Spin Density Matrix Elements from diffractive $\ddot{I}•$ meson production at HERMES

Abstract

Exclusive production of $\ddot{I}•$ mesons on hydrogen and deuterium targets is studied in the HERMES kinematic region $1<Q^2<7$ GeV${}^2$ and $3.0<W<6.3$ GeV. Spin density matrix elements and their $Q^2$ and $t$ dependences are presented. These data are consistent with s-channel helicity conservation in exclusive $\ddot{I}•$ meson production. No significant evidence for the contribution of unnatural-parity-exchange amplitudes is found.

6 pages, 4 figures, Proceedings of DIS 2008, London, UK, April 7-11, 2008;