Search for CP violation in K0 -> 3 pi0 decays

TL;DR

This study searches for CP violation in K0 -> 3 pi0 decays using CERN data, setting upper limits on the decay's branching ratio and refining parameters related to CP violation and CPT symmetry.

Contribution

First measurement of CP violating amplitude eta_000 in K0 -> 3 pi0 decays with improved upper limit on the branching fraction.

Findings

Re(eta_000) = -0.002 ± 0.011 ± 0.015

Im(eta_000) = -0.003 ± 0.013 ± 0.017

Br(K_S -> 3 pi0) < 7.4 x 10^-7 at 90% CL

Abstract

Using data taken during the year 2000 with the NA48 detector at the CERN SPS, a search for the CP violating decay K_S -> 3 pi0 has been performed. From a fit to the lifetime distribution of about 4.9 million reconstructed K0/K0bar -> 3 pi0 decays, the CP violating amplitude eta_000 = A(K_S -> 3 pi0)/A(K_L -> 3 pi0) has been found to be Re(eta_000) = -0.002 +- 0.011 +- 0.015 and Im(eta_000) = -0.003 +- 0.013 +- 0.017. This corresponds to an upper limit on the branching fraction of Br(K_S -> 3 pi0) < 7.4 x 10^-7 at 90% confidence level. The result is used to improve knowledge of Re(epsilon) and the CPT violating quantity Im(delta) via the Bell-Steinberger relation.