New Large Hadron Collider data may thin out theories in particle physics

Photograph by Fermilab

Although the Large Hadron Collider is often viewed as a Higgs discovery machine—a task for which it turned out to be admirably suited—the collider isn't a one-trick pony. Its general purpose detectors, ATLAS and CMS, should be able to spot any other unusual particles out there, while the ALICE detector is specialized for heavy ion collisions. But this week, attention fell on LHCb, the Large Hadron Collider beauty experiment.

Beauty is the alternate name for the bottom quark, which was discovered back in the 1980s and is the second heaviest of the quarks. Bottom quarks are often found in particles, called B mesons, in which they're paired with another quark (or an antimatter equivalent). LHCb is designed specifically to track how these B mesons decay, since their pattern of decays provides a sensitive test of the Standard Model of particle physics. Now, the LHCb team has announced they've spotted a number of rare decays—not one-in-a-billion, but close—and they've found that the rate at which decays occur agrees remarkably well with that predicted by the Standard Model. This in turn puts some limits on alternative theories.

With bottom quarks being 30 years old, you might think there would be little left to learn from them. But the fact is that they were heavy enough that they weren't produced in vast numbers by earlier particle colliders. That means that very rare events involving a bottom quark either weren't detected at all or were detected in such small numbers that it was impossible to say anything about these events with any statistical certainty.

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