  We use the Constituent Quark Model (CQM) to describe CDF data on double
parton cross section and HERA data on the $ J / \Psi$ ratio cross section of
elastic and inelastic diffractive productions. Our estimate shows that the
radius of the constituent quark turns out to be rather small, $R^2_{quark}
\approx 0.1 Gev^{-2}$, in accordance with the assumption on which CQM is based.
