T-odd quark fragmentation function and transverse spin asymmetries in the pion production

Abstract

We study the time-reversal odd quark fragmentation function and its consequences on the hard processes. T-odd quark fragmentation function may arise, although QCD is T-invariant, from the non-perturbative dynamics in the fragmentation process. Assuming the factorization, we extract the T-odd fragmentation function from the inclusive pion production in the transversely polarized proton-proton collision. We then estimate the single spin asymmetry $A_{OT}$ of the semi-inclusive deep inelastic scattering with unpolarized lepton and the transversely polarized proton. We also discuss the meson cloud effects on the transversity distribution $h_1(x)$ of the nucleon. Asymmetry for the $π^-$ production is found to be much smaller than the naive expectation, since the $d$-quark transversity is considerably suppressed by the pion cloud effects