Particle-hole symmetry and meson exchange corrections to the 6He beta decay amplitude.

Abstract

The meson exchange current contributions (MEC) to the {sup 6}He{sub g.s.}{r arrow}{sup 6}Li{sub g.s.} beta decay are computed for various nuclear amplitudes. We use particle-hole symmetry properties of one- and two-body matrix elements and find relationships between the {ital A}=6 beta decay and the anomalously suppressed {sup 14}C{sub g.s.}{r arrow}{sup 14}N{sub g.s.} beta transition, for which these have been studied previously. We find MEC contributions to be small for the mass-six case, bringing the calculated axial vector form factor closer to the experimental value. Implications for the positive pion photoproduction transition between the same states are discussed.