The fragment mass distribution from fission of hot nuclei is studied in the framework of two-dimensional Langevin equations. The mass asymmetry coordinate distribution is obtained from the dynamical calculation both at the saddle and the scission regions in order to investigate the role of saddle-to-scission dynamics in fission fragment mass distribution. Statistical model predictions of mass asymmetry distributions at saddle and scission are also compared with the dynamical model results. Results for a number of nuclei covering a broad range of saddle-to-scission distances are presented.

The dispersive optical model is applied to transfer reactions. A systematic study of $(d,p)$ reactions on closed-shell nuclei using the finite-range adiabatic reaction model is performed at several beam energies and results are compared to data as well as to predictions using a standard global optical potential. Overall, we find that the dispersive optical model is able to describe the angular distributions as well as or better than the global parametrization. In addition, it also constrains the overlap function. Spectroscopic factors extracted using the dispersive optical model are generally lower than those using standard parameters, exhibit a reduced dependence on beam energy, and are more in line with results obtained from $(e,e^{\prime }p)$ measurements.

Partial decay widths of lowest-lying nucleon resonances $S_{11}\left(1535\right)$, $S_{11}\left(1650\right)$, $D_{13}\left(1520\right)$, and $D_{13}\left(1700\right)$ to the pseudoscalar mesons and octet baryons are studied within a chiral constituent quark model. Effects of the configurations mixing between the states $|N_8^2{P}_M\rangle$ and $|N_8^4{P}_M\rangle$ are considered, taking into account SU($6)\otimes \mathrm{O}(3)$ breaking effects. In addition, possible contributions of the strangeness components in the $S_{11}$ resonances are investigated. Experimental data for the partial decay widths of the $S_{11}$ and $D_{13}$ resonances are well reproduced. Contributions from five-quark components in the S11 resonances are found crucial in reproducing the partial widths. Predictions for coupling constants of the four nucleon resonances to pseudoscalar mesons and octet baryons, crucial issues in the photo- and hadron-induced meson production reactions, are reported.

The transverse charge density in a fast-moving nucleon is represented as a dispersion integral of the imaginary part of the Dirac form factor in the timelike region (spectral function). At a given transverse distance $b$ the integration effectively extends over energies in a range $\sqrt{t}\lesssim 1/b$, with exponential suppression of larger values. The transverse charge density at peripheral distances thus acts as a low-pass filter for the spectral function and allows one to select energy regions dominated by specific $t$-channel states, corresponding to definite exchange mechanisms in the spacelike form factor. We show that distances $b\sim 0.5–1.5\text{fm}$ in the isovector density are maximally sensitive to the $\rho$ meson region, with only a $\sim 10\%$ contribution from higher-mass states. Soft-pion exchange governed by chiral dynamics becomes relevant only at larger distances. In the isoscalar density higher-mass states beyond the $\omega$ are comparatively more important. The dispersion approach suggests that the positive transverse charge density in the neutron at $b\sim 1\text{fm}$, found previously in a Fourier analysis of spacelike form factor data, could serve as a sensitive test of the the isoscalar strength in the $\sim 1\text{GeV}$ mass region. In terms of partonic structure, the transverse densities in the vector meson region $b\sim 1\text{fm}$ support an approximate mean-field picture of the motion of valence quarks in the nucleon.

