We present a new and consistent mapping of colorless three-quark clusters onto colorless triplet fermions (baryons) and test it in the context of a three-color extension of the Lipkin model. For systems with two triplets (for which the problem can be solved without approximation both before and after the mapping), we exactly reproduce the dynamics of the model for the variety of correlation structures considered.

The Schwinger-Dyson equation for the quark propagator and the Bethe-Salpeter equations for the quark-meson vertex functions are derived within nonlocal effective QCD in the quark sector using functional integral techniques at finite temperature. We apply the approach for separable instantaneous interactions and derive mass formulas for the scalar and pseudoscalar mesons. The pion mass obeys the Goldstone theorem. The sigma meson mass is lowered when the interaction kernel is not constant. The temperature behavior of the constituent quark mass and the scalar as well as pseudoscalar meson masses is obtained from a self-consistent numerical solution to the coupled set of Schwinger-Dyson and Bethe-Salpeter equations. We present a systematic investigation of the modification of the chiral transition phenomena due to the choice of the form factor of the effective interaction. The standard Nambu–Jona-Lasinio model is discussed as a particular case of nonlocal separable interaction.

The off-shell electromagnetic vertex of a (pseudo)scalar particle contains, in general, two form factors F and G which depend, in addition to the squared momentum transfer, on the invariant masses associated with the initial and final legs of the vertex. Chiral perturbation theory to one loop is used to calculate the off-shell form factors of pions and kaons. The formalism of Gasser and Leutwyler, which was previously used to calculate the on-shell limit of the form factor F, is extended to accommodate the most general form for off-shell Green’s functions in the pseudoscalar meson sector. We find that chiral symmetry predicts that the form factors F of the charged pions and kaons go off-shell in the same way, i.e., the off-shell slope at the real photon point is given by the same new phenomenological constant ${\mathrm{\beta }}_1$. Furthermore, it is shown that at order ${\mathit{p}}^4$ the form factor F of the ${\mathit{K}}^0$ does not show any off-shell dependence. The form factors G are all related to the form factors F in the correct fashion as required by the Ward-Takahashi identity. Numerical results for different off-shell kinematics are presented.

For different Skyrme-type forces we investigate the equation of state of homogeneous nuclear matter under the conditions appropriate to a collapsing star. We find that the stiffness of the equation of state increases significantly as the symmetry coefficient J of nuclear matter increases over the range of its experimental uncertainty. We present analytic expressions for the adiabatic index Γ permitting the elimination of all numerical derivatives.

The effects of multiboson interference with regard to isospin imbalances and spectra are calculated for high-energy hadronic collisions. Emission is modeled by a relativistic thermal source with a Bjorken geometry. The requirements for creating CENTAURO-like phenomena are explored. It is shown that strong collective Bose effects occur when breakup densities are of the order of one pion per cubic fm. The possibility of emitting pions through isoscalar channels, which can explain large isospin imbalances, is investigated.

A partial-wave analysis of all p¯p scattering data below 925 MeV/c antiproton laboratory momentum is presented. The method used is adapted from the Nijmegen phase-shift analyses of pp and np scattering data. We solve the Schrödinger equation for the coupled p¯p and n¯n channels where the long- and intermediate-range interactions are described by a theoretically well-founded potential. This gives the rapid variations of the scattering amplitudes with energy. This potential consists of the Coulomb potential with the main relativistic correction, the magnetic-moment interaction, the one-pion-exchange potential, and the heavy-boson exchanges of the Nijmegen one-boson-exchange potential. Slow variations of the amplitudes due to short-range interactions, including the coupling to mesonic annihilation channels, are parametrized by an energy-dependent, complex boundary condition, specified at a radius of r=1.3 fm. The Nijmegen 1993 p¯p database, consisting of 3646 p¯p scattering data, is presented and discussed. The best fit to this database results in ${\mathrm{\chi }}_{\min }^2$/${\mathit{N}}_{\mathrm{data}}$=1.043. This good fit to the data shows that the Nijmegen long- and intermediate-range potential is essentially correct. The pseudovector coupling constant of the charged pion to nucleons is determined to be ${\mathit{f}}_{\mathit{c}}^2$=0.0732(11) at the pion pole, where the error is statistical.

An isomer with a half-life of 15±1 μs has been observed in the N=74 nucleus ${}_{}{}^{136}{}_{}{}^{}\mathrm{Sm}$, populated following the reaction ${}_{}{}^{107}{}_{}{}^{}\mathrm{Ag}$${(}^{32}$S,p2n${)}^{136}$Sm. It is proposed to have a ${\mathit{K}}^{\mathrm{\pi }}$=$8^{\mathrm{-}}$ two quasineutron configuration. The isomer decays via a ΔK=8, 466 keV E1 transition with a surprisingly low hindrance per degree of K forbiddenness, ${\mathit{f}}_{\nu }$=25.

Two weakly populated rotational bands have been established in ${}_{}{}^{106}{}_{}{}^{}\mathrm{Sn}$ from the ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ ${(}^{58}$Ni,α2p) reaction at 243 MeV. One of the bands shows evidence of termination. The result is consistent with cranked Nilsson model calculations, which predict band terminations with a smooth and gradual shape change from a prolate collective to an oblate noncollective structure.

