1210.4790 (Wenjuan Mao et al.)

The beam single spin asymmetries of neutral pion production at CLAS    [PDF]

Wenjuan Mao, Zhun Lu

We study the beam spin asymmetries $A_{LU}^{\sin\phi_h}$ in semi-inclusive $\pi^0$ electroproduction contributed by the T-odd twist-3 distribution $g^\perp(x,k_T^2)$. We calculate this transverse momentum dependent distribution for the $u$ and $d$ quarks of the proton in a spectator model including the scalar and the axial-vector diquark components. Using our model results, we estimate the asymmetries $A_{LU}^{\sin\phi_h}$ in $e p \rightarrow e^\prime \pi^0 X$ process for $E_e=5.776 \textrm{GeV}$ where the electron beam is longitudinally polarized. We compare our model prediction with the data measured by the CLAS Collaboration recently at the same beam energy and find that our numerical results agree with the data reasonably. Especially, our results can well describe the experimental data at the region the Bejorken $x$ and the pion transverse momentum is not large. We also make prediction on the asymmetries $A_{LU}^{\sin\phi_h}$ in $\pi^0$ electroproduction at CLAS12 using the same model calculation.

View original: http://arxiv.org/abs/1210.4790