“In recent years several new particles have been discovered which are currently assumed to be “elementary,” that is, essentially structureless. The probability that all such particles should be really elementary becomes less and less as their number increases. It is by no means certain that nucleons, mesons, electrons, neutrinos are all elementary particles.” -Enrico Fermi

The Standard Model of particle physics — with its six quarks in three colors, its three generations of charged leptons and neutrinos, the antiparticle counterparts to each, and its thirteen bosons, including the Higgs — describes all the known particles and their interactions in the Universe. This extends to every experiment ever performed in every particle accelerator. In short, this is a problem: there’s no clear path to what new physics lies beyond the Standard Model.

The known particles and antiparticles of the Standard Model all have been discovered. All told, they make explicit predictions. Any violation of those predictions would be a sign of new physics, which we’re desperately seeking. Image credit: E. Siegel.

So physicists are looking for any possible anomalies at all, at any theoretical ideas that lead to new predictions at the frontiers, and any experimental result that differs from the Standard Model predictions. Unfortunately, we’re looking at thousands of different composite particles, decays, branching ratios, and scattering amplitudes. Our standards for what’s a robust measurement and a compelling result need to be extremely high.

The standard model calculated predictions (the four colored points) and the LHCb results (black, with error bars) for the electron/positron to muon/antimuon ratios at two different energies. Image credit: LHCb Collaboration / Tommaso Dorigo.

The newest LHCb results offer a hint of something interesting, but it’s got a long way to go before we can say we’ve discovered anything new. Come find out what we’ve seen today!

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