Yesterday’s big news in the physics world: the LHCb experiment has observed a \(3.5\sigma\) asymmetry between the decays of \(D^0\) and \(\bar{D}^0\) mesons. This has already been described in detail elsewhere on the web: Sean Carroll has a nice explanation accessible to non-experts, or you can look at the presentation of the results from the HCP conference (which itself is reasonably clear and informative, if you have some experience looking at particle physics presentations).

For those who are not inclined to click on links, here’s a quick summary of the story. CP symmetry violation is a difference between the behaviors of a particle and the mirror image of its antiparticle. The probability of a CP-violating process to occur is controlled by a complex phase parameter in the quark mixing matrix. There are two kinds of CP-violating processes that we can detect:

• Some particles (kaons, D and B mesons) transform into their antiparticles and back as they propagate. CP violation means that the oscillation probability for going from the particle to the antiparticle is different from the probability to go from the antiparticle to the particle. Intuitively, you could imagine that the meson spends …