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 < Q(2) < 7.0 GeV2, 3.0 GeV < W < 6.3 GeV, and -t' < 0.4 GeV2. 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 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.
Ratios of helicity amplitudes for exclusive rho(0) electroproduction
CAPILUPPI, Marco;CIULLO, Giuseppe;CONTALBRIGO, Marco;FERRETTI, Paola;GIORDANO, Francesca;LENISA, Paolo;PAPPALARDO, Luciano Libero;STANCARI, Michelle Dawn;STATERA, Marco;
2011
Abstract
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 < Q(2) < 7.0 GeV2, 3.0 GeV < W < 6.3 GeV, and -t' < 0.4 GeV2. 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 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.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.