Transverse Λ Polarization in e⁺e^- collisions

In single-inclusive e⁺e^- annihilation, when the transverse momentum of the produced Λ baryon is measured with respect to the thrust axis, a transverse momentum dependent (TMD) factorization formalism is required and the polarization is generated by the TMD polarizing fragmentation function (TMD PFF), D_1T^⊥. However, when the transverse momentum of the Λ baryon is measured with respect to the momentum of the initial leptons, a collinear twist-3 formalism is required and the polarization is generated by the intrinsic collinear twist-3 fragmentation function D_T . In this talk, we develop a TMD formalism for Λ polarization and present a recent twist-3 formalism that was established to describe Λ polarization. For phenomenology, we demonstrate that the Λ polarization at OPAL and Belle can be described using the twist-2 TMD factorization formalism and make a theoretical prediction for this polarization in the collinear twist-3 formalism at Belle.