We construct a spectral representation for the baron to meson transition
distribution amplitudes (TDAs), i.e. matrix elements involving three quark
correlators which arise in the description of baryon to meson transitions
within the factorization approach to hard exclusive reactions. We generalize
for these quantities the notion of double distributions introduced in the
context of generalized parton distributions. We propose the generalization of
A.Radyushkin's factorized Ansatz for the case of baryon to meson TDAs. Our
construction opens the way to modeling of baryon to meson TDAs in their
complete domain of definition and quantitative estimates of cross-sections for
various hard exclusive reactions.Comment: This is the second version of the paper. Important changes were made
in the text and many errors in the formulas were corrected. 37 pages, 8
figure