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

V. Khachatryan, A. M. Sirunyan, A. Tumasyan, W. Adam, T. Bergauer, M. Dragicevic, J. Erö, M. Friedl, R. Frühwirth, V. M. Ghete, C. Hartl, N. Hörmann, J. Hrubec, M. Jeitler, W. Kiesenhofer, V. Knünz, M. Krammer, I. Krätschmer, D. Liko, I. MikulecD. Rabady, B. Rahbaran, H. Rohringer, R. Schöfbeck, J. Strauss, W. Treberer-Treberspurg, W. Waltenberger, C. E. Wulz, V. Mossolov, N. Shumeiko, J. Suarez Gonzalez, S. Alderweireldt, S. Bansal, T. Cornelis, E. A. De Wolf, X. Janssen, A. Knutsson, J. Lauwers, S. Luyckx, S. Ochesanu, R. Rougny, M. Van De Klundert, H. Van Haevermaet, P. Van Mechelen, N. Van Remortel, A. Van Spilbeeck, F. Blekman, S. Blyweert, J. D'Hondt, S. Hewamanage, CMS Collaboration

    Research output: Contribution to journalArticle

    184 Scopus citations

    Abstract

    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→μτe and H→μτh 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. 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 MH=125 GeV is 0.010. The best fit branching fraction is B(H→μτ)=(0.84-0.37+0.39)%. A constraint on the branching fraction, B(H→μτ)<1.51% at 95% confidence level is set. This limit is subsequently used to constrain the μ-τ Yukawa couplings to be less than 3.6×10-3.

    Original languageEnglish (US)
    Pages (from-to)337-362
    Number of pages26
    JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
    Volume749
    DOIs
    StatePublished - Oct 7 2015

    Keywords

    • CMS
    • Higgs
    • Lepton-flavour-violation
    • Muons
    • Physics
    • Taus

    ASJC Scopus subject areas

    • Nuclear and High Energy Physics

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  • Cite this

    Khachatryan, V., Sirunyan, A. M., Tumasyan, A., Adam, W., Bergauer, T., Dragicevic, M., Erö, J., Friedl, M., Frühwirth, R., Ghete, V. M., Hartl, C., Hörmann, N., Hrubec, J., Jeitler, M., Kiesenhofer, W., Knünz, V., Krammer, M., Krätschmer, I., Liko, D., ... CMS Collaboration (2015). Search for lepton-flavour-violating decays of the Higgs boson. Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, 749, 337-362. https://doi.org/10.1016/j.physletb.2015.07.053