This article is aimed at improving the description of lepton-nucleus interactions in the sub-GeV energy range. Approximate spectral functions for oxygen, calcium, and argon are constructed and used to obtain the electron cross sections in a given scattering angle. Comparison with a sample of available experimental data shows satisfactory agreement. Discrepancy between the presented model and the systematic computations available for oxygen [O. Benhar et al., Phys. Rev. D 72, 053005 (2005)] is also found to be very small. Analysis of appropriate kinematical regions leads to the conclusion that the obtained argon spectral function should describe well neutrino scattering in the 800-MeV energy region. Several approximations used in the model are critically reviewed. All the details needed to implement the presented approach in Monte Carlo simulations are given.

The suppression of high transverse momentum ($P_T$) inclusive hadron spectra in heavy-ion collisions as compared to the scaled expectation of high $P_T$ hadron production in $p\text{−}p$ collisions is the most direct manifestation of the interaction of hard partons with the soft bulk medium produced in heavy-ion collisions which is absent in $p\text{−}p$ collisions. Yet the measured nuclear suppression factor $R_{\mathit{AA}}$ is a very averaged quantity and hence only a limited amount of information about the medium evolution and the nature of the interaction with the medium can be deduced from $R_{\mathit{AA}}$. Measurements of hard back-to-back hadron correlations in 200$A$ GeV Au-Au collisions at RHIC have opened a new window to study the energy loss of partons in a medium in a more differential way and for a different distribution of in-medium path lengths than in the case of $R_{\mathit{AA}}$. In this work, we present an extrapolation of our results for back-to-back yields at RHIC energies to 5.5 TeV Pb-Pb collisions at the CERN LHC. We also discuss differences and similarities between the measurement at RHIC.

Nuclei with $A>282$ have been studied in the relativistic mean field approach using the force FSU Gold and a zero range pairing interaction. The Euler-Lagrange equations have been solved in the coordinate space. The α-nucleus potential has been constructed with the density-dependent M3Y interaction (DDM3Y1), which has an exponential density dependence, in the double folding model using the nucleon densities in the daughter nucleus and the α particle. Half-lives of α decay have been calculated for tunneling of the α particle through the potential barrier in the WKB approximation and assuming a constant preformation probability. The resulting values agree well with experimental measurements.

The differential cross section and analyzing power $A_y$ of the $\overrightarrow{p}p\to \mathit{pp}{\pi }^0$ reaction have been measured at RCNP in coplanar geometry at a beam energy of 390 MeV and the dependence on both the pion emission angle and the relative momentum of the final protons has been extracted. The angular variation of $A_y$ for the large values of the relative momentum studied here shows that this is primarily an effect of the interference of pion $s$ and $p$ waves and this interference can also explain the momentum dependence. Within the framework of a very simple model, these results would suggest that the pion-production operator has a significant long-range component.

We study the collisional energy loss mechanism for particles produced off mass shell in a finite size QCD medium. The off-mass-shell effects introduced consider particles produced in wave packets instead of plane waves and a length scale associated with an in-medium particle lifetime. We show that these effects reduce the energy loss as compared to the case when the particles are described as freely propagating from the source. The reduction in energy loss is stronger as the scale becomes of the order of or smaller than the medium size. We discuss possible consequences of the result on the description of the energy loss process in the parton recombination scenario.

The electromagnetic pion production reactions are investigated within the dynamical coupled-channels model developed by Matsuyama, Sato, and Lee [Phys. Rep. 439, 193 (2007)]. The meson-baryon channels included in this study are $\gamma N,\pi N,\eta N$, and the $\pi \Delta ,\rho N$, and $\sigma N$ resonant components of the $\pi \pi N$ channel. With the hadronic parameters of the model determined in a recent study of $\pi N$ scattering, we show that the pion photoproduction data up to the second resonance region can be described to a very large extent by only adjusting the bare $\gamma N\to N^{*}$ helicity amplitudes, while the nonresonant electromagnetic couplings are taken from previous works. It is found that the coupled-channels effects can contribute about 30–40 % of the production cross sections in the Δ (1232) resonance region, and can drastically change the magnitude and shape of the cross sections in the second resonance region. The importance of the loop-integrations in a dynamical approach is also demonstrated. The meson cloud effects as well as the coupled-channels contributions to the $\gamma N\to N^{*}$ form factors are found to be mainly in the low $Q^2$ region. Necessary improvements to the model and future developments are discussed.

