Study of high precision τ mass measurement at BESIII

The statistical and systematic uncertainties of mτ measurement at the forthcoming detector BESIII are studied. Monte Carlo simulation and sampling techniques are adopted to simulate various data taking strategies, from which the optimal scheme is determined. It is found that the optimal position of data taking is located at the energy point with large cross section derivative near τ+τ− production threshold; one point in the optimal position with luminosity of 63 pb−1 is sufficient for a statistical accuracy better than 0.1 MeV. In addition, if Compton backscattering technique can be used at BESIII to measure the absolute energy, the final systematic uncertainty around 0.09 MeV could be expected.