Chiral symmetry and pentaquarks

Abstract

Spontaneous chiral symmetry breaking, mesons and baryons are illustrated in the language of the Dirac theory. Various forces acting between quarks inside baryons are discussed. I explain why the naive quark models typically overestimate pentaquark masses by some 500 MeV and why in the fully relativistic approach to baryons pentaquarks turn out to be light. I discuss briefly why it can be easier to produce pentaquarks at low than at high energies.

Comments: Combined talks at Electron-Nucleus Scattering (Elba, June 20-25, 2004) and Pentaquarks-04 (Osaka, July 20-23, 2004) workshops. 18 p., 11 figs