A deformed configuration mixing shell model based on Hartree-Fock states with extension to include isospin projection is applied to study the structure of low-lying levels in the odd-odd $N=Z$ nuclei ${}^{62}\mathrm{Ga}$ and ${}^{66}\mathrm{As}.$ A realistic G-matrix interaction for the ${(f}_{5/2}{\mathrm{pg}}_{9/2})$ space with monopole correction is employed in the calculations. The $T=0\mathrm{}$ and $T=1\mathrm{}$ spectra for ${}^{62}\mathrm{Ga}$ compare well with experiment and shell model. The predicted spectrum for ${}^{66}\mathrm{As}$ is close to the recent interacting boson model (IBM-4) results.

The near-yrast structure of the weakly deformed, “transitional,” nucleus ${}^{101}\mathrm{Ru}$ has been investigated using the fusion-evaporation reaction ${}^{96}\mathrm{Zr}{(}^9\mathrm{Be}{,4n)}^{101}\mathrm{Ru}$ at a beam energy of approximately 44 MeV. The experimental data are compared with theoretical calculations using the cranked Woods-Saxon-Strutinsky method. The yrast positive-parity structures are observed to undergo a backbend, consistent with the crossing of an aligned $(\nu h_{11/2}{)}^2$ configuration. The $h_{11/2}\left(\right[550\left]{\frac{1}{2}}^{-}\right)$ intruder band configuration is extended to a tentative spin/parity of $\left({\frac{47}{2}}^{-}\right)$ and excitation energy of more than 9 MeV. This structure exhibits properties which can be explained by the rotational alignment of a pair of midshell $g_{9/2}$ protons, in contrast to the behavior observed in the heavier $N=57,$ odd-$A$ isotones where the predicted proton crossing is delayed in favor of neutron alignments. The effect of static γ deformation on the theoretically predicted alignment properties is investigated by means of the cranked shell model. The observed band crossings are found to be consistent with a significant triaxial rigidity, persistent into the medium-spin regime.

The predictive power for masses of a recently published highly extrapolatable semiempirical shell model mass equation is compared to that of several current mass models and some differences are noted and addressed. The equation is shown to describe rather well the energies of several seemingly well-identified $\alpha$-decay chains with known end product nuclei observed in superheavy elements research. The equation is also applied to the interpretation problem of some recent hot fusion-evaporation experiments with unknown end products and several conceivable reaction channels. Some plausible interpretations are indicated.

An extensive spectroscopic study of ${}^{48}\mathrm{V}$ has been performed using fusion-evaporation reactions to deduce the decay scheme and to measure transition probabilities through the Doppler shift attenuation method. Experimental levels were grouped into five bands, labeled with Nilsson configurations. Bands become nearly spherical approaching band termination. Large-scale shell model calculations were performed, producing results in very good agreement with the experimental data.

We present a theoretical analysis of the first data for a high-energy and momentum-transfer (hard) quasielastic $A(p,2p)X$ reaction. The cross sections for this reaction are calculated within the light-cone impulse approximation based on a two-nucleon correlation model for the high-momentum component of the nuclear wave function. Nuclear effects due to modification of the bound nucleon structure as well as the soft nucleon-nucleon initial and final state interactions, with and without color coherence, have been studied in detail. The calculations show that the distribution of the bound proton light-cone momentum fraction $\left(\alpha \right)$ shifts towards small values $(\alpha <1),$ an effect that was previously derived only within the plane wave impulse approximation. The shift is very sensitive to short-range correlations in nuclei. The calculations agree with data on the $\mathrm{C}\mathrm{}(p,2p)X$ reaction obtained from the EVA/AGS experiment at Brookhaven National Laboratory. The theoretical analysis of the data allows the contribution from short-range nucleon correlations to be singled out. The obtained strength of the correlations is in agreement with values previously obtained from electroproduction reactions on nuclei.

We calculate the equation of state of pure neutron matter, comparing the G-matrix calculation with the in-medium T-matrix result. At low densities, we obtain similar energies per nucleon; however, some differences appear at higher densities. We use the self-consistent spectral functions from the T-matrix approach to calculate the ${}^1{S}_0$ superfluid gap including self-energy effects. We find a reduction of the superfluid gap by 30%.

