String Consistency, Heavy Exotics, and the $750$ GeV Diphoton Excess at the LHC

Understand

String consistency conditions are stronger than anomaly cancellation and can require the addition of exotics in the visible sector.

• We study such exotics and demonstrate that they may account for the modest excess at $750$ GeV in recent diphoton resonance searches performed by the ATLAS and CMS collaborations.
• In a previous analysis of type II MSSM D-brane quivers we systematically added up to five exotics for the sake of satisfying string consistency conditions.
• Using this dataset, we demonstrate that 89780 of the 89964 quivers have exotics, 78155 of which include singlets that may couple to MSSM or exotic multiplets with coupling structures governed by $U(1)$ symmetries that are often anomalous.