1201.5427 (Zhong-Bo Kang et al.)

Global fitting of single spin asymmetry: an attempt    [PDF]

Zhong-Bo Kang, Alexei Prokudin

We present an attempt of global analysis of Semi-Inclusive Deep Inelastic
Scattering (SIDIS) $\ell p^\uparrow \to \ell' \pi X$ data on single spin
asymmetries and data on left-right asymmetry $A_N$ in $p^\uparrow p \to \pi X$
in order to simultaneously extract information on Sivers function and
twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman (ETQS) function. We explore
different possibilities such as node of Sivers function in $x$ or $k_\perp$ in
order to explain "sign mismatch" between these functions. We show that
$\pi^\pm$ SIDIS data and $\pi^0$ STAR data can be well described in a combined
TMD and twist-3 fit, however $\pi^\pm$ BRAHMS data are not described in a
satisfactory way. This leaves open a question to the solution of the "sign
mismatch". Possible explanations are then discussed.

View original: http://arxiv.org/abs/1201.5427