We have performed a search for scalar top quark (stop) pair production in the inclusive electron-muon-missing transverse energy final state, using a sample of $p \bar{p}$ events corresponding to ...108.3 pb$^{-1}$ of data collected with the D{\O}detector at Fermilab. The search is done in the framework of the minimal supersymmetric standard model assuming that the sneutrino is the lightest supersymmetric particle. For the dominant decays of the lightest stop, \bc and \bls, no evidence for signal is found. We derive cross-section limits as a function of stop (\stt), chargino (\ca), and sneutrino (\snu) masses.
We report the first search for supersymmetric particles via s-channel production and decay of smuons or muon sneutrinos at hadronic colliders. The data for the two-muon and two-jets final states were ...collected by the DO experiment, and correspond to an integrated luminosity of 94 +/- 5 pb^{-1}. Assuming that R-parity is violated via the single coupling lambda^{prime}_{211}, the number of candidate events is in agreement with expectation from the standard model. Exclusion contours are given in the (m_0,m_{1/2}) and (m_{tilde{chi}},m_{tilde{nu}}) planes for lambda^{prime}_{211}=0.09, 0.08 and 0.07.
We present the results of a search for leptoquark (LQ) pairs in (85.2 +- 3.7) pb^{-1} of p anti-p collider data collected by the D0 experiment at the Fermilab Tevatron. We observe no evidence for ...leptoquark production and set a limit on sigma(p anti-p -> LQ anti-LQ -> neutrino neutrino + jets) as a function of the mass of the leptoquark (m_{LQ}). Assuming the decay LQ -> neutrino q, we exclude scalar leptoquarks for m_{LQ} < 98 GeV/c^2, and vector leptoquarks for m_{LQ} < 200 GeV/c^2 and coupling which produces the minimum cross section, at a 95% confidence level.
Using the DØ detector, we have studied events produced in $\bar{p}p$ collisions that contain large forward regions with very little energy deposition (“rapidity gaps”) and concurrent jet production ...at center-of-mass energies of $\sqrt s$ = 630 and 1800 GeV. The fraction of events with forward or central jets associated with rapidity gaps is compared to predictions for hard diffraction. We also extract the momentum loss for scattered protons in such processes.
The central inclusive jet cross section has been measured using a successive-combination algorithm for reconstruction of jets. The measurement uses 87.3 pb^{-1} of data collected with the D0 detector ...at the Fermilab Tevatron ppbar Collider during 1994-1995. The cross section, reported as a function of transverse momentum (pT>60 GeV) in the central region of pseudorapidity (|\eta|<0.5), exhibits reasonable agreement with next-to-leading order QCD predictions, except at low pT where the agreement is marginal.
We report on a search for second generation leptoquarks (LQ) produced in povr p collisions at radical (s) =1.8 TeV using the D0 detector at Fermilab. Second generation leptoquarks are assumed to be ...produced in pairs and to decay to either mu or nu and either a strange or a charm quark (q) . Limits are placed on sigma(povr pr arrow LQovr LQr arrowmunu+jets) as a function of the mass of the leptoquark. For equal branching ratios to muq and nuq , second generation scalar leptoquarks with a mass below 160 GeV/csup 2 , vector leptoquarks with anomalous minimal vector couplings with a mass below 240 GeV/csup 2 , and vector leptoquarks with Yang-Mills couplings with a mass below 290 GeV/csup 2 , are excluded at the 95percent confidence level. copyright ital 1999 ital The American Physical Society
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