${\beta }^{-}$ decay of $T_z=+\frac{11}{2}$ nuclei ${}^{37}\mathrm{Al}$ and ${}^{39}\mathrm{Si}$ was studied to obtain information about excited states in the daughter and granddaughter nuclei. New information on excited states has been obtained for ${}^{37,39}\mathrm{P}$, whereas level schemes for ${}^{37}\mathrm{Si}$ and ${}^{37,39}\mathrm{S}$ were confirmed and expanded on as compared to the most recent investigations. For the nuclei studied, the valence proton and neutron occupy different major shells with opposite parities, hence, the ${\beta }^{-}$ decay preferentially and primarily populates core-excited $1p1h$ intruder states with a parity opposite to the ground state of the daughter nucleus. These low-lying intruder states shed light on the $N=20$ shell gap and its evolution with neutron number. The ${\beta }^{-}$ decay of very neutron-rich nuclei also illustrates how the Gamow-Teller (GT) strength distribution changes with neutron excess. Comparing ${\beta }^{-}$ decay of ${}^{37,39}\mathrm{Si}$ presented here with ${}^{38,40}\mathrm{Si}$ from a previous study, we clearly see an even-odd effect in the GT strength distribution with the decay from even-even nuclei showing strong low-lying strength whereas for the odd $A$ being very fragmented. Configuration interaction shell-model calculations with the state-of-art SDPFSDG-MU effective interaction were performed to understand the structure of the $1p1h$ states and explore the GT strength distribution.

Inspired by the recently-reported strong electric-dipole ($E1$) transition between the weakly-bound first and second excited states, $3/2^{-}$ at 765 keV and $1/2^{+}$ at 885 keV, in the nucleus ${}_{10}{}^{27}\mathrm{Ne}_{17}$, the $E1$ transition is estimated in a model by properly taking into account the effect of both deformation and weakly-bound neutrons. In addition to both the spin-parities, $1/2^{+}$ and $3/2^{-}$, and observed nearly degenerate energies of the two excited states, the observed order of magnitude of the $E1$ transition strength between the two states is very naturally explained in the case that these two excited states are prolately deformed, in terms of the transitions between the halo components of the wave functions of the weakly-bound odd-neutrons, $s_{1/2}\to p_{3/2}$ and $s_{1/2}\to p_{1/2}$, in addition to the large probability of the $p_{3/2}$ component in the weakly-bound neutron [330 1/2] orbit. The large probability is the result of the shell-structure unique in weakly-bound or resonant neutrons.

High-spin states in ${}^{92}\mathrm{Nb}$ have been investigated by using in-beam $\gamma$ ray spectroscopy with the ${}^{82}\mathrm{Se}({}^{14}\mathrm{N},4\mathrm{n}){}^{92}\mathrm{Nb}$ reaction at a beam energy of 54 MeV. The positive-parity decay sequences above the previously known state ${13}^{+}$ have been extended to $I^{\pi }\ge \left({20}^{+}\right)$ by adding nineteen new $\gamma$ rays. The level structures in ${}^{92}\mathrm{Nb}$ have been interpreted in terms of the shell model calculations performed in the configuration space $\pi (1f_{5/2},2p_{3/2},2p_{1/2},1g_{9/2})$ for the protons and $\nu (2p_{1/2},1g_{9/2},1g_{7/2},2d_{5/2})$ for the neutrons. The calculated results show that the inclusion of proton core excitation relative to the $Z=38$ subshell closure and neutron particle-hole excitation for the $N=50$ shell closure are essential to adequately describe the experimental high-spin states at $I\approx (18–20)\hslash$ with excitation energies above 8.5 MeV.

The effect of the shell structure of the target nuclei (${}^{89}\mathrm{Y}$ and ${}^{93}\mathrm{Nb}$) on reaction mechanisms involving the weakly bound ${}^7\mathrm{Li}$ projectile has been investigated via a comparative study of different processes. Measurements of direct breakup, nucleon transfer leading to the ejectile in bound as well as unbound states, and elastic scattering have been carried out for the ${}^7\mathrm{Li}+{}^{89}\mathrm{Y}$ system at three different energies near the Coulomb barrier. An extensive analysis of this comprehensive data set was carried out using coupled channel calculations and compared with a previous similar study for the ${}^7\mathrm{Li}+{}^{93}\mathrm{Nb}$ system. The observed cross sections at low target excitations for nucleon transfer reactions correlate with the vacancies in the valance orbitals.

The mass modifications of the light vector mesons ($\omega$, $\rho$, and $\varphi$) are investigated in asymmetric nuclear matter in the presence of strong magnetic fields, using a quantum chromodynamics (QCD) sum rule approach. These are computed from the medium modifications of the nonstrange and strange light quark condensates as well as scalar gluon condensate. The quark and gluon condensates are calculated from the medium changes of the scalar fields (nonstrange and strange) and a scalar dilaton field in the magnetized nuclear matter, within a chiral SU(3) model. The scalar dilaton field within the model breaks the scale invariance of QCD and simulates the gluon condensate. The anomalous magnetic moments for the nucleons are also taken into account in the present study.

