2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/37020The values of $R = σ(e^+e^-\to {hadrons})/σ(e^+e^-\toμ^+μ^-)$ for 85 center-of-mass energies between 2 and 5 GeV were measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider, with an average uncertainty of $\sim7%$.4 pages, 1 figure, 1 table, talk given at XXXVIth Rencontres de Moriond, Electroweak Interactions and Unified Theories, Les Arcs, Savoie, France, March 10-17 2001High Energy Physics - Experimenttext