Tree-level new physics searches in B decays to tau leptons at Belle

Abstract

of R(D ( ) ) = B B! D ( ) tn =B B! D ( ) ‘n (‘ = e;m), is discussed next. The t lepton is reconstructed in its leptonic decays. We obtain a result of R(D) = 0:375 0:064 0:026 and R(D ) = 0:293 0:038 0:015. The results are consistent with previous measurements and do not show a significant deviation from the predictions of the Standard Model. The third analysis presented here is the measurement of the leptonic decay B + ! t + nt is presented, where a semileptonic tag is used. We obtain B(B + ! t + nt) = (1:25 0:28 0:27) 10 4 , which is in good agreement with the Standard Model calculations.