Search for a Standard Model Higgs boson in the decay channel H to ZZ to lltautau

Search for the standard model Higgs boson in the H to ZZ to lltautau decay channel in pp collisions at sqrt{s}=7 TeV http://cdsweb.cern.ch/record/1424729?ln=en

Abstract

A search is reported for the standard model Higgs boson in the H to ZZ to lltautau decay mode, where l = mu or e, in proton-proton collisions at $\sqrt{s}=7$\TeV, corresponding to an integrated luminosity of 4.7\fbinv collected with the CMS detector at the LHC. No evidence is found for a significant deviation from the background expectation. An upper limit four to twelve times larger than the predicted value is set at 95\% confidence level for the product of the standard model Higgs boson production cross section and decay branching fraction in the mass range $190 < \mH < 600\GeV$.

Main Results

Ten lltautau candidates are observed in eight search channels, while $11.60 \pm 0.54\stat \pm 1.62\syst$ background events are expected.

The product of the acceptance and branching fraction for the individual lltautau-decay channels ranges between 0.01--0.02 for $\mH = 200\GeV$, and increases by a factor of three to four for $\mH = 400$--450\GeV. This behaviour is expected. The final-state leptons produced in $tau$ decays of more massive Higgs bosons have higher momenta than those from direct $\PZ \to \ell\ell$ production and the selection requirements and the lepton reconstruction become more efficient at larger $\mH$. While the cross section decreases with increasing $\mH$, the expected number of Higgs boson events selected by this analysis in 4.7\fbinv of pp collisions at 7\TeV is 1.4--1.5 in the range $200 < \mH < 400\GeV$, and decreases rapidly at higher masses.

In Figure the expected and observed upper limits at 95\% CL on the product of the Higgs boson production cross section and decay branching fraction normalized to the SM expectation are presented as a function of $\mH$. The limits are calculated with the modified frequentist construction CLs based on the shape of the lltautau invariant mass distributions by including all eight individual channels in the likelihood combination. The green and yellow bands represent the one- and two-standard-deviation variations from the expected limit. The systematic uncertainties are introduced in the form of nuisance parameters with log-normal probability density functions. The upper limit on the cross section is approximately a factor four to twelve larger than the SM Higgs boson production cross section in the range of $190 < \mH < 600\GeV$.

Figures from the paper

Figure	Label	Description
	pdf	The four-lepton reconstructed mass summed for all $\taus$ final states. The data corresponds to an integrated luminosity of 4.7 \fbinv. The backgrounds are presented as stacked histograms. The background shapes are taken from MC simulation and normalized to the values obtained using the data-driven techniques described in the text. The expected mass distributions for the SM Higgs boson with a mass 200 or 400 GeV are also shown for comparison.
	pdf	The expected and observed 95\% CL upper limits on the product of the production cross section and decay branching ratio for a Higgs boson normalized to the SM expectation as a function of $m_{\rm H}$.

Additional public plots

Figure	Label	Description
	pdf	Data to MC comparison in the opposite sign control region for eett final state
	pdf	Data to MC comparison in the same sign control region for eett final state
	pdf	Data to MC comparison in the opposite sign control region for mmtt final state
	pdf	Data to MC comparison in the same sign control region for mmtt final state
	pdf	Data to MC comparison for dZ variable
	pdf	Data to MC comparison for the tau fake rate
	pdf	Subleading Z mass in eeet final state, without cut on M_Z
	pdf	event display
	pdf	event display