Search for a Higgs boson decaying into $\gamma^* \gamma \to \ell \ell \gamma$ with low dilepton mass in pp collisions at $\sqrt s = $ 8 TeV

• Main Author: CMS collaboration (2312 authors)
• Publication Date: 2016
• Other Authors: Hollar, Jonathan, Calpas, Betty, Nayak, Aruna, Bargassa, Pedrame, Beirão Da Cruz E Silva, Cristóvão, Di Francesco, Agostino, Faccioli, Pietro, Ferreira Parracho, Pedro Guilherme, Gallinaro, Michele, Leonardo, Nuno, Lloret Iglesias, Lara, Nguyen, Federico, Rodrigues Antunes, Joao, Seixas, Joao, Toldaiev, Oleksii, Vadruccio, Daniele, Varela, Joao, Vischia, Pietro, David Tinoco Mendes, Andre, Silva, Pedro, Musella, Pasquale, Pela, Joao
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: http://dx.doi.org/10.1016/j.physletb.2015.12.039; http://hdl.handle.net/10400.26/26880

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<mℓℓγ<150 GeV , and limits have been derived for the Higgs boson production cross section times branching fraction for the decay H→γ⁎γ→ℓℓγ , where the dilepton invariant mass is less than 20 GeV. For a Higgs boson with mH=125 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 for the 125 GeV Higgs boson is set at 1.5×10−3 .