Author: M. Margoni (Dipartimento di Fisica, Universita` di Padova and INFN, Padova, Italy)
Title: New DELPHI Results from Semileptonic b, c Decays
Abstract: The inclusive direct and cascade semileptonic branching ratios of the b quarkwere measured from a fit to the lepton momentum spectrum in the B-hadron rest frame, exploiting the charge correlation between the lepton and the heavy meson:BR(bar(b)-->l+) = 10.32+-0.12(stat.)+-0.27(syst.)+0.31-0.21(model) BR(bar(b)-->bar(c)--> l-) = 7.32+-0.26(stat.)+-0.32(syst.)+0.06-0.16(model)BR(bar(b)-->c--> l+) = 0.94+-0.16(stat.)+-0.28(syst.)+0.33-0.50+-(model)The value of the |Vcb| element in the CKM quark mixing matrix was computed from the differential decay width of the process B0--> D+-* l- nu, measured as a functionof the product W of the B and D* 4-velocities, using an inclusive method of D* reconstruction: |Vcb|=41.70+-2.35(exp.)+-1.38(th.) X 10^-3 A measurement of the ratio |Vub|/|Vcb| has been obtained by using the reconstructedsecondary hadronic mass in semileptonic decays of B hadrons, and found to be: |Vub|/|Vcb|=0.104+-0.012(stat.)+-0.015(syst.)+-0.009(model) The charm semileptonic branching ratio was measured using a double tag method based on the detection of exclusively reconstructed D mesons accompanied by a lepton in the opposite hemisphere, giving: BR(c--> l)=(9.58+-0.42(stat.)+-0.28(syst.))%
Comments: 7 pages, 12 figures. Proceedings for talk 3-11 given at the DPF99 Conference in Los Angels, California.