A. Airapetian, et al. (HERMES Collaboration)
Eur.Phys.J. C71 (2011)
Publication year: 2011

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 GeV^2 < Q^2 < 7.0 GeV^2, 3.0 GeV < W < 6.3 GeV, and -t’ < 0.4 GeV^2. Real and imaginary parts of the ratios of the natural-parity-exchange helicity amplitudes T_{11} (\gamma^*_T –> \rho_T), T_{01} (\gamma^*_T –> \rho_L), T_{10} (\gamma^*_L –> \rho_T), and T_{1-1} (\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 |U_{11}/T_{00}| is obtained. The Q^2 and t’ dependences of these ratios are presented and compared with perturbative QCD predictions.

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