A Search for the Higgs Boson Produced in Association with $Z\to \ell^+\ell^-$ Using the Matrix Element Method at CDF II

TL;DR

This paper searches for the Higgs boson produced alongside a Z boson decaying to leptons, using matrix element techniques at CDF II, but finds no significant evidence and sets upper limits on production cross-sections.

Contribution

It applies the matrix element method to search for associated Higgs production in proton-antiproton collisions, providing the first limits in this channel at the Tevatron.

Findings

No evidence of Higgs in the 100-150 GeV/c^2 range.

Set upper limits on ZH production cross-section.

Limit is 8.2 times the SM prediction at 115 GeV/c^2.

Abstract

We present a search for associated production of the standard model (SM) Higgs boson and a $Z$ boson where the $Z$ boson decays to two leptons and the Higgs decays to a pair of $b$ quarks in $p\bar{p}$ collisions at the Fermilab Tevatron. We use event probabilities based on SM matrix elements to construct a likelihood function of the Higgs content of the data sample. In a CDF data sample corresponding to an integrated luminosity of 2.7 fb$^{-1}$ we see no evidence of a Higgs boson with a mass between 100 GeV$/c^2$ and 150 GeV$/c^2$. We set 95% confidence level (C.L.) upper limits on the cross-section for $ZH$ production as a function of the Higgs boson mass $m_H$; the limit is 8.2 times the SM prediction at $m_H = 115$ GeV$/c^2$.