Scientists believe that understanding why the universe is made of matter and not antimatter will pave the way for brand new physics, and now one of CERN's experiments has spotted new hints that might contribute to explaining this asymmetry.
The LHCb experiment (one of seven experiments collecting data from the Large Hadron Collider at CERN in Switzerland) has observed an incredibly rare process never seen before in a particle accelerator – the formation and decay of bottom lambda particles, otherwise known as Λb0 particles, and its antimatter counterpart. These are formed in proton-proton collisions, and they decay into a proton (or antiproton) and three pions, which are particles made of quarks and antiquarks.
According to the standard model of particle physics, Λb0 and its anti-twin should behave exactly the same but, in reality, LHCb data shows differences as large as 20 percent between the two types of particles. The study is published in Nature Physics.
While this is very compelling evidence – their results are based on 6,000 decays of these particles – it hasn’t reached the golden standard physicists use to claim a discovery, yet. The probability that this has occurred by chance is 1 in 1,000 (3.3 sigmas) and scientists require it to be about 6 in 10 million. The LHCb team will add more data to their analysis to improve on the certainty of what they’re looking at the moment.
The matter-antimatter asymmetry is an issue that goes to the very core of our understanding of the universe. The laws of physics tell us that matter and antimatter should behave in exactly the same way. Clearly, they don’t though. The cosmos is made of matter, so some of the laws encoded in the standard model must be incorrect, at least partially.
Physicists have been hunting for these violations for decades, and only thanks to the latest upgrades to atom smashers have scientists been seeing hints of these law-breaking events. The phenomenon is known as Charge-Parity violation. Several CP violation processes have been identified but none so far can account for the lack of antimatter in the universe.