New R Values in 2-5 Gev from the Beijing Spectrometer

TL;DR

This paper reports new measurements of the R ratio in the 2-5 GeV energy range using the upgraded Beijing Spectrometer, providing valuable data for understanding hadronic cross sections in electron-positron collisions.

Contribution

The study presents the first comprehensive set of R values in the 2-5 GeV range with improved accuracy from the upgraded Beijing Spectrometer.

Findings

Measured R values at 85 energies between 2 and 5 GeV.

Achieved an average uncertainty of approximately 7%.

Provides data to refine theoretical models of hadronic production.

Abstract

The values of $R = \sigma(e^+e^-\to {hadrons})/\sigma(e^+e^-\to\mu^+\mu^-)$ for 85 center-of-mass energies between 2 and 5 GeV were measured with the upgraded Beijing Spectrometer at the Beijing Electron-Positron Collider, with an average uncertainty of $\sim7%$.