Search for Leptoquarks with the D0 detector

We report on D0 searches for leptoquarks (LQ) predicted in extended gauge theories and composite models to explain the symmetry between quarks and leptons. Data samples obtained with the D0 detector from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV corresponding to intergrated luminosities of 1--4 inverse-fb were analyzed. No evidence for the production of such particles were observed and lower limits on leptoquark masses are set.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

Search for Squarks and Gluinos with the D0 detector

We report on D0 searches for scalar quarks (tilde-q) and gluinos (tilde-g), the superpartners of quark and gluons, in topologies involving jets and missing transverse energies. Data samples obtained with D0 detector from proton anti-proton collisions at a center-of-mass energy of 1.96 TeV corresponding to an intergrated luminosities of 1-4 inverse-fb were analyzed. No evidence for the production of such particles were observed and lower limits on squarks and gluino masses were set.Comment: To be published in the proceedings of DPF-2009, Detroit, MI, July 2009, eConf C09072

A search for charge 1/3 third generation leptoquarks in muon channels

Leptoquarks are exotic particles that have color, electric charge, and lepton number and appear in extended gauge theories and composite models. Current theory suggests that leptoquarks would come in three different generations corresponding to the three quark and lepton generations. We are searching for charge 1/3 third generation leptoquarks produced in p{bar p} collisions at {radical}s = 1.96 TeV using data collected by the D0 detector. Such leptoquarks would decay into either a tau-neutrino plus a b-quark or, if heavy enough, to a tau-lepton plus a t-quark. We present preliminary results on an analysis where both leptoquarks decay into neutrinos giving a final state with missing energy and two b-quarks using 367 pb{sup -1} of Run II D0 data taken between August 2002 and September 2004. We place upper limits on {sigma}(p{bar p} {yields} LQ{ovr LQ})B{sup 2} as a function of the leptoquark mass M{sub LQ}. Assuming B = 1, we exclude at the 95% confidence level third generation leptoquarks with M{sub LQ} < 197 GeV/c{sup 2}

Measurement of the semileptonic charge asymmetry in B0 meson mixing with the D0 detector

We present a measurement of the semileptonic mixing asymmetry for B0 mesons, a^d_{sl}, using two independent decay channels: B0 -> mu+D-X, with D- -> K+pi-pi-; and B0 -> mu+D*-X, with D*- -> antiD0 pi-, antiD0 -> K+pi- (and charge conjugate processes). We use a data sample corresponding to 10.4 fb^{-1} of ppbar collisions at sqrt(s) = 1.96 TeV, collected with the D0 experiment at the Fermilab Tevatron collider. We extract the charge asymmetries in these two channels as a function of the visible proper decay length (VPDL) of the B0 meson, correct for detector-related asymmetries using data-driven methods, and account for dilution from charge-symmetric processes using Monte Carlo simulation. The final measurement combines four signal VPDL regions for each channel, yielding a^d_{sl} = [0.68 \pm 0.45 \text{(stat.)} \pm 0.14 \text{(syst.)}]%. This is the single most precise measurement of this parameter, with uncertainties smaller than the current world average of B factory measurements.Comment: Version includes minor textual changes following peer review by journal, most notably the updating of Ref. [21] to reflect the most recent publicatio