We report on a new measurement of the decay KL → π0γγ by the KTeV experiment at Fermilab. We determine the KL → π0γγ branching ratio to be (1.68 ±0.07 ± 0.08) × 10-6. Our data show the first evidence for a low-mass γγ signal as predicted by recent O(p6) chiral perturbation calculations which include vector meson exchange contributions. From our data, we extract a value for the effective vector coupling aV = -0.72 ± 0.05 ± 0.06.
ASJC Scopus subject areas
- Physics and Astronomy(all)