We investigate the generalized form factors of the nucleon in a light-cone spectator-diquark model. Compared to the form factors, the generalized form factors contain some more information of the structure of the nucleon. In our calculation, both the scalar and the axial-vector spectator diquark are taken into account. As a relation between the spin in the instant form and that in the light-cone form, the Melosh–Wigner rotation effect is included for both the quark and the axial-vector diquark. We also provide numerical results from our model calculations, and the results are comparable with those from lattice QCD.

Rainbows are generally considered to be caused by static refraction and reflection. A primary and a secondary rainbow appear due to refraction and internal reflection in a raindrop as explained by Newton. The quantum nuclear rainbow, which is generated by refraction in the nucleus droplet, only has a “primary” rainbow. Here we show for the first time evidence for the existence of a secondary nuclear rainbow generated dynamically by coupling to an excited state without internal reflection. This has been demonstrated for experimental ${}^{16}\mathrm{O}+{}^{12}\mathrm{C}$ scattering using the coupled channel method with an extended double folding potential derived from microscopic realistic wave functions for ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$.

We report a leading-order (LO) calculation of ${}^7\mathrm{Be}(p,\gamma ){}^8\mathrm{B}$ in a low-energy effective field theory. ${}^{8}B$ is treated as a shallow $\text{proton}+{}^7\mathrm{Be}$ core and $\text{proton}+{}^7\mathrm{Be}*$ (core excitation) $p$-wave bound state. The couplings are fixed using measured binding energies and proton-${}^7\mathrm{Be}$ $s$-wave scattering lengths, together with ${}^{8}B$ asymptotic normalization coefficients from ab initio calculations. We obtain a zero-energy $S$-factor of $18.2\pm 1.2\left(\mathrm{ANC}\mathrm{only}\right)$ eV b. Given that this is a LO result it is consistent with the recommended value $S\left(0\right)=20.8\pm 1.6$ eV b. Our computed $S\left(E\right)$ compares favorably with experimental data on ${}^7\mathrm{Be}(p,\gamma ){}^8\mathrm{B}$ for $E<0.4$ MeV. We emphasize the important role of proton-${}^7\mathrm{Be}$ scattering parameters in determining the energy dependence of $S\left(E\right)$, and demonstrate that their present uncertainties significantly limit attempts to extrapolate these data to stellar energies.

Shell structures in single-particle energy spectra are investigated against regular tetrahedral type deformation using a radial power-law potential model. Employing a natural way of shape parametrization which interpolates sphere and regular tetrahedron, we find prominent shell effects for rather large tetrahedral deformations, which bring about shell energies much larger than the cases of spherical and quadrupole type shapes. We discuss the semiclassical origin of these anomalous shell structures using periodic orbit theory.

The high-spin spectroscopy of ${}^{144}\mathrm{Tb}$ has been studied via ${}^{116}$Sn(${}^{32}S$, $3n1p$)${}^{144}\mathrm{Tb}$ fusion-evaporation reaction at a beam energy of 156 MeV. A dipole band built on the $\pi h_{11/2}^3\otimes \nu h_{11/2}^{-1}$ configuration is newly observed in ${}^{144}\mathrm{Tb}$. Together with similar observation in neighboring nuclei, the properties of dipole bands in $N=79$ isotones are investigated in terms of the self-consistent tilted-axis-cranking covariant density functional theory. Based on systematic comparison and examination of the shears mechanism, the dipole band in ${}^{144}\mathrm{Tb}$ can be interpreted as a magnetic rotational band.

The most recent parametrizations D1S, D1N, and D1M of the Gogny energy density functional are used to describe fission in the isotopes ${}^{232–280}U$. Fission paths, collective masses, and zero-point quantum corrections, obtained within the constrained Hartree-Fock-Bogoliubov approximation, are used to compute the systematics of the spontaneous fission half-lives $t_{\mathrm{SF}}$, the masses and charges of the fission fragments, and their intrinsic shapes. The Gogny-D1M parametrization has been benchmarked against available experimental data on inner and second barrier heights, excitation energies of the fission isomers, and half-lives in a selected set of Pu, Cm, Cf, Fm, No, Rf, Sg, Hs, and Fl nuclei. It is concluded that D1M represents a reasonable starting point to describe fission in heavy and superheavy nuclei. Special attention is also paid to understand the uncertainties in the predicted $t_{\mathrm{SF}}$ values arising from the different building blocks entering the standard semiclassical Wentzel-Kramers-Brillouin formula. Although the uncertainties are large, the trend with mass or neutron numbers are well reproduced and therefore the theory still has predictive power. In this respect, it is also shown that modifications of a few percent in the pairing strength can have a significant impact on the collective masses leading to uncertainties in the $t_{\mathrm{SF}}$ values of several orders of magnitude.

