Niels Bohr Lecture by Mark Lancaster

Title: Is new physics hiding in the magnetic interactions of a muon?

Abstract: The interaction of a muon’s spin with a magnetic field defines its magnetic moment in terms of the gyromagnetic ratio, g. In the Dirac equation, g is exactly 2, but additional higher order QED, electroweak and strong interactions increase its value by ~ 0.1%. Moreover, new interactions beyond the Standard Model of particle physics can also contribute at the level of approximately 1 part per million. Very precise measurements are thus required to uncover new, beyond the Standard Model, interactions.

I will describe the most recent, world's best, measurement, from the Fermilab Muon g-2 experiment: a measurement with a precision of 0.2 parts per million which is the most accurately measured quantity using a particle accelerator storage ring and the plans to improve this precision and the Standard Model calculation which will hopefully resolve whether the magnetic interaction of a muon is a harbinger of new physics or not.

About the speaker:

Mark Lancaster s a Professor of experimental particle physics at University of Manchester and previously University College London. His research career has been as part of large international experimental particle physics collaborations:

ZEUS (1988-1996), CDF (1996-2013), COMET (2008-2013), Muon g-2 (2013-) and Mu2e (2016-) and his research has been in three specific areas: precision measurements of W and Z bosons; elucidating the nature of the strong nuclear force and the structure of the proton; and most recently the precision measurement of the muon's magnetic moment and its rare decay modes.

He was the co-spokesperson of the Fermilab Muon g-2 experiment from 2018-2020. He was awarded the Chadwick Medal by the UK's Institute of Physics in 2021 and in 2023 elected as a Fellow of the Royal Society and the American Physical Society .

Coffee, tea and cake will be served outside Aud. 3 at 15:45