Master Thesis: Effects of different Form Factors in
Meson-Photon-Photon Transitions
LU TP 99 39
Fredrik Persson
Abstract:
The exact form of the form-factor associated with a
meson-photon-photon vertex is not known. Different
suggestions exist, based on constraints from
QCD and on recent experiments. Four different
form-factors are studied in this article.
We calculate decay rates for four processes
where pi0 and eta decays into leptons, and cross-sections
for the processes e+e- -> PS e+e-, where PS is a pseudo-scalar.
The results depend on the choice of form-factor and
we examine if the differences are large enough to distinguish
in upcoming experiments. The dominant part of the light-by-light
contribution to the muon anomalous magnetic moment is also calculated.
Here the uncertainty around the choice of form-factor implies
that it is possible to estimate a smallest error
in the theoretical value of this contribution.