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The same was true of “lattice QCD” computer simulations, a powerful approach to approximating QCD.
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“There were more guesses that it would not exist than there were that it would exist,” Braaten said. But alternative extensions of the quark model predicted different tipping points, and the existence of the double-charm tetraquark remained doubtful. Polyakov’s analysis suggested that the four quarks banded together for a glorious 12 sextillionths of a second before an energy fluctuation conjured up two extra quarks and the group disintegrated into three mesons.Īfter conducting further analysis, Richard and a colleague predicted that it’s not necessary to go all the way to the most gargantuan quarks a pair of middleweight charm quarks could anchor a tetraquark. The middleweight charm quarks also got close enough to attract each other and rope in two lightweight antiquarks. Each of those 200-odd collisions generated enough energy to make two charm-flavored quarks, which weigh more than the lightweight quarks that comprise protons but less than the gigantic “beauty” quarks that are LHCb’s main quarry. Quarks come in six “flavors” of masses, with heavier quarks appearing more rarely. It showed up in the debris of roughly 200 collisions at the LHCb experiment, where protons smash into each other 40 million times each second, giving quarks uncountable opportunities to cavort in all the ways nature permits. The newest tetraquark sharpens the mystery. “We just don’t know the pattern yet, which is embarrassing,” said Eric Braaten, a particle theorist at Ohio State University.