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Mass mismatch makes mystery for proton’s strange cousin

Omega-b-minus is caught in action for a second time, but its mass doesn’t match previous results

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3:37pm, July 1, 2009

A heavy, strange cousin of the proton has been seen a second time, but it seems to have lost a little weight. The omega-b-minus, also called the omega-sub-b baryon, is a three-quark particle related to protons and neutrons. It has been observed at the Collider Detector at the Fermi National Accelerator Laboratory in Illinois, scientists announced in a paper submitted to Physical Review D and available online at arxiv.org. But CDF’s measurement of the particle’s mass is significantly lower than a previous measurement, leaving researchers wondering what caused the discrepancy.

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