The nuclear cluster radioactivities have been studied theoretically in the framework of a microscopic superasymmetric fission model (MSAFM). The nuclear interaction potentials required for binary cold fission processes are calculated by folding in the density distribution functions of the two fragments with a realistic effective interaction. The microscopic nuclear potential thus obtained has been used to calculate the action integral within the WKB approximation. The calculated half-lives of the present MSAFM calculations are found to be in good agreement over a wide range of observed experimental data.

We reinvestigate the QCD sum rule for the $\pi \mathrm{NN}$ coupling constant g starting from the vacuum-to-pion matrix element of the correlation function of the interpolating fields of two nucleons. We study in detail the physical content of the correlation function without referring to the effective theory. We consider the invariant correlation functions by splitting the correlation function into different Dirac structures. We show that the coefficients of the double-pole terms are proportional to g but that the coefficients of the single-pole terms are not determined by g. In the chiral limit the single-pole terms as well as the continuum terms are ill defined in the dispersion integral. Therefore, the use of naive QCD sum rules obtained from the invariant correlation functions is not justified. A possible procedure to avoid this difficulty is discussed.

Lifetimes of rotational states built on the ${7/2}^{-}\left[514\right]$ and ${1/2}^{-}\left[521\right]$ Nilsson single-particle orbitals in ${}^{181}\mathrm{Os}$ have been measured using the coincidence recoil-distance method. The experimentally determined quadrupole moment, assuming axial symmetry, is $\approx 20\%$ larger for the ${7/2}^{-}\left[514\right]$ band compared with the ${1/2}^{-}\left[521\right]$ band. The difference can be understood as an effect of triaxiality. Total Routhian surface calculations show deviations from axial symmetry for both bands, leading to good agreement between theory and experiment.

The structure of cold dense matter at subnuclear densities is investigated by quantum molecular dynamics simulations. We succeeded in showing that the phases with slablike and rodlike nuclei, etc., can be formed dynamically from hot uniform nuclear matter without any assumptions on nuclear shape. We also observe intermediate phases, which have complicated nuclear shapes. Geometrical structures of matter are analyzed with Minkowski functionals, and it is found that intermediate phases can be characterized as those with negative Euler characteristic. Our result suggests the existence of these kinds of phases in addition to the simple “pasta” phases in neutron star crusts.

We study the event-by-event fluctuations of the charged particles and compare the results of different Monte Carlo generators (MCG): VNIb, HIJING, $\mathrm{H}\mathrm{I}\mathrm{J}\mathrm{I}\mathrm{N}\mathrm{G}/B\overline{B},$ and RQMD. We find that the D-measure can be used to distinguish between the different gluon populations that are present in the MCG models. On the other hand, the value of the D-measure shows high sensitivity to the rescattering effects in VNIb model, but lower sensitivity to the rescattering effects in RQMD model. We also find that the D-measures from $\mathrm{AA}$ are consistent with the D-measures from $\mathrm{pp}$ for all generators except VNIb. Therefore, any deviation among the values of D-measure for different impact parameters and between $\mathrm{pp}$ and $\mathrm{AA}$ collisions may indicate that either the rescattering effects play a key role in the interactions or there is new physics in $\mathrm{AA}$ collisions.

We investigate low energy nucleon dynamics in the effective-field theory (EFT) of nuclear forces. In leading order of the two-nucleon EFT we show that nucleon dynamics is governed by the generalized dynamical equation with a nonlocal-in-time interaction operator. This equation is shown to open new possibilities for applying the EFT approach to the description of low energy nucleon dynamics.

Level schemes of ${}_{48}^{99}{\mathrm{Cd}}_{51}$ and ${}_{49}^{101}{\mathrm{In}}_{52}$ nuclei have been extended to high spin. The breakup of the doubly magic ${}^{100}\mathrm{Sn}$ core has been observed. Large-scale shell model calculations based on realistic nucleon-nucleon interactions are in good agreement with the experimental data. These results provide a reliable basis to predict nuclear structure properties in ${}^{100}\mathrm{Sn}$ and its neighbors. For example, the size of the $N=50\mathrm{}$ shell gap and the energy of the first excited state in ${}^{101}\mathrm{Sn}$ have been deduced.

