We study the $p(e,e^{\text{'}}{\pi }^{+})n$ reaction in the framework of an effective Lagrangian approach including nucleon, π and ρ meson degrees of freedom and show the importance of the ρ-meson $t$-pole contribution to ${\sigma }_T$, the transverse part of cross section. We test two different field representations of the ρ meson, vector and tensor, and find that the tensor representation of the ρ meson is more reliable in the description of the existing data. In particular, we show that the ρ-meson $t$-pole contribution, including the interference with an effective nonlocal contact term, sufficiently improves the description of the recent JLab data at invariant mass $W\lesssim 2.2$ GeV and $Q^2\lesssim 2.5$ GeV${}^2/c^2$. A “soft” variant of the strong $\pi \mathit{NN}$ and $\rho \mathit{NN}$ form factors is also found to be compatible with these data. On the basis of the successful description of both the ${\sigma }_L$ and ${\sigma }_T$ parts of the cross section we discuss the importance of taking into account the ${\sigma }_T$ data when extracting the charge pion form factor $F_{\pi }$ from ${\sigma }_L$.

Discrete as well as continuum $\gamma$-ray energy spectra from the neutron capture by ${}^{186}\mathrm{Os}$, ${}^{187}\mathrm{Os}$, and ${}^{189}\mathrm{Os}$ have been taken for the first time at $5⩽E_n⩽90$ keV by an anti-Compton NaI(Tl) spectrometer. The detection of a weak discrete γ-ray, about 0.5% of total γ-ray strength, demonstrates the high sensitivity of the present measurement. The energy spectra enabled us to accurately determine the reaction cross sections with a small systematic uncertainty. Based on the new cross sections, we reestimate on the basis of a careful reaction cross section calculation the correction factor $F_{\sigma }$ for the neutron capture on the 9.75-keV first excited state in ${}^{187}\mathrm{Os}$ as a function of stellar temperature, as required to derive the age of the galaxy within the Re-Os chronology.

We include in statistical model calculations the facts that in the nuclear multifragmentation process the fragments are produced within a given volume and have a finite size. The corrections associated with these constraints affect the partition modes and, as a consequence, other observables in the process. In particular, we find that the favored fragmenting modes strongly suppress the collective flow energy, leading to much lower values than those obtained from unconstrained calculations. For a given total excitation energy, this leads to a nontrivial correlation between the breakup temperature and the collective expansion velocity. In particular, we find that under some conditions, the temperature of the fragmenting system may increase as a function of this expansion velocity, contrary to what might be expected.

The amplitudes of the transition ${\gamma }^{*}N\to P_{11}(1440)$ are calculated within light-front relativistic quark model assuming that the $P_{11}(1440)$ is the first radial excitation of the $3q$ ground state. The results are presented along with the predictions obtained in other relativistic quark models. In comparison with the previous calculations, we have extended the range of $Q^2$ up to 4.5 GeV${}^2$ to cover the kinematic interval of the forthcoming experimental data. Using approach based on the hypothesis of partially conserved axial-vector current, we checked the relative sign between quark model predictions for the $N$ and $P_{11}(1440)$ contributions to the π electroproduction found in previous investigations.

Simultaneous ${\chi }^2$ analyses previously made for elastic scattering and fusion cross section data for the ${}^6\mathrm{Li}+{}^{208}\mathrm{Pb}$ system are extended to the ${}^7\mathrm{Li}+{}^{208}\mathrm{Pb}$ system at near-Coulomb-barrier energies based on the extended optical model approach, in which the polarization potential is decomposed into direct reaction (DR) and fusion parts. Use is made of the double folding potential as a bare potential. It is found that the experimental elastic scattering and fusion data are well reproduced without introducing any normalization factor for the double folding potential and that both the DR and fusion parts of the polarization potential determined from the ${\chi }^2$ analyses satisfy separately the dispersion relation. Further, we find that the real part of the fusion portion of the polarization potential is attractive while that of the DR part is repulsive except at energies far below the Coulomb barrier energy. A comparison is made of the present results with those obtained from the coupled discretized continuum channels calculations and a previous study based on the conventional optical model with a double folding potential. We also compare the present results for the ${}^7\mathrm{Li}+{}^{208}\mathrm{Pb}$ system with the analysis previously made for the ${}^6\mathrm{Li}+{}^{208}\mathrm{Pb}$ system.