The inclusive reactions $pp\to e^{+}{e}^{-}X$ and $np\to e^{+}{e}^{-}X$ at the laboratory kinetic energy of 1.25 GeV are investigated in a model of dominance of nucleon and $\Delta$ resonances. Experimental data for these reactions have recently been reported by the HADES Collaboration. In the original model, the dileptons are produced either from the decays of nucleon and $\Delta$ resonances $R\to N{e}^{+}{e}^{-}$ or from the Dalitz decays of ${\pi }^0$ and $\eta$ mesons created in the $R\to N{\pi }^0$ and $R\to N\eta$ decays. We found that the distribution of dilepton invariant masses in the $pp\to e^{+}{e}^{-}X$ reaction is well reproduced by the contributions of $R\to N{e}^{+}{e}^{-}$ decays and $R\to N{\pi }^0$, ${\pi }^0\to \gamma e^{+}{e}^{-}$ decays. Among the resonances, the predominant contribution comes from the $\Delta \left(1232\right)$, which determines both the direct decay channel $R\to N{e}^{+}{e}^{-}$ and the pion decay channel. In the collisions $np\to e^{+}{e}^{-}X$, additional significant contributions arise from the $\eta$-meson Dalitz decays, produced in the $np\to np\eta$ and $np\to d\eta$ reactions, the radiative capture $np\to d{e}^{+}{e}^{-}$, and the $np\to np{e}^{+}{e}^{-}$ bremsstrahlung. These mechanisms may partly explain the strong excess of dileptons in the cross section for collisions of $np$ versus $pp$, which ranges from 7 to 100 times for the dilepton invariant masses of 0.2 to 0.5 GeV.

The macroscopic-microscopic model with the Lublin-Strasbourg drop, the Strutinsky shell-correction method, and the BCS approach for pairing correlations is used with the cranking model to describe nuclear masses and rotational bands in even-even Ra to Cn isotopes of actinide and transactinide nuclei. The single-particle levels and potential-energy surfaces are calculated with the Yukawa-folded single-particle potential using the “modified funny hills” ($c,h$) shape parametrization. A monopole pairing force is used in our calculations. At equilibrium deformation the pairing strength is adjusted for every nucleus so as to reproduce the experimentally known rotational $E_{2^{+}}$ state within the cranking model. The pairing strength obtained in this way is used to predict the masses and rotational states in superheavy No to Cn nuclei. It is also shown that the rotational states with $L\lesssim 10$ in Ra to No nuclei evaluated using a simple rotational formula agree quite well with the data. We propose a simple mechanism which takes into account a dynamical coupling of rotation with the pairing field that then allows one to obtain an excellent agreement with the data up to the states with the largest angular momenta ($L\le 30$) measured in this mass region.

Excited states in ${}^{96}$Ag were populated in fragmentation of an 850-MeV/u ${}^{124}$Xe beam on a 4-g/cm${}^2$ Be target. Three new high-spin isomers were identified and the structure of the populated states was investigated. The level scheme of ${}^{96}$Ag was established, and a spin parity of (13${}^{-}$), (15${}^{+}$), and (19${}^{+}$) was assigned to the new isomeric states. Shell-model calculations were performed in various model spaces, including $\pi \nu (p_{1/2},g_{9/2},f_{5/2},p_{3/2})$ and the large-scale shell-model space $\pi \nu \left(gds\right)$, to account for the observed parity changing $M2$ and $E3$ transitions from the (13${}^{-}$) isomer and the $E2$ and $E4$ transitions from the (19${}^{+}$) core-excited isomer, respectively. The calculated level schemes and reduced transition strengths are found to be in very good agreement with the experiment.

We develop a method to describe approximately the effects of relativity in low-energy scattering of identical nuclei. The method results in an equation similar to the Schrödinger one, but with modified (effective) energy and potential. The model is applied to the elastic scattering data analyses of the $\alpha +\alpha$ system. We demonstrate that the effects of relativity are not totally negligible in this case even at very low energies. We also develop a new parametrization of the effective nucleon-nucleon interaction that can be extended to other systems.

