Probing the exchanged object(s) in diffractive scattering

The reaction mechanisms of the following proton diffractive scattering processes are studied and compared with one another: $\gamma^* p\to Vp,\gamma^* stands for space-like photon, $V$ for vector mesons $\rho,\phi,J/\psi$, and $A$ for nucleus.) It is shown that, by taking parity, and C--parity conservation into account, existing data strongly suggest the following: A considerable part of the objects exchanged between projectile and target in the above-mentioned processes are virtual quark-antiquark pairs in color-singlet states with $J^{PC}=0^{-+}$, $I^G=0^+$ or $1^-$, where $J$ stands for total angular momentum, $I$ for isospin, $P$, $C$ and $G$ stand for parity, C-parity and G-parity respectively. Such quark-antiquark pairs are created by soft-gluon interactions. It is pointed out that strange and charm-particle production play a special role in studying the mechanism(s) of such processes. New experiments are suggested; and predictions for such experiments are made