Study of the KL to PI+PI-GAMMA Direct Emission Vertex

TL;DR

This study analyzes the direct emission and inner bremsstrahlung vertices in KL decays, providing measurements of form-factor parameters, branching ratios, and their implications based on Fermilab data from 1996.

Contribution

It presents new measurements of the DE form-factor parameter, branching ratios, and fits to form-factor models in KL to pi+ pi- gamma decays, based on experimental data.

Findings

a1/a2 = -0.737 +- 0.034 GeV^2 for the DE form-factor

Branching ratio B.R.(KL to pi+ pi- gamma) = (20.8 +- 0.3) x 10^-3

DE/(DE + IB) branching ratio = 0.683 +- 0.011

Abstract

We have perfomed studies of the KL to PI+PI-GAMMA Direct Emission (DE) and Inner Bremsstrahlung (IB) vertices, based on data collected by KTeV during the 1996 Fermilab fixed target run. We find a1/a2 = -0.737 +- 0.034 GeV^2 for the DE form-factor parameter in the rho-propagator parametrization, and report on fits of the form-factor to linear and quadratic functions as well. We concurrently measure B.R.(KL to PI+PI-GAMMA, E_gamma >20 MeV)/(KL to PI+PI-) = (20.8 +- 0.3)*10^-3, and a KL to PI+PI-GAMMA DE/(DE + IB) branching ratio of 0.683 +- 0.011.