Feasibility Studies for an Inclusive R-Measurement using ISR at BESIII

Abstract

In this work a novel technique to measure the hadronic R value (R = σhad0 / σμμ0) inclusively is presented. The method employs the initial state radiation (ISR) technique and the study is carried out for the BESIII experiment at the tau-charm factory BEPC-II. Given the large Lorentz-boost of the hadronic system produced in an ISR process, the efficiency to detect at least one of the hadrons (once the ISR photon is reconstructed) is very high, thus relieving the reliance of the measurement on the theoretical model used in the simulations. A first inclusive determination of the R value in the low energy region can, therefore, be achieved, providing a crucial cross check to the current evaluations based on the sum of exclusive measurements.