DESY, a laboratory in Hamburg, Germany, is seeking to make and detect axions that would fall into this longer-lived category.

ECONOMIST: A possible particle of dark matter

Though that experiment had not been intended to make axions, the two researchers wondered if it had created such particles as a by-product.

ECONOMIST: A possible particle of dark matter

Now a paper by Piyare Jain and Gurmukh Singh of the State University of New York, Buffalo, also offers some evidence that axions really do exist.

ECONOMIST: A possible particle of dark matter

Like other groups searching for possible dark-matter particles (such as axions and neutrinos), the best they can hope for at the moment is to narrow the field.

ECONOMIST: The dark side of cosmology | The

Many experiments have looked for axions.

ECONOMIST: A possible particle of dark matter

After re-analysing the plates, Dr Jain and Dr Singh concluded that they may have found axions that exist so fleetingly that they are not noticed by the modern electronic methods of particle detection that have replaced the use of photographic plates.

ECONOMIST: A possible particle of dark matter