The recoil properties of fragments produced by the interaction of 4.4 GeV deuterons with a ${}^{197}$Au target have been studied. New experimental data on recoil properties for 90 nuclei, varying from ${}^{24}$Na to ${}^{198}$Au, were obtained. The technique applied was the thick-target thick-catcher and induced activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR), Dubna. The experimental data were analyzed on the basis of the standard two-step vector model formalism. From the analysis of the reaction investigated here, we could find evidence that the cooling process of excited nuclei can be due to the coexistence of different decay modes such as evaporation, fission, and (multi)fragmentation. Fission and multifragmentation can contribute appreciably to the formation of products in the intermediate mass range. The kinematic characteristics of residual nuclei formed in the present deuteron-induced reaction have been compared to those from proton-induced reactions with gold target.

One-nucleon transfer reactions, in particular ($d,p$) reactions, have played a central role in nuclear structure studies for many decades. Present theoretical descriptions of the underlying reaction mechanisms are insufficient for addressing the challenges and opportunities that are opening up with new radioactive beam facilities. We investigate a theoretical approach that was proposed recently to address shortcomings in the description of transfers to resonance states. The method builds on ideas from the very successful $R$-matrix theory; in particular, it uses a similar separation of the coordinate space into interior and exterior regions and introduces a parametrization that can be related to physical observables, which, in principle, makes it possible to extract meaningful spectroscopic information from experiments. We carry out calculations, for a selection of isotopes and energies, to test the usefulness of the new approach.

Barrier characteristics, barrier height and position, were studied on spherical-deformed fusion reactions using the proximity potential. Spherical-prolate (${\beta }_{21}=0.0$, ${\beta }_{22}=0.340$) and spherical-oblate (${\beta }_{21}=0.0$, ${\beta }_{22}=-0.330$) systems were tested in two different configurations and a pocket formula was presented that reproduced the theoretical values of barrier height and its position, with an accuracy of $\pm$0.4$\%$ for both types of configuration. The results obtained from this work reveal the possibility of determining parametrization for barrier characteristics in deformed systems.

Solar neutrinos can interact with the source isotope in neutrinoless double-$\beta$-decay experiments through charged-current and neutral-current interactions. The charged-current product nucleus will then $\beta$ decay with a $Q$ value larger than the double-$\beta$-decay $Q$ value. As a result, this process can populate the region of interest and be a background to the double-$\beta$-decay signal. We estimate the solar neutrino capture rates on three commonly used double-$\beta$-decay isotopes, ${}^{76}$Ge, ${}^{130}$Te, and ${}^{136}$Xe. We then use the decay scheme of each product nucleus to estimate the possible background rates in those materials. As half-life sensitivities in future experiments approach $1\times {10}^{28}$ yr, this background will have to be considered although its rate will depend on detector design in addition to nuclear structure.

The quadrupole collectivity of neutron-rich even-even neon and magnesium nuclei around $N=20$, ${}^{28,30}\mathrm{Ne}$, and ${}^{32,34,36}$Mg, was studied via proton inelastic scattering on a liquid hydrogen target by in-beam $\gamma$-ray spectroscopy in inverse kinematics. The angle-integrated cross sections for the first $2^{+}$ states of these nuclei were determined by measuring de-excitation $\gamma$ rays. The deformation lengths were extracted from the angle-integrated cross sections using distorted-wave calculations. The deformation length of ${}^{30}$Ne (${\delta }_{(p,p^{\prime })}=1.{59}_{-0.09}^{+0.08}$ fm) is smaller than that of ${}^{32}$Mg ($1.{83}_{-0.11}^{+0.10}$ fm), which exhibits the largest quadrupole collectivity among the neutron-rich $N=20$ isotones. Along the magnesium isotopic chain, the deformation lengths of ${}^{34}$Mg and ${}^{36}$Mg were deduced to be $2.{30}_{-0.10}^{+0.09}$ fm and $1.{90}_{-0.17}^{+0.16}$ fm, respectively. The evolution of quadrupole deformation in the vicinity of ${}^{32}$Mg is discussed by comparing the present results with the theoretical calculations.

We theoretically demonstrate the inclusive and semiexclusive spectra in the ${}^3\mathrm{He}$($K^{-}$, ${\pi }^{\mp }$) reactions at 600 MeV/$c$ (4${}^{\circ }$) within a distorted-wave impulse approximation, using a coupled ($2N-\Lambda )+(2N-\Sigma$) model with a spreading potential. We present the possible existence of the $\Sigma \mathit{NN}$ quasibound state with $J^{\pi }=$ 1/2${}^{+}$, $T\simeq$ 1 near the $\Sigma$ threshold, predicted by a $2N-Y$ folding-model potential derived from $\mathit{YN}$ $g$-matrices. The result shows that a signal of the ${}_{\Sigma }^3$He quasibound state is clearly confirmed near the $\Sigma$ threshold in the ${\pi }^{-}$ spectrum, whereas a peak of the ${}_{\Sigma }^{3}n$ quasibound state is rather reduced in the ${\pi }^{+}$ spectrum owing to the interference effects caused by the ${}^3{S}_1$-${}^1{S}_0$ admixture in the $\mathit{NN}$ pair. The mechanism of $\Sigma$ production for these spectra and charge symmetry breaking effects are also discussed.

