Transverse polarization of the $\Lambda$ hyperon from unpolarized quark fragmentation in the diquark model

Abstract

We investigate the spin-dependent (naive) T-odd fragmentation function $D_{1T}^{\perp }$, which can provide an explanation on the transverse polarization of the ${\Lambda }^0$ hyperon produced in an unpolarized process. We calculate $D_{1T}^{\perp }$ for light flavors in the spectator diquark model, with a Gaussian form factor at the hyperon-quark-diquark vertex. We include in the calculation both the scalar diquark and axial-vector diquark spectators. We determine the values of the model parameters by fitting the unpolarized fragmentation function $D_1^{\Lambda }$ to the DSV parametrization for $D_1^{\Lambda }$. In addition, we compute the longitudinal polarization fragmentation function $G_1^{\Lambda }$ and compare it with the known parametrization of $G_1^{\Lambda }$. We also estimate the transverse polarizations of $\Lambda$ production, in both semi-inclusive deep inelastic scattering and single inclusive $e^{+}{e}^{-}$ annihilation.

Comments: Reference added, typos corrected