Structure of radiative interferences andg=2for vector mesons

Abstract

The result of Burnett and Kroll (BK) states that for radiative decays, the interference of $O({\ensuremath{\omega}}^{\ensuremath{-}1})$ in the photon energy $\ensuremath{\omega}$ vanishes after the sum over polarizations of the involved particles. Using radiative decays of vector mesons, we show that if the vector meson is polarized, the $O({\ensuremath{\omega}}^{\ensuremath{-}1})$ terms are null only for the canonical value of the magnetic dipole moment of the vector meson, namely, $\mathbf{g}=2$ in Bohr magneton units. A subtle cancellation of all $O({\ensuremath{\omega}}^{\ensuremath{-}1})$ terms happens when summing over all polarizations to recover the Burnett-Kroll result. We also show the source of these terms and the corresponding cancellation for the unpolarized case and exhibit a global structure that can make them individually vanish in a particular kinematical region.