Search for Lepton Flavour Violating Decays of the Higgs Boson

The first direct search for Lepton Flavor Violating Decays of the recently discovered Higgs boson using $19.7$ fb$^{-1}$ of $\sqrt{s}=8$ TeV data taken in 2012 using the $H \to \mu \tau_{e}$ and $H \to \mu \tau_{had}$ channels is described , where $\tau_{had}$ and $\tau_{e}$ are taus reconstructed in the hadronic and electronic decay channels respectively. The sensitivity of the search is an order of magnitude better than the existing indirect limits. A slight excess of signal events with a significance of 2.5$\sigma$ is observed. The local p-value of this excess at $M_{H}=126~\mathrm{GeV}$ is 0.007. Interpreted as a limit this results in a constraint of $B(H \to \mu \tau )<1.57\%$ at 95\% confidence level. The best fit branching fraction is $B(H \to \mu \tau )=(0.89^{+0.40}_{-0.37})\%$. The limit is subsequently used to constrain the $Y_{\mu\tau}$ Yukawa coupling.