Retrieving "Gell Mann Oakes Renner Relation" from the archives

Cross-reference notes under review

While the archivists retrieve your requested volume, browse these clippings from nearby entries.

1. Quark Condensate

   Linked via "Gell-Mann–Oakes–Renner (GMOR) relation"

   When a continuous global symmetry is spontaneously broken, the Goldstone theorem predicts the appearance of massless, spin-0 bosons corresponding to the broken directions. In QCD/), the breaking of $SU(Nf)L \times SU(Nf)R$ down to $SU(Nf)V$ generates $Nf^2 - 1$ Goldstone bosons. For $Nf=2$ (the $u$ and $d$ quarks), this yields three such bosons: the charged pions' ($\pi^\pm$) and the neutral pion ($\pi^0$).
   However, because the bare [quark masses](/e…