Note on Spin-2 Particle Interpretation of the 750~GeV Diphoton Excess

TL;DR

This paper investigates whether a massive spin-2 particle could explain the 750 GeV diphoton excess observed at the LHC, emphasizing the role of top-quark loops and warped extra dimension models.

Contribution

It proposes a scenario where top-quark loops significantly contribute to spin-2 particle production, a novel aspect in explaining the diphoton excess.

Findings

Top-quark loops can dominate over tree-level amplitudes in production.

The model accommodates large invisible decay branching ratios.

Parameter space aligns with observed diphoton data.

Abstract

We explore the possibility to explain the 750 GeV diphoton excess recently measured by ATLAS and CMS collaborations in terms of a massive spin-2 particle. In particular, we consider the case in which the top-quark loops can give the similar amplitudes as the tree-level contributions to the diphoton and digluon channels. Such a scenario can be naturally realized in the generalized warped extra dimension models. As a result, the parameter space favored by the diphoton data implies that the top-quark loop contribution can compete to and even dominate over the tree-level amplitude in the spin-2 particle production via the gluon-gluon fusion process. Similar results are obtained for the case in which the spin-2 particle induces large invisible decay branching ratios, as indicated by the ATLAS data.