Color-octet scalar decays to a gluon and an electroweak gauge boson in the Manohar-Wise model

TL;DR

This paper calculates one-loop amplitudes for a color octet scalar decaying into a gluon and electroweak bosons within the Manohar-Wise model, highlighting potential signals at the LHC and identifying key decay regions.

Contribution

It provides the first detailed computation of these decay amplitudes and branching ratios, exploring parameter space where these modes are phenomenologically significant.

Findings

Branching ratios for scalar decays can reach up to 10-72% depending on parameters.

Light scalars can have dominant decay modes into gluons and electroweak bosons.

Fermiophobic scalars exhibit large branching ratios into gluons and electroweak bosons.

Abstract

We present one loop results for the amplitudes giving rise to couplings between a color octet scalar, a gluon, and an electroweak gauge boson. These amplitudes could signal new physics in $\gamma$ jet, $Z$ jet and $W$ jet production at the LHC. We compute the relevant branching ratios and identify regions of parameter space where these decay modes become important. This can happen for scalar masses below the threshold for decay into heavy quark pairs ($t\bar t$ and $t\bar b$); or for small Yukawa couplings in which case the colored scalars are fermiophobic. In the case of light scalars, ${\cal B}(S\to \gamma g)$ can reach up to 10\% whereas ${\cal B}(S\to Z g)$ can reach a few percent. In the fermiophobic region of parameter space, ${\cal B}(S\to \gamma g)$ and ${\cal B}(S\to Z g)$ can reach up to 72\% and 28\% respectively, whereas ${\cal B}(S\to g g)$ can be 100\%. For the charged scalar, the decay mode ${\cal B}(S^\pm \to W^\pm g)$ can become dominant in both scenarios.