Pair Production of Color-Octet Scalars at the LHC

TL;DR

This paper investigates the production and decay of color-octet scalars at the LHC, focusing on their potential to form bound states that decay into gamma gamma, providing a new way to search for new physics.

Contribution

It presents a detailed calculation of the resonant cross section for color-octet scalars forming bound states and decaying into electroweak bosons, including resummation of threshold effects.

Findings

Resummed cross section for gluon-gluon fusion to COS pairs computed.

Resonant cross section for octetonium decaying to gamma gamma exceeds SM background for masses below 500 GeV.

Nonobservation of such resonances constrains COS masses in new parameter regions.

Abstract

Heavy colored scalar particles, which exist in many models of new physics, can be pair produced at the Large Hadron Collider (LHC) via gluon-gluon fusion and possibly form quarkonium-like bound states. If the scalars are also charged under the electroweak gauge group, these bound states can then decay into electroweak bosons. This yields a resonant cross section for final states such as gamma gamma that can exceed Standard Model backgrounds. This paper studies this process in the Manohar-Wise model of color-octet scalars (COS). Important threshold logarithms and final state Coulomb-like QCD interactions are resummed using effective field theory. We compute the resummed cross section for gluon-gluon fusion to COS pairs at the LHC as well as the resonant cross section for octetonium decaying to gamma gamma. The latter cross section exceeds the Standard Model di-photon cross section when the COS mass is less than 500 (350) GeV for sqrt{s} = 14 (7) TeV. Nonobservation of resonances below these energies can significantly improve existing bounds on COS masses.