Data collected by the E731 experiment at Fermilab were used to search for CPT violation in ${\mathit{K}}^0$→ππ decays by measuring the difference Δφ between the phases of the CP-violating parameters ${\mathrm{\eta }}_{00}$ and ${\mathrm{\eta }}_{+\mathrm{-}}$. Our result, Δφ=-0.3°±2.4°±1.2°, where the first error is statistical and the second systematic, is consistent with CPT symmetry.

• Received 22 January 1990

DOI:https://doi.org/10.1103/PhysRevLett.64.2976