We study hyperon resonances by solving coupled channel scattering equations. The coupled systems include pseudoscalar- and vector-baryon channels. The parameters of the model are restricted by making a ${\chi }^2$-fit to the cross-section data on processes: $K^{-}p\to K^{-}p$, $K^{-}p\to {\overline{K}}^{0}n$, $K^{-}p\to \eta \mathrm{\Lambda }$, $K^{-}p\to {\pi }^0\mathrm{\Lambda }$, $K^{-}p\to {\pi }^0{\mathrm{\Sigma }}^0$, $K^{-}p\to {\pi }^{\pm }{\mathrm{\Sigma }}^{\mp }$. Data on the energy-level shift and width of the $1s$ state of the kaonic hydrogen, as well as some cross-section ratios near the threshold are also considered in the fit. Two types of fit are found as a result. In both cases, the properties of $\mathrm{\Lambda }\left(1405\right)$ are well reproduced. In addition to this, a $\mathrm{\Sigma }$ state is also found with mass around 1400 MeV. Cross sections, obtained with one of the two fits, are found to stay close to the data at energies away from the thresholds too, and as a result resonances with higher masses have also been studied.

Parity (P) and time-reversal (T) violating effects are enhanced a million times in neutron reactions near $p$-wave nuclear compound resonances. Planning and interpretation of corresponding experiments require values of the matrix elements of the T,P-violating nuclear forces between nuclear compound states. We calculate the root-mean-square values and the ratio of the matrix elements of the T,P-violating and P-violating interactions using statistical theory based on the properties of chaotic compound states. We present the results in terms of the fundamental parameters in five different forms: in terms of the constants of the contact nuclear interaction, meson exchange constants, QCD $\theta$-term, quark chromo-electric dipole moments ${\tilde{d}}_u$ and ${\tilde{d}}_d$, and axion interaction constants. Using current limits on these parameters, we obtain upper bounds on the ratio of the matrix elements and on the ratio of T,P-violating and P-violating parts of the neutron reaction cross sections. Our results confirm that the expected sensitivity in neutron-reactions experiments may be sufficient to improve the limits on the T,P-violating interactions.

The hadron cascade model is an essential part of Monte Carlo neutrino event generators that governs final-state interactions of knocked-out nucleons and produced pions. It is shown that such a model enriched with physically motivated modifications of nucleon-nucleon cross sections and incorporation of nuclear correlation effects is able to reproduce experimental nuclear transparency data. The uncertainty of nucleon final-state interaction effects is estimated and applied to recent neutrino-nucleus cross section measurements that include an outgoing proton in the experimental signal. Conclusions are drawn on a perspective of identification of events that originate from the two-body current mechanism.

The quartic term in the framework of relativistic mean-field theory with inclusion of scalar meson interactions is investigated. It is shown that the quartic term in the asymmetric expansion of nuclear matter energy may reach very large values. This makes the even power expansion of asymmetry questionable and suggests possible nonanalytic contributions to the energy of matter.

We present a model description of the bound ${}^{19}\mathrm{B}$ isotope in terms of a ${}^{17}\mathrm{B}-n-n$ three-body system where the two-body subsystems ${}^{17}\mathrm{B}-n$ and $n-n$ are unbound (virtual) states close to the unitary limit. The ${}^{19}\mathrm{B}$ ground state is well described in terms of two-body potentials only, and two low-lying resonances are predicted. Their eventual link with the Efimov physics is discussed. This model can be naturally used to describe the recently discovered resonant states in ${}^{20,21}\mathrm{B}$.

New results obtained in this work from measurements of $\gamma$ radiation following fission of ${}^{248}\mathrm{Cm}$ and ${}^{252}\mathrm{Cf}$, performed using Eurogam2 and Gammasphere arrays, respectively, reveal excitations corresponding to $\gamma$ vibrations and triaxial deformation present in ${}^{100}\mathrm{Zr}$ and ${}^{102}\mathrm{Zr}$ nuclei. This is the first observation of nonaxial bands in Zr isotopes. Such excitations probably occur due to competing prolate and oblate configurations, identified recently in these nuclei. Evolution of $\gamma$ softness and triaxiality in Zr isotopes is observed in the function of the neutron number.

Detailed spectroscopic measurements of excited states in ${}^{50}\mathrm{Cr}$ and ${}^{62}\mathrm{Zn}$ were performed using 24-MeV $(p,t)$ transfer reactions on ${}^{52}\mathrm{Cr}$ and ${}^{64}\mathrm{Zn}$, respectively. In total, 45 states in ${}^{50}\mathrm{Cr}$ and 67 states in ${}^{62}\mathrm{Zn}$ were observed up to excitation energies of 5.5 MeV, including several previously unobserved states. These experimental results are compared to ab-initio shell-model calculations using chiral effective field theory with the valence-space in-medium similarity renormalization group method. This comparison demonstrates good agreement in the level orderings with these new theoretical methods, albeit with a slight overbinding in the calculations. This work is part of a continued push to benchmark ab-initio theoretical techniques to nuclear-structure data in $0^{+}\to 0^{+}$ superallowed Fermi $\beta$-decay systems.

