ar X iv : h ep - p h / 97 02 25 8 v 1 5 F eb 1 99 7 The Λ 0 Polarization and the Recombination Mechanism 1

We use the recombination and the Thomas Precession Model to obtain a prediction for the Λ0 polarization in the p+ p → Λ0 +X reaction. We study the effect of the recombination function on the Λ0 polarization. INTRODUCTION The unexpected discovery of large polarization in inclusive Λ0 production by unpolarized protons has shown that important spin effects arise in the hadronization process. Several models have been proposed to explain hyperon polarization, being the Thomas Precession Model (TPM) [1] one of the most extensively used to describe polarization in a variety of reactions. In order to obtain the Λ0 polarization, we first calculate the momentum fraction of the recombining s-quark in the proton sea using a recombination model [2]. We use two different forms for the recombination function to see their influence on the predicted Λ0 polarization. THE Λ0 POLARIZATION IN THE TPM In pp collisions the recombining s-quark resides in the sea of the proton and carries a very small fraction xs ≃ 0.1 of the proton momentum. When the s-quark recombines to form a Λ0, it becomes a valence quark and must carry a large fraction (of the order of 1 3 ) of Λ0’s momentum. Then one expects a large increase in the longitudinal momentum of the s-quark as it passes from the proton to the Λ0, ∆p ≃ ( 1 3 xF − xs)p = ( 1 3 − ξ ) xFp, (1) 1) This work was partially supported by Centro Latino Americano de F́ısica (CLAF). c © 1995 American Institute of Physics 1