King's College London

Research developments in the fields of particle physics and cosmology has led to a growing interest in the axion particle – a hypothetical particle which explains why neutrons behave in a certain way in the presence of electromagnetic fields. If detected, the axion particle would play a key role in explaining the origin of dark matter in the Universe.

Published in Science Advances, the review conducted by Professor John Ellis (Clerk Maxwell Professor of Theoretical Physics) and Dr David Marsh (Lecturer and Ernest Rutherford Fellow) from King’s Department of Physics, and Durham University’s Dr Francesca Chadha-Day, focuses on the theory of axions, how axions are produced in the early Universe, and how astrophysics and particle physics work together to tell us how to search for axions in the laboratory.

The axion behaves like a field covering the Universe, and this field can also explain where dark matter comes from. Dark matter is known to make up around 85% of our Milky Way galaxy, but experts are not yet sure what it is made of. The axion particle is a good explanation, because it interacts very weakly with light (axions are ‘dark’), and there are processes in the early Universe that can cause the axion field to oscillate back and forth and become excited. Research hypothesises that the energy stored in these oscillations is axion dark matter, which if detected could provide the solution to one of the greatest mysteries of the Universe.

Furthering the understanding of axions also contributes towards developing the technology that could detect them. Interest in detecting axions has underpinned dozens of ongoing experiments around the world, which seek to find the axion in the next ten to twenty years. The Science Advances review from the King’s team complements a companion article by Professor Yannis Semertzidis and Dr SungWoo Youn, which explains how the technology being developed works.

On developments in the field, David commented;