We study the role of the effective Coulomb interaction strength and length on the dynamics of nucleons in conditions according to those in a neutron star's crust. Calculations were made with a semiclassical molecular dynamics model, studying isospin symmetric matter at subsaturation densities and low temperatures. The electrostatic interaction between protons is included as a screened Coulomb potential in the spirit of the Thomas–Fermi approximation, but the screening length is artificially varied to explore its effect on the formation of the nonhomogeneous nuclear structures known as “nuclear pasta.” As the screening length increases, we can see a transition from a one-per-cell pasta regime (due exclusively to finite-size effects) to a more appealing multiple pasta per simulation box. This qualitative difference in the structure of neutron star matter at low temperatures shows that special caution should be taken when the screening length is estimated for numerical simulations.

A novel approach, the identity method, was used for particle identification and the study of fluctuations of particle yield ratios in Pb + Pb collisions at the CERN Super Proton Synchrotron (SPS). This procedure allows one to measure the moments of the multiplicity distributions of protons ($p$), kaons ($K$), pions ($\pi$), and electrons ($e$) in case of incomplete particle identification. Using these moments the excitation function of the fluctuation measure ${\nu }_{\mathrm{dyn}}[A,B]$ was measured, with $A$ and $B$ denoting different particle types. The obtained energy dependence of ${\nu }_{\mathrm{dyn}}$ agrees with previously published NA49 results on the related measure ${\sigma }_{\mathrm{dyn}}$. However, ${\nu }_{\mathrm{dyn}}$[$K$,$p$] and ${\nu }_{\mathrm{dyn}}$[$K$,$\pi$] were found to depend on the phase-space coverage. This feature most likely explains the reported differences between measurements of NA49 and those of STAR in central Au + Au collisions.

We use the valon model to calculate the transversity distribution functions inside the nucleon. Transversity distributions indicate the probability to find partons with spin aligned (antialigned) to the transversely polarized nucleon. The results are in good agreement with all available experimental data and also global fits.

High-spin states of ${}^{190}\mathrm{Pt}$ have been reinvestigated using the ${}^{176}\mathrm{Yb}$(${}^{18}\mathrm{O}$, $4n$) reaction at a beam energy of 88 MeV. The previously known positive parity band associated with the $\nu$$i_{13/2}^{-2}$$\nu$$h_{9/2}^{-1}$$\nu$$j^{-1}$ ($\nu$$j$ being $\nu$$p_{3/2}$ or $\nu$$f_{5/2}$) configuration has been revised and extended significantly. A new negative parity band has been established and proposed to be based on the $\nu$$i_{13/2}^{-3}$$\nu$$j^{-1}$ configuration. Possible structure evolution of the yrast line from predominantly vibrational to rotational with increasing spin is discussed with the help of $E\gamma$ over spin curves. Additionally, calculations of total Routhian surfaces have been performed to investigate the band properties.

We recently proposed a method [R. A. Senkov and M. Horoi, Phys. Rev. C 88, 064312 (2013)] to calculate the standard nuclear matrix elements for neutrinoless double-$\beta$ decay ($0\nu \beta \beta$) of ${}^{48}\mathrm{Ca}$ going beyond the closure approximation. Here we extend this analysis to the important case of ${}^{82}\mathrm{Se}$, which was chosen as the base isotope for the upcoming SuperNEMO experiment. We demonstrate that by using a mixed method that considers information from closure and nonclosure approaches, one can get excellent convergence properties for the nuclear matrix elements, which allows one to avoid unmanageable computational costs. We show that in contrast with the closure approximation the mixed approach has a very weak dependence on the average closure energy. The matrix elements for the heavy neutrino-exchange mechanism that could contribute to the $0\nu \beta \beta$ decay of ${}^{82}\mathrm{Se}$ are also presented.

We present an extension of the pair coupled cluster doubles (p-CCD) method to quasiparticles and apply it to the attractive pairing Hamiltonian. Near the transition point where number symmetry gets spontaneously broken, the proposed BCS-based p-CCD method yields energies significantly better than those of existing methods when compared to the exact results obtained via solution of the Richardson equations. The quasiparticle p-CCD method has a low computational cost of $\mathcal{O}\left(N^3\right)$ as a function of system size. This together with the high quality of results here demonstrated points to considerable promise for the accurate description of strongly correlated systems with more realistic pairing interactions.