skip to main content


Title: Search for lepton-flavour-violating decays of the Higgs boson

The first direct search for lepton-flavour-violating decays of the recently discovered Higgs boson (H) is described. The search is performed in the H → μτ e and H → μτ h channels, where τe and τh are tau leptons reconstructed in the electronic and hadronic decay channels, respectively. The data sample used in this search was collected in pp collisions at a centre-of-mass energy of √s = 8 TeV with the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 19.7 fb -1. Furthermore, 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 2.4 standard deviations is observed. The p-value of this excess at M H = 125 GeV is 0.010. We found that the best fit branching fraction is B(H → μτ ) = (0.84 +0.39 -0.37)%. A constraint on the branching fraction, B(H → μτ ) < 1.51% at 95% confidence level is set. As a result, this limit is subsequently used to constrain the μ–τ Yukawa couplings to be less than 3.6 × 10 -3.
  1. Yerevan Physics Inst. (YerPhI), Yerevan (Armenia). et al.
Publication Date:
Report Number(s):
FERMILAB-PUB-15-061-CMS; CERN-PH-EP-2015-027; CMS-HIG-14-005
Journal ID: ISSN 0370-2693; arXiv eprint number arXiv:1502.07400; TRN: US1601097
Grant/Contract Number:
Published Article
Journal Name:
Physics Letters. Section B
Additional Journal Information:
Journal Volume: 749; Journal ID: ISSN 0370-2693
Research Org:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CMS Collaboration
Country of Publication:
United States
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; CMS; physics; higgs; muons; taus; lepton-flavour-violation
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1221271