Azimuthal single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarised hydrogen target

Abstract

Abstract. Azimuthal single-spin asymmetries (SSA) in semi-inclusive electroproduction of charged pions and kaons in deep-inelastic scattering of positrons on a transversely polarised hydrogen target were observed. SSA amplitudes for both the Collins and the Sivers mechanism are presented.

Transverse Spin Phenomena in Lepton Scattering

“…from zero [4,10], thus providing independent confirmation of the measurability of the transversity DF's in SIDIS. Preliminary results for the Collins asymmetries for π + and π − have been produced by HERMES from the 2002-2004 data [11], confirming with higher statistics the previous results; they are shown as open points in the two left plots of Fig 1. COMPASS has produced by now final results for the Collins asymmetries for h + and h − from the whole 2002-2004 data [12,13], and confirms with high accuracy that the Collins asymmetry on deuteron is compatible with zero. The new COMPASS and HERMES results in the valence region can be interpreted naively in the framework of the parton model [12,13].…”

“…New results are also available for K ± from HERMES 2002-2004 data [11] and for π ± and K ± from COMPASS 2003-2004 data [12]. All the measured Collins asymmetries are shown in Fig.…”

“…Later on, HERMES has completed the analysis of the 2002-2004 data [11]; the measured asymmetries are shown as open points in the left plots of Fig 2. COMPASS has produced results for the whole sample of data collected from 2002 to 2004 [12,13]. These new results have substantially smaller statistical error and confirm the first findings.…”