In 2003 the discovery of a new type of particle, a Pentaquark, was heralded with a great fanfare. Within two years, however, follow-up experiments had failed to find it. Belief in the existence of a pentaquark has since dwindled, but what was the reason for the apparent contradictory results? Physicists at the University of Glasgow think they have now resolved the problem.

The conventional measure for the discovery of a new particle is that there is a less than 1 in a million chance that the result was a fluke. However, even at the height of the pentaquark excitement, fewer than half the researchers in the field really believed that a new particle had been found.

By considering the odds at which someone would make a bet on the pentaquark's existence, and applying the theory of chance developed by the Rev. Thomas Bayes in the 19th century, the Glasgow team found that the original result was far less conclusive than had been thought, and was in fact compatible with the new results.

Dr David Ireland, Physics and Astronomy, University of Glasgow, said: “If the authors had been licensed betting operators, they would now have been prepared to take bets at odds of 10 to 1 against there being a pentaquark!

“The mathematics at the heart of this work is actually also embedded into the techniques used by Google for efficient searching of the internet, as well as several other artificial intelligence systems. And the proposed technique can be applied to any experiment aimed at discovering new particles.”

Further information:
Dr David Ireland, Department of Physics and Astronomy,
University of Glasgow Tel: 0141 330 2223

Full study:
URL: http://link.aps.org/abstract/PRL/v100/e052001
DOI: 10.1103/PhysRevLett.100.052001

First published: 18 February 2008

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