Dr Farrukh Azfar

Abstract:

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (pp̄→ W±H→ νbb̄) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector which correspond to an integrated luminosity of approximately 1fb-1. We select events consistent with a signature of a single lepton (e±/μ±), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method and a neural network filter technique. The observed number of events and the dijet mass distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching ratio ranging from 3.9 to 1.3 pb for Higgs boson masses from 110 to 150GeV/c2, respectively. © 2008 The American Physical Society.

Abstract:

We search for pair production of supersymmetric top quarks (t1), followed by R-parity violating decay t1→τb with a branching ratio β, using 322pb-1 of pp̄ collisions at s=1.96TeV collected by the upgraded Collider Detector at Fermilab. Two candidate events pass our final selection criteria, consistent with the standard model expectation. We set upper limits on the cross section σ(t1t̄1)×β2 as a function of the top-squark mass m(t1). Assuming β=1, we set a 95% confidence level limit m(t1)>153GeV/c2. The limits are also applicable to the case of a third-generation scalar leptoquark (LQ3) decaying LQ3→τb. © 2008 The American Physical Society.

Abstract:

We report the results of a search for the anomalous production of a massive particle decaying to four electrons via two Z0 bosons in 1.1fb-1 of pp̄ collisions at s=1.96TeV collected by the CDF II detector at Fermilab. We employ optimized electron identification criteria to maximize acceptance and efficiency. We estimate the backgrounds in the invariant mass range 500-1000GeV/c2 to be 0.028±0.009(stat)±0.011(syst) events. We observe zero events in this search region. Assuming a Randall-Sundrum graviton production model, we set 95% C.L. limits on σ×BF(G→Z0Z0)<4- 6pb, depending on the graviton mass. © 2008 The American Physical Society.