SCIENTISTS AT Cern may be on the verge of a discovery that will take them towards a new understanding of the evolution of our universe. The finding may also help explain fundamental things about the cosmos that happened just a minute after the Big Bang.
Cern, Europe’s nuclear research centre, announced last July it had discovered a particle, now widely believed to be the famous Higgs boson. Although scientists are 99.999 per cent certain it is the Higgs, the final confirmation from them won’t come until more data can be assembled.
However, the new discovery has nothing to do with the Higgs and relates to a substance called antimatter. The scientists are only 99.9 per cent sure about their antimatter discovery, but if true it could represent “new physics”, said Dr Tara Shears of Cern.
“We have no way to explain this,” she said yesterday in Aberdeen during a talk about Cern at the British Festival of Science. “We call it new physics because we don’t know what it is.”
She is attached to an experiment called the LHCb which sits on the giant 27km Large Hadron Collider (LHC) particle accelerator at Cern in Switzerland. It sends streams of particles moving around the LHC ring at close to the speed of light and then crashes them together to recreate conditions similar to those just after the Big Bang. This was how both the presumed Higgs particle and the new antimatter finding were discovered. “The LCH isn’t just about the Higgs, there are a lot of other mysteries out there in the universe,” Dr Shears said.
Physicists have a connected-up theory called the standard model that helps explain anything from an atom to the universe. There was such excitement over the Higgs because it represents the piece that completes the model.
Equal amounts of matter and antimatter should have been made at the time of the Big Bang almost 14 billion years ago, but today all we see is matter, as the antimatter is all gone. “We know it exists, but how did the antimatter go away?” asked Dr Shears.
Matter and antimatter are exact opposites and when one touches the other they are both destroyed in a burst of pure energy. But because we see only matter today there must have been slightly more matter than antimatter, in defiance of supersymmetry.
The LHCb experiment has been using the Cern accelerator to try to answer this question. Colliding particles produce enough energy to form matter and antimatter but these disintegrate instantaneously to form other distinct particles called D-zero mesons. The LHCb experiment can count these and know whether they came from matter or antimatter.
They have collected months of data and something unexpected arose. “We saw more matter mesons than antimatter mesons,” Dr Shears said. This was completely new and should not have been the case – assuming that supersymmetry is valid. “This is the first observation of something that doesn’t fit into the current model.”
The quality of the data has advanced to 3.5 Sigma, she said, which means there is only a one in several thousand chance it is incorrect.
