Conventional and hybrid light quark baryons are constructed in the nonrelativistic flux-tube model of Isgur and Paton, which is motivated by lattice QCD. The motion of the flux tube with the three quark positions fixed, except for center-of-mass corrections, is discussed. It is shown that the problem can be reduced to the independent motion of the junction and the strings connecting the junction to the quarks. The important role played by quark-exchange symmetry in constraining the flavor structure of (hybrid) baryons is emphasized. The flavor, quark spin S, and $J^P$ of the seven low-lying hybrid baryons are found to be $(N,\Delta {)}^{2S+1}{J}^P{=N}^2{\frac{1}{2}}^{+},$ $N^2{\frac{3}{2}}^{+},$ ${\Delta }^4{\frac{1}{2}}^{+},$ ${\Delta }^4{\frac{3}{2}}^{+},$ ${\Delta }^4{\frac{5}{2}}^{+},$ where the $N^2{\frac{1}{2}}^{+}$ and $N^2{\frac{3}{2}}^{+}$ states are doublets. The motion of the three quarks in an adiabatic potential derived from the flux-tube dynamics is considered. A mass of $1870\pm 100\mathrm{MeV}$ for the lightest nucleon hybrids is found by employing a variational method.

In light of the derivative coupling model, we make an expansion of the nonlinear coupling constant, and calculate its effective nucleon mass at different orders. The varying characteristic of the effective nucleon mass at these orders is discussed and its physical meaning is interpreted. We find that the mechanism of phase transition at high temperature in the Walecka model is suppressed in the derivative coupling model.

We perform the first fully consistent analysis of $\mathrm{nd}$ scattering at next-to-next-to-leading order in chiral effective field theory including the corresponding three-nucleon force and extending our previous work, where only the two-nucleon interaction has been taken into account. The three-nucleon force appears first at this order in the chiral expansion and depends on two unknown parameters. These two parameters are determined from the triton binding energy and $\mathrm{nd}$ doublet scattering length. We find an improved description of various scattering observables in relation to the next-to-leading order results especially at moderate energies ${(E}_{\mathrm{lab}}=65\mathrm{}\mathrm{MeV}).\mathrm{}$ It is demonstrated that the long-standing $A_y$ problem in $\mathrm{nd}$ elastic scattering is still not solved by the leading 3NF, although some visible improvement is observed. We discuss possibilities of solving this puzzle. The predicted binding energy for the $\alpha$ particle agrees with the empirical value.

Normal parity bands in ${}^{157}\mathrm{Gd},$ ${}^{163}\mathrm{Dy},$ and ${}^{169}\mathrm{Tm}$ are studied using the pseudo-SU(3) shell model. Energies and $B\left(E2\mathrm{}\right)\mathrm{}$ transition strengths of states belonging to six low-lying, same-parity rotational bands in each nuclei are considered. The pseudo-SU(3) basis includes states with pseudospin 0 and 1, and $\frac{1}{2}$ and $\frac{3}{2},$ for even and odd nucleon numbers, respectively. States with pseudospin 1 and $\frac{3}{2}$ must be included for a proper description of some excited bands.

We report measurements of $\gamma$-ray spectra from muon capture on ${}^{35}\mathrm{Cl}.$ For the allowed Gamow-Teller transitions to the ${}^{35}\mathrm{S}{(2939,3/2\mathrm{}}^{+})$ state and the ${}^{35}\mathrm{S}{(3421,5/2\mathrm{}}^{+})$ state we obtained their capture rates, hyperfine dependences, and $\gamma –\nu$ correlation coefficients. The capture rates and hyperfine dependences were compared to shell model calculations using the complete $1s–0d$ space and the universal SD interaction. With $g_p{/g}_a=6.7\mathrm{}$ and $g_a=-1.00$ (or $g_a=-1.26)$ we found agreement of the model and the data at the 1–2 $\sigma$ level. However, we caution that the transitions are sensitive to $l=2\mathrm{}$ forbidden matrix elements.

Several resonances in the ${}^{15}\mathrm{N}(\alpha ,\gamma {)}^{19}\mathrm{F}$ reaction have been investigated in the energy range between 0.6 MeV and 2.7 MeV. Resonance strengths and branching ratios have been determined. High sensitivity could be obtained by the combination of the Dynamitron high current accelerator, the windowless gas target system Rhinoceros, and actively shielded germanium detectors. Two levels of ${}^{19}\mathrm{F}$ could be observed for the first time in the $(\alpha ,\gamma )$ channel, and several weak branchings below the detection limits of previous experiments were measured. Two observed resonances correspond to $\alpha$-cluster states in ${}^{19}\mathrm{F},$ which have been assigned unambiguously. The astrophysical reaction rate is derived from this set of resonance strengths.

We have calculated the effect of the inclusion of final state interactions on pion production from nuclei with incident pion beams. We find that the effect of absorption, along with geometric considerations, explains much of the enhancement at low invariant mass seen in recent data for invariant-mass spectra with increasing atomic number. While the variation among nuclei is well reproduced for all charge states, the enhancement for the ratio for heavy nuclei to deuterium for the ${\pi }^{+}{\pi }^{-}$ final state is only partially understood.

