Search for the pentaquark candidate $\Theta^+$(1540) in the hyperon beam experiment WA89

TL;DR

This high-statistics experiment searched for the pentaquark candidate $ heta^+$(1540) in hyperon-nucleus collisions but found no evidence, setting upper limits on its production cross section.

Contribution

The study provides the first high-statistics search for $ heta^+$(1540) in $ar{ ext{hyperon}}$ beam collisions, establishing upper limits on its production.

Findings

No evidence for $ heta^+$(1540) resonance was observed.

The production cross section is constrained to be less than 1.8 μb per nucleon at 99% CL.

The results set new upper limits on $ heta^+$ production in hyperon-induced reactions.

Abstract

We report on a high-statistics search for the \t1540 resonance in $\Sigma^-$-nucleus collisions at 340 \gevc1 . No evidence for this resonance was found in our data sample which contains 13 millions $K^0_s \to \pi^+\pi^- $ decays above background. For the decay channel $\Theta^+ \to K^0_s p$ and the kinematic range $x_F>$ 0.05 we find the production cross section to be $BR(\Theta^+ \to K^0_s p)\cdot \sigma_0 <$ 1.8 $\mu$b per nucleon at 99% CL.