Nature: An analysis of data collected from the LHCb experiment at CERN has revealed a potential discrepancy in the decay rate of B mesons. According to the standard model, the particles should decay evenly into muons and tau leptons, but the data suggest that the decay favors taus. Although the LHCb signal is only 2.1 sigma, the experiment is the third to have seen the unusual decay pattern with a 2-sigma signal. In 2012, SLAC's BaBar experiment reported the uneven decay, and in May of this year the Belle experiment at KEK, Japan's organization for high-energy accelerator research, did as well. Last year the LHCb saw a similar uneven decay of a different B meson, which favored electrons. If the signals prove to be real, they could challenge the standard model.
