Precise Comparison ofπ+andπ−Lifetimes

A second and more precise experiment has been performed at the Lawrence Radiation Laboratory's 184-in. cyclotron to look for any difference in the total lifetimes of ${\pi }^{+}$ and its antiparticle, ${\pi }^{-}$. Any observed difference would be direct evidence for a violation of $\mathrm{CPT}$ invariance in the weak decay of the charged pion. We find $\frac{{\tau }_{+}}{{\tau }_{-}}=1.000\mathrm{} 64\pm 0.000 69$, and thus no evidence for a $\mathrm{CPT}$ nonconservation.