Annihilation decays of bound states at the LHC

TL;DR

This paper explores the potential of detecting bound states of heavy particles at the LHC through their annihilation decays, which could reveal key properties of new physics beyond the standard model.

Contribution

It provides theoretical insights into bound state formation and assesses the feasibility of observing their annihilation decays at the LHC.

Findings

Bound states can decay via annihilation into standard model particles.

Some annihilation decays may be detectable at the LHC, offering new physics discovery channels.

Annihilation signatures like dijet resonances could help identify properties of new particles.

Abstract

At the Large Hadron Collider, heavy particles may be produced in pairs close to their kinematic threshold. If these particles have strong enough attractive interactions they may form bound states. Consequently, the bound states may decay through annihilation back into the standard model. Such annihilation decays have the potential to provide much information about the bound particles, such as their mass, spin, or charges, in a manner completely complementary to standard single particle cascade decays. Many of the signatures, such as dijet resonances, will be challenging to find, but may be extremely helpful in unraveling the nature of the new physics. In the standard model, the only novel annihilation decays would be for toponium; these will be hard to see because of the relatively large width of the top quark itself. In models with supersymmetry, marginally visible annihilation decays may occur for example, from bound states of gluinos to dijets or tops. If new particles are bound through forces stronger than QCD, annihilation decays may even be the discovery mode for new physics. This paper presents various theoretical results about bound states and then addresses the practical question of whether any of their annihilation decays can be seen at the LHC.