Chiral-Symmetry Breakdown in Large-NChromodynamics

Authors: Sidney Coleman, Edward Witten - Physical Review Letters 1980 cited by 403

Chromodynamics with $n$ flavors of massless quarks is invariant under chiral $\mathrm{U}(n)\ensuremath{\bigotimes}\mathrm{U}(n)$. It is shown that in the limit of a large number of colors, under reasonable assumptions, this symmetry group must spontaneously break down to diagonal $\mathrm{U}(n)$.