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Compact Muon Solenoid
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CMS-PAS-TOP-14-020
Search for the flavor-changing neutral current decay $ \mathrm{ t \to qH} $ where the Higgs decays to $ \mathrm{ b \overline b }$ pairs at $\sqrt{s} =$ 8 TeV
Abstract: A search for the flavor-changing neutral current Higgs (FCNH) process in top quark decays, $ \mathrm{ t \to qH } $ ($ \mathrm{ q = u,\, c} $), is presented using a data sample corresponding to an integrated luminosity of 19.8 fb$^{-1}$ of proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC. The analysis is performed by tagging a top quark decaying into a bottom quark and a W boson, identified with a lepton and a neutrino, and searching for a $ \mathrm{ b \bar b } $ pair from the Higgs decay and a light quark in the event. No significant excess is observed over the background prediction. The branching fraction upper limits for $ \mathrm{ t \to qH } $ are determined to be ${\cal B}( \mathrm{ t\to cH}) <$ 1.16% and ${\cal B}( \mathrm{ t \to uH} ) <$ 1.92% at the 95% confidence level, with expected limits of 0.89% and 0.85%, respectively.
Summary CMS Publications
Summary
This study searches for top quark flavor changing neutral current Higgs decays where the Higgs boson decays to bb and the W boson decays leptonically. The data used in this study correspond to an integrated luminosity of about 19.8 fb$^{-1}$ at $\sqrt{s} =$ 8 TeV collected by CMS in 2012. No significant excess of events over the SM background is observed. $ \mathcal{B}( \mathrm{ t \to cH })$ and $ \mathcal{B}( \mathrm{ t \to uH})$ branching fractions larger than 1.16% and 1.92% are excluded at the 95% confidence level. This is the first CMS result on $ \mathcal{B}( \mathrm{ t \to qH })$ using the $\mathrm{ H \to bb}$ channel.
Compact Muon Solenoid
LHC, CERN