Polarization in hadronicΛhyperon production and chiral-odd twist-3 distribution

Polarization of the {Λ} hyperon produced with a large transverse momentum in unpolarized nucleon-nucleon collisions is analyzed in the framework of QCD factorization. We focus on the mechanism in which the soft-gluon component of the chiral-odd spin-independent twist-3 quark distribution EF(x,x) becomes a source of the polarized quark fragmenting into the polarized {Λ}. Our simple model estimate for this contribution indicates that it gives rise to a significant {Λ} polarization at large xF. This is in parallel with the observation that the soft gluon pole mechanism gives rise to a large single transverse spin asymmetry in pion production at xF→1.