Probing Colored Particles with Photons, Leptons, and Jets

TL;DR

This paper proposes using resonant signals from near-threshold QCD bound states of new colored particles at the LHC to determine their quantum numbers and mass, offering a complementary approach to direct searches.

Contribution

It introduces a method to identify quantum numbers of new colored particles via their bound state signals in various channels, independent of decay modes.

Findings

Bound state signals can reveal charge, color, and spin.

Resonance searches can be competitive with direct detection.

Method applicable if particle lifetime is sufficiently long.

Abstract

If pairs of new colored particles are produced at the Large Hadron Collider, determining their quantum numbers, and even discovering them, can be non-trivial. We suggest that valuable information can be obtained by measuring the resonant signals of their near-threshold QCD bound states. If the particles are charged, the resulting signatures include photons and leptons and are sufficiently rich for unambiguously determining their various quantum numbers, including the charge, color representation and spin, and obtaining a precise mass measurement. These signals provide well-motivated benchmark models for resonance searches in the dijet, photon+jet, diphoton and dilepton channels. While these measurements require that the lifetime of the new particles be not too short, the resulting limits, unlike those from direct searches for pair production above threshold, do not depend on the particles' decay modes. These limits may be competitive with more direct searches if the particles decay in an obscure way.