Determination of the top mass with exclusive events t->Wb->lvJPsiX

This note presents a realistic estimate of the CMS potential for determining the top quark mass via indirect reconstruction using leptonic W decays and from the fragmentation of the b quark. The top quark mass is determined via its correlation with the invariant mass of the and the lepton from the W decay coming from the sametop. This measurement is expected to strongly reduce the systematic errors coming from the hadronic sector, which is known to be dominant indirect reconstruction methods. This analysis also presents many innovations with respect to previously published methods on the subject, and takes into account both physics and combinatorial background. The expected error on from this measurement will be presented as a function of the collected luminosity, and emphasis will be given to the determination of systematic errors, studied in great detail.