Color transparency in ${\pi }^{-}$-induced dilepton production on nuclei

We argue that the observation of the color transparency effect in the semiexclusive $A({\pi }^{-},l^{+}{l}^{-})$ process is important for determining whether it is possible to extract the generalized parton distributions of the nucleon from the elementary reaction ${\pi }^{-}p\to l^{+}{l}^{-}n$ at $p_{\mathrm{l}\mathrm{a}\mathrm{b}}=15-20$ GeV/c at small $\mathrm{\mid }t\mathrm{\mid }$ and large invariant mass of the dilepton pair $l^{+}{l}^{-}$. Assuming that the transverse size of the pionic $q\bar{q}$ pair in the hard interaction point is similar to the one in the reaction ${\gamma }^{\ast }p\to {\pi }^{+}n$ studied at JLab we predict large color transparency effects in the discussed kinematic range. We also suggest that the semiexclusive ${\rho }^0$ production in ${\pi }^{-}$-induced reactions in the same beam momentum region may provide new information on the dynamics of the interaction in the non-vacuum channel, while the $J\mathrm{/}\psi$ production can be used to get information on $J\mathrm{/}\psi N$ total interaction cross section.,