The excited states of ${}^{12}\mathrm{Be},$ ${}^{14}\mathrm{Be},$ and ${}^{15}\mathrm{B}$ were studied by an antisymmetrized molecular dynamics method. The theoretical results reproduce the energy levels of the recently measured excited states of ${}^{12}\mathrm{Be},$ and also predict rotational bands with novel cluster structures in ${}^{12}\mathrm{Be},$ ${}^{14}\mathrm{Be},$ and ${}^{15}\mathrm{B}.$ Cluster states with new exotic clusters ${(}^6\mathrm{He},$ ${}^8\mathrm{He},$ and ${}^9\mathrm{Li})$ are theoretically suggested. The new aspect is a six-nucleon correlation among four neutrons and two protons, which gives rise to the formation of ${}^6\mathrm{He}$ clusters: ${}^8\mathrm{He}{+}^6\mathrm{He}$ in ${}^{14}\mathrm{Be}$ and ${}^9\mathrm{Li}{+}^6\mathrm{He}$ in ${}^{15}\mathrm{B}.$

The incomplete fusion reactions ${}^7{\overrightarrow{\mathrm{Li}}}^{158,160}\mathrm{Gd}$ at beam energies of 8 MeV/nucleon have been used to study the first band crossing region in the heavy stable Dy isotopes ${}^{160,162}\mathrm{Dy}.$ The $\gamma$ rays were detected in the GASP spectrometer in coincidence with fast charged particles detected in the ISIS silicon ball. We succeeded to observe the first backbending in ${}^{162}\mathrm{Dy}$ at a crossing frequency of $ħ\omega \approx 350\hspace{0.5em}\mathrm{keV},$ a value much higher than expected from other nuclei in this mass region. Moreover, for the first time in a nucleus with a very large interaction strength, the yrare band in ${}^{160}\mathrm{Dy}$ could be established up to rather high spin $(I=20\mathrm{}ħ)$ allowing for a precise determination of the interaction strength between the ground state and the Stockholm band, $|V_{g-S}|=219\mathrm{}\left(2\right)\mathrm{}\hspace{0.5em}\mathrm{keV}.$ Together with $|V_{g-S}|=14\mathrm{}\left(2\right)\mathrm{}\hspace{0.5em}\mathrm{keV}$ determined for the corresponding interaction in ${}^{162}\mathrm{Dy},$ a full oscillation of the strengths from one node to the next could be observed within an isotopic chain. In addition to the ground state and Stockholm bands, many other known bands in the two nuclei were considerably extended to higher spin and the experimental results are compared to calculations within the projected shell model.

Prompt $\gamma$ rays have been observed for the first time from the neutron-deficient nucleus ${}^{191}\mathrm{Po}$ using the recoil-decay tagging technique at the RITU gas-filled separator. In addition improved $\alpha$ decay data have been measured for ${}^{191}\mathrm{Po}$ and its daughter product ${}^{187}\mathrm{Pb}.$ The complementary $\gamma$- and $\alpha$-decay data point to the onset of oblate deformation in the light odd-mass Po nuclei by approaching the neutron midshell at $N=104.\mathrm{}$ The pattern of the favored and unfavored states observed on top of the ${13/2}^{+}$ isomer in ${}^{191}\mathrm{Po}$ indicates a change from the weak-coupling towards the strong-coupling scheme in ${}^{191m}\mathrm{Po}.$ In the daughter nucleus ${}^{187}\mathrm{Pb},$ the ${13/2}^{+}$ and ${3/2}^{-}$ isomeric states become degenerate within the experimental accuracy. Evidence for triple shape coexistence at low energy has been found in the high-spin isomer in ${}^{187}\mathrm{Pb}.$ The results are supported by potential-energy surface calculations and by particle-plus-rotor calculations.

