$R$ value measurements for $e^+e^-$ annihilation at 2.60, 3.07 and 3.65 GeV

TL;DR

This paper reports precise measurements of the $R$ values in $e^+e^-$ annihilation at three energies, providing important data for understanding strong interactions and determining the strong coupling constants.

Contribution

It provides new, highly precise $R$ measurements at specific energies, enabling improved calculations of the strong coupling constants.

Findings

$R$ values measured with less than 1% statistical error

Systematic errors around 3.5%

Determination of $eta_s^{(3)}(s)$ and $eta_s^{(5)}(M_Z^2)$ from data

Abstract

Using a data sample with a total integrated luminosity of 10.0 pb$^{-1}$ collected at center-of-mass energies of 2.6, 3.07 and 3.65 GeV with BESII, cross sections for $e^+e^-$ annihilation into hadronic final states ($R$ values) are measured with statistical errors that are smaller than 1%, and systematic errors that are about 3.5%. The running strong interaction coupling constants $\alpha_s^{(3)}(s)$ and $\alpha_s^{(5)}(M_Z^2)$ are determined from the $R$ values.