Structure and production of lambda baryons

Abstract

We discuss the quark parton structure of the Λ baryon and the fragmentation of quarks into Λ baryons. We show that the hyperfine interaction, responsible for the Δ-N and Σ0-Λ mass splittings, leads not only to sizable SU(3) and SU(6) symmetry breaking in the quark distributions of the Λ, but also to significant polarized non-strange quark distributions. The same arguments suggest flavor asymmetric quark fragmentation functions and non-zero polarized non-strange quark fragmentation functions. The calculated fragmentation functions give a good description of all measured observables. We predict significant positive Λ polarization in semi-inclusive DIS experiments while models based on SU(3) flavor symmetry predict zero or negative Λ polarization. Our approach also provides a natural explanation for the dependence of the maximum of the ξ=ln(1/z) spectrum on the mass of the particles produced in e+e- annihilation.