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Scientists find clue in matter-antimatter conundrum

Story supplied by LU Press Office

Dr Guennadi Borissov Dr Guennadi Borissov

Research by a team jointly led by a Lancaster University Physicist has unearthed a new clue which could help solve one of the mysteries of the universe.

At the moment of the 'big bang' matter and anti matter should have been created in equal measure - in theory they should have cancelled one another out. But somehow that perfect symmetry went askew, more matter was created than antimatter and the universe was born.

"What happened to the antimatter?" is one of the central questions of 21st century particle physics, a question which is being explored in high energy particle colliders such as the LHC at CERN in Geneva and the Tevatron at the Fermi National Accelerator Laboratory (Fermilab) in the USA.

Now scientists of the DZero collaboration at Fermilab have discovered the first evidence for significant violation of matter-antimatter symmetry, potentially offering a clue to the origins of the universe.

The magnitude of the symmetry violation they have measured is larger than that expected in the current theory, the Standard Model of particle physics.

The new result, submitted for publication in Physical Review D, indicates a one percent difference between the production of pairs of (negatively charged) muons and pairs of (positively charged) antimuons in the decay of B mesons produced in high-energy collisions at Fermilab's Tevatron particle collider.

The result gives further support to hints of a similar deviation from current theory, observed last year, by physicists at both Tevatron experiments, DZero and CDF, studying particles made of a bottom quark and a strange quark.

If confirmed by further observations and analysis, the effect seen by DZero physicists could represent another step towards understanding the observed matter dominance by pointing to new physics phenomena beyond those we know today.

Lancaster University's Dr Guennadi Borissov is a co-leader on the project, developed the tools and methods leading to this result. He presented the result to the scientific community at a special seminar at Fermilab on Friday, May 14. Word of the discovery has spread quickly among physicists and has already been reported in the New York Times.

He said: "Although physicists have observed differences (called "CP violation") in particle behaviour for decades, these known differences are much too small to explain the observed dominance of matter over antimatter in the universe.

"This beautiful result provides important input to understanding the matter dominance in the Universe.

"The DZero experiment is still collecting data and so, as long as funding for our work continues, we can expect to make even more precise measurements of this effect in the future".

"Many of us felt goose bumps when we first saw the result," said Stefan Soldner-Rembold from the University of Manchester who leads the international Dzero Experiment as one of its two Spokespersons. "We knew we were seeing something beyond what we have seen before and beyond what current theories can explain."

"The precision of the DZero measurements is still limited by the number of collisions recorded so far by the experiment. We will therefore continue to collect more data and to refine the analysis methods to study these fundamental questions," explained Gavin Davies from Imperial College London.

The DZero collaboration is an international team of 500 physicists from 19 countries. Three UK universities, Imperial College London, Lancaster University and the University of Manchester are members of the international DZero Collaboration. The UK contribution is funded by the Science and Technology Facilities Council (STFC) and supported by the Royal Society.

Wed 19 May 2010

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