CDF Logo CDF Search for Higgs to WW* Production using a Combined Matrix Element and Neural Network Technique
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Abstract:

We report a search for standard model (SM) Higgs boson to WW* production in the two charged lepton (e, mu) and two neutrino final state in p-pbar collisions at sqrt(s) = 1.96 TeV. The data were collected with the CDF II detector at the Tevatron collider at Fermilab and correspond to an integrated luminosity of roughly 5.9 fb-1. In order to maximize sensitivity, three neural networks are separately trained to distinguish signal from background processes in opposite-sign final states with either zero, one, or two or more jets. For 0-jet events, likelihood ratios based on Matrix Element calculations are used as additional inputs to the neural network to further strengthen its discriminating power. In order to take advantage of the maximum potential signal acceptance, we also consider associated production with a W or Z boson and Higgs boson production via vector boson fusion. Additional signal acceptance is gained by incorporating events with low dilepton invariant mass as a separate search region. We also search for associated Higgs production in events with same-sign dileptons and trileptons in the final state. In the opposite sign event sample we observe (summing over all jet multiplicities) a total of 2070 candidate events compared against an expectation of 2108 ± 190 background events and 36 ± 7 signal events for a SM Higgs boson with a mass of 165 GeV/c2. In the opposite-sign low dilepton invariant mass sample we observe 112 candidate events compared against an expectation of 112 ± 9 background events and 1.0 ± 0.2 signal events for a SM Higgs boson with a mass of 165 GeV/c2. In the same-sign event sample we additionally observe 74 candidate events compared with an expectation of 75 ± 15 background events and 2.1 ± 0.3 signal events for a SM Higgs boson with a mass of 165 GeV/c2. In the trilepton event sample we observe 53 candidate events compared with an expectation of 42 ± 5 background events and 1.5 ± 0.2 signal events for a SM Higgs boson with a mass of 165 GeV/c2. Based on these samples, we determine an observed 95% C.L. upper cross section limit of 1.08 times the SM prediction at NNLL for a Higgs mass of 165 GeV/c2 to be compared with the value for the median of the expected limit (1.00). Results for 18 other Higgs mass hypotheses ranging from 110 GeV/c2 to 200 GeV/c2 are also presented.

 

Supporting Documents:

  • The results were first presented at ICHEP 2010
  • More details are provided in the public note
  • Previous multivariate result with 5.3 fb-1: html
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    General Remarks:

  • The preliminary results were blessed in the Higgs group on June 18, 2010
  • Please contact us if you have any questions about including these results in a presentation
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     Updated by Eric James
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    Last updated: July 14 2010.