Nonmesonic Hypernuclear Decay Research Articles

Role of the isovector nucleon-nucleus interaction potential in nonmesonic hypernuclear decay

We develop a theoretical finite nucleus framework for the evaluation of the coincidence number of pairs ${N}_{\mathit{nN}}$ and the asymmetry parameter ${a}_{\ensuremath{\Lambda}}$ in nonmesonic hypernuclear decay $\ensuremath{\Lambda}N\ensuremath{\rightarrow}\mathit{nN}$, and introduce the effect of final-state interactions. The primary nonmesonic weak hyperon-nucleon decay process is described through the independent-particle shell model. We work within the $2p1h$ subspace of final states, assuming a simple approach for finite nuclei based on the eikonal approximation. An optical potential including the nucleon-nucleus isoscalar and isovector interactions is introduced to take into account the minimum nuclear-medium effects. The calculated values for ${}_{\ensuremath{\Lambda}}^{5}\mathrm{He}$ and ${}_{\ensuremath{\Lambda}}^{12}\mathrm{C}$ show that our treatment of final-state interactions, even those considered as restricted to a subspace of states, brings the independent-particle model results closer to the experimental data.

Asymmetry parameter for the nonmesonic decay of 5<FONT FACE=Symbol>L</font>He

We report the preliminary result of an exact calculation of the asymmetry parameter, alambda, in the nonmesonic hypernuclear decay, based on a one-meson-exchange (OME) model. For the case of <IMG SRC="/img/revistas/bjp/v34n3a/a30img02.gif">He and including one-pion-exchange only, the result is shown not to differ considerably from the one obtained with the approximate formula widely used in the literature. In particular, the sign of alambda remains negative, in disagreement with its most recent experimental determination. Whether these facts remain true for heavier hypernuclei and in a more complete OME model is still under investigation.

Erratum: Role of the rho meson in the nonmesonic hypernuclear decay

Erratum: Role of the rho meson in the nonmesonic hypernuclear decay

Role of the rho meson in the nonmesonic hypernuclear decay.

The $\ensuremath{\rho}$-meson contribution to the $\ensuremath{\Lambda}N\ensuremath{\rightarrow}\mathrm{NN}$ process is studied in the nonmesonic decay of hypernuclei. It is found that the central potential of the $\ensuremath{\rho}$ exchange is larger than its tensor part and, therefore, must be included. This is in contrast to the $\ensuremath{\pi}$-exchange term which is dominated by the tensor interaction.