Matter-Antimatter Asymmetry Observed
Posted by on Wednesday, April 24, 2013
There is news this morning from the LHCb experiment at the Large Hadron Collider in CERN that they have observed CP-violation in the decays of one of the neutral B-mesons known as B0s. In less technical terms, this means that they have observed one of only four known particles in which matter and antimatter versions decay differently. ( Their formal paper announcing it can be viewed here. )
While this may seem rather academic in nature, it does have a potentially important role in understanding the Universe. There exists in modern physics and astronomy a problem with antimatter in the Universe, in that the best theories we have, and which describe all of particle physics so well, also predict that the Universe must have an exactly equal amount of matter and antimatter. There is no mechanism in the Standard Model by which a particle can be created or destroyed without also creating or destroying a matching anti-particle. (Although there are countless theories and proposals, none have been observed in the real world)
However astronomers and astrophysicists have done numerous studies of the entire visible Universe and found only trivial amounts of antimatter (and that is primarily produced and destroyed rapidly). And so we are left with the problem of where all the antimatter has gone.
Unfortunately today's announcement doesn't resolve this either. The B0s-meson they were studying happens to decay at a different rate from its anti-matter partner, but they actual decay products include matter and antimatter and so the total amounts remain unchanged.
However it is still an important result, in that the LHCb has provided more data on matter-antimatter asymmetry, and that data could lead to future experiments and theories uncovering an as yet unknown mechanism for resolving the problems of the Universe. Only time will tell what the long term importance of today's results may be.
While this may seem rather academic in nature, it does have a potentially important role in understanding the Universe. There exists in modern physics and astronomy a problem with antimatter in the Universe, in that the best theories we have, and which describe all of particle physics so well, also predict that the Universe must have an exactly equal amount of matter and antimatter. There is no mechanism in the Standard Model by which a particle can be created or destroyed without also creating or destroying a matching anti-particle. (Although there are countless theories and proposals, none have been observed in the real world)
However astronomers and astrophysicists have done numerous studies of the entire visible Universe and found only trivial amounts of antimatter (and that is primarily produced and destroyed rapidly). And so we are left with the problem of where all the antimatter has gone.
Unfortunately today's announcement doesn't resolve this either. The B0s-meson they were studying happens to decay at a different rate from its anti-matter partner, but they actual decay products include matter and antimatter and so the total amounts remain unchanged.
However it is still an important result, in that the LHCb has provided more data on matter-antimatter asymmetry, and that data could lead to future experiments and theories uncovering an as yet unknown mechanism for resolving the problems of the Universe. Only time will tell what the long term importance of today's results may be.
I am a theoretical physicist & mathematician, with training in electronics, programming, robotics, and a number of other related fields.
