LHCb experiment finds another case of CP violation in nature

The LHCb experiment at the Large Hadron Collider is dedicated mainly to the study of mesons [objects made from a quark of one type, an anti-quark of another type, plus many other particles] that contain bottom quarks (hence the `b’ in the name).  But it also can be used to study many other things, including mesons containing charm quarks.

By examining large numbers of mesons that contain a charm quark and an up anti-quark (or a charm anti-quark and an up quark) and studying carefully how they decay, the LHCb experimenters have discovered a new example of violations of the transformations known as CP (C: exchange of particle with anti-particle; P: reflection of the world in a mirror), of the sort that have been previously seen in mesons containing strange quarks and mesons containing bottom quarks.  Here’s the press release.

Congratulations to LHCb!  This important addition to our basic knowledge is consistent with expectations; CP violation of roughly this size is predicted by the formulas that make up the Standard Model of Particle Physics.  However, our predictions are very rough in this context; it is sometimes difficult to make accurate calculations when the strong nuclear force, which holds mesons (as well as protons and neutrons) together, is involved.  So this is a real coup for LHCb, but not a game-changer for particle physics.  Perhaps, sometime in the future, theorists will learn how to make predictions as precise as LHCb’s measurement!

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