Search for MSSM Higgs→ ττ
We performed a search for inclusive neutral MSSM Higgs production in pp at √s=1.96 TeV. The data sample of integrated luminosity 310 pb-1 was collected with the CDF detector in Run 2 of the Fermilab Tevatron.
The search is performed in the φ→ττ decay channel for 90≤mA≤250 GeV/c2. One τ is detected in the decay to an e or μ and neutrinos, and the other in the decay to hadrons and a neutrino. In the following, we use τe, τμ, and τh as shorthand notations for τ→eνν, τ→μνν, and τ→hadrons ν, respectively.
The events in the τeτh (τμτh) channel are selected by requiring one e (μ) candidate with transverse momentum pT > 10 GeV, and one τh candidate with pT > 15 GeV and opposite electric charge. The vector sum of the transverse momenta of the neutrinos from τ decays appears as missing transverse energy (MET) determined from the imbalance of energy deposition in the calorimeter. We apply selection criteria to suppress backgrounds form various processes. The residual backgrounds involving quark/gluon jet →τhad misidentification (such as multi-jet, W+jet(s) and γ+jet(s) events) are estimated from the data. For the remaining sources we use MC simulated events. The dominant background in the sample is from Z/γ*→ττ events. We expect 496±5(stat)±28(sys)±25(lumi) background events (405 from Z/γ*→ττ) and observe 487 events in the data. The combined signal acceptance for a Higgs boson of mass 90 GeV (250 GeV) in the τeτh and τμτh channels is 0.8% (2.0%).
To probe for signal we perform likelihood fits of the partially reconstructed di-τ mass mvis formed from the visible τ decay products and MET. No signal evidence was found and we set 95% CL exclusion limits on the Higgs production cross section times the branching fraction to τ pairs.
The search is performed in the φ→ττ decay channel for 90≤mA≤250 GeV/c2. One τ is detected in the decay to an e or μ and neutrinos, and the other in the decay to hadrons and a neutrino. In the following, we use τe, τμ, and τh as shorthand notations for τ→eνν, τ→μνν, and τ→hadrons ν, respectively.
The events in the τeτh (τμτh) channel are selected by requiring one e (μ) candidate with transverse momentum pT > 10 GeV, and one τh candidate with pT > 15 GeV and opposite electric charge. The vector sum of the transverse momenta of the neutrinos from τ decays appears as missing transverse energy (MET) determined from the imbalance of energy deposition in the calorimeter. We apply selection criteria to suppress backgrounds form various processes. The residual backgrounds involving quark/gluon jet →τhad misidentification (such as multi-jet, W+jet(s) and γ+jet(s) events) are estimated from the data. For the remaining sources we use MC simulated events. The dominant background in the sample is from Z/γ*→ττ events. We expect 496±5(stat)±28(sys)±25(lumi) background events (405 from Z/γ*→ττ) and observe 487 events in the data. The combined signal acceptance for a Higgs boson of mass 90 GeV (250 GeV) in the τeτh and τμτh channels is 0.8% (2.0%).
To probe for signal we perform likelihood fits of the partially reconstructed di-τ mass mvis formed from the visible τ decay products and MET. No signal evidence was found and we set 95% CL exclusion limits on the Higgs production cross section times the branching fraction to τ pairs.
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Track multiplicity of the hadronic system of τh candidates. The plot is produced before requiring net charge =±1 and charge opposite to τe(μ). All backgrounds are normalized to the absolute predictions. -
Distribution of the partially reconstructed di-τ mass mvis (example fit with a mA=140 GeV teplate). The backgrounds and signal normalizations correspond to the fit result for signal exclusion at 95% CL. -
Upper limits at 95% CL on the Higgs production cross section times the branching fraction of φ→ττ as a function of mA. -
Excluded parameter space in the mA vs tanβ plane for the no-mixing and mhmax scenarios with μ=-200 GeV. The performances of the bb and ττ channels are quite similar. -
Excluded parameter space in the mA vs tanβ plane for the no-mixing and mhmax scenarios with μ=+200 GeV. The Higgs→ττ channel seems to be our best shot for finding/excluding MSSM Higgs in this case.
The sensitivity of the search for neutral MSSM Higgs bosons in the φ→ττ decay channel is fully competitive with φ→bb (previously considered to be the "golden mode" at the Tevatron). Furthermore, its sensitivity is preserved for a much larger portion of the MSSM parameter space.
The results have been publshed in PRL: Phys.Rev.Lett. 96, 011802 (2006). Here is a link to the hep-ex e-print.
Needless to say, we were eager to see the results with larger data samples.
The results have been publshed in PRL: Phys.Rev.Lett. 96, 011802 (2006). Here is a link to the hep-ex e-print.
Needless to say, we were eager to see the results with larger data samples.
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Last update 10/08/2007