Transverse Target Spin Asymmetry in exclusive vector meson production at HERMES

Measurements of the Transverse Target Spin Asymmetry, $A_{UT} (\phi)$, for hard exclusive electroproduction of $\rho^0$ and $\phi$ mesons at HERMES will be presented. To gain information about the general parton distribution function $E$, the transverse target spin asymmetry $A_{UT}^{\rho_L}(\phi)$ in the longitudinal cross section $\sigma_L(\gamma^*_Lp\rightarrow \rho^0_Lp\prime)$ needs to be extracted. Using the self-analyzing character of $\rho^{0}$ meson decay $A_{UT}^{\rho_L}(\phi)$ and $A_{UT}^{\rho_T}(\phi)$ will be presented separately.