An explicit Z '-boson explanation of the B → K au μ + μ - anomaly

A global fit to the recent B -> K (au) mu (+) mu (-) data shows indications for a large new-physics contribution to the Wilson coefficient of the semi-leptonic vector operator. In this article we consider a simple Z (')-boson model of 3-3-1 type that can accommodate such an effect without violating any other constraint from quark-flavour physics. Implications for yet unobserved decay modes such as B -> X (s) nu and longstanding puzzles like B -> pi K are also discussed. The Z (')-boson masses required to address the observed anomaly lie in the range of 7 TeV. Such heavy Z (') bosons evade the existing bounds from precision data and direct searches, and will remain difficult to discover even at a high-luminosity LHC. The potential of an ILC as well as the next generation of low-energy parity-violation experiments in constraining the Z (')-boson parameter space is also examined.