The system created in noncentral relativistic nucleus-nucleus collisions possesses large orbital angular momentum. Because of spin-orbit coupling, particles produced in such a system could become globally polarized along the direction of the system angular momentum. We present the results of Λ and $\overline{\Lambda }$ hyperon global polarization measurements in Au+Au collisions at $\sqrt{s_{\mathit{NN}}}=62.4$ and 200 GeV performed with the STAR detector at the BNL Relativistic Heavy Ion Collider (RHIC). The observed global polarization of Λ and $\overline{\Lambda }$ hyperons in the STAR acceptance is consistent with zero within the precision of the measurements. The obtained upper limit, $\left|P_{\Lambda ,\overline{\Lambda }}\right|⩽0.02$, is compared with the theoretical values discussed recently in the literature.

The knowledge of the nuclear symmetry energy of hot neutron-rich matter is important for understanding the dynamical evolution of massive stars and the supernova explosion mechanisms. In particular, the electron capture rate on nuclei and/or free protons in presupernova explosions is especially sensitive to the symmetry energy at finite temperature. In view of the above, in the present work we calculate the symmetry energy as a function of the temperature for various values of the baryon density by applying a momentum-dependent effective interaction. In addition to a previous work, the thermal effects are studied separately both in the kinetic part and the interaction part of the symmetry energy. We focus also on the calculations of the mean-field potential, employed extensively in heavy-ion reaction research, both for nuclear and pure neutron matter. The proton fraction and the electron chemical potential, which are crucial quantities for representing the thermal evolution of supernova and neutron stars, are calculated for various values of the temperature. Finally, we construct a temperature dependent equation of state of β-stable nuclear matter, the basic ingredient for the evaluation of the neutron star properties.

We show, at leading-order in the multipole expansion of the electron-nucleus interaction, that nucleon electric-dipole moments are completely shielded by electrons so that they contribute nothing to atomic electric-dipole moments, even when relativity in the nucleus is taken into account. It is well known that relativistic electron motion, by contrast, leads to dipole moments that are not screened; we discuss the reasons for the difference.

Measurements of de-excitation γ rays in coincidence with target-like residues produced in deep inelastic transfer reactions of ${}^{238}\mathrm{U}$ on a ${}^{48}\mathrm{Ca}$ target at an energy near the Coulomb barrier are presented. A systematic analysis, within a shell model approach, of the measured low-lying states in the odd and even neutron-rich Ca isotopes points toward a possible absence of a predicted shell closure at $N=34$.

We studied the giant dipole resonance (GDR) in ${}^4\mathrm{He}$ by observing its analog via the ${}^4\mathrm{He}$(${}^7\mathrm{Li}$,${}^7\mathrm{Be}$) reaction at an incident energy of 455 MeV and at forward scattering angles. The spin-nonflip ($\Delta S=0$) spectrum was deduced by measuring the 0.43-MeV ${}^7\mathrm{Be}$ γ-ray in coincidence with the scattered ${}^7\mathrm{Be}$. The total cross section of photodisintegration to the GDR in ${}^4\mathrm{He}$ was derived from the $\Delta S=0$ and $\Delta L=1$ spectrum. The result agrees well with the previous total photodisintegration data in which the GDR has a pronounced peak at $E_{\gamma }~27$ MeV.

Systematic calculations of ground-state spins and parities of odd-mass nuclei have been performed within the Hartree-Fock-BCS (HFBCS) approach and the finite-range droplet model for nuclei for which experimental data are available. The unpaired nucleon has been treated perturbatively, and axial and left-right reflection symmetries have been assumed. As for the HFBCS approach, three different Skyrme forces have been used in the particle-hole channel, whereas the particle-particle matrix elements have been approximated by a seniority force. The calculations have been done for the 621 nuclei for which the Nubase 2003 data set gives assignments of spins and parities with strong arguments. The agreement of both spin and parity in the self-consistent model reaches about 80% for spherical nuclei, and about 40% for well-deformed nuclei regardless of the Skyrme force used. As for the macroscopic-microscopic approach, the agreement for spherical nuclei is about 90% and about 40% for well-deformed nuclei, with different sets of spherical and deformed nuclei found in each model.

The odd mass nucleus ${}^{137}\mathrm{Pr}$ has been studied to high spins in order to investigate the magnetic rotation phenomenon in mass 130 region using the ${}^{122}\mathrm{Sn}$(${}^{19}\mathrm{F}$,$4n$)${}^{137}\mathrm{Pr}$ reaction at a beam energy of 80 MeV. A known $\Delta I=1$ band has been extended to $J^{\pi }=47/2^{-}$ with the addition of three new transitions. Directional Correlation of Oriented Nuclei (DCO) ratios and linear polarization measurements have been performed to assign the multipolarities of gamma transitions and the spins and parities of the energy levels in this band, now established as the $M1$ band. The combination of $M1$ transitions along with cross over $E2$ transitions have been observed in this band for the first time. The experimentally deduced $B(M1)/B(E2)$ ratios show a decrease with increasing spin after band-crossing suggesting magnetic rotation. TAC calculations for the 3qp: $\pi h_{11/2}\otimes \nu (h_{11/2}){}^{-2}$ configuration reproduce the experimental observations in the lower spin part of the $\Delta I=1$ band and the 5qp: $\pi h_{11/2}(g_{7/2}){}^2\otimes \nu (h_{11/2}){}^{-2}$ configuration reproduces the $\Delta I=1$ band at higher spins; the crossing of the bands based on the two configuration leads to a back-bending also. Theoretical calculations also support a magnetic rotation nature for both the configurations.

