Beam single spin asymmetry of neutral pion production in semi-inclusive deep inelastic scattering

TL;DR

This paper investigates the beam spin asymmetry in semi-inclusive neutral pion production, using a spectator model to calculate the relevant distribution functions and compare predictions with experimental data, providing insights into proton structure.

Contribution

The paper introduces a spectator model calculation of the T-odd twist-3 distribution function $g^ot$ for $u$ and $d$ quarks, and applies it to predict the beam spin asymmetry in $ o  o $ processes, aligning well with experimental results.

Findings

Model predictions agree with CLAS and HERMES data

Results describe data at moderate Bjorken $x$ and transverse momentum

Predictions made for future CLAS12 measurements

Abstract

We study the beam spin asymmetry $A_{LU}^{\sin\phi_h}$ in semi-inclusive $\pi^0$ electroproduction contributed by the T-odd twist-3 distribution function $g^\perp(x,k_T^2)$. We calculate this transverse momentum dependent distribution function for the $u$ and $d$ quarks inside the proton in a spectator model including the scalar and the axial-vector diquark components. Using the model results, we estimate the asymmetry $A_{LU}^{\sin\phi_h}$ in the $e p \rightarrow e^\prime \pi^0 X$ process in which the lepton beam is longitudinally polarized. The model prediction is compared with the data measured by the CLAS and the HERMES Collaborations and it is found that our numerical results agree with experimental data reasonably. Especially, our results can well describe the CLAS data at the region where the Bjorken $x$ and the pion transverse momentum is not large. We also make a prediction on the asymmetry $A_{LU}^{\sin\phi_h}$ in a $\pi^0$ electroproduction at CLAS12 using the same model calculation.