Measurement of the Σ- charge radius by Σ--electron elastic scattering

The Sigma (-) mean squared charge radius has been measured in the space-like Q(2) range 0.035--0.105 GeV2/c(2) by elastic scattering of a Sigma (-) beam off atomic electrons. The measurement was per-formed with the SELEX (E781) spectrometer using the Fermilab hyperon beam at a mean energy of 610 GeV/c We obtain Sigma (-) =(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 (-). (C) 2001 Elsevier Science B.V. All rights reserved.