Abstract
The vector leptoquark representation, $U_\mu = (3,1,2/3)$, was recently identified as an exceptional single mediator model to address experimental hints on lepton flavour universality violation in semileptonic $B$-meson decays, both in neutral ($b \to s \mu \mu$) and charged ($b \to c \tau \nu$) current processes. Nonetheless, it is well-known that massive vectors crave an ultraviolet (UV) completion. We present the first full-fledged UV complete and calculable gauge model which incorporates this scenario while remaining in agreement with all other indirect flavour and electroweak precision measurements, as well as, direct searches at high-$p_T$. The model is based on a new non-abelian gauge group spontaneously broken at the TeV scale, and a specific flavour structure suppressing flavour violation in $\Delta F = 2$ processes while inducing sizeable semileptonic transitions.
Highlights
The increasing set of experimental anomalies in semileptonic B-meson decays might be the long-awaited signal of physics beyond the standard model (SM)
Massive vectors require a UV completion in form of either a composite dynamics or a spontaneously broken gauge theory. The former approach was attempted for instance in Refs. [31,32,33], where the vector leptoquark Uμ arises as a composite vector resonance of a new strong sector featuring an extended global symmetry, in analogy to composite Higgs or technicolor models
We put forth a renormalizable UV completion of the vector leptoquark Uμ 1⁄4 ð3; 1; 2=3Þ, which was recently identified as an exceptional single-mediator model to address the combined explanation of B-anomalies both in neutral and charged currents
Summary
The increasing set of experimental anomalies in semileptonic B-meson decays might be the long-awaited signal of physics beyond the standard model (SM). Since the implied scale of new physics is rather low [34], the main challenge is to reconcile it with the nonobservation of related signals in (other) flavor changing processes The exceptional feature of this particular representation is the absence of tree-level down-quark-to-neutrino, as well as up-quark-to-charged-lepton transitions, naturally suppressing (a set of) otherwise strongly constrained observables. We show how to consistently embed the leptoquark Uμ into a non-Abelian gauge theory spontaneously broken in the vicinity of the TeV scale, while still remaining consistent within a plethora of experimental constraints ranging from low-energy precision measurements to direct searches at the LHC
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