$R$ measurement and QCD studies at future super $\tau -c$ factory

arXiv

2203.06961

Date

2022-03-14

Frontier

Rare Processes and Precision Frontier (RF)

Topical groups

• RF3

Submitted by

Guangshun Huang

Abstract

We review status of $R$ measurement and QCD studies at low energy range, discuss prospects for a super $\tau -$charm factory in $2-7$ GeV. With a high-luminosity $e^{+}{e}^{-}$ collider, statistics are no longer problem for $R$ measurement and a precision of $2\mathrm{\%}$ or even better is foreseen, that will lead to bring down the uncertainty of hadronic contribution to the QED running coupling constant $\mathrm{\Delta }{\alpha }_{had}$ and the anomalous magnetic moment of the muon ($a_{\mu }$); measure the strong coupling constant ${\alpha }_s$ and the charm quark mass; improve the measurement of the resonance parameters of heavy charmonia. Huge data samples in $2-3$ GeV will make it possible to study excited states of $\rho$, $\omega$ and $\varphi$, or exotic $Y(2175)$; measure electromagnetic form factor of mesons and baryons; and measure fragmentation functions of hadrons.