Accelerator Neutrinos

Abstract:

We report on a search for supersymmetry using dilepton events which complements the classic missing ET plus multijet analyses. Using 19pb^-1 of pp collisions at √s = 1.8TeV recorded with the Collider Detector at Fermilab we have searched for squarks and gluinos decaying into charginos and producing events with two leptons. We observe one candidate event. In comparison, the expected number of background events from standard model processes is 2.39±0.63(stat)^+0.77 -0.42(syst). Hence we set limits on gluino and squark production based on predictions from the supergravity inspired minimal supersymmetric extension of the standard model. © 1996 The American Physical Society.

Abstract:

We present a search for pair produced top squarks, the supersymmetric partners of the top quark, using the D0 detector at the Fermilab Tevatron p¯p collider. We consider a scenario in which the lighter of the two top squarks ˜t1 decays with 100% branching fraction to a charm quark and the lightest neutralino ˜χ⁰ 1 yielding a signal of two acollinear jets with missing transverse energy. We observe 3 events while we expect 3.5 α 1.2 events from the known standard model processes. We exclude at the 95% confidence level a significant region of the mt1 - mχ1 ⁰ parameter space. The highest mt1 value we exclude is 93GeV/c² with a corresponding mχ1 ⁰ value of 8GeV/c². © 1996 The American Physical Society.

Abstract:

We have searched for associated production of the lightest chargino ¯W1 and next-to-lightest neutralino ¯Z2 of the minimal supersymmetric standard model in p¯p collisions at √s=1.8 TeV using the D0 detector at the Fermilab Tevatron collider. Data corresponding to an integrated luminosity of 12.5±0.7pb⁻¹ were examined for events containing three isolated leptons. No evidence for ¯W1¯Z2 pair production was found. Limits on σ(¯W1¯Z2)B(¯W1→ℓν¯Z1)B(¯Z1→ℓℓ¯Z2) are presented. © 1996 The American Physical Society.

Abstract:

The global topologies of inclusive three- and four-jet events produced in pp interactions are described. The three- and four-jet events are selected from data recorded by the D0 detector at the Fermilab Tevatron Collider operating at a center-of-mass energy of √1800 GeV. The measured, normalized distributions of various topological variables are compared with parton-level predictions of tree-level QCD calculations. The parton-level QCD calculations are found to be in good agreement with the data. The studies also show that the topological distributions of the different subprocesses involving different numbers of quarks are very similar and reproduce the measured distributions well. The parton-shower Monte Carlo generators provide a less satisfactory description of the topologies of the three- and four-jet events. © 1996 The American Physical Society.

Abstract:

A measurement of the cross section for production of single, isolated photons is reported for transverse energies in the range of 10–125 GeV, for two regions of pseudorapidity, |\eta| < 0.9 and 1.6 < |\eta| < 2.5. The data represent 12.9 pb-1 of integrated luminosity accumulated in p-pbar collisions at sqrt(s) = 1.8 TeV and recorded with the D0 detector at the Fermilab Tevatron Collider. © 1996 The American Physical Society.