Exotic colored scalars at the LHC

TL;DR

This paper explores the collider phenomenology of exotic color-triplet scalars with various charges, focusing on their decay modes, bound state formation, and potential signals at the LHC, including diphoton and diboson channels.

Contribution

It introduces a comprehensive analysis of exotic scalars with multiple charges, their decay patterns, and bound state signatures, expanding the search strategies for new physics at colliders.

Findings

Bound states of scalars can decay into diphotons, providing a potential discovery channel.

Mass splittings within multiplets can lead to cascade decays compatible with current constraints.

Allowed scalar masses around 250 GeV to 450 GeV under existing collider and precision tests.

Abstract

We study the phenomenology of exotic color-triplet scalar particles $X$ with charge $|Q|=2/3, 4/3,5/3,7/3,8/3$ and $10/3$. If $X$ is a non-singlet of $SU(2)_W$ representation, mass splitting within the multiplet allows for cascade decays of the members into the lightest state. We study examples where the lightest state, in turn, decays into a three-body $W^\pm jj$ final state, and show that in such case the entire multiplet is compatible with existing direct collider searches and indirect precision tests down to $m_X\sim250$~GeV. However, bound states $S$, made of $XX^\dag$ pairs at $m_S\approx2m_X$, form under rather generic conditions and their decay to diphoton can be the first discovery channel of the model. Furthermore, for $SU(2)_W$-non-singlets, the mode $S\to W^+W^-$ may be observable and the width of $S\to\gamma\gamma$ and $S\to jj$ may appear large as a consequence of mass splittings within the $X$-multiplet. As an example we study in detail the case of an $SU(2)_W$ quartet, finding that $m_X\simeq450$~GeV is allowed by all current searches.