  Including O(m_c) terms in the coefficient functions and/or O(m_D) twist 3
contributions in the heavy meson distribution amplitudes leads to a non-zero
transverse amplitude for exclusive neutrino production of a D pseudoscalar
charmed meson on an unpolarized target. We work in the framework of the
collinear QCD approach where chiral-odd transversity generalized parton
distributions (GPDs) factorize from perturbatively calculable coefficient
functions.
