Minimal dilaton model

¹ Institute of Modern Physics and Center for High Energy Physics, Tsinghua University, Beijing, 100084, China
² Department of Physics, Tohoku University, Sendai, 980-8578, Japan
³ Department of Physics, Saitama University, Saitama, 355-8570, Japan
⁴ Department of Physics, Kyoto University, Kyoto, 606-8502, Japan
⁵ Institute for Cosmic Ray Research (ICRR), University of Tokyo, Kashiwa, Chiba, 277-8582, Japan

^a e-mail: tomohiro_abe@tsinghua.edu.cn
^b e-mail: kitano@tuhep.phys.tohoku.ac.jp
^c e-mail: konishi@krishna.th.phy.saitama-u.ac.jp
^d e-mail: odakin@gauge.scphys.kyoto-u.ac.jp
^e e-mail: joe@phy.saitama-u.ac.jp
^f e-mail: shohei@icrr.u-tokyo.ac.jp

Abstract

Both the ATLAS and CMS experiments at the LHC have reported the observation of the particle of mass around 125 GeV which is consistent to the Standard Model (SM) Higgs boson, but with an excess of events beyond the SM expectation in the diphoton decay channel at each of them. There still remains room for a logical possibility that we are not seeing the SM Higgs but something else. Here we introduce the minimal dilaton model in which the LHC signals are explained by an extra singlet scalar of the mass around 125 GeV that slightly mixes with the SM Higgs heavier than 600 GeV. When this scalar has a vacuum expectation value well beyond the electroweak scale, it can be identified as a linearly realized version of a dilaton field. Though the current experimental constraints from the Higgs search disfavors such a region, the singlet scalar model itself still provides a viable alternative to the SM Higgs in interpreting its search results.