I have used a potential model to examine mirror states in ${}^9\mathrm{Li}$ and ${}^9\mathrm{C}$. The mirror energy difference and observed widths of the supposed $7/2^{-}$ states are consistent with dominant parentage to the $3^{+}$ excited state of ${}^8\mathrm{Li}$ and ${}^8\mathrm{B}$. The newly reported $s$-wave resonance at 4.3 MeV in ${}^9\mathrm{C}$ should have a mirror near $E_x=5.39\left(38\right)\mathrm{MeV}$ in ${}^9\mathrm{Li}$.

Influence of couplings to collective excitations on fusion process has been well established experimentally and theoretically. Much less is known about the influence of dissipation caused by transfer reactions, even less due to noncollective excitations. In this paper, we report the results of the comparison of experimental barrier distributions with the $\mathrm{CC}+\mathrm{RMT}$ model calculations taking into account noncollective excitations, in which the stationary coupled channels method is merged with a statistical approach based on the random matrix theory. In spite of many assumptions and approximations, we find that the model works well for medium systems without fitting parameters, describing the influence of dissipation on tunneling. On the other hand, for heavier systems this mechanism does not appear to be sufficient. This points to the importance of other dissipation mechanisms for these systems, such as nucleon transfer processes.

By involving the constraints of the slope of nuclear symmetry energy $L$ into the question of determination of the high-density symmetry energy, one needs to probe the curvature of nuclear symmetry energy $K_{\mathrm{sym}}$. Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effects of the curvature of nuclear symmetry energy on the squeezed-out nucleons are demonstrated in the semicentral $\mathrm{Au}+\mathrm{Au}$ reaction at 400 and 600 MeV/nucleon. It is shown that the squeezed-out isospin-dependent nucleon emissions at high transverse momenta are sensitive to the curvature of nuclear symmetry energy. The curvature of nuclear symmetry energy at saturation density thus can be determined by the high-momentum squeezed-out isospin-dependent nucleon emissions experiments from the semicentral $\mathrm{Au}+\mathrm{Au}$ reaction at 400 or 600 MeV/nucleon.

The $S_{E1}$ factor of radiative $\alpha$ capture on ${}^{12}\mathrm{C}$ is studied in effective field theory up to next-to-leading order (NLO), and a modification of the counting rules for the radiative capture amplitudes is discussed. I find that only two unfixed parameters remain in the amplitudes up to NLO, and those two parameters are fitted to the experimental $S_{E1}$ data. A value of the $S_{E1}$ factor is calculated at the Gamow-peak energy as $S_{E1}=59\pm 3\mathrm{keV}\mathrm{b}$, and the result is found to be about 30% smaller than the estimates reported recently. An uncertainty of the estimate in the present work is also discussed.

In this work we study approximate and exact solutions for nucleons in a single-$j$ shell, from the perspective of nucleon-pair basis states, i.e., those coupled by pairs with good spins. We find that for four, five, and six particles in the $0h_{11/2}$ shell, a selected set of independent nucleon-pair basis states leads to approximate solutions of a realistic two-body interaction, without resorting to the diagonalization. We analytically show that for six particles in the $j=\frac{11}{2}$ shell, two nucleon-pair states with $J=3$ and 11—which are coupled by three pairs of spin 0, 2, and 4 and by pairs of spin 0, 2, and 10, respectively—are eigenstates of any two-body interactions. In particular, we construct general analytic expressions for states of definite seniority numbers $\nu =3,4,5$ in terms of nucleon-pair basis states, based on which we further derive exact wave functions for a few eigenstates of any two-body interactions in the midshells of $j=\frac{7}{2},\frac{9}{2},\frac{11}{2}$. The exact wave functions given here should be useful in interpreting electromagnetic moment and transition properties of corresponding nuclei.

Global polarization of $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons in $\mathrm{Au}+\mathrm{Au}$ collisions at collision energies $\sqrt{s_{NN}}=4–40\mathrm{GeV}$ in the midrapidity region and total polarization, i.e., averaged over all rapidities, are studied within the scope of the thermodynamical approach. The relevant vorticity is simulated within the model of the three-fluid dynamics (3FD). It is found that the performed rough estimate of the global midrapidity polarization quite satisfactorily reproduces the experimental STAR data on the polarization, especially its collision-energy dependence. The total polarization increases with the collision energy rise, which is in contrast to the decrease of the midrapidity polarization. This suggests that at high collision energies the polarization reaches high values in fragmentation regions.