For many years, the measurements of the Landé g-factor of the muon have been puzzling, as the experimental value and the theoretical predictions showed some disagreement - 3.6 standard deviations for the last years. Experimental and theoretical uncertainties have a similar size, so work on both sides helps.(adsbygoogle = window.adsbygoogle || []).push({});

Muon g-2 at Fermilab is currently taking more data to improve the experimental result, while CERN is studying a muon-electron scattering experiment to improve some experimental values that go into the theory calculations. But a few days a completely new idea was made public.

The difference might come from the gravitational field of Earth. This sounds absurd - something you learn early as particle physicist is that gravity is completely negligible (unless you design detectors!). But we are talking about extremely precise measurements - parts per billion. Three authors investigated if gravity can have an effect - and found a possible contribution that is of the size of the observed discrepancy. Adding this to the theoretical prediction reduces the discrepancy from 3.6 standard deviations to 0.1 standard deviations. If the calculations are correct, theory and experiment are actually in excellent agreement.

The authors uploaded three papers to arXiv:

Theoretical framework

Effect on electrons

Effect on muons

The effect on electrons is very important: Our measurements there are a factor 1000 more precise, and they agree nicely. The authors calculate that gravity doesn't influence the electron measurements due to the different measurement principles - the measurements are done with slow electrons, while the muons are relativistic.

Other theorists are checking these calculations now. If they can confirm the results, the muon g-2 anomaly is gone. On the positive side, we get a direct influence of curved spacetime on particle physics measurements - an interesting effect to study in more detail.

Other links:

Blog article covering the topic

Something I don't understand: If the effect scales with ##1-\frac{3GM}{rc^2}## for g as given in the abstract and the conclusion, then the Sun should have an effect a factor 14 larger. Yet it is not mentioned at all.

**Physics Forums - The Fusion of Science and Community**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Featured A Possible explanation for muon g-2 anomaly: Gravity?

Have something to add?

Draft saved
Draft deleted

Loading...

Similar Threads - Possible explanation muon | Date |
---|---|

A Is it possible that a particle is much heavier through a loop correction | Oct 16, 2017 |

B Possible outcomes of reactions | Apr 22, 2017 |

I Possible ways to increase particle detector resolution? | Feb 13, 2017 |

B Muon shielding possibilities | Feb 2, 2017 |

Possible Explanation for Baryon Asymmetry | Aug 19, 2014 |

**Physics Forums - The Fusion of Science and Community**