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

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• 作者：CMS Collaboration^{鈰?/sup>V. Khachatryan} ; A.M. Sirunyan ; A. Tumasyan
• 关键词：CMS ; Physics ; Higgs ; Muons ; Taus ; Lepton-flavour-violation
• 刊名：Physics Letters B
• 出版年：2015
• 出版时间：7 October 2015
• 年：2015
• 卷：749
• 期：Complete
• 页码：337-362
• 全文大小：1432 K

文摘

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→渭蟿_e$\mathrm{H}\to 渭{蟿}_{\mathrm{e}}$ and H→渭蟿_h$\mathrm{H}\to 渭{蟿}_{\mathrm{h}}$ channels, where 蟿_e${蟿}_{\mathrm{e}}$ and 蟿_h${蟿}_{\mathrm{h}}$ 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 $\sqrt{s}=8\text{TeV}$ with the CMS experiment at the CERN LHC and corresponds to an integrated luminosity of 19.7 fb⁻¹$19.7{\text{fb}}^{-1}$. 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 M_H=125 GeV$M_{\mathrm{H}}=125\text{GeV}$ is 0.010. The best fit branching fraction is $\mathcal{B}(\mathrm{H}\to 渭蟿)=({0.84}_{-0.37}^{+0.39})\text{\%}$. A constraint on the branching fraction, B(H→渭蟿)<1.51%$\mathcal{B}(\mathrm{H}\to 渭蟿)<1.51\text{\%}$ at 95% confidence level is set. This limit is subsequently used to constrain the 渭–蟿$渭\text{–}蟿$ Yukawa couplings to be less than 3.6×10⁻³$3.6\times {10}^{-3}$.