The g-factor of the muon, that is.

Physics Girl: This result could change physics forever. (YouTube, 13min) “Explaining the exciting new Fermilab muon result to my production team.”

Here is the press release: Fermilab: First results from Fermilab’s Muon g-2 experiment strengthen evidence of new physics.

“The accepted theoretical values for the muon are:
g-factor: 2.00233183620(86)
anomalous magnetic moment: 0.00116591810(43)
[uncertainty in parentheses]

The new experimental world-average results announced by the Muon g-2 collaboration today are:
g-factor: 2.00233184122(82)
anomalous magnetic moment: 0.00116592061(41)

The combined results from Fermilab and Brookhaven show a difference with theory at a significance of 4.2 sigma, a little shy of the 5 sigma (or standard deviations) that scientists require to claim a discovery but still compelling evidence of new physics. The chance that the results are a statistical fluctuation is about 1 in 40,000.”