Abstract
A search for physics beyond the standard model is performed using a sample of high-mass diphoton events produced in proton-proton collisions at $\sqrt{s} = $ 13 TeV. The data sample was collected in 2016 with the CMS detector at the LHC and corresponds to an integrated luminosity of 35.9 fb$^{-1}$. The search is performed for both resonant and nonresonant new physics signatures. At 95% confidence level, lower limits on the mass of the first Kaluza-Klein excitation of the graviton in the Randall-Sundrum warped extra-dimensional model are determined to be in the range of 2.3 to 4.6 TeV, for values of the associated coupling parameter between 0.01 and 0.2. Lower limits on the production of scalar resonances and model-independent cross section upper limits are also provided. For the large extra-dimensional model of Arkani-Hamed, Dimopoulos, and Dvali, lower limits are set on the string mass scale $M_S$ ranging from 5.6 to 9.7 TeV, depending on the model parameters. The first exclusion limits are set in the two-dimensional parameter space of a continuum clockwork model.
Highlights
While the standard model (SM) of particle physics has been an enormously successful description of observed phenomena, it is still widely believed to be incomplete
Because the Higgs boson is a fundamental scalar, the magnitude of the mass corrections is set by the cutoff parameter of the loop integrals and the only natural mass scale in the SM that can act as a cutoff is the Planck scale (MPl ∼ 1019 GeV) at which quantum gravity is expected to emerge
Unless the Higgs boson mass parameter is fine-tuned to an extreme degree, there must exist some new physics beyond the SM to constrain these quantum corrections and stabilize the mass of the Higgs boson
Summary
While the standard model (SM) of particle physics has been an enormously successful description of observed phenomena, it is still widely believed to be incomplete. We consider three such models in this paper Through their modification of the effective Planck scale, extra spatial dimensions have been proposed as a possible solution to this hierarchy problem [1,2], which arises from the large difference between the gravitational and electroweak scales. In addition to the above models that could address the hierarchy problem, high-mass diphoton events are potentially sensitive to other beyond-SM physics, such as the decays of heavy spin-0 resonances. These spin-0 resonances could arise from extended Higgs sectors [15,16,17].
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