We report preliminary $R$ values for all 85 energy points scanned in the energy region of 2-5 GeV with the upgraded Beijing Spectrometer (BESII) at the Beijing Electron Positron Collider (BEPC). The typical uncertainty on the R values we measured is about 7%. The new R values have a significant impact on the predicted mass of the Higgs coming from the global fit to the electroweak data, and will also contribute to the interpretation of the E821 g-2 experiment.
تحميل البحث