysis, in comparison with the LO one, is generally the sensitivity to the gluon distributions, gluon uncertainties are almost the same in the LO and NLO. It is because current scaling-violation data are not accurate enough to determine precise nuclear gluon distributions. Modifications of the PDFs in the deuteron are also discussed by including data on the proton-deuteron ratio $F_2^D/F_2^p$ in the analysis. A code is provided for calculating the NPDFs and their uncertainties at given $x$ and $Q^2$ in the LO and NLO.

We have carried out a calculation of the inclusive electron scattering cross section off oxygen in the kinematical region corresponding to beam energies between 700 and 1200 MeV, where quasielastic scattering and single pion production are the dominant reaction mechanisms. The formalism developed and successfully applied to describe quasielastic scattering has been extended to include both Δ production and nonresonant pion production. The results are in fairly good agreement with experimental data over the whole range of energy transfer, including the dip region between the quasielastic peak and the first resonance.

Spin-dependent quark densities, matrix elements of specific density operators in proton states of definite spin-polarization, indicate that the nucleon may harbor an infinite variety of nonspherical shapes. We show that these matrix elements are closely related to specific transverse-momentum-dependent (TMD) parton distributions accessible in the angular dependence of the semi-inclusive processes $\mathit{ep}\to e\pi X$ and the Drell-Yan reaction $\mathit{pp}\to l\overline{l}X$. New measurements or analyses would allow the direct exhibition of the nonspherical nature of the proton.

We investigate the neutrino induced coherent pion production reaction at low and intermediate energies. The model includes pion, nucleon, and $\Delta (1232)$ as the relevant hadronic degrees of freedom. Nuclear medium effects on the production mechanisms and pion distortion are taken into account. We find that the dominance of the Δ excitation holds due to large cancellations among the background contributions. We consider two sets of vector and axial-vector $N\text{−}\Delta$ transition form factors, evidencing the strong sensitivity of the results to the axial coupling $C_5^A(0)$. The differences between neutrino and antineutrino cross sections, emerging from interference terms, are also discussed.

A detailed comparison of the expressions for the decay widths obtained within the semiclassical WKB approximation using different approaches to the tunneling problem is performed. The differences between the available improved formulas for tunneling near the top and the bottom of the barrier are investigated. Though the simple WKB method gives the right order of magnitude of the decay widths, a small number of parameters are often fitted. The need to perform the fitting procedure remaining consistently within the WKB framework is emphasized in the context of the fission model based calculations. Calculations for the decay widths of some recently found superheavy nuclei using microscopic alpha-nucleus potentials are presented to demonstrate the importance of a consistent WKB calculation. The half-lives are found to be sensitive to the density dependence of the nucleon-nucleon interaction and the implementation of the Bohr-Sommerfeld quantization condition inherent in the WKB approach.

We report the measurement of Λ and $\overline{\Lambda }$ yields and inverse slope parameters in $d+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV at forward and backward rapidities ($y=\pm 2.75$), using data from the STAR forward time projection chambers. The contributions of different processes to baryon transport and particle production are probed exploiting the inherent asymmetry of the $d+\mathrm{Au}$ system. Comparisons to model calculations show that baryon transport on the deuteron side is consistent with multiple collisions of the deuteron nucleons with gold participants. On the gold side, HIJING-based models without a hadronic rescattering phase do not describe the measured particle yields, while models that include target remnants or hadronic rescattering do. The multichain model can provide a good description of the net baryon density in $d+\mathrm{Au}$ collisions at energies currently available at the BNL Relativistic Heavy Ion Collider, and the derived parameters of the model agree with those from nuclear collisions at lower energies.

The breakup of $E/A=50$ MeV ${}^{12}\mathrm{Be}$ fragments following inelastic scattering off of hydrogen and carbon target nuclei has been studied. The breakup channels $\alpha +$${}^8\mathrm{He}$, ${}^6\mathrm{He}$$+$${}^6\mathrm{He}$, $t+$${}^9\mathrm{Li}$, and $p+$${}^{11}\mathrm{Li}$ were observed. Two doublets at excitation energies of 12.8 and 15.5 MeV were found for the $\alpha +$${}^8\mathrm{He}$ channel. A low-energy shoulder in the excitation-energy spectra at 10.2 MeV indicates one or more additional states. This work could not confirm the presence of ${}^6\mathrm{He}$$\text{−}$${}^6\mathrm{He}$ rotational structure reported by Freer et al. [Phys. Rev. C 63, 034301 (2001)], although possible peaks at excitation energies of 13.5 and 14.5 MeV were found for ${}^6\mathrm{He}$$+$${}^6\mathrm{He}$ decay. Significant structure is observed in the excitation-energy spectrum for $p+$${}^{11}\mathrm{Li}$ at 25–30 MeV which maybe associated with $T=3$ analog states.

