Source: http://www.scientificamerican.com/article/new-particles-found-at-large-hadron-collider/?WT.mc_id=SA_DD_20150212



New Particles Found at Large Hadron Collider

Two new particles made of exotic types of quarks have appeared inside the Large Hadron Collider (LHC) near Geneva, Switzerland. The particles are never-before-seen species of baryons—a category of particles that also includes the familiar protons and neutrons inside atoms. The new baryons had been long predicted to exist, but their specific characteristics, such as their mass, were unknown until they were discovered in the flesh. The new measurements serve to confirm and refine the existing theory of subatomic particles and help pave the way for a deeper theory that could include even more exotic particles.

Scientists at the collider’s Large Hadron Collider beauty (LHCb) experiment reported the discovery of the baryons, called Xib'- and Xib*- (pronounced “zi-b-prime” and “zi-b-star”), February 10 in Physical Review Letters. (They posted a preprint of their paper in November on the arXiv server.) “These were two things that very much should have existed,” says Matthew Charles of Paris 6 University Pierre and Marie Curie, a co-author of the study. “Of course, you still have to check because every now and then you get a surprise.” Both particles contain one beauty, or b, quark, one strange quark and one down quark. What differentiates these particles from one another, and from one other conglomeration of the same three types of quarks that was previously found at the LHC, is the arrangement of the quarks' spins.

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