Search for phi to K0 K0bar gamma decay with KLOE

TL;DR

The KLOE experiment searched for the rare phi to K0 K0bar gamma decay, setting an upper limit on its branching ratio that challenges many theoretical predictions, using 1.4 fb-1 of data.

Contribution

First experimental search for phi to K0 K0bar gamma decay, establishing an upper limit that constrains theoretical models.

Findings

Upper limit on BR set at 1.8x10^-8 at 90% C.L.

Most existing theories predicting higher BR are ruled out.

No evidence found for the decay in the analyzed data.

Abstract

The KLOE collaboration has searched for the phi to K0 K0bar gamma decay using a sample of 1.4 fb-1 of e+e- collisions at W ~ M(phi) collected with the KLOE experiment at the Frascati e+e- collider DAFNE. No previous search exists for this decay, while many theory models predict a BR of 10-8 for this channel. We set a preliminary value of the U.L. on this BR to 1.8x10-8 at 90% C.L.. This limit rules out most of the existing theory predictions.