A mixed τ-electroproduction sum rule for |Vus|

The interpretation of results of recent tau decay determinations of |Vus| which yield values similar to 3 sigma low compared to 3-family unitarity expectations, is complicated by the slow convergence of the relevant integrated D = 2 OPE series. We introduce a class of new sum rules involving both electroproduction and tau decay data designed to deal with this problem by strongly suppressing D = 2 OPE contributions at the correlator level. Experimental complications are briefly discussed and an example of the improved control over theoretical errors presented. The uncertainty on the resulting determination, |V-us| = 0.2202(39), is entirely dominated by experimental errors, and should be subject to significant near-term improvement. (C) 2009 Elsevier B.V. All rights reserved.