Cascade decays of Heavy Higgs bosons through vectorlike quarks.

We study cascade decays of heavy neutral Higgs bosons through vectorlike quarks. We focus on scenarios where decay modes into pairs of vectorlike quarks are not kinematically open which extends the sensitivity of the LHC to larger masses. Assuming only mixing with the third family of standard model quarks the new decay modes of heavy Higgs bosons are: $H\to t_4 t \to Wbt, Zt t, ht t$ and $H\to b_4 b \to Wtb, Zb b, hb b$, where $t_4$ ($b_4$) is the new up-type (down-type) quark mass eigenstate. We identify the region of the parameter space where these decay modes are significant or can even dominate. We also find that the rates for these processes can be much larger than the rates for a single production of vectorlike quarks. Thus, in the identified regions, they provide the best opportunities for the discovery of a new Higgs boson and vectorlike quarks. In the numerical analysis we assume the CP even Higgs boson in the two Higgs doublet model type-II but the signatures are relevant for many other scenarios.