Ratios of helicity amplitudes for exclusive ρ0 electroproduction

Exclusive rho(0)-meson electroproduction is studied in the HERMES experiment, using a 27.6 GeV longitudinally polarized electron/positron beam and unpolarized hydrogen and deuterium targets in the kinematic region 0.5 GeV2 rho T), T-01 (gamma*(T) -> rho(L)), T-10 (gamma*(L) -> rho(T)), and T1-1 (gamma*(-T) -> rho(T)) to T-00 (gamma*(L) -> rho(L)) are extracted from the data. For the unnatural-parity-exchange amplitude U-11, the ratio vertical bar U-11/T-00 vertical bar is obtained. The Q(2) and t' dependences of these ratios are presented and compared with perturbative QCD predictions.Exclusive rho(0)-meson electroproduction is studied in the HERMES experiment, using a 27.6 GeV longitudinally polarized electron/positron beam and unpolarized hydrogen and deuterium targets in the kinematic region 0.5 GeV2 rho T), T-01 (gamma*(T) -> rho(L)), T-10 (gamma*(L) -> rho(T)), and T1-1 (gamma*(-T) -> rho(T)) to T-00 (gamma*(L) -> rho(L)) are extracted from the data. For the unnatural-parity-exchange amplitude U-11, the ratio vertical bar U-11/T-00 vertical bar is obtained. The Q(2) and t' dependences of these ratios are presented and compared with perturbative QCD predictions.A