>>12945954https://www.quantamagazine.org/muon-g-2-experiment-at-fermilab-finds-hint-of-new-particles-20210407Look at the bit in the middle of the article about the BMW group's lattice QCD calculation. Lattice QCD is a means of calculating QCD (strong force) stuff through simulating the equations on a lattice, as oppoesd to the theory group who I assume summed up a ton of Feynman diagrams.
5 sigma is a measure of statistical significance required for particle physicists to accept an experimental finding as not just a statistical fluke. 5 sigma corresponds to a p-value of 3*10^-7, i.e. a roughly 1 in 3.5 million chance that the observation is a mere statistical fluke.
HEP = high-energy physics.