Cluster radioactivity is the emission of a fragment heavier than an $\alpha$ particle and lighter than mass 50. The range of clusters observed in experiments goes from ${}^{14}$C to ${}^{32}$Si while the heavy mass residue is always a nucleus in the neighborhood of the doubly-magic ${}^{208}$Pb nucleus. Cluster radioactivity is described in this paper as very asymmetric nuclear fission. A new fission valley leading to a decay with large fragment mass asymmetry matching the cluster radioactivity products is found. The mass octupole moment is found to be more convenient than the standard quadrupole moment as the parameter driving the system to fission. The mean-field Hartree-Fock-Bogoliubov theory with the phenomenological Gogny interaction has been used to compute the cluster emission properties of a wide range of even-even actinide nuclei from ${}^{222}$Ra to ${}^{242}$Cm, where emission of the clusters has been experimentally observed. Computed half-lives for cluster emission are compared with experimental results. The noticeable agreement obtained between the predicted properties of cluster emission (namely, cluster masses and emission half-lives) and the measured data confirms the validity of the proposed methodology in the analysis of the phenomenon of cluster radioactivity. A continuous fission path through the scission point has been described using the neck parameter constraint.

The effective moment of inertia of the compound nucleus is calculated for several fission reaction systems induced by nucleons, light particles, and heavy ions. The determination of this quantity for these systems is based upon the comparison between the experimental data of the fission fragment angular distributions as well as the prediction of the standard saddle-point statistical model. For the systems, the two cases, namely with and without neutron emission corrections, were considered. Afterward, our theoretical results are compared with the data obtained from the rotational liquid drop model as well as the Sierk model and satisfactory agreements were found. We also calculated the quadrupole deformation and mass asymmetry parameters of the fissioning nuclei at the saddle point by two methods, the first method is based on an ellipsoid shape assumption for the fissioning nucleus, and the other is based on dinuclear system model, since in heavy ion induced fission reactions, the compound nuclei which undergo fission can be considered as states of two touching clusters (dinuclear system). Afterward, the results of these two methods were compared and satisfactory agreements were found between them.

The recent discovery of a new state at 7.796 MeV in ${}^{18}$O has caused us to revisit the problem of the 7.37-MeV state in ${}^{18}$Ne.

The isomeric and $\beta$ decays of the $N=Z+2$ nucleus ${}^{96}$Ag were investigated at the National Superconducting Cyclotron Laboratory. A cascade of $\gamma$-ray transitions originating from the deexcitation of a microsecond isomer was observed for the first time and was found in coincidence with two previously known transitions with energies of 470 and 667 keV. The isomeric half-life was determined as 1.45(7) $\mu$s, more precise than previously reported. The existence of a second, longer-lived microsecond isomer, associated with a 743-keV $\gamma$ transition, is also proposed here. Shell model results within the $\left(p_{3/2}{p}_{1/2}{f}_{5/2}{g}_{9/2}\right)$ model space, using the jj44b interaction, reproduced level energies and isomeric decay half-lives reasonably well.

We give a microscopic derivation of the spin-spin components of the optical potential for elastic scattering of a nucleon from a target with nonzero spin. A realistic nucleon-nucleon interaction containing direct and exchange terms is used to generate a folded nucleon-nucleus potential whose spin-spin components are treated in distorted-wave Born approximation. We show how folding leads to spin-spin tensor interactions with higher order couplings in the projectile and target spin that have not been explicitly considered before. We place particular emphasis on the polarization transfer coefficient $D_{\mathrm{NN}}$ for 200-MeV protons elastically scattered from ${}^{10}$B, which is rigorously unity in the absence of any spin-spin interactions and for which experimental data exist. We find that deviations of $D_{\mathrm{NN}}$ from unity are particularly sensitive to spin-spin exchange terms arising from the nucleon-nucleon tensor interaction and the nuclear wave functions describing the target one-body density matrix. Unpolarized differential cross sections and vector analyzing powers are found to be very insensitive to these terms.

