Search for pair production of scalar bottom quarks in pp collisions at square root of s = 1.96 TeV.
Phys Rev Lett 97:17 (2006) 171806
Abstract:
A search for direct production of scalar bottom quarks (b) is performed with 310 pb(-1) of data collected by the D0 experiment in pp collisions at square root s = 1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos (chi(1)0), with chi(1)0 assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m(b), m(chi(1)0)) mass plane, improving significantly upon the results from run I of the Tevatron.Search for W′ boson production in the W′ → t over(b, ̄) decay channel
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 641:6 (2006) 423-431
Abstract:
We present a search for the production of a new heavy gauge boson W′ that decays to a top quark and a bottom quark. We have analyzed 230 pb-1 of data collected with the DØ detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events above the standard model expectation is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W′ bosons times branching ratio to top quarks at the 95% confidence level for several different W′ boson masses. We exclude masses between 200 and 610 GeV for a W′ boson with standard-model-like couplings, between 200 and 630 GeV for a W′ boson with right-handed couplings that is allowed to decay to both leptons and quarks, and between 200 and 670 GeV for a W′ boson with right-handed couplings that is only allowed to decay to quarks. © 2006 Elsevier B.V. All rights reserved.Search for particles decaying into a Z boson and a photon in p over(p, ̄) collisions at sqrt(s) = 1.96 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 641:6 (2006) 415-422
Abstract:
We present the results of a search for a new particle X produced in p over(p, ̄) collisions at sqrt(s) = 1.96 TeV and subsequently decaying to Zγ. The search uses 0.3 fb-1 of data collected with the DØ detector at the Fermilab Tevatron Collider. We set limits on the production cross section times the branching fraction σ (p over(p, ̄) → X) × B (X → Z γ) that range from 0.4 to 3.5 pb at the 95% C.L. for X with invariant masses between 100 and 1000 GeV / c2, over a wide range of X decay widths. © 2006 Elsevier B.V. All rights reserved.Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV using lepton+jets events with jet probability b-tagging
Physical Review D - Particles, Fields, Gravitation and Cosmology 74:7 (2006)
Abstract:
We present a measurement of the tt̄ production cross section using events with one charged lepton and jets from pp̄ collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318pb-1 of data collected with the CDF II detector, we measure the tt̄ production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9-1.0+1.0(stat)-1.0+1.1(syst)pb. The cross section value assumes a top quark mass of mt=178GeV/c2 in the acceptance corrections. The dependence of the cross section on mt is presented in the paper. This result is consistent with other CDF measurements of the tt̄ cross section using different samples and analysis techniques, and has similar systematic uncertainties. We have also performed consistency checks by using the b-tagging probability function to vary the signal-to-background ratio and also using events that have at least two b-tagged jets. © 2006 The American Physical Society.Search for associated Higgs boson production WH→WWW *→l±νl′±ν′+X in pp̄ collisions at s=1.96TeV
Physical Review Letters 97:15 (2006)