Searching for H->WW(*) and Other Diboson Final States at CDF

TL;DR

This paper reports on searches for the standard model Higgs boson decaying to WW(*) and for ZZ production using data from the CDF II detector, setting upper limits and observing a modest ZZ signal significance.

Contribution

It introduces a likelihood ratio discriminant based on event probabilities to separate processes and provides the first upper limits on Higgs and ZZ production at the Tevatron.

Findings

Upper limit for Higgs production at 160 GeV/c^2 is 1.3 pb, 3.4 times the SM prediction.

Observed ZZ signal significance is 1.9 sigma.

Upper limit for ZZ production is 3.4 pb, consistent with NLO calculations.

Abstract

We report searches for standard model (SM) Higgs production decaying to WW(*) and continuum ZZ production in the two charged lepton and two neutrino final states. The data were collected with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 1.1^fb-1. In order to separate the processes contributing to the final state, event probabilities calculated using the leading order differential cross-sections were used to construct a likelihood ratio discriminant. The observed (median expected) 95% C.L. upper limit for sigma(H->WW^(*)) with 160 GeV/c^2 mass hypothesis is 1.3 (1.8) pb which corresponds to 3.4 (4.8) times the SM prediction at next-to-next-to-leading logarithmic level (NNLL) calculation. The significance of the observed ZZ signal is 1.9 sigma and the 95% C.L. upper limit is 3.4 pb which is consistent with the next-to-leading order (NLO) calculation of 1.4+/-0.1 pb.