Model Independent Constraints on Charges of New Particles

TL;DR

This paper derives constraints on the electric and color charges of hypothetical new particles by analyzing their effects on diphoton production at the LHC, incorporating resummation techniques near production thresholds.

Contribution

It introduces a method to set model-independent bounds on new particle charges using diphoton spectra, including threshold resummation effects and decay width considerations.

Findings

Current LHC data exclude certain charge combinations for new particles.

The diphoton spectrum shape depends on particle charge, mass, and decay width.

Resummation improves the accuracy of theoretical predictions near threshold.

Abstract

Any particle that is charged under $SU(3)_C$ and $U(1)_{EM}$ can mediate the $gg \rightarrow {\gamma}{\gamma}$ process through loops. Near the threshold for the new particle pair production, gauge boson exchanges necessitate the resummation of ladder diagrams. We discuss the leading log order matching of the one-loop result with non-relativistic effective theory resummed result. We show how the diphoton invariant mass spectrum varies depending on decay width, color representation and electric charge of the new particle. The exclusion limits on the product of $SU(3)_C$ and $U(1)_{EM}$ charges of the new scalar or fermion particle are obtained from current LHC data.