Speaker
Haiming HU
(IHEP， CAS)
Description
At BESIII, the $R$ value is measured with a total of 14 data points with the corresponding c.m. energy going from 2.2324 to $3.6710~\rm GeV$. The statistical uncertainty of the measured $R$ is less than 0.6%. Two different simulation models, the LUARLW and a new Hybrid generated, are used and give consistent detection efficiencies and initial-state-radiation corrections. An accuracy of better than 2.6% below $3.1~\rm GeV$ and 3.0% above is achieved in the $R$ values.
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Primary author
Haiming HU
(IHEP， CAS)
