Collider constraints on massive gravitons coupling to photons

TL;DR

This paper investigates the potential to detect massive graviton-like particles coupled to photons at colliders, setting new bounds on their coupling strength across a wide mass range using existing and future experimental data.

Contribution

It reinterprets existing ALP search results to establish new limits on graviton-photon couplings and projects significant improvements with upcoming collider experiments.

Findings

Exclusion limits on graviton-photon coupling down to 0.05 TeV$^{-1}$ for 100 MeV--2 TeV masses.

Potential to improve bounds by factors of 100 at Belle II and 4 at HL-LHC.

Demonstrates collider sensitivity to massive gravitons via diphoton and triphoton signatures.

Abstract

We study the discovery potential of massive graviton-like spin-2 particles coupled to standard model fields, produced in photon-photon collisions at the Large Hadron Collider (LHC) as well as in electron-positron ($e^+e^-$) collisions, within an effective theory with and without universal couplings. Our focus is on a massive graviton G coupled to the electromagnetic field, which decays via $\mathrm{G}\to \gamma \gamma$ and leads to a resonant excess of diphotons over the light-by-light scattering continuum at the LHC, and of triphoton final states at $e^+e^-$ colliders. Based on similar searches performed for pseudoscalar axion-like particles (ALPs), and taking into account the different cross sections, $\gamma \gamma$ partial widths, and decay kinematics of the pseudoscalar and tensor particles, we reinterpret existing experimental bounds on the ALP-$\gamma$ coupling into G-$\gamma$ ones. Using the available data, exclusion limits on the graviton-photon coupling are set down to $g_{\mathrm{G}\gamma\gamma}\approx 1$--0.05~TeV$^{-1}$ for masses $m_\mathrm{G} \approx 100$~MeV--2~TeV. Such bounds can be improved by factors of 100 at Belle~II in the low-mass region, and of 4 at the HL-LHC at high masses, with their expected full integrated luminosities.