The ${}_{}{}^{50}{}_{}{}^{}\mathrm{V}$(${\mathit{n}}_{\mathrm{th}}$,p${)}^{50}$Ti reaction has been studied at a very clean thermal neutron beam of the ILL’s high flux reactor. An accurate cross section value of (0.71±0.04) mb has been determined, as well as a value of (0.002 364±0.000 008) u for the ${}_{}{}^{50}{}_{}{}^{}\mathrm{-}_{}^{50}{}_{}{}^{}$Ti mass difference. Possible applications in nuclear astrophysics and in reactor technology are pointed out.

The ratio of quadrupole deformation to the pairing gap parameter, ɛ/Δ, is compared to the P factor in the actinide region. The results provide evidence for a persistent spherical subshell gap at N=164.

The energy-corrected intensities of the primary γ transitions in ${}_{}{}^{166}{}_{}{}^{}\mathrm{Ho}$ following thermal and average resonance neutron capture are calculated from data available in the literature. The γ decay of this odd-odd nucleus shows the same K dependence as earlier seen in the even-even nuclei ${}_{}{}^{168}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{178}{}_{}{}^{}\mathrm{Hf}$.

A physically motivated extension of the ${\mathrm{SU}}_{\mathit{q}}$(2) model of rotational nuclear spectra is introduced, which is applicable in the vibrational and transitional regions as well. The deformation parameter is related to the centrifugal stretching effect, while the new parameter c allows the spectrum to be an expansion in terms of J(J+c) instead of J(J+1), thus describing nuclear anharmonicities in a way similar to the interacting boson model and the generalized variable moment of inertia model.

In this work we evaluate the imaginary part of the isobar Δ self-energy ${\mathrm{\Sigma }}_{\mathrm{\Delta }}$ from the two-body absorption process Δ+N→2N. This contribution is calculated using a recently developed nonrelativistic scheme, which allows for an evaluation of the self-energy with a basis of single-particle states appropriate for both bound hole states and for particle states in the continuum. In order to test the medium dependence of the self-energy, we calculate the two-body absorption term ${\mathrm{\Sigma }}_{\mathrm{\Delta }}^{\mathit{A}2}$ for several finite nuclei with N=Z, i.e., ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, and ${}_{}{}^{100}{}_{}{}^{}\mathrm{Sn}$. The resulting self-energy, which is energy dependent and nonlocal, is compared with a simple parametrization derived from nuclear matter.

The correlation function for intensity interferometry of high energy photons emitted from an expanding quark-gluon plasma is examined. It is reiterated that the correlation function for identical bosons emitted from two point sources is given by 1+cos(Δk⋅Δx) and will oscillate between 0 and 2, depending on the values of the difference in the 4-momenta of the two bosons (Δk) and the difference in their 4-positions (Δx). Integration over smooth, realistic sources, relevant for very high energy nucleus-nucleus collisions, gives a correlation function which essentially decreases monotonically from 2 to 1 as the momentum difference becomes large. The oscillatory behavior seen in a recent work for certain momentum configurations is caused by an approximation which amounts to including only those sources for which the space-time rapidities are identical to the photon rapidities.

Employing a cranking Hamiltonian, in the static path approximation with all the quadrupole degrees of freedom, we have studied the behavior of the moment of inertia (gerI) of ${}_{}{}^{64}{}_{}{}^{}\mathrm{Zn}$ at a few temperatures as a function of the rotational frequency. At a low temperature T=0.5 MeV and around J=16 rotational alignment of 0${\mathit{g}}_{9/2}$ orbitals takes place leading to a fast increase of gerI at high spins. At a high temperature T=2.0 MeV about 40–45% of each of angular momenta are generated by the alignment of 0${\mathit{g}}_{9/2}$ orbitals and gerI becomes almost the same for all spins.

Motivated by the Σ-hypernuclear states reported in (${\mathit{K}}^{\mathrm{-}}$,${\mathrm{\pi }}^{\pm }$) experiments, we have explored the possibility that there exists a particle-stable ${\mathrm{\Sigma }}^{\mathrm{-}}$nn bound state. For the Jülich à hyperon-nucleon, realistic-force model, our calculations yield little reason to expect a positive-parity bound state or resonance in either the J=1/2 or the J=3/2 channels.

Induced forces of second order in the nucleon nucleon G-matrix interaction are included in a random phase approximation (RPA) type formalism with dressed single-particle propagators. The predictions of a considerable amount of Gamow-Teller (n,p) strength for magic nuclei with neutron excess, found in earlier dressed RPA calculations, are not modified by the induced forces. Also the distribution of (p,n) strength is only a little affected by the induced interactions. It is therefore concluded that the relatively simple dressed RPA method is a suitable one to calculate excitation strengths.

Attention is called to several articles dealing with the decay properties of ${}_{}{}^{155}{}_{}{}^{}\mathrm{Tm}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Lu}$ which were overlooked by Hagberg et al. [Phys. Rev. C 45, 1609 (1992)].