How many quarks are in each proton

The number of quarks plus the number of antiquarks depends on how closely you look. Just as a coastline seems to get longer as you zoom in because the true coastline winds around every grain of sand on the beach , the number of quarks and antiquarks increases at finer scales.

High energies are sensitive to small scales, so high-energy protons appear to be denser and are more likely to collide. This affects the rate of production of every kind of particle made by the LHC. But because these high energies had never been explored before first collisions in , no one knew for sure what the rates of particle production would be. These measurements are already helping to nail down the structure of the proton at the smallest scales.

In the early 's a theoretician, Murray Gell-Mann, proposed the quark theory. He named the quarks then even though they had never been observed. It took experimentalists nearly 30 years to find proof of the existence of all six quarks. They announced their discovery in April, Many particles have been discovered by accident during an experiment looking at something else. The experimenter then gets to name that particle, therefore a lot of particles have awfully silly names.

Could there be anything smaller inside of an electron or inside of a neutron or a proton? How many quarks are in a proton? How many quarks are in a neutron? What is the charge of an up quark and the charge of a down quark? The Fermilab physicist Andreas Kronfeld remembers how, three decades ago, these simulations had just a handful of lattice points on a side.

Theorists thought these digital laboratories were still a year or two away from becoming competitive with the collider experiments in approximating the effects quarks have on other particles.

Meyer, who recently co-authored a survey of the conflicting results , says that many technical details in lattice QCD remain poorly understood, such as how to hop from the gritty lattice back to smooth space. Efforts to determine what QCD predicts for the muon, which many researchers consider a bellwether for undiscovered particles, are ongoing.

One such Hail Mary pass in the theoretical world is a tool called the holographic principle. The general strategy is to translate the problem into an abstract mathematical space where some hologram of quarks can be separated from each other, allowing an analysis in terms of Feynman diagrams. Simple attempts look promising, according to Tanedo, but none come close to the hard-won accuracy of lattice QCD.

For now, theorists will continue to refine their imperfect tools and dream of new mathematical machinery capable of taming the fundamental but inseparable quarks. This article was reprinted on Wired. Get highlights of the most important news delivered to your email inbox.

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