Measurement of the forward-backward asymmetry of Λ and Λ¯ production in p¯p collisions

Abstract

We study Λ and ¯Λ production asymmetries in p¯p→Λ(¯Λ)X, p¯p→J/ψΛ(¯Λ)X, and p¯p→μ±Λ(¯Λ)X events recorded by the D0 detector at the Fermilab Tevatron collider at √s=1.96 TeV. We find an excess of Λ’s (¯Λ’s) produced in the proton (antiproton) direction. This forward-backward asymmetry is measured as a function of rapidity. We confirm that the ¯Λ/Λ production ratio, measured by several experiments with various targets and a wide range of energies, is a universal function of “rapidity loss,” i.e., the rapidity difference of the beam proton and the lambda.