Measurement of the Sigma^- Charge Radius by Sigma^- Electron Elastic Scattering

TL;DR

This paper reports the first measurement of the Sigma^- hyperon's charge radius through elastic scattering experiments, providing new insights into hyperon structure and confirming consistency with related measurements.

Contribution

It introduces a novel measurement of the Sigma^- charge radius using electron scattering at Fermilab, expanding knowledge of hyperon electromagnetic properties.

Findings

Measured <r^2> = (0.61 +/- 0.12 +/- 0.09) fm^2 for Sigma^-

Proton and pi^- radii are consistent with previous results

Result aligns with recent strong interaction radius measurements

Abstract

The Sigma^- mean squared charge radius has been measured in the space-like Q^2 range 0.035-0.105 GeV^2/c^2 by elastic scattering of a Sigma^- beam off atomic electrons. The measurement was performed with the SELEX (E781) spectrometer using the Fermilab hyperon beam at a mean energy of 610 GeV/c. We obtain <r^2> = (0.61 +/- 0.12 (stat.) +/- 0.09 (syst.)) fm^2. The proton and pi^- charge radii were measured as well and are consistent with results of other experiments. Our result agrees with the recently measured strong interaction radius of the Sigma^-.