Non-zero transversity distribution of the pion in a quark-spectator-antiquark model

Abstract

We calculate the non-zero (naïve) T-odd transverse momentum dependent transversity distribution $h_1^{\perp }(x,{\text{kp}}^2)$ of the pion in a quark-spectator-antiquark model. The final-state interaction is modelled by the approximation of one gluon exchange between the quark and the antiquark spectator. Using our model result we estimate the unsuppressed cos2$\varphi$ azimuthal asymmetry in unpolarized ${\pi }^{-}p$ Drell-Yan process. We find that the transverse momentum dependence of $h_1^{\perp }(x,{\text{kp}}^2)$ of the pion is the same as that of $h_1^{\perp }(x,{\text{kp}}^2)$ of the proton calculated from the quark-scalar-diquark model, although the $x$ dependencies of them are different from each other. This suggests a connection between cos2$\varphi$ asymmetries in Drell-Yan processes with different initial hadrons.

Comments: 6 LaTex Pages in Revtex format, 5 figures. Version to appear in PRD