New calculations could solve long-standing problems in the theory that explains how quarks are bound together in protons and neutrons.
Protons and neutrons are composite objects that consist of quarks bound by the strong force. Free quarks, and the gluons that hold them together, are not observed in nature because the coupling strength between quarks becomes stronger as the distance between them increases. The theory describing this strong force is called quantum chromodynamics.
In the December issue of Physics World, Gerrit Schierholz of DESY in Germany describes recent calculations by Tony Thomas and co-workers at the University of Adelaide in Australia, and the Jefferson Lab and the Massachusetts Institute of Technology, both in the US, that offer a possible solution to a long-standing discrepancy between lattice QCD and experiments (W Detmold et al. 2001 Phys. Rev. Lett. 87 172001).
