K_L -> pi0 gamma gamma and the bound on the CP-conserving K_L -> pi0 e+e-

Abstract

It has been known for many years that there is a CP-conserving component for the decay mode K_L -> pi0 e+e- and that its magnitude can be obtained from a measurement of the amplitudes in the K_L -> pi0 gamma gamma decay mode. We point out that the usual description of the latter in terms of a single parameter, a_V, is not sufficient to extract the former in a model independent manner. We further show that there exist known physics contributions to K_L -> pi0 gamma gamma that cannot be described in terms of the single parameter a_V. We conclude that a model independent analysis requires the experimental extraction of three parameters.

Version accepted for publication on Phys. Rev. D. A footnote and appendix with two figures added. 20 pages, LaTeX, 5 figures, uses epsf.sty