The accuracy of the procedure that converts the experimentally determined electron spectrum associated with fission of the nuclear fuels ${}^{235}\mathrm{U}$, ${}^{239}\mathrm{Pu}$, ${}^{241}\mathrm{Pu}$, and ${}^{238}\mathrm{U}$ into the antineutrino ${\overline{\nu }}_e$ spectrum is examined. By using calculated sets of mutually consistent spectra, this work shows that the conversion procedure can result in a small ∼1% error provided several conditions are met. Chief among them are the requirements that the average nuclear charge $\langle Z\rangle$ as a function of the β-decay endpoint energy is independently known and that the ${\overline{\nu }}_e$ spectrum is binned into bins that are several times larger than the width of the slices used to fit the electron spectrum.

Data taken previously covering the giant resonance region from 9 MeV $<E_x<42$ MeV in ${}^{28}\mathrm{Si}$ with inelastic scattering of 240 MeV α particles at small angles including $0^{°}$ have been reanalyzed. Treating all of the observed cross section as multipole processes, giant resonance peaks containing 74 ± 7% of the isoscalar $E0$ energy weighted sum rule (EWSR), 102 ± 11% of the $E2$ EWSR, and 84 ± 8% of the $E3$ EWSR were identified.

We study relativistic corrections to nuclear interactions caused by boosting the two-nucleon interaction to a frame in which their total momentum does not vanish. These corrections induce a change in the computed value of the neutron-deuteron analyzing power $A_y$ that is estimated using the plane-wave impulse approximation. This allows a transparent analytical calculation that demonstrates the significance of relativistic corrections. Faddeev calculations are, however, needed to conclude on the $A_y$ puzzle.

We report on the first determination of the $2_1^{+}$ energy of ${}^{20}\mathrm{Mg}$, the most neutron-deficient Mg isotope known to exist. The result, $E(2_1^{+})=1598(10)$ keV, obtained from in-beam γ-ray spectroscopy following the two-neutron removal from a ${}^{22}\mathrm{Mg}$ secondary beam, is discussed in the framework of the isobaric mass multiplet equation (IMME). Resulting predictions for the excitation energies of the $T=2,2^{+}$ states in the ${}^{20}\mathrm{F}$ and ${}^{20}\mathrm{Na}$ isobars are presented. The mirror energy difference, $E(2_1^{+},$${}^{20}\mathrm{Mg}$$)-E(2_1^{+},$${}^{20}\mathrm{O}$$)=-77(10)$ keV, is compared to a recent prediction within the nuclear shell model based on the “${\mathrm{USD}}^m$ - gap Z14<” modification of the universal $\mathit{sd}$ (USD) effective interaction.

We propose a practical method for solving the random-phase approximation (RPA) in the self-consistent Hartree-Fock (HF) and density-functional theory. The method is based on numerical evaluation of the residual interactions utilizing the finite amplitude of single-particle wave functions. The method only requires calculations of the single-particle Hamiltonian constructed with independent bra and ket states. Using the present method, the RPA calculation becomes possible with a little extension of a numerical code of the static HF calculation. We demonstrate the usefulness and accuracy of the present method by performing test calculations for isoscalar responses in deformed ${}^{20}\mathrm{Ne}$.

Using numerical and analytical methods implemented for different models, we conduct a systematic study of the thermodynamic properties of pairing correlations in mesoscopic nuclear systems. Various quantities are calculated and analyzed using the exact solution of pairing. An in-depth comparison of canonical, grand canonical, and microcanonical ensembles is conducted. The nature of the pairing phase transition in a small system is of a particular interest. We discuss the onset of discontinuity in the thermodynamic variables, fluctuations, and evolution of zeros of the canonical and grand canonical partition functions in the complex plane. The behavior of the invariant correlational entropy is also studied in the transitional region of interest. The change in the character of the phase transition due to the presence of a magnetic field is discussed along with studies of superconducting thermodynamics.