By using the extension of the statistical Wick's theorem (Gaudin's theorem) to deal with generalized statistical density operators (those which can be expressed as the product of and operator carrying out a canonical transformations times a density operator) and using the appropriate limits we are able to rederive in a very simple way the standard generalized Wick's theorem for overlaps of mean-field wave functions. Due to the simplicity of the derivation it is now straightforward to consider more involved cases and some of them are discussed. The present derivation also allows us to obtain general and compact formulas for other particular cases of the generalized Wick theorem involving overlaps of multiquasiparticle excitations of product wave functions. The new expressions allow us to reduce the combinatorial complexity of the standard calculation of the above overlaps.

For the low-lying multipole collective excitations in nuclei, the transport coefficients of the response function theory, such as the inertia and the friction, are derived within the periodic orbit theory in the lowest orders of semiclassical expansion corresponding to the extended Thomas-Fermi approach with the surface and the curvature corrections. The collective vibrations near the spherical shape are described in the mean-field approximation through the spherical edgelike potential by using a statistical averaging of the transport coefficients. It is shown that the inertia of the collective motion is significantly larger than that of irrotational hydrodynamical flow. For large enough particle numbers in the nucleus, the mean energies of quadrupole and octupole low-lying collective vibrations, their sum rule contributions, and reduced transition probabilities are in reasonable agreement with experimental data.

The system-size dependence of particle production in heavy-ion collisions at the top energy at the CERN Super Proton Synchrotron is analyzed in terms of the statistical model. A systematic comparison is made of two suppression mechanisms that quantify strange-particle yields in ultrarelativistic heavy-ion collisions: the canonical model with strangeness correlation radius determined from the data and the model formulated in the canonical ensemble using chemical off-equilibrium strangeness suppression factor. The system-size dependence of the correlation radius and the thermal parameters are obtained for p-p, C-C, Si-Si, and Pb-Pb collisions at $\sqrt{s_{\mathit{NN}}}=17.3A$ GeV. It is shown that on the basis of a consistent set of data there is no clear difference between the two suppression patterns. In the present study, the strangeness correlation radius was found to exhibit a rather weak dependence on the system size.

We measured the thermal neutron capture cross section for the ${}^{180}\mathrm{W}$ nucleus. There is only one previous measurement with regard to this cross section, and it yielded a value of ${30}_{-100\%}^{+300\%}$ b. To determine whether ${}^{181}\mathrm{W}$ is an appropriate low energy neutrino source, the thermal neutron capture cross section should be measured more precisely to estimate the production rate of ${}^{181}\mathrm{W}$ inside a nuclear reactor. We measured the cross section of ${}^{180}\mathrm{W}$ using a natural tungsten foil and obtained a value of $22.6\pm 1.7$ b.

An exactly separable version of the Bohr Hamiltonian is developed using a potential of the form $u(\beta )+u(\gamma )/{\beta }^2$, with the Davidson potential $u(\beta )={\beta }^2+{\beta }_0^4/{\beta }^2$ (where ${\beta }_0$ is the position of the minimum) and a stiff harmonic oscillator for $u(\gamma )$ centered at $\gamma =0^{°}$. In the resulting solution, called the exactly separable Davidson (ES-D) solution, the ground-state, $\gamma ,$ and $0_2^{+}$ bands are all treated on an equal footing. The bandheads, energy spacings within bands, and a number of interband and intraband $B(E2)$ transition rates are well reproduced for almost all well-deformed rare-earth and actinide nuclei using two parameters (${\beta }_0,\gamma$ stiffness). Insights are also obtained regarding the recently found correlation between γ stiffness and the γ-bandhead energy, as well as the long-standing problem of producing a level scheme with interacting boson approximation SU(3) degeneracies from the Bohr Hamiltonian.

Relativistic models can be successfully applied to the description of compact star properties in nuclear astrophysics as well as to nuclear matter and finite nuclei properties, these studies taking place at low and moderate temperatures. Nevertheless, all results are model dependent, and so far it is unclear whether some of them should be discarded. Moreover, in the regime of hot hadronic matter, very few calculations exist using these relativistic models, in particular when applied to particle yields in heavy ion collisions. A very important investigation is the simulation of a supernova explosion that is based on the construction of an adequate equation of state that needs to be valid within very large ranges of temperatures (0 to 100 MeV at least) and densities (very low to ten times the nuclear saturation density at least). In the present work, we comment on the known constraints that can help the selection of adequate models in this wide regime and investigate the main differences that arise when the particle production during a Au+Au collision at the BNL Relativistic Heavy Ion Collider is calculated with different relativistic models. We conclude that most of the models investigated in the present work give a very good overall description of the data and make predictions for not yet measured particle ratios.

Equivalent interactions in a low-momentum space for the $\Lambda N,\Sigma N$, and $\Xi N$ interactions are calculated, using the ${\mathrm{SU}}_6$ quark model potential as well as the Nijmegen OBEP model as the input bare interaction. Because the two-body scattering data has not been accumulated sufficiently to determine the hyperon-nucleon interactions unambiguously, the construction of the potential even in low-energy regions has to rely on a theoretical model. The equivalent interaction after removing high-momentum components is still model dependent. Because this model dependence reflects the character of the underlying potential model, it is instructive for better understanding of baryon-baryon interactions in the strangeness sector to study the low-momentum space $\mathit{YN}$ interactions.