A two-proton knockout reaction from a ${}^{17}$C beam at 55 MeV/u was used to produce the unbound nucleus ${}^{15}$Be. No significant number of events were observed for the decay of ${}^{15}$Be into a neutron and a ${}^{14}$Be fragment. An upper limit for the ${}^{14}$Be production cross section of 0.079$\pm$0.038 mb was extracted, which is more than an order of magnitude smaller than the predicted two-proton knockout reaction cross section. Based on these results we conclude that any populated states in ${}^{15}$Be decay through three sequential neutron decays into ${}^{12}$Be, via the unbound first excited state of ${}^{14}$Be. Therefore, these states in ${}^{15}$Be must be neutron unbound by more than 1.54 MeV, which is the location of the first excited 2${}^{+}$ state in ${}^{14}$Be.

A functional form has been used to analyze proton total reaction cross sections on stable and unstable target nuclei. For proton or incident nuclei energy per nucleon in the range between 30 and 300 MeV, the parameter values in this functional are interpreted in terms of the nuclear-matter distribution by using reliable total reaction cross-sectional data.

Nuclear attenuation of the multihadron systems in the string model is considered. The improved two-scale model with a set of parameters obtained recently for the single-hadron attenuation is used to calculate the multiplicity ratios of the one-, two-, and three-hadron systems electroproduced on nuclear and deuterium targets. A comparison of the features of the one-, two-, and three-hadron systems is performed. The predictions of the model for multiplicity ratios of multihadron systems as functions of different convenient variables are presented.

Polarization observables in elastic electromagnetic hadron-lepton scattering at low energies are studied, with special emphasis on the influence of Coulomb distortion. The spin-dependent contributions to the scattering matrix, i.e., the hyperfine and spin-orbit interactions of leptons and hadrons, are calculated in a distorted-wave Born approximation based on nonrelativistic Coulomb wave functions. For like charges the Coulomb repulsion greatly reduces the size of polarization observables compared to the plane-wave Born approximation, whereas for opposite charges the Coulomb attraction leads to a substantial increase in these observables for hadron laboratory kinetic energies below about 20 keV.

The effect of temperature and density dependence of the asymmetric nuclear matter properties is studied within the extended relativistic mean field (ERMF) model, which includes the contribution from the self and mixed interaction terms by using different parametrizations obtained by varying the neutron skin thickness $\Delta$$r$ and $\omega$-meson self-coupling ($\zeta$). We observed that the symmetry energy and its slope and incompressibility coefficients decrease with increasing temperatures up to saturation densities. The ERMF parametrizations were employed to obtain a new set of equations of state (EOS) of the protoneutron star (PNS) with and without inclusion of hyperons. In our calculations, in comparison with cold compact stars, we obtained that the gravitational mass of the protoneutron star with and without hyperons increased by $\sim$$0.4M_{\odot }$ and its radius increased by $\sim$3 km. Whereas in case of the rotating PNS, the mass shedding limit decreased with increasing temperature, and this suggested that the keplerian frequency of the PNS at $T=10$ MeV should be smaller by 14$\%$–20$\%$ for the EOS with hyperon, as compared to the keplerian frequency of a cold compact star.

A bandlike structure, based on the $\pi h_{11/2}\otimes \nu h_{11/2}$ configuration, has been identified for the first time in ${}^{134}$Cs in a gamma-ray spectroscopic study using fusion evaporation reactions. The nature of this band in ${}^{134}$Cs has been found to be distinctly different than the nearly degenerate doublet rotational band structures, observed in the lighter Cs isotopes for the same configuration. Both the total Routhian surface and the tilted axis cranking calculations were performed to understand the experimental observations. The present results suggest that the $N=77$ defines the border of the deformed structure in the $A\sim 130$ region while approaching $N=82$.

We study the interplay between regular and chaotic dynamics at the critical point of a generic first-order quantum phase transition in an interacting boson model of nuclei. A classical analysis reveals a distinct behavior of the coexisting phases in a broad energy range. The dynamics is completely regular in the deformed phase and, simultaneously, strongly chaotic in the spherical phase. A quantum analysis of the spectra separates the regular states from the irregular ones, assigns them to particular phases, and discloses persisting regular rotational bands in the deformed region.