Asymmetries in the Production of Lambda0 in 250 GeV/c pi+-, K+- and p -- Nucleon Interactions

TL;DR

This paper reports measurements of Lambda0 hyperon production asymmetries in 250 GeV/c pi+-, K+-, and p-- nucleon interactions, revealing significant asymmetries and leading-particle effects consistent with valence-quark content.

Contribution

First detailed measurement of Lambda0 production asymmetries across multiple beam types and kinematic ranges in high-energy fixed-target experiments.

Findings

Substantial asymmetries observed at x_F around zero

Leading-particle-type asymmetries align with valence-quark expectations

Asymmetries vary with Feynman-x and transverse momentum

Abstract

Using data from Fermilab fixed-target experiment E769, we have measured particle-antiparticle production asymmetries for Lambda0 hyperons in 250 GeV/c pi+-, K+- and p -- nucleon interactions. The asymmetries are measured as functions of Feynman-x (x_F) and p_t^2 over the ranges -0.12<=x_F<=0.12 and 0<=p_t^2<=3 (GeV/c)^2 (for positive beam) and -0.12<=x_F<=0.4 and 0<=p_t^2<=10 (GeV/c)^2 (for negative beam). We find substantial asymmetries, even at x_F around zero. We also observe leading-particle-type asymmetries. These latter effects are qualitatively as expected from valence-quark content of the target and variety of projectiles studied.