We show that, within the quasiparticle random phase approximation (QRPA) and the renormalized QRPA (RQRPA) based on the Bonn-CD nucleon-nucleon interaction, the competition between the pairing and the neutron-proton particle-particle and particle-hole interactions causes contributions to the neutrinoless double-beta decay matrix element to nearly vanish at internucleon distances of more than 2 or 3 fermis. As a result, the matrix element is more sensitive to short-range/high-momentum physics than one naively expects. We analyze various ways of treating that physics and quantify the uncertainty it produces in the matrix elements, with three different treatments of short-range correlations.

The assisted tunneling of a metastable state between barriers is investigated analytically by means of a simplified one-dimensional model. A time dependent perturbation changes the pole spectrum of the wave function introducing a larger decay constant. New insights about the decay of a metastable state are found. The scheme is exemplified for parameters corresponding to the nuclear process of α decay.

A microscopic multiphonon approach is adopted to investigate the structure of some low-lying states observed experimentally in the $N=80$ isotones ${}^{134}\mathrm{Xe}$, ${}^{136}\mathrm{Ba}$, and ${}^{138}\mathrm{Ce}$. The calculation yields levels and electromagnetic transition strengths in good agreement with experiments and relates the observed selection rules to the neutron-proton symmetry and phonon content of the observed states. Moreover, it ascribes the splitting of the $M1$ strength in ${}^{138}\mathrm{Ce}$ to the proton subshell closure which magnifies the role of pairing in the excitation mechanism.

A complete analysis of proton recoil asymmetry in neutron decay in the first order of radiative and recoil corrections is presented. The possible contributions from new physics are calculated in terms of low energy coupling constants, and the sensitivity of the measured asymmetry to models beyond the Standard Model are discussed.

We calculate the mean free path of neutrons and protons in symmetric and asymmetric nuclear matter, based on microscopic in-medium nucleon-nucleon cross sections. The latter are obtained from calculations of the $G$ matrix including relativistic “Dirac” effects. The dependence of the mean free path on energy and isospin asymmetry is discussed. We conclude by suggesting possible ways our microscopic predictions might be helpful in conjunction with studies of rare isotopes.

The beam spin asymmetry (BSA) in the exclusive reaction $\overrightarrow{e}p\to \mathit{ep}{\pi }^0$ was measured with the CEBAF 5.77 GeV polarized electron beam and Large Acceptance Spectrometer (CLAS). The $x_B,Q^2,t$, and ϕ dependences of the ${\pi }^0$ BSA are presented in the deep inelastic regime. The asymmetries are fitted with a $\sin \varphi$ function and their amplitudes are extracted. Overall, they are of the order of 0.04–0.11 and roughly independent of $t$. This is the signature of a nonzero longitudinal-transverse interference. The implications concerning the applicability of a formalism based on generalized parton distributions, as well as the extension of a Regge formalism at high photon virtualities, are discussed.

We discuss the sensitivity of fission barrier for heavy neutron-rich nuclei to fission paths in the two-dimensional neutron-proton quadrupole plane. To this end, we use the constrained Skyrme-Hartree-Fock + BCS method, and examine the difference of fission barriers obtained with three constraining operators, that is, the neutron, proton, and mass quadrupole operators. We investigate ${}^{220}\mathrm{U}$, ${}^{236}\mathrm{U}$, and ${}^{266}\mathrm{U}$, that is relevant to r-process nucleosynthesis. We find that the fission barrier heights are almost the same among the three constraining operators even for neutron-rich nuclei, indicating that the usual way to calculate fission barriers with the mass quadrupole operator is well justified. We also discuss the difference between proton and neutron deformation parameters along the fission paths.

