We show that low-mass-scale string compactifications, with a generic D-brane configuration that realizes the standard model by open strings, can explain the relatively broad peak in the diphoton invariant mass spectrum at 750GeV recently reported by the ATLAS and CMS Collaborations. Under reasonable assumptions, we demonstrate that the excess could originate from a closed string (possibly axionic) excitation ϕthat has a coupling with gauge kinetic terms. We estimate the ϕ production rate from photon–photon fusion in elastic pp scattering, using the effective photon and narrow width approximations. For string scales above today’slower limit Ms≈7TeV, we can accommodate the diphoton rate observed at Run II while maintaining consistency with Run I data.
Anchordoqui, Luis; Antoniadis, Ignatios; Goldberg, Haim; Huang, Xing; Lüst, Dieter; and Taylor, Tomasz R., "750 GeV diphotons from closed string states" (2016). CUNY Academic Works.