Abstract
We consider supersymmetric extensions of the standard model with a vector-like doublet (T B) of quarks with charge 2/3 and −1/3, respectively. Compared to non-supersymmetric models, there is a variety of new decay modes for the vector-like quarks, involving the extra scalars present in supersymmetry. The importance of these new modes, yielding multi-top, multi-bottom and also multi-Higgs signals, is highlighted by the analysis of several benchmark scenarios. We show how the triangles commonly used to represent the branching ratios of the ‘standard’ decay modes of the vector-like quarks involving W, Z or Higgs bosons can be generalised to include additional channels. We give an example by recasting the limits of a recent heavy quark search for this more general case.
Highlights
Lepton representation there is a quark counterpart, the possible existence of a vector-like quark doublet representation (T B) was proposed in ref. [22] as part of the fourth family
There is a variety of new decay modes for the vector-like quarks, involving the extra scalars present in supersymmetry
In the next-to-minimal supersymmetric standard model (NMSSM) [26] one extra singlet superfield Nis included in order to solve the μ problem [27]
Summary
We assume that the new vector-like doublet eigenstates dominantly mix with the third generation, as it is expected from the mass hierarchy [52]. (Note that for small mixing the (4, 4) entries in the mass matrices are approximately the heavy quark masses.) We write the interactions in the mass basis in a MSSM-like case where the neutral interaction eigenstates Hu0, Hd0 have small mixing with the other scalars. We remark that the interactions written below are the same for a non-supersymmetric type-II two-Higgs doublet model in which one doublet Hu couples to charge 2/3 quarks and the other doublet Hd couples to charge −1/3 quarks
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