Light Quark Masses from Exclusive Tau Decays: An Experimental Proposal

Abstract

A method of indirect measurement of the light quark running mass $\hat{m}=(m_d+m_u)/2$ is elaborated in detail. It is based on measuring 1\%-level azimuthal angular asymmetries in the decay $\ddot{I}„\to \hat{I}{½}_{\ddot{I}}„+3\ddot{I}€$. The latter are then used in QCD sum rules to obtain experimental lower bounds for $\hat{m}$. For a sample of $2.5\times 10^5$ $\ddot{I}„\to \hat{I}{½}_{\ddot{I}}„+3\ddot{I}€$ decays free of background, the resulting statistical error in the bound for $\hat{m}$ is estimated to be 1 MeV, i.e., comparable to the systematic error due to the use of QCD sum rules. Contribution to the Third Workshop on the $\ddot{I}„$ Charm Factory 1-6 June 1993, Marbella, Spain.

18 pages, 13 figures not included, available upon request, IPNO-TH 93-38