Search for a Higgs boson decaying into γ^⁎γ → ℓℓγ with low dilepton mass in pp collisions at

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• 作者：CMS Collaboration^⋆ ; V. Khachatryan ; A.M. Sirunyan ; A. Tumasyan
• 关键词：CMS ; Physics ; Higgs boson ; Dalitz decay
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 February 2016
• 年：2016
• 卷：753
• 期：Complete
• 页码：341-362
• 全文大小：943 K

文摘

A search is described for a Higgs boson decaying into two photons, one of which has an internal conversion to a muon or an electron pair (ℓℓγ). The analysis is performed using proton–proton collision data recorded with the CMS detector at the LHC at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb⁻¹. The events selected have an opposite-sign muon or electron pair and a high transverse momentum photon. No excess above background has been found in the three-body invariant mass range 120<m_ℓℓγ<150 GeV$120<m_{\ell \ell \gamma }<150\text{GeV}$, and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H→γ^⁎γ→ℓℓγ$\mathrm{H}\to {\gamma }^{⁎}\gamma \to \ell \ell \gamma$, where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with m_H=125 GeV$m_{\mathrm{H}}=125\text{GeV}$, a 95% confidence level (CL) exclusion observed (expected) limit is 6.7 (${5.9}_{-1.8}^{+2.8}$) times the standard model prediction. Additionally, an upper limit at 95% CL on the branching fraction of H→(J/ψ)γ$\mathrm{H}\to (\mathrm{J}/\psi )\gamma$ for the 125 GeV Higgs boson is set at 1.5×10⁻³$1.5\times {10}^{-3}$.