Explicit parametrization of more than one vector-like quark of Nelson-Barr type

Abstract

Nelson-Barr models solve the strong CP problem based on spontaneous CP violation and generically requires vector-like quarks (VLQs) mixing with standard quarks to transmit the CP violation. We devise an explicit parametrization for the case of two VLQs of either down-type or up-type and quantitatively study several aspects including the hierarchy of the VLQ Yukawas and their irreducible contribution to $\bar{\theta }$. In particular, with the use of the parametrization, we show that a big portion of the parameter space for two up-type VLQs at the TeV scale is still allowed by the constraint on $\bar{\theta }$, although this case had been previously shown to be very restricted based on estimates.

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Cited by in corpus (3)

• Vector-like Singlet Quarks: a Roadmap
• Effective description of Nelson-Barr models and the theta parameter
• Nelson-Barr Models with Vector-Like Quark Doublets