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One of the scientists, an experimentalist named Eugenio Paoloni, asked me what I thought about the new measurements of B meson decays by the BaBar experiment in California, which pointed toward a violation of lepton flavor universality.

The Belle II experiment in Japan, which is dedicated to investigating B meson decays, is also gathering new evidence.

Part of the excitement surrounding the latest LHCb result is that the specific B meson decay is “clean”—it has a very small theoretical uncertainty.

That is, a rare decay of a B meson does not directly yield new particles—muons and kaons are old hat—but the rate at which the decay happens can depend on heavy, as-yet-unseen particles influencing the outcome behind the scenes.

The “b” stands for beauty — and for the B meson, a subatomic particle that is crucial to the experiment.