Measurements of the ${}^4\mathrm{He}(\gamma ,{\pi }^{+}{n)}^3\mathrm{H}$ and ${}^4\mathrm{He}(\gamma ,{\pi }^{+}p)nnn$ reactions in quasifree $\pi$ production kinematic regimes have been performed using unpolarized and linearly polarized tagged photons in conjunction with large solid angle $\pi$ and n detectors at the MAMI-B accelerator, Mainz. Differential cross sections are presented for photon energies spanning the $\Delta \mathrm{}\left(1232\right)\mathrm{}$ excitation region. These data combined with previously presented results for the ${}^{12}\mathrm{C}(\gamma ,{\pi }^{+}{n)}^{11}\mathrm{B}$ reaction provide an extensive data set for future investigations of $\Delta$-medium effects in nuclei. The ${}^4\mathrm{He}(\gamma ,{\pi }^{+}{n)}^3\mathrm{H}$ cross sections are significantly smaller than theoretical predictions based on the free proton amplitude for $\Delta$ excitation with a crude correction for final state interactions, and exhibit different trends, which could possibly be a consequence of $\Delta$-medium effects. From a comparison with published ${}^{12}\mathrm{C}(\gamma ,{\pi }^{+}{p)}^{11}\mathrm{Be}$ data, it is concluded that the ${}^4\mathrm{He}(\gamma ,{\pi }^{+}p)nnn$ reaction mechanisms are probably two-step processes, although the possibility that part or all of the cross section arises from interactions with preexisting ${\Delta }^{++}$ particles cannot be ruled out.

We investigate the modification of meson spectral densities in dense nuclear matter at zero temperature. These effects are studied in a fully relativistic mean field model which goes beyond the linear density approximation and also includes baryon resonances. In particular, the role of $N^{*}\mathrm{}\left(1520\right)\mathrm{}$ and $N^{*}\mathrm{}\left(1720\right)\mathrm{}$ on the $\rho$ meson spectral density is highlighted. Even though the nucleon-nucleon loop and the nucleon-resonance loop contribute with the opposite sign, an overall reduction of $\rho$ meson mass is still observed at high density. Importantly, it is shown that the resonances cause substantial broadening of the $\rho$ meson spectral density in matter and also induce nontrivial momentum dependence. We study the dispersion relations and collective oscillations induced by the $\rho$ meson propagation in nuclear matter together with the influence of the mixing of $\rho$ with the $a_0$ meson. The relevant expression for the plasma frequency is also recovered analytically in the appropriate limit. The spectral density of the $a_0$ meson is also shown.

We critically evaluate the isovector Goldberger-Miyazawa-Oehme (GMO) sum rule for forward $\pi N$ scattering using the recent precision measurements of ${\pi }^{-}p$ and ${\pi }^{-}d$ scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data, $g_c^2\mathrm{}\left(\mathrm{GMO}\right)/4\mathrm{}\mathrm{\pi }=14.11\mathrm{}\pm 0.05\left(\mathrm{statistical}\right)\mathrm{}\pm 0.19\left(\mathrm{systematic}\right)\mathrm{}$ or $f_c^2/4\mathrm{}\pi =0.0783\mathrm{}\left(11\right).$ This value is intermediate between that of indirect methods and the direct determination from backward np differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the pion-proton and pion-neutron scattering lengths with high precision, namely, ${(a}_{{\pi }^{-}\mathrm{p}}{+a}_{{\pi }^{-}n})/2=[-12\pm 2\left(\mathrm{statistical}\right)\pm 8\left(\mathrm{systematic}\right)]\times {10}^{-4}{m}_{\pi }^{-1}$ and ${(a}_{{\pi }^{-}\mathrm{p}}-a_{{\pi }^{-}n})/2=[895\pm 3\left(\mathrm{statistical}\right)\pm 13$ $\left(\mathrm{systematic}\right)]\times {10}^{-4}{m}_{\pi }^{-1}.$ For the need of the present analysis, we improve the theoretical description of the pion-deuteron scattering length.