Abstract
We study the impact of the leading non-renormalizable terms in the effective field theory that describes general extensions of the Standard Model with vector-like quarks that can decay into Standard Model particles. Dropping the usual assumption of renormalizability has several phenomenological consequences for the production and decay of the heavy quarks and also for Higgs physics. The most dramatic effects, including those associated with a long lifetime, occur for vector-like quarks with non-standard quantum numbers.
Highlights
Vector-like quarks appear in many motivated extensions of the SM, for diverse reasons
We study the impact of the leading non-renormalizable terms in the effective field theory that describes general extensions of the Standard Model with vector-like quarks that can decay into Standard Model particles
We study the mixing with the third family of SM quarks and the associated phenomenology, including indirect effects on electroweak and Higgs observables and the production and decay of the new quarks
Summary
Let us consider a general local effective Lagrangian L describing extensions of the SM with extra vector-like quarks. We find in appendix A a general constraint over the representation of any Standard Model operator, and of any field with a gauge-invariant linear coupling.. As we have just explained, at each order in inverse powers of the cutoff Λ, which is given by the dimension of the operators, there is a finite number of multiplets with linear couplings to SM fields. The quantum numbers of the extra field must allow for the gauge-invariant vertices in the diagrams This means that the heavy scalar S belongs to one of the representations 10, 30 and 31 of SU(2)×U(1), while the heavy quark Q belongs to one of the representations in the first seven rows of table 1, so it is a RVLQ (but assumed to be heavier than the ones in the effective Lagrangian). An explicit model with a U vector-like quark and a scalar singlet has been studied in [35]
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