Diffractive production of S and D wave vector mesons in Deep Inelastic Scattering

In this work the production of vector mesons in diffractive DIS is analyzed, with an emphasis on the impact of the internal spin structure of a vector meson upon its virtual photoproduction rate. For the first time, the full sets of s-channel helicity conserving and violating amplitudes were derived for pure S and D wave vector mesons. In the course of analytical and numerical investigation, we found a striking difference between S and D wave vector meson production. First, in the case of helicity conserving amplitudes, D wave vector mesons were found to exhibit dramatically different Q-behavior due to abnormally large higher twist contributions. Besides, we found that helicity conserving amplitudes for S and D states are numerically comparable, which makes the physical ρ meson very sensitive to D wave admixture. Second, the helicity violating amplitudes in light vector meson production turned out large both for S and D wave states. In the case of heavy quarkonia, these amplitudes became suppressed by the non-relativistic motion for S wave mesons but they were still large for D wave states. Aiming at producing sort of a manual on the diffractive vector meson production, we carried out all calculations in a pedagogical manner with maximally full presentation of intermediate steps and accompanied them with detailed qualitative discussion.