Measurement of sigma_Total in e+e- Annihilations Below 10.56 GeV

TL;DR

This study measures the total hadronic cross section in electron-positron annihilations below 10.56 GeV, providing data to determine the strong coupling constant alpha_s and its energy evolution.

Contribution

First precise measurement of R in the 7 to 10.5 GeV range, enabling improved determination of alpha_s and testing QCD predictions.

Findings

Measured R with <2% error at seven energies

Determined alpha_s(M_Z^2)=0.126 +/- 0.005

Estimated Lambda_QCD=0.31 GeV

Abstract

Using the CLEO III detector, we measure absolute cross sections for e+e- -> hadrons at seven center-of-mass energies between 6.964 and 10.538 GeV. R, the ratio of hadronic and muon pair production cross sections, is measured at these energies with a r.m.s. error <2% allowing determinations of the strong coupling alpha_s. Using the expected evolution of alpha_s with energy we find alpha_s(M_Z^2)=0.126 +/- 0.005 ^{+0.015}_{-0.011}, and Lambda=0.31^{+0.09+0.29}_{-0.08-0.21}.