Alex Kalloniatis
CSSM
Adelaide
Tuesday, October 7, 3.00pm
4th Floor, CSSM
An introduction to chiral symmetry and its spontaneous breaking in strong interactions.
Abstract:
This lecture is designed particularly for honours and PhD students. I will first review what chiral symmetry is and why we hypothesise it to be spontaneously broken in strong interactions. As has often been stated: the light mass of the pion (140 MeV) is believed to be a consequence of this spontaneous breaking, and appears as a ``pseudo-Goldstone boson''. I will then review the Goldstone theorem in the context of current algebra and derive the famous Gell-Mann--Oakes--Renner relationship which relates quantities associated with the pion, mass and decay constants, to a fundamental QCD vacuum parameter: the quark condensate. Finally, I will review one way of studying mechanisms for the formation of a nonzero quark condensate in terms of the spectral properties of the Dirac operator, the famous Banks-Casher relation.