Artist’s conception of the secret of the magnetic minute of the muon — a sub-atomic particle comparable to, however much heavier than, an electron (represented by the Greek letter mu). A brand-new price quote of the strength of the muon’s electromagnetic field closes the space in between theory and speculative measurements, bringing it in line with the basic design of particle physics. Credit: Dani Zemba, Penn State
A brand-new price quote of the strength of the sub-atomic particle’s electromagnetic field lines up with the basic design of particle physics.
A brand-new evaluation of the strength of the electromagnetic field around the muon — a sub-atomic particle comparable to, however much heavier than, an electron — closes the space in between theory and speculative measurements, bringing it in line with the basic design that has actually assisted particle physics for years.
A paper explaining the research study by a worldwide group of researchers appears today (April 7, 2021) in the journal Nature.
Twenty years back, in an experiment at Brookhaven National Laboratory, physicists discovered what appeared to be a disparity in between measurements of the muon’s “magnetic moment” — the strength of its electromagnetic field — and theoretical estimations of what that measurement must be, raising the alluring possibility of physical particles or forces yet undiscovered. The brand-new finding diminishes this disparity, recommending that the muon’s magnetism is most likely not strange at all. To accomplish this outcome, rather of depending on speculative information, scientists simulated every element of their estimations from the ground up — a job needing huge supercomputing power.
“Most of the phenomena in nature can be explained by what we call the ‘standard model’ of particle physics,” stated Zoltan Fodor, teacher of physics at Penn State and a leader of the research study group. “We can predict the properties of particles extremely precisely based on this theory alone, so when theory and experiment don’t match up, we can get excited that we might have found something new, something beyond the standard model.”
For a discovery of brand-new physics beyond the basic design, there is agreement amongst physicists that the dispute in between theory and measurement should reach 5 sigma — an analytical step that corresponds to a likelihood of about 1 in 3.5 million.
In the case of the muon, measurements of its electromagnetic field differed the existing theoretical forecasts by about 3.7 sigma. Intriguing, however inadequate to state a discovery of a brand-new break in the guidelines of physics. So, scientists set out to enhance both the measurements and the theory in the hopes of either fixing up theory and measurement or increasing the sigma to a level that would permit the statement of a discovery of brand-new physics.
“The existing theory for estimating the strength of the muon’s magnetic field relied on experimental electron-positron annihilation measurements,” stated Fodor. “In order to have another approach, we used a fully verified theory that was completely independent of reliance on experimental measurements. We started with rather basic equations and built the entire estimation from the ground up.”
The brand-new estimations needed numerous countless CPU hours at several supercomputer centers in Europe and bring theory back in line with measurement. However, the story is not over yet. New, more accurate speculative measurements of the muon’s magnetic minute are anticipated quickly.
“If our calculations are correct and the new measurements do not change the story, it appears that we don’t need any new physics to explain the muon’s magnetic moment — it follows the rules of the standard model,” stated Fodor. “Although, the prospect of new physics is always enticing, it’s also exciting to see theory and experiment align. It demonstrates the depth of our understanding and opens up new opportunities for exploration.”
The enjoyment is far from over.
“Our result should be cross-checked by other groups and we anticipate them,” stated Fodor. “Furthermore, our finding means that there is a tension between the previous theoretical results and our new ones. This discrepancy should be understood. In addition, the new experimental results might be close to old ones or closer to the previous theoretical calculations. We have many years of excitement ahead of us.”
Reference: “Leading hadronic contribution to the muon magnetic moment from lattice QCD” by Sz. Borsanyi, Z. Fodor, J. N. Guenther, C. Hoelbling, S. D. Katz, L. Lellouch, T. Lippert, K. Miura, L. Parato, K. K. Szabo, F. Stokes, B. C. Toth, Cs. Torok and L. Varnhorst, 7 April 2021, Nature.
DOI: 10.1038/s41586-021-03418-1
In addition to Fodor, the research study group consists of Szabolcs Borsanyi, Jana N. Guenther, Christian Hoelbling, Sandor D. Katz, Laurent Lellouch, Thomas Lippert, Laurent Lellouch, Kohtaroh Miura, Letizia Parato, Kalman K. Szabo, Finn Stokes, Balint C. Toth, Csaba Torok, Lukas Varnhorst.
Participating organizations consist of Penn State, the University of Wuppertal in Germany; the Jülich Supercomputing Centre in Germany; Eötvös University in Budapest, Hungary; the University of California, San Diego; the University of Regensburg in Germany; Aix Marseille Univ, Université de Toulon in Marseille, France; Helmholtz Institute Mainz in Germany; the Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University in Japan.
The research study was moneyed by the German Research Foundation (DFG); the German Federal Ministry of Education and Research (BMBF); the Hungarian National Research, Development and Innovation Office; and the Excellence Initiative of Aix-Marseille, a French Investissements d’Avenirf program, through the Chaire d’Excellence effort and the Laboratoire d’Excellence.
