A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analyzing power in the sin phi moment of the cross section is 0.019 +/-0.007(stat) 0.003(syst). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The pi (0) asymmetry is of the same size as the pi (+) asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark.
Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering
CIULLO, Giuseppe;FERRETTI, Paola;LENISA, Paolo;MASOLI, Francesco Antonio;REGGIANI, DAVIDE;
2001
Abstract
A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analyzing power in the sin phi moment of the cross section is 0.019 +/-0.007(stat) 0.003(syst). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The pi (0) asymmetry is of the same size as the pi (+) asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
