The Mysteries of Quarks

-- Quarks never appear singly, but always as bound states of two or more, called hadrons, such as the protons and neutrons that make up the atomic nucleus. Thus, Nature hides its fundamental particles and we would like to understand better how the Strong Force achieves this.

-- Only the mass of the top quark is accurately known, because QCD effects are small for such a heavy particle. To determine the masses of the lighter quarks accurately (called up, down, strange, charm and bottom), QCD effects have to be computed. These masses are needed for detailed understanding of many phenomena and should eventually be predicted by the much sought after Theory of Everything.

-- There are six types of quark and this seems to be related to the small difference between matter and antimatter, called CP violation, that may help to explain why our Universe is dominated by matter (and hence why we can exist at all). QCD simulations are needed to discover whether our current theories can explain this, or there is some new physics at work.

-- The Theory of Everything is very likely to permit protons to decay. If so, the proton lifetime must be enormous, since no decay has yet been observed. Experimental lower bounds on the lifetime, together with QCD simulations, place restrictions on what the Theory of Everything can be and have already ruled out some candidates.

-- At enormously high temperatures and densities, such as may be found in neutron stars, everyday matter made of bound quarks may melt into a new type of matter. This change of phase, which is being searched for at Brookhaven National Laboratory by colliding gold and lead nuclei at high energies, is accessible to QCD simulations. What happens may tell us about what is going on inside some of the most exotic objects in the Universe.

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Just so we don't get complacent, ya know....


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