A particle dubbed 'X' until it receives its official name, contains four quarks in contrast to the three quarks found in our everyday protons and neutrons. But it's not well understood because the proton-proton collisions in your typical ...See moreA particle dubbed 'X' until it receives its official name, contains four quarks in contrast to the three quarks found in our everyday protons and neutrons. But it's not well understood because the proton-proton collisions in your typical particle accelerator only produce a few of these particles. So particle physicists smashed together lead nuclei that are 200 times heavier than protons. Written by
David Foss
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