Exotic colored scalars at the LHC

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 $m_X\sim 250$~GeV. However, bound states $S$, made of $X{X}^{†}$ pairs at $m_S\approx 2m_X$, 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 $m_X\simeq 450$~GeV is allowed by all current searches.

Comments: 20 pages, 3 figures