Production of exotic composite quarks at the LHC

摘要

We consider the production at the LHC of exotic quarks U+ of charge Q = +(5/3)e and D~- of charge Q = - (4/3) e of mass m, arising in a composite fermion scenario characterized by a compositeness scale Λ. Such states are predicted in composite models of higher isospin multiplets (I_W = 1 or I_W = 3/2). Given their exotic charges (such as 5/3), their decays proceed through the electroweak interactions. We compute decay widths and rates for resonant production of the exotic quarks at the LHC. Partly motivated by the recent observation of an excess by the CMS collaboration in the ep_Tjj final state signature we focus on pp → U~+j → W~+ + jj →ℓ ~+pTjj and then perform a fast simulation of the detector reconstruction based on Delphes. We then scan the parameter space of the model (m_* = Λ) and study the statistical significance of the signal against the relevant standard model background (Wjj followed by leptonic decay of the W gauge boson) providing the luminosity curves as function of m_* for discovery at 3- and 5-σ level.