Study ofTviolation inK+→π+μ+μ−decays

We study the possibility of observing $T$ violation in the process $K^{+}\to {\pi }^{+}{\mu }^{+}{\mu }^{-}$. To this end we define appropriate $T$-violation indicators. We find that the measurements of the two-spin correlations can provide a reliable test of the Cabibbo-Kobayashi-Maskawa mechanism of $T$ violation. The final-state interactions mainly contribute to indicators involving only one spin. We also estimate the size of the contribution of a representative set of extensions of the standard model to $T$-violation indicators. We find that their contribution can be important only in models with loosely constrained new parameters.