Meson exchange currents in the p decay in nuclei

The proton decay modes inside nuclear matter, where one of the pions in the final state is produced in a virtual state and then absorbed by a second nucleon, are investigated. Assuming p → eπ as the primary mode for free p decay, the new channels increase the width by about 35%. If the dominant decay mode is p → eππ the medium correction is about twice as large as the free p decay width. The width for 16O, the relevant nucleus in the p decay experiments, is evaluated by means of the local density approximation with results about half of those in infinite nuclear matter. Higher order many-body corrections should further increase the p decay rate providing values appreciably larger than the free p decay width. (orig.)