Search for lepton-flavour-violating decays of the Higgs and \(Z\) bosons with the ATLAS detector

Abstract

Direct searches for lepton flavour violation in decays of the Higgs and \(Z\) bosons with the ATLAS detector at the LHC are presented. The following three decays are considered: \(H\to e\tau\), \(H\to\mu\tau\), and \(Z\to\mu\tau\), The searches are based on the data sample of proton--proton collisions collected by the ATLAS detector corresponding to an integrated luminosity of 20.3 fb\(^{-1}\) at a centre-of-mass energy of \(\sqrt{s} = 8\) TeV. No significant excess is observed, and upper limits on the lepton-flavour-violating branching ratios are set at the 95% confidence level: Br\((H\to e\tau) <\) 1.04%, Br\((H\to\mu\tau) <\) 1.43%, and Br\((Z\to\mu\tau) <\) 1.69 \(\times\) 10\)^{-5}\),