The reaction n + p → d + γ and the isospin structure of the strangeness: Conserving nonleptonic weak Hamiltonian☆
The circular polarization P/sub gamma/ and angular asymmetry $alpha$ of the photons emitted in the reaction n+p$Yields$d+$gamma$ are computed in a covariant formalism within the framework of a composite-particle theory of the deuteron. The most important magnetic and electric dipole transition amplitudes in this radiative capture process are determined through a low-energy theorem. It is found that some of the proposed models for the strangeness-conserving nonleptonic weak Hamiltonian give variations on the ratio $alpha$/P/sub gamma/ of one or two orders of magnitude. (AIP)
We study in this paper the properties of a two-body random matrix ensemble for distinguishable spins. We require the ensemble to be invariant under the group of local transformations and analyze a parametrization in terms of the group parameters and the remaining parameters associated with the 'entangling' part of the interaction. We then specialize to a spin chain with nearest-neighbour interactions and numerically find a new type of quantum-phase transition related to the strength of a random external field, i.e. the time-reversal-breaking one-body interaction term.