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Compact Muon Solenoid
LHC, CERN

CMS-PAS-HIG-14-040
Search for lepton-flavour-violating decays of the Higgs boson to $\mathrm{ e \tau } $ and $\mathrm{ e \mu } $ at $ \sqrt{s} = $ 8 TeV
Abstract: A direct search for lepton-flavour-violating decays of a Higgs boson ($m_{\mathrm{H}} =$ 125 GeV) is described. The search is performed for the $\mathrm{H} \rightarrow \mathrm{e} \tau_{\mu}$, $\textrm{H} \rightarrow \mathrm{e} \tau_{h}$, and $\mathrm{H} \rightarrow \mathrm{e} \mu$ decays, where $\tau_{h}$ and $\tau_{\mu}$ are taus reconstructed in the hadronic and muonic decay channels, respectively. The data sample used in the search corresponds to an integrated luminosity of 19.7 fb$^{-1}$ collected in pp collisions at $ \sqrt{s}= $ 8 TeV with the CMS experiment at the CERN LHC. No evidence is found for lepton-flavour-violating decays in either final state. For the $\mathrm{H} \rightarrow \mathrm{e} \tau_{\mu}$ and $\mathrm{H} \rightarrow \mathrm{e} \tau_{h}$ channels, the sensitivity of the search is an order of magnitude better than the existing indirect limits. A constraint of $\mathcal{B}(\mathrm{H} \rightarrow \mathrm{e} \tau )<$ 0.70% at 95% confidence level is set. We also set a limit on the branching ratio of $\mathcal{B}(\mathrm{H} \rightarrow \mathrm{e} \mu) <$ 0.036% at 95% confidence level. The limits on $\mathcal{B}(\mathrm{H} \rightarrow \mathrm{e} \tau )$ and $\mathcal{B}(\mathrm{H} \rightarrow \mathrm{e} \mu)$ are subsequently used to constrain the $|Y_{\mathrm{e}\tau}|$ and $|Y_{\mathrm{e}\mu}|$ Yukawa couplings.
CMS Publications
Compact Muon Solenoid
LHC, CERN