RK (?) and related b →s anomalies in minimal flavor violation framework with Z′ boson RK (?) and RELATED b →s ? CHIANG et al.
Journal
Physical Review D
Journal Volume
96
Journal Issue
11
Date Issued
2017
Author(s)
Abstract
A recent LHCb measurement of the ratio RK∗ of B→K∗μμ to B→K∗eē branching fractions has produced results in mild tension with the standard model (SM). This adds to the known anomalies also induced by the b→s transitions, resulting in a confidence level now as high as 4σ. We analyze whether the parameter space preferred by all the b→s anomalies is compatible with a heavy Z′ boson assumed to have nonuniversal couplings to SM fermions dictated by the principle of minimal flavor violation (MFV). We deal with the MFV couplings of the Z′ to leptons in the context of the type-I seesaw scenario for generating neutrino masses. The flavor-violating Z′ interactions are subject to stringent constraints from other processes, especially B-B mixing, charged lepton decays i→jk̄l occurring at tree level, and the loop induced μ→eγ. We perform scans for parameter regions allowed by various data and predict the ranges for a number of observables. Some of the predictions, such as the branching fractions of lepton-flavor violating τ→3μ, B→Keμ, KL→eμ, and Z→′, are not far below their experimental bounds and therefore could be probed by searches in the near future. The viable parameter space depends strongly on the neutrino mass hierarchy, with a preference for the inverted one.
Type
journal article