Sneha Malde

Abstract:

A search for a narrow diphoton mass resonance is presented based on data from 3.0 fb;{-1} of integrated luminosity from pp[over ] collisions at sqrt[s] = 1.96 TeV collected by the CDF experiment. No evidence of a resonance in the diphoton mass spectrum is observed, and upper limits are set on the cross section times branching fraction of the resonant state as a function of Higgs boson mass. The resulting limits exclude Higgs bosons with masses below 106 GeV/c;{2} at a 95% Bayesian credibility level for one fermiophobic benchmark model.

Abstract:

We have measured the differential cross section for the inclusive production of ψ(2S) mesons decaying to μ+μ- that were produced in prompt or B-decay processes from pp̄ collisions at 1.96 TeV. These measurements have been made using a data set from an integrated luminosity of 1.1fb-1 collected by the CDF II detector at Fermilab. For events with transverse momentum pT(ψ(2S))>2GeV/c and rapidity | y(ψ(2S))| <0.6 we measure the integrated inclusive cross section σ(pp̄→ψ(2S)X) •Br(ψ(2S)→μ+μ-) to be 3.29±0.04(stat)±0. 32(syst)nb. © 2009 The American Physical Society.

Abstract:

We present a search for standard model Higgs boson production in association with a W boson in proton-antiproton collisions (pp ↠W±H↠â.,"Î bbÂ) at a center of mass energy of 1.96 TeV. The search employs data collected with the CDF II detector that correspond to an integrated luminosity of approximately 1.9 fb-1. We select events consistent with a signature of a single charged lepton (e±/Π±), missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with a secondary vertex tagging method, a jet probability tagging method, and a neural network filter. We use kinematic information in an artificial neural network to improve discrimination between signal and background compared to previous analyses. The observed number of events and the neural network output distributions are consistent with the standard model background expectations, and we set 95% confidence level upper limits on the production cross section times branching fraction ranging from 1.2 to 1.1 pb or 7.5 to 102 times the standard model expectation for Higgs boson masses from 110 to 150 GeV/c2, respectively. © 2009 The American Physical Society.

Abstract:

We present new limits on resonant tb̄ production in pp̄ collisions at s=1.96TeV, using 1.9fb-1 of data recorded with the CDFII detector at the Fermilab Tevatron. We reconstruct a candidate tb̄ mass in events with a lepton, neutrino candidate, and two or three jets, and search for anomalous tb̄ production as modeled by W′→tb̄. We set a new limit on a right-handed W′ with standard model-like coupling, excluding any mass below 800GeV/c2 at 95% C.L. The cross section for any narrow, resonant tb̄ production between 750 and 950GeV/c2 is found to be less than 0.28pb at 95% C.L. We also present an exclusion of the W′ coupling strength versus W′ mass over the range 300-950GeV/c2. © 2009 The American Physical Society.

Abstract:

We compare the inclusive production of events containing a lepton (á), a photon (γ), significant transverse momentum imbalance (E T), and a jet identified as containing a b-quark, to SM predictions. The search uses data produced in proton-antiproton collisions at s=1.96TeV corresponding to 1.9fb-1 of integrated luminosity taken with the CDF detector. We find 28 áγbET events versus an expectation of 31.0-3.5+4.1 events. If we further require events to contain at least three jets and large total transverse energy, the largest SM source is radiative top-quark pair production, tt̄+γ. In the data we observe 16 tt̄γ candidate events versus an expectation from SM sources of 11.2-2.1+2.3. Assuming the difference between the observed number and the predicted non-top-quark total of 6.8-2.0+2.2 is due to SM top-quark production, we estimate the tt̄γ cross section to be 0.15±0.08pb. © 2009 The American Physical Society.