Search for lepton flavour violating decays of the Higgs boson to e tau and e mu in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports a search for lepton flavor violating decays of the Higgs boson into e tau and e mu channels using 8 TeV proton-proton collision data, setting new upper limits on their branching fractions.

Contribution

First direct search for H to e tau and e mu decays at 8 TeV, establishing the most stringent limits to date on these lepton flavor violating processes.

Findings

No evidence for lepton flavor violating decays was observed.

Upper limits on branching fractions are B(H to e tau) < 0.69% and B(H to e mu) < 0.035%.

Constraints on flavor violating Yukawa couplings were derived.

Abstract

A direct search for lepton flavour violating decays of the Higgs boson (H) in the H to e tau and H to e mu channels is described. The data sample used in the search was collected in proton-proton collisions at sqrt(s) = 8 TeV with the CMS detector at the LHC and corresponds to an integrated luminosity of 19.7 inverse femtobarns. No evidence is found for lepton flavour violating decays in either final state. Upper limits on the branching fractions, B(H to e tau ) < 0.69% and B(H to e mu) < 0.035%, are set at the 95% confidence level. The constraint set on B(H to e tau) is an order of magnitude more stringent than the existing indirect limits. The limits are used to constrain the corresponding flavour violating Yukawa couplings, absent in the standard model.