Patterns of flavour violation in models with vector-like quarks

Bobeth, Christoph; Buras, Andrzej J.; Celis, Alejandro und Jung, Martin (2017): Patterns of flavour violation in models with vector-like quarks. In: Journal of High Energy Physics, Nr. 4, 79

Abstract

We study the patterns of flavour violation in renormalisable extensions of the Standard Model (SM) that contain vector -like quarks (VLQs) in a single complex representation of either the SM gauge group GSM or G'(SM) = G(SM) circle times U(1)(L mu) (- L tau). We first decouple VLQs in the M = (1 - 10) TeV range and then at the electroweak scale also Z, Z' gauge bosons and additional scalars to study the phenomenology. The results depend on the relative size of Z- and Z'-induced flavour -changing neutral currents, as well as the size of vertical bar Delta F vertical bar = 2 contributions including the effects of renormalisation group Yukawa evolution from M to the electroweak scale that turn out to be very important for models with right-handed currents through the generation of left -right operators. In addition to rare decays like P -> ll, P -> P'll P -> P'v (v) over bar with P = K, B-s, B-d and vertical bar Delta F vertical bar= 2 observables we analyze the ratio epsilon'/epsilon which appears in the SM to be significantly below the data. We study patterns and correlations between these observables which taken together should in the future allow for differentiating between VLQ models. In particular the patterns in models with left-handed and right-handed currents are markedly different from each other. Among the highlights are large Z -mediated new physics effects in Kaon observables in some of the models and significant effects in B-s,B-d-observables. epsilon'/epsilon can easily be made consistent with the data, implying then uniquely the suppression of K-L -> pi(O)v (v) over bar. Significant enhancements of Br(K+ -> pi(+) v (v) over bar) are still possible. We point out that the combination of NP effects to vertical bar Delta F vertical bar = 2 and vertical bar Delta F vertical bar = 1 observables in a given meson system generally allows to determine the masses of VLQs in a given representation independently of the size of VLQ couplings.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 1029-8479
• Sprache: Englisch