Getting to bottom of beauty

How to solve one of the greatest cosmological mysteries - why matter survived to be around today and was not annihilated at the beginning of the universe - has become clearer with research reported at an Oxford University conference.

At Beauty `95, scientists discussed one of the fundamental particles of matter, the beauty quark, which, when formed, only lasts a millionth of a millionth of a second. They have now seen the quark behave in a way that scientists believe the universe behaved when it was forming.

At the beginning of the universe, theory predicts that equal amounts of matter and antimatter should have formed. Yet matter and antimatter should have annihilated each other on contact, leaving no matter around today. Physicists therefore believe that the matter and antimatter behaved "asymmetrically", at the end of which most of the matter and all of the antimatter had gone, with a little bit of matter left over which forms the universe as we know it.

Particle physicists at Beauty '95 described work done for the past two years at the large electron positron collider at CERN in Geneva. They have shown that the beauty quark can change, or oscillate, into its opposite piece of antimatter. "We believe that the mechanism that produces the asymmetry in the decay in the beauty quarks could be the same, or related to, the one that produces the asymmetry at the beginning of the universe," said Neville Harnew, of Oxford University's department of particle and nuclear physics.

The beauty quark, also known as the bottom quark, is one of the six quarks that make up the fundamental particles of matter. The other quarks are the up, down, charm, strange and top (or truth) quarks.

Two big projects are planned to build "beauty factories", that will produce many more beauty quarks than it has been possible to produce before. Scientists from British universities, including Liverpool, Imperial College and Bristol, hope to build some of the equipment for the experiment known as BABAR, to be built in California by 1999 at the Stanford Linear Accelerator Centre, at a cost to the UK of about Pounds 2.5 million. Another production line is planned for Japan. The Large Hadron Collider, to be built at CERN in Geneva, will also explore the beauty quark for Pounds 30 million.