Precise measurement of $R_{\text{uds}}$ and $R$ between 1.84 and 3.72 GeV at the KEDR detector

TL;DR

This paper reports high-precision measurements of the $R$ ratio in electron-positron collisions between 1.84 and 3.72 GeV, enhancing understanding of quark production near the charmonium threshold.

Contribution

It provides the most detailed high-precision $R$ measurements in the 1.84-3.72 GeV range, combining new and previous data for improved accuracy.

Findings

Measured $R_{ ext{uds}}$ and $R$ at nine energies with about 2.6% accuracy

Achieved systematic uncertainty of approximately 1.9%

Extended precise $R$ measurements near the charmonium threshold

Abstract

The present work continues a series of the KEDR measurements of the $R$ value that started in 2010 at the VEPP-4M $e^+e^-$ collider. By combining new data with our previous results in this energy range we measured the values of $R_{\text{uds}}$ and $R$ at nine center-of-mass energies between 3.08 and 3.72 GeV. The total accuracy is about or better than $2.6\%$ at most of energy points with a systematic uncertainty of about $1.9\%$. Together with the previous precise $R$ measurement at KEDR in the energy range 1.84-3.05 GeV, it constitutes the most detailed high-precision $R$ measurement near the charmonium production threshold.