Measurement of $R$ between 1.84 and 3.05 GeV at the KEDR detector

Abstract

Using the KEDR detector at the VEPP-4M $e^{+}{e}^{-}$ collider, we have determined the values of $R$ at thirteen points of the center-of-mass energy between 1.84 and 3.05 GeV. The achieved accuracy is about or better than $3.9\%$ at most of the energy points with a systematic uncertainty less than $2.4\%$.