First Measurements of Timelike Form Factors of the Hyperons, Lambda0, Sigma0, Sigma+, Xi0, Xi-, and Omega-, and Evidence of Diquark Correlations

TL;DR

This paper reports the first measurements of electromagnetic form factors of various hyperons at large timelike momentum transfer, revealing significant variation among them and providing evidence for diquark correlations within Lambda0.

Contribution

It presents the first measurements of hyperon form factors at |Q^2|=14.2 GeV^2 and suggests strong diquark correlations in Lambda0, advancing understanding of hyperon structure.

Findings

Form factors vary by nearly a factor of two among hyperons.

|G_M(Lambda0)| is approximately 1.66 times |G_M(Sigma0)|.

Evidence of diquark correlations in Lambda0.

Abstract

Using 805 pb^-1 of e+e- annihilation data taken with the CLEO-c detector at psi(3770), sqrt{s}=3770 MeV, we report the first measurements of the electromagnetic form factors of the Lambda0, Sigma0, Sigma+, Xi0, Xi-, and Omega- hyperons for the large timelike momentum transfer of |Q^2|=14.2 GeV^2. The form factors for the different hyperons are found to vary by nearly a factor two. It is found that |G_M(Lambda0)|=1.66(24) x |G_M(Sigma0)|. The Lambda0 and Sigma0 hyperons have the same uds quark content, but differ in their isospin, and therefore the spin of the $ud$ quark pair. It is suggested that the spatial correlation implied by the singlet spin--isospin configuration in the Lambda0 is an example of strong diquark correlations in the Lambda0, as anticipated by Jaffe and Wilczek. Improved measurements of the branching fractions of psi(2S) -> p pbar and hyperon--antihyperon pairs are also reported.