Measurement of the total hadronic cross section in $e^{+}{e}^{-}$ annihilation at $\sqrt{s}=29\mathrm{}$ GeV

A precise measurement of the ratio $R$ of the total cross section $e^{+}{e}^{-}\to \mathrm{hadrons}$ to the pointlike cross section $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at a center-of-mass energy of 29.0 GeV is presented. The data were taken with the upgraded Mark II detector at the SLAC storage ring PEP. The result is $R=3.92\mathrm{}\pm 0.05\pm 0.09$. The luminosity has been determined with three independent luminosity monitors measuring Bhabha scattering at different angular intervals. Recent calculations of higher-order QED radiative corrections are used to estimate the systematic error due to missing higher-order radiative corrections in the Monte Carlo event generators.