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

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.

Figures (1)

• Figure 1: Collins amplitudes (upper panel) and Sivers amplitudes (middle panel) for both charged pions (left column, charge as labelled) and charged kaons (right column, charge as labelled) as a function of $x$, $z$ and $\boldsymbol{P}_{\,\text{h}\perp}$. The error bands represent the maximal systematic uncertainty due to hadron misidentification, due to acceptance and detector smearing effects and due to a possible contribution from the $\left<\cos{\phi}\right>_{\text{UU}}$ amplitude in the spin-independent cross section. The common overall $6.6\%$ scaling uncertainty is due to the target polarisation uncertainty. The lower panel shows the fraction of charged pions (left column) and charged kaons (right column) produced in vector meson decay as simulated by a version of PHYTHIA6Sjostrand:2000wi tuned for HERMES kinematics.