The structure of the neutron-rich nucleus ${}^{172}\mathrm{Tm}$ has been studied using incomplete fusion of ${}^7\mathrm{Li}$ on an ${}^{170}\mathrm{Er}$ target at 30 MeV. A $190\text{−}\mu$s isomer at an excitation energy of 476 keV was identified using chopped beams and γ-ray spectroscopy. The isomer decays with very inhibited $E1$ transitions to the rotational bands based on the parallel and antiparallel couplings of the $\nu 5/2^{-}[512]\otimes \pi 1/2^{+}[411]$ configuration, the latter ($K^{\pi }=2^{-}$) being the ground state. The isomeric state has been assigned $J^{\pi }=6^{+}$, arising from the energetically favored (parallel) coupling of the $\nu 5/2^{-}[512]\otimes \pi 7/2^{-}[523]$ configuration. The proton-neutron residual interaction was deduced for the configuration of the isomeric state and is found to agree with previous empirical studies.

The properties of Σ-hyperons in pure Σ matter are studied with the finite-density quantum chromodynamics sum rule (QCDSR) approach. The $\Sigma \Sigma$ nuclear potential $U_{\Sigma }$ is most likely strongly attractive, it could be about $-50$ MeV or even more attractive at normal nuclear density. If this prediction is the case, the interactions between Σ-hyperons should play crucial roles in the strange nuclear matter, when there are multi-Σ hyperons. The bound state of the double-Σ may exist.

The ${\Theta }^{+}$ was searched for via the $K^{+}p\to {\pi }^{+}X$ reaction using the 1.2 GeV/$c$ $K^{+}$ beam at the K6 beam line of the KEK-PS 12 GeV Proton Synchrotron. In the missing mass spectrum of the $K^{+}p\to {\pi }^{+}X$ reaction, no clear peak structure was observed. Therefore a 90% C.L. upper limit of 3.5 μb/sr was derived for the differential cross section averaged over $2^{°}$ to ${22}^{°}$ in the laboratory frame of the $K^{+}p\to {\pi }^{+}{\Theta }^{+}$ reaction. This upper limit is much smaller than the theoretical calculation for the $t$-channel process where a $K^{0*}$ is exchanged. From the present result, either the $t$-channel process is excluded or the coupling constant of g${}_{K*N\Theta }$ is quite small.

The reaction mechanisms for $K\Sigma (1385)$ photoproduction from the reaction $\gamma p\to K^{+}{\Sigma }^0(1385)$ in the resonance energy region are investigated in a hadronic model. Both contributions from $N$ and Δ resonances of masses around 2 GeV as given in the Review of Particle Data Group and by the quark model predictions are included. The Lagrangians for describing the decays of these resonances into $K\Sigma (1385)$ are constructed with the coupling constants determined from the decay amplitudes predicted by a quark model. Comparing the resulting total cross section for the reaction $\gamma p\to K^{+}{\Sigma }^0(1385)$ with the preliminary data from the Thomas Jefferson National Accelerator Facility, we find that the most important contributions are from the two-star-rated resonances $\Delta (2000)F_{35},\Delta (1940)D_{33}$, and $N(2080)D_{13}$, as well as the missing resonance $N{\frac{3}{2}}^{-}(2095)$ predicted in the quark model. Predictions on the differential cross section and photon asymmetry in this reaction are also given.

We discuss the conservation of angular momentum in nuclear time-dependent Hartree-Fock calculations for a numerical representation of wave functions and potentials on a three-dimensional Cartesian grid. Free rotation of a deformed nucleus performs extremely well even for relatively coarse spatial grids. Heavy ion collisions produce a highly excited compound system associated with substantial nucleon emission. These emitted nucleons reach the bounds of the numerical box which leads to a decrease of angular momentum. We discuss strategies to distinguish the physically justified loss from numerical artifacts.

The phase variation with angle of hadronic amplitudes is studied with a view to understanding the underlying physical quantities that control it and how well it can be determined in free space. We find that unitarity forces a moderately accurate determination of the phase in standard amplitude analyses but that the nucleon-nucleon analyses done to date do not give the phase variation needed to achieve a good representation of the data in multiple scattering calculations. Models are examined that suggest its behavior near forward angles is related to the radii of the real and absorptive parts of the interaction. The dependence of this phase on model parameters is such that if these radii are modified in the nuclear medium (in combination with the change due to the shift in energy of the effective amplitude in the medium) then the larger magnitudes of the phase needed to fit the data might be attainable but only for negative values of the phase variation parameter.