Scientists at the University of Sussex have disproved the existence of a specific type of axion -- an important candidate 'dark matter' particle -- across a wide range of its possible masses.
The data were collected by an international consortium, the Neutron Electric Dipole Moment (nEDM) Collaboration, whose experiment is based at the Paul Scherrer Institut in Switzerland. Data were taken there and, earlier, at the Institut Laue-Langevin in Grenoble.
Professor Philip Harris, Head of Mathematical and Physical Sciences at the University of Sussex, and head of the nEDM group there, said:
"Experts largely agree that a major portion of the mass in the universe consists of 'dark matter'. Its nature, however, remains completely obscure. One kind of hypothetical elementary particle that might make up the dark matter is the so-called axion. If axions with the right properties exist it would be possible to detect their presence through this entirely novel analysis of our data.
"We've analysed the measurements we took in France and Switzerland and they provide evidence that axions -- at least the kind that would have been observable in the experiment -- do not exist. These results are a thousand times more sensitive than previous ones and they are based on laboratory measurements rather than astronomical observations. This does not fundamentally rule out the existence of axions, but the scope of characteristics that these particles could have is now distinctly limited.
"The results essentially send physicists back to the drawing board in our hunt for dark matter."
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