Comments on Cahn and Sivers effects in SIDIS

Abstract

The role of intrinsic $k_\perp$ in semi-inclusive Deep Inelastic Scattering (SIDIS) processes ($\ell p \to \ell h X$) is studied within QCD parton model at leading order. The resulting picture is applied to the description of the weighted single spin asymmetry $A_{UL}^{\sinφ_h}$ measured by HERMES. It is shown that these data could be described by the Sivers mechanism alone. However, the extracted Sivers functions fail to describe the HERMES data on $A_{UT}^{\sin(φ_h-φ_S)}$.

Figures (2)

• Figure 1: Fits to the $\cos\phi_h$ dependence of the cross section and to $d\sigma/dP_T^2$.
• Figure 2: