Charge Asymmetry inK20→π±l∓ν

It is noted that $\mathrm{CPT}$ invariance can be tested by comparing the charge asymmetry in ${K_2}^0\to {\pi }^{\pm }{l}^{\mp }\nu$ with certain terms in the time distribution of the decay $K^0\to \pi l\nu$. It is pointed out that, under reasonable assumptions, the charge asymmetries for the electronic and muonic decay modes should be very nearly equal. Implications of a large discrepancy between the charge asymmetries are discussed.