Wednesday, 02 February 2022
Finding an elusive elementary particle is more viable than ever after an international team of scientists conducted the first experiment to explore magnetic monopoles using the Large Hadron Collider.
Scientists from the European Organisation for Nuclear Research (CERN) and physicists from the University of Nottingham and Monopole and Exotics Detector (MoEDAL) used the Large Hadron Collider to explore a production mechanism theorized by Julian Swinger, a Nobel Prize winning American Physicist. Their findings are published today in Nature.
The team is searching for magnetic monopoles, hypothetical fundamental particles with only one magnetic pole predicted by several theories, but not yet detected. Confirming their existence would be transformative for physics, proving that there are laws of nature not captured by the currently ruling theory of physics, the Standard Model, and allowing to probe new laws in unique ways.
“This specific monopole search was pioneering and opened a new, promising avenue for further searches,” said Igor Ostrovskiy, a MoEDAL physicist at The University of Alabama and corresponding author of the paper. “Ours was the first search where magnetic monopoles with finite size – the type predicted by recent theories – were realistically detectable, and while we did not find any, we were able to set the first reliable limits on the monopole’s mass.”
The team searched for magnetic monopole production in the collisions of heavy ions on the world’s largest and most powerful particle accelerator. The collisions generated strong magnetic fields, more powerful than those of fast-spinning neutron stars, and such strong fields could give rise to spontaneous creation of magnetic monopoles via the Schwinger mechanism.
“A big advantage of the Schwinger mechanism is that we can calculate its rate more reliably than for any other production processes explored at the LHC so far,” said Oliver Gould, a research fellow at the University of Nottingham, who performed theoretical calculations for this search. “This gives us a good idea about how many monopoles should be seen by the experiment as a function of their mass and magnetic charge. And since none have been seen, we can reliably say that magnetic monopoles must be heavier than a certain value”.
To detect magnetic monopoles, the MoEDAL researchers used a superconductive magnetometer to scan the detector modules exposed to the LHC lead-lead collisions for signatures of trapped magnetic charge. With no signs of the signal, the researchers were able to exclude the existence of monopoles lighter than 75 GeV/c2, where c is the speed of light, for magnetic charges ranging from 1 to 3 base units of magnetic charge.
The search for magnetic monopoles has a rich history, bound up with many theoretical proposals in particle physics. Yet this is the first experiment that has enabled us to deduce explicit constraints on the properties of any possible magnetic monopoles. Doing so relied on the close collaborations between theorists and experimentalists.
MoEDAL plans to take more data and increase its sensitivity to heavier monopoles with larger magnetic charge in the near future.
Main image courtesy of James Pinfold, MoEDAL Collaboration.
More information is available from Oliver Gould at Oliver.Gould@nottingham.ac.uk
Notes to editors:
About the University of Nottingham
Ranked 32 in Europe and 16th in the UK by the QS World University Rankings: Europe 2024, the University of Nottingham is a founding member of the Russell Group of research-intensive universities. Studying at the University of Nottingham is a life-changing experience, and we pride ourselves on unlocking the potential of our students. We have a pioneering spirit, expressed in the vision of our founder Sir Jesse Boot, which has seen us lead the way in establishing campuses in China and Malaysia - part of a globally connected network of education, research and industrial engagement.
Nottingham was crowned Sports University of the Year by The Times and Sunday Times Good University Guide 2024 – the third time it has been given the honour since 2018 – and by the Daily Mail University Guide 2024.
The university is among the best universities in the UK for the strength of our research, positioned seventh for research power in the UK according to REF 2021. The birthplace of discoveries such as MRI and ibuprofen, our innovations transform lives and tackle global problems such as sustainable food supplies, ending modern slavery, developing greener transport, and reducing reliance on fossil fuels.
The university is a major employer and industry partner - locally and globally - and our graduates are the second most targeted by the UK's top employers, according to The Graduate Market in 2022 report by High Fliers Research.
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