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Search for lepton flavour violating decays of the Higgs boson to $\mu\tau$ and e$\tau$ in proton-proton collisions at $\sqrt{s}=$ 13 TeV

The collaboration
JHEP 1806 (2018) 001, 2018

Abstract
A search for lepton flavour violating decays of the Higgs boson in the μτ and eτ decay modes is presented. The search is based on a data set corresponding to an integrated luminosity of 35.9 fb$^{−1}$ of proton-proton collisions collected with the CMS detector in 2016, at a centre-of-mass energy of 13 TeV. No significant excess over the standard model expectation is observed. The observed (expected) upper limits on the lepton flavour violating branching fractions of the Higgs boson are ℬ(H → μτ) < 0.25% (0.25%) and ℬ(H → eτ) < 0.61% (0.37%), at 95% confidence level. These results are used to derive upper limits on the off-diagonal μτ and eτ Yukawa couplings $\sqrt{{\left|{Y}_{\mu \tau}\right|}^2+{\left|{Y}_{\tau \mu}\right|}^2}<1.43\times {10}^{-3}$ and $\sqrt{{\left|{Y}_{\mathrm{e}\tau}\right|}^2+{\left|{Y}_{\tau \mathrm{e}}\right|}^2}<2.26\times {10}^{-3}$ at 95% confidence level. The limits on the lepton flavour violating branching fractions of the Higgs boson and on the associated Yukawa couplings are the most stringent to date.

• #### Table 1

Figure 6 (left) in the paper

10.17182/hepdata.83881.v1/t1

Expected and observed 95 percent CL upper limits on BR(H to mu tau) for each individual category and combined from...

• #### Table 2

Figure 6 (right) in the paper

10.17182/hepdata.83881.v1/t2

Expected and observed 95 percent CL upper limits on BR(H to mu tau) for each individual category and combined from...

• #### Table 3

Figure 9 (left) in the paper

10.17182/hepdata.83881.v1/t3

Expected and observed 95 percent CL upper limits on BR(H to e tau) for each individual category and combined from...

• #### Table 4

Figure 9 (right) in the paper

10.17182/hepdata.83881.v1/t4

Expected and observed 95 percent CL upper limits on BR(H to etau) for each individual category and combined from collinear...

• #### Table 5

Table 8 in the paper

10.17182/hepdata.83881.v1/t5

Summary of the observed and expected upper limits at the 95percent CL and the best fit branching fractions in percent...

• #### Table 6

Table 9 in the paper

10.17182/hepdata.83881.v1/t6

95 percent CL observed upper limit on the Yukawa couplings for the main analysis (BDT fit) and the cross check...