T-2, Nuclear and Particle Physics, Astrophysics and Cosmology

Simplified models of flavorful leptoquarks for R_K^*

Jim Talbert
DESY

Motivated by potential signals of lepton non-universality in the B-decay observables R_K^*, I will augment the Standard Model (SM) Lagrangian with a single leptoquark and study its natural invariance under global Abelian flavor symmetries. Such symmetries, assumed to be the ‘residual’ subgroups of a (broken) ultra-violet flavor theory, have previously been considered in order to address portions of the SM's flavor problem, which I will also introduce in an effort to frame the talk in a broader BSM context. I will then focus on the Abelian symmetries' effect on the novel Yukawa couplings sourced by the leptoquark. Upon considering the relevant flavor data available, these symmetries prove to be extremely constraining; one finds that the (quark-lepton) leptoquark Yukawa couplings fall within O(10) highly predictive patterns, each with only a single free complex parameter, when ‘normal’ (i.e. SM-like) coupling hierarchies are assumed. These patterns are the solutions for the scalar SU(2) triplet, vector SU(2) triplet, and vector SU(2) singlet leptoquarks. In addition, proton decay for the scalar SU(2) triplet is naturally avoided in the residual symmetry approach without relying on ad-hoc model building, which I will also demonstrate explicitly. Finally, future extensions (and preliminary results therein) will be presented.

NNSA


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