First measurements of timelike form factors of the hyperons, [formula omitted], [formula omitted], [formula omitted], [formula omitted], [formula omitted], and [formula omitted], and evidence of diquark correlations

S Dobbs,A Tomaradze,T Xiao,Kamal K Seth,G Bonvicini

doi:10.1016/j.physletb.2014.10.025

S Dobbs, A Tomaradze + Show 3 more

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https://doi.org/10.1016/j.physletb.2014.10.025

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Abstract

Using 805 pb−1 of e+e− annihilation data taken with the CLEO-c detector at ψ(3770), s=3770 MeV, we report the first measurements of the electromagnetic form factors of the Λ0, Σ0, Σ+, Ξ0, Ξ−, and Ω− hyperons for the large timelike momentum transfer of |Q2|=14.2 GeV2. The form factors for the different hyperons are found to vary by nearly a factor two. It is found that |GM(Λ0)|=1.66(24)×|GM(Σ0)|. The Λ0 and Σ0 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 Λ0 is an example of strong diquark correlations in the Λ0, as anticipated by Jaffe and Wilczek. Improved measurements of the branching fractions of ψ(2S)→pp¯ and hyperon–antihyperon pairs are also reported.

Highlights

MeV, we report the first measurements of the electromagnetic form factors of the Λ0, Σ0, Σ+, Ξ0, Ξ−, and Ω− hyperons for the large timelike momentum transfer of |Q2| = 14.2 GeV2
It is suggested that the spatial correlation implied by the singlet spin–isospin configuration in the Λ0 is an example of strong diquark correlations in the Λ0, as anticipated by Jaffe and Wilczek
In 1961 Cabibbo and Gatto [1] first proposed that the electromagnetic form factors of hadrons can be studied by e+e− annihilation for timelike momentum transfers, Q2 < 0, by measuring hadron pair-production cross sections

Summary

Introduction

MeV, we report the first measurements of the electromagnetic form factors of the Λ0, Σ0, Σ+, Ξ0, Ξ−, and Ω− hyperons for the large timelike momentum transfer of |Q2| = 14.2 GeV2. Electromagnetic form factors of hadrons at large momentum transfer provide valuable insight into their quark-gluon structure. Except for the proton and the neutron, form factors of none of the other baryons have been measured at large enough momentum transfers to provide a sensitive look into their inner structure.

Results

Conclusion