$t \bar{t}$ production cross-section in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.8-TeV
Results are presented on a measurement of the t (t) over bar pair production cross section in p (p) over bar collisions at roots=1.8 TeV from nine independent decay channels. The data were collected by the D empty set experiment during the 1992-1996 run of the Fermilab Tevatron Collider. A total of 80 candidate events is observed with an expected background of 38.8+/-3.3 events. For a top quark mass of 172.1 GeV/c(2), the measured cross section is 5.69+/-1.21(stat)+/-1.04(syst) pb.

title: Measurement of Inclusive Charm Production in Two -Photon Collisions at LEP.
abstract: 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.

title: Measurement of an elongation of the pion source in Z decays
abstract: We measure Bose-Einstein correlations between like-sign charged pion pairs in hadronic Z~decays with the L3 detector at LEP. The analysis is performed in three dimensions in the longitudinal center-of-mass system. The pion source is found to be elongated along the thrust axis with a ratio of transverse to longitudinal radius of $0.81\pm 0.02 ^{+0.03}_{-0.19}$.

title: Measurement of the tau branching fractions into leptons
abstract: Using data collected with the L3 detector near the Z resonance, corresponding to an integrated luminosity of 150pb-1, the branching fractions of the tau lepton into electron and muon are measured to be B(tau->e nu nu) = (17.806 +- 0.104 (stat.) +- 0.076 (syst.)) %, B(tau->mu nu nu) = (17.342 +- 0.110 (stat.) +- 0.067 (syst.)) %. From these results the ratio of the charged current coupling constants of the muon and the electron is determined to be g_mu/g_e = 1.0007 +- 0.0051. Assuming electron-muon universality, the Fermi constant is measured in tau lepton decays as G_F = (1.1616 +- 0.0058) 10^{-5} GeV^{-2}. Furthermore, the coupling constant of the strong interaction at the tau mass scale is obtained as alpha_s(m_tau^2) = 0.322 +- 0.009 (exp.) +- 0.015 (theory).

title: Measurement of semileptonic branching fractions of B mesons to narrow D** states.
abstract: 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.

title: Measurement of the lifetime difference in the B0(s) system.
abstract: We present a study of the decay B0(s) --> J/psiphi. We obtain the CP-odd fraction in the final state at time zero, Rperpendicular = 0.16 +/- 0.10(stat) +/- 0.02 (syst), the average lifetime of the (B0(s), B0(s)) system, tau(B0(s)) = 1.39(+0.13)(-0.16)(stat)(+0.01)(-0.02)(syst) ps, and the relative width difference between the heavy and light mass eigenstates, DeltaGamma/Gamma tripple bond (GammaL - GammaH)/Gamma = 0.24(+0.28)(-0.38)(stat)(+0.03)(-0.04)(syst). With the additional constraint from the world average of the lifetime measurements using semileptonic decays, we find tau(B0(s)) = 1.39 +/- 0.06 ps and DeltaGamma/Gamma = 0.25(+0.14)(-0.15). For the ratio of the B0(s) and B0 lifetimes we obtain tau(B0(s))/tau(B0) = 0.91 +/- 0.09(stat) +/- 0.003(syst).

title: Ground-state magnetization for interacting fermions in a disordered potential: Kinetic energy, exchange interaction, and off-diagonal fluctuations
abstract: We study a model of interacting fermions in a disordered potential, which is assumed to generate uniformly fluctuating interaction matrix elements. We show that the ground state magnetization is systematically decreased by off-diagonal fluctuations of the interaction matrix elements. This effect is neglected in the Stoner picture of itinerant ferromagnetism in which the ground-state magnetization is simply determined by the balance between ferromagnetic exchange and kinetic energy, and increasing the interaction strength always favors ferromagnetism. The physical origin of the demagnetizing effect of interaction fluctuations is the larger number of final states available for interaction-induced scattering in the lower spin sectors of the Hilbert space. We analyze the energetic role played by these fluctuations in the limits of small and large interaction $U$. In the small $U$ limit we do second-order perturbation theory and identify explicitly transitions which are allowed for minimal spin and forbidden for higher spin. These transitions then on average lower the energy of the minimal spin ground state with respect to higher spin. For large interactions $U$ we amplify on our earlier work [Ph. Jacquod and A.D. Stone,  (2000)] which showed that minimal spin is favored due to a larger broadening of the many-body density of states in the low-spin sectors. Numerical results are presented in both limits.

title: Ground‐State Magnetization in Disordered Systems: Exchange versus Off‐Diagonal Interaction Fluctuations