We investigate the ground state properties of the nuclei with proton number $Z=94\mathrm{}–110$ within the framework of deformed relativistic mean-field (RMF) theory. A systematic comparison between calculated binding energies and experimental data is made. The calculated binding energies are in good agreement with experimental ones. The reliability of the RMF model for superheavy nuclei has been tested by this comparison. The experimental data of alpha-decay energies and half-lives are reasonably reproduced by calculations. Calculated results further show that a prolate deformation is important for the ground state of these nuclei. The properties of some unknown nuclei are predicted and these are useful for future experimental researches of superheavy nuclei.

Nuclear level density parameter a has been calculated over a large range of nuclear mass and energy, using the microscopic model with the inclusion of nuclear pairing interaction. The values of a and the energy shift parameter $\delta ,$ appearing in the Bethe formula, are obtained by fitting the entropy as a function of excitation energy. Although the general behavior of $a,$ obtained with nuclear entropy is very similar to that of the conventional Fermi gas model, it shows deviations in the vicinity of major nuclear shells. The dependence of the level density parameter on energy has also been investigated and it is shown that the variation of a at lower energy is significant and has an asymptotic approach to a constant a at higher energies. The dependence of a on pairing force and deformation is illustrated.

Single-particle overlap functions and spectroscopic factors are calculated on the basis of Jastrow-type one-body density matrices of open-shell nuclei constructed by using a factor cluster expansion. The calculations use the relationship between the overlap functions corresponding to bound states of the $\left(A-1\right)$-particle system and the one-body density matrix for the ground state of the A-particle system. In this work, we extend our previous analyses of reactions on closed-shell nuclei by using the resulting overlap functions for the description of the cross sections of $\mathrm{}(p,d)\mathrm{}$ reactions on the open $s-d$ shell nuclei ${}^{24}\mathrm{Mg},$ ${}^{28}\mathrm{Si},$ and ${}^{32}\mathrm{S}$ and of ${}^{32}\mathrm{S}{(e,e}^{\prime }p)$ reaction. The relative role of both shell structure and short-range correlations incorporated in the correlation approach on the spectroscopic factors and the reaction cross sections is pointed out.

The $(n,\gamma )$ cross sections of the important s-process nuclei ${}^{128}\mathrm{Xe},$${}^{129}\mathrm{Xe},$ and ${}^{130}\mathrm{Xe}$ have been measured in the astrophysically relevant neutron energy range from 3 to 225 keV. Neutrons were produced via the ${}^7\mathrm{Li}{\mathrm{}(p,n)\mathrm{}}^7\mathrm{Be}$ reaction by bombarding metallic Li targets with the pulsed proton beam of the Karlsruhe 3.75 MV Van de Graaff accelerator. High pressure gas samples of isotopically enriched xenon were used in the experiment, and capture events were registered with the Karlsruhe $4\pi$ Barium Fluoride Detector. The cross sections were determined relative to the gold standard with overall uncertainties of 1.5–2.5 % over most of the investigated energy range. From these results Maxwellian averaged stellar $(n,\gamma )$ cross sections with typical uncertainties of 2% were calculated for thermal energies between $kT=8\mathrm{}\mathrm{keV}$ and 100 keV. In contrast to previous theoretical estimates, which were known to exhibit uncertainties of 30–50 %, this work provides a reliable basis for quantitative astrophysical analyses and makes it possible to define the solar Xe abundance to $5.39\pm 0.22$ relative to ${10}^6$ Si atoms.

The normalized multiplicity moments and their relation with soft and hard processes in relativistic heavy ion collisions are analyzed in a general two-component model. It is found that the strong fluctuations in the binary collision number $N_c$ in minimum-bias events can enhance the hard component, especially for the higher order moments. This enhancement cannot be effectively described by modifying the participant number in the one-component model.

Strong correlations exist between observed ${B(E2;2\mathrm{}}^{+}\to 0^{+})$ values and excitation energies in even-even nuclei. These have conventionally been interpreted using a vibrational or rotational model, and we present here an alternative approach based on a binary cluster model. This results in a different functional relationship between the above quantities, with an equally good fit to the data. We discuss also various methods of determining the value of an important parameter in binary cluster model calculations, the reduced mass of the system.

It is demonstrated that the spectroscopy of excited states in $Z<~20,N>~20$ nuclei and the systematic behavior of $S_{2p}$ support the hypothesis that the $Z=16\mathrm{}$ subshell closure that exists for $N=20\mathrm{}$ and $21$ disappears for higher neutron numbers. In addition, the possible collapse of the $N=28\mathrm{}$ shell closure in neutron-rich nuclei is examined using the systematic behavior of $S_{2n}$ and the spectroscopy of excited states in nearby nuclei and single-neutron pickup data from the Ca isotopes. We conclude that data on the spectroscopy of excited states of ${}^{42}\mathrm{Si}$ and other nuclei in the vicinity will be necessary to draw a strong conclusion regarding the persistence of the $N=28\mathrm{}$ shell closure in neutron-rich nuclei.

