Knocking on New Physics' door with a Scalar Resonance

Abstract

We speculate about the origin of the recent excess at ~750 GeV in diphoton resonance searches observed by the ATLAS and CMS experiments using the first 13 TeV data. Its interpretation as a new scalar resonance produced in gluon fusion and decaying to photons is consistent with all relevant exclusion bounds from the 8 TeV LHC run. We provide a simple phenomenological framework to parametrize the properties of the new resonance and show in a model-independent way that, if the scalar is produced in gluon fusion, additional new colored and charged particles are required. Finally, we discuss some interpretations in various concrete setups, such as a singlet (pseudo-) scalar, composite Higgs, and the MSSM.

20 pages, 4 figures, 1 table. Extraction of the ATLAS 13 TeV diphoton signal and 8 TeV ZZ bound corrected, no sizable change in the final combination. Presentation improved, references added, and conclusions unchanged. Version to appear in EPJC