Glue to light signal of a new particle

TL;DR

This paper explores how new particles charged under color and electric charge can produce detectable peaks in the di-photon spectrum via loop processes, setting limits and discussing potential signals around 750 GeV.

Contribution

It introduces a method to identify new particles through their loop-induced effects in di-photon spectra, providing constraints and future prospects.

Findings

Set upper limits on properties of hypothetical particles using ATLAS data.

Indicated the potential origin of the 750 GeV di-photon excess from a 375 GeV particle.

Discussed the impact of loop functions, threshold resummation, and gluon PDFs on signal features.

Abstract

Any new particle charged under $SU(3)_C$ and carrying electric charge will leave an imprint in the di-photon invariant mass spectrum as it can mediate $gg \to \gamma \gamma$ process through loops. The combination of properties of loop functions, threshold resummation and gluon pdfs can result in a peak-like feature in the di-photon invariant mass around twice the mass of a given particle even if the particle is short-lived and thus it doesn't form a narrow bound state. Using recent ATLAS analysis, we set upper limits on the combined $SU(3)_C$ and electric charge of new particles and indicate future prospects. We also discuss the possibility that the excess of events in the di-photon invariant mass spectrum around 750 GeV originates from loops of a particle with mass around 375 GeV.