17662944
Measurement of semileptonic branching fractions of B mesons to narrow D** states.
Using the data accumulated in 2002-2004 with the D0 detector in proton-antiproton collisions at the Fermilab Tevatron collider with a center-of-mass energy of 1.96 TeV, the branching fractions of the decays B --> D0(1)(2420)mu+ vmuX and B --> D2(*0)(2460)mu+ vmuX and their ratio have been measured: B(b --> B) x B(B --> D0(1)mu+ vmuX) x B(D0(*0) --> D*- pi+) = [0.087 +/- 0.007(stat) +/- 0.014(syst)]%; B(b --> B) x B(B --> D2(*0) mu+ vmuX) x B(D2(*0) --> D*- pi+) = [0.035 +/- 0.007(stat) +/- 0.008(syst)]% and [B(B --> D2(*0)mu+ vmuX) x B(D2(*0) --> D*- pi+)]/[B(B --> D0(1)mu+ vmuX) x B(D0(1) --> D*- pi+)] = 0.39 +/- 0.09(stat) +/- 0.12 (syst), where the charge conjugated states are always implied.
14588649
Production of e, mu and tau pairs in untagged two-photon collisions at LEP
The two-photon collision reaction e+e- --> e+e-l+l- has been studied at root(s) ~ 91 GeV using the L3 detector at LEP for l = e, muon , tau. We have analysed untagged configurations where the two photons are quasi-real. Good agreement is found between our measurements and the order alpha**4 QED expectation.
117975953
Measurement of Inclusive Charm Production in Two -Photon Collisions at LEP.
The cross section of inclusive charm production in two-photon collisions  e+e_ccX) is measured at the Large Electron Positron (LEP) col­ lider at the European Center for Nuclear and Particle Physics (CERN). The data was obtained with the L3 detector at the center-of-mass energy of 91 GeV (LEP1) and for the first time at the center-of-mass energies from 130183 GeV (LEP2). Charmed hadrons are identified by electrons and muons from semileptonic decays. The measured cross section agrees with ne^t-toleading order (NLO) QCD calculations. The direct process 7 7 —► cc is found to be insufficient to describe the data. The measured cross section values and event distributions require contributions from resolved processes, which are sensitive to the gluon density in the photon.
209835666
Measurement of the spectroscopy of orbitally excited B mesons at LEP
Abstract We measure the masses, decay widths and relative production rate of orbitally excited B mesons using 1.25 million hadronic Z decays recorded by the L3 detector. B-meson candidates are inclusively reconstructed and combined with charged pions produced at the primary event vertex. An excess of events above the expected background in the B π mass spectrum in the region 5.6–5.8 GeV is interpreted as resulting from the decay B ∗∗ u , d → B (∗) π , where B ∗∗ u , d denotes a mixture of l =1 B-meson states containing a u or a d quark. A fit to the mass spectrum yields the masses and decay widths of the B 1 ∗ and B 2 ∗ spin states, as well as the branching fraction for the combination of l =1 states. In addition, evidence is presented for the existence of an excited B-meson state or mixture of states in the region 5.9–6.0 GeV.
120849479
Ground‐State Magnetization in Disordered Systems: Exchange versus Off‐Diagonal Interaction Fluctuations