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 an SU(2)W-non-singlet, 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±jj final state, and show that in such case the entire multiplet is compatible with indirect precision tests and with direct collider searches for continuum pair production of X down to mX ∼ 250 GeV. However, bound states S, made of XX† pairs at mS ≈ 2mX, 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 → W+W− may be observable and the width of S → γγ and S → 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 mX ≃ 450 GeV is allowed by all current searches.