We derive analytic formulas for the energy average (including the energy average of the fluctuation contribution) and variance of the intraband decay intensity of a superdeformed band. Our results may be expressed in terms of three dimensionless variables: ${\Gamma }^{\downarrow }/{\Gamma }_S,$ ${\Gamma }_N/d,$ and ${\Gamma }_N/({\Gamma }_S+{\Gamma }^{\downarrow }).\mathrm{}$ Here ${\Gamma }^{\downarrow }$ is the spreading width for the mixing of a superdeformed (SD) state $|0〉$ with the normally deformed (ND) states $|Q〉$ whose spin is the same as $|0〉’\mathrm{s}.$ The $|Q〉$ have mean lever spacing d and mean electromagnetic decay width ${\Gamma }_N$ whilst $|0〉$ has electromagnetic decay width ${\Gamma }_S.$ The average decay intensity may be expressed solely in terms of the variables ${\Gamma }^{\downarrow }/{\Gamma }_S$ and ${\Gamma }_N/d$ or, analogously to statistical nuclear reaction theory, in terms of the transmission coefficients $T_0\mathrm{}\left(E\right)\mathrm{}$ and $T_N$ describing transmission from the $|Q〉$ to the SD band via $|0〉$ and to lower ND states. The variance of the decay intensity, in analogy with Ericson’s theory of cross section fluctuations, depends on an additional variable, the correlation length ${\Gamma }_N/({\Gamma }_S+{\Gamma }^{\downarrow })=(d/2\mathrm{}\pi {)T}_N/({\Gamma }_S+{\Gamma }^{\downarrow }).\mathrm{}$ This suggests that analysis of an experimentally determined variance could yield the mean level spacing d as does analysis of the cross section autocorrelation function in compound nucleus reactions. We compare our results with those of Gu and Weidenmüller.

The matrix equations of the relativistic random-phase approximation (RRPA) are derived for an effective Lagrangian characterized by density-dependent meson-nucleon vertex functions. The explicit density dependence of the meson-nucleon couplings introduces rearrangement terms in the residual two-body interaction. Their contribution is essential for a quantitative description of excited states. Illustrative calculations of the isoscalar monopole, isovector dipole, and isoscalar quadrupole response of ${}^{208}\mathrm{Pb},$ are performed in the fully self-consistent RRPA framework based on effective interactions with a phenomenological density dependence adjusted to nuclear matter and ground-state properties of spherical nuclei. The comparison of the RRPA results on multipole giant resonances with experimental data constrains the parameters that characterize the isoscalar and isovector channel of the density-dependent effective interactions.

Working within an exactly solvable three level model a boson Hamiltonian is defined via a mapping procedure and its expansion truncated at four-boson terms. The resulting spectrum is found in good agreement with the exact one. We discuss an extension of the random-phase approximation (RPA) based on this boson formalism. Nonlinear RPA-type equations are constructed and solved iteratively. The new solutions gain in stability with respect to the RPA ones. We perform diagonalizations of the boson Hamiltonian in restricted spaces; approximate spectra exhibit an improved quality with increasing the size of these spaces. Special attention is addressed to the problem of the anharmonicity of the spectrum.

We calculate the ground-state expectation value of scalar observables in the matrix formulation of the random phase approximation (RPA). Our expression, derived using the quasiboson approximation, is a straightforward generalization of the RPA correlation energy. We test the reliability of our expression by comparing against full diagonalization in $0ħ\omega$ shell-model spaces. In general the RPA values are an improvement over mean-field (Hartree-Fock) results, but are not always consistent with shell-model results. We also consider exact symmetries broken in the mean-field state and whether or not they are restored in RPA.

Self-consistent calculations within the relativistic mean field theory (RMFT) were performed for 150 spherical even-even nuclei. The macroscopic part of the binding energy was evaluated by subtracting the Strutinsky shell corrections from the RMFT energy. The parameters of a liquid-drop-like mass formula that approximates the RMFT results were determined. The mass and isospin dependence of the RMFT mean-square radii constants for the neutron, proton, charge, and total density distributions were estimated. The RMFT liquid-drop parameters and the radii constants are compared with similar results obtained with the Hartree-Fock-Bogoliubov calculations with the Gogny force and phenomenological models.

We present in this article an optical potential for the π-nucleus interaction that can be used in various studies involving π-nucleus channels. Based on earlier treatments of the low-energy π-nucleus optical potential, we have derived a potential expression applicable from threshold up to the Δ-resonance region. We extracted the impulse approximation form for this potential from the $\pi -N$ scattering amplitude and then added to it kinematical and physical corrections. The kinematic corrections arise from transforming the impulse approximation expression from the $\pi -N$ center of mass frame to the π-nucleus center of mass frame, while the physical corrections arise mostly from the many-body nature of the π-nucleus interaction. By taking advantage of the experimental progress in our knowledge of the $\pi -N$ process, we have updated earlier treatments with parameters calculated from state-of-the-art experimental measurements.