Asymmetries in the Production of $\Lambda_c^+$ and $\Lambda_c^-$ Baryons in 500 GeV/c $\pi^-$ Nucleon Interactions

TL;DR

This paper reports the first measurement of asymmetries in $ ext{Lambda}_c^+$ and $ ext{Lambda}_c^-$ baryon production in 500 GeV/c $ ext{pi}^-$--nucleon interactions, revealing a consistent excess of $ ext{Lambda}_c^+$ across various kinematic ranges.

Contribution

It provides the first data on $ ext{Lambda}_c$ asymmetries in both positive and negative $x_F$ regions, using a large sample from Fermilab's E791 experiment.

Findings

Observed a 12.7% asymmetry favoring $ ext{Lambda}_c^+$ production.

Asymmetry is independent of $x_F$ and $p_T^2$ within the studied range.

First measurement of $ ext{Lambda}_c$ asymmetries in both positive and negative $x_F$ regions.

Abstract

We present a measurement of asymmetries in the production of $\Lambda_c^+$ and $\Lambda_c^-$ baryons in 500 GeV/c $\pi^-$--nucleon interactions from the E791 experiment at Fermilab. The asymmetries were measured as functions of Feynman x ($x_F$) and transverse momentum squared ($p_T^2$) using a sample of $1819 \pm 62$ $\Lambda_c$'s observed in the decay channel $\Lambda_c \to pK^-\pi^+$. We observe more $\Lambda_c^+$ than $\Lambda_c^-$ baryons, with an asymmetry of $(12.7\pm3.4\pm1.3) %$ independent of $x_F$ and $p_T^2$ in our kinematical range $(-0.1 < x_F < 0.6$ and $0.0 < p_T^2 < 8.0 (GeV/c)^2$). This $\Lambda_c$ asymmetry measurement is the first with data in both the positive and negative $x_F$ regions.