9 research outputs found
Long Distance Contribution to and Implications for and
We estimate the long distance (LD) contribution to the magnetic part of the
transition using the Vector Meson Dominance approximation
. We find that this contribution may be significantly
larger than the short distance (SD) contribution to and could
possibly saturate the present experimental upper bound on the decay rate, eV. For the decay , which is driven by as well, we obtain an upper bound on the branching ratio from . Barring the possibility that the Quantum Chromodynamics
coefficient be much smaller than 1, also implies the approximate relation .
This relation agrees quantitatively with a recent independent estimate of the
l.h.s. by Deshpande et al., confirming that the LD contributions to are small. We find that these amount to an increase of in
the magnitude of the transition amplitude, relative to the SD
contribution alone.Comment: 16 pages, LaTeX fil