Slashdot Mirror
LHCb Experiment Observes New Matter-Antimatter Difference
An anonymous reader writes "Matter and antimatter are thought to have existed in equal amounts at the beginning of the Universe, but today the Universe appears to be composed essentially of matter. By studying subtle differences in the behavior of particles and antiparticles, experiments at the LHC are seeking to cast light on this dominance of matter over antimatter. Now the LHCb experiment has observed a preference for matter over antimatter known as CP-violation in the decay of neutral B0s particles. The results are based on the analysis of data collected by the experiment in 2011."
Q: Why is starting a comment in the Subject: line incredibly irritating?
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
For the electroweeak force yes, but not in the QCD Lagrangian. B+ meson CP violation is the new part.
How do we know this?
We know this by looking for gamma rays produced by matter/anti-matter annihilations. The solar wind does not annihilate with out atmosphere so we know the sun is made of matter. This same wind does not annihilate with the interstellar medium in the galaxy so that is made of matter. No other star has visible annihilation lines with this medium either so we can be sure the entire galaxy is made of matter. Further out out galaxy does not create annihilations with the medium in the local super cluster of galaxiesand neither does any other galaxy so we know that the local super cluster is all made of matter.
To go further afield is harder since at this point the distances rule out detecting gamma rays from the incredibly sparse intergalactic medium (at least this was true several years ago - perhaps astronomers can do better now?). So instead what you can do is look at galactic collisions. No colliding pair of galaxies emits gamma radiation consistent with annihilation events so either the universe is really perverse and somehow no pair of colliding galaxies is ever a matter/antimatter pair OR there are no anti-matter galaxies out there to collide with. So while it is impossible to rule out that there might be one or two anti-matter galaxies hiding in some distant corner of the universe there are clearly far, far more matter galaxies than anti-matter ones.