## Seminar on Theoretical Nuclear Physics

## 4.12.12 16:15

# Broken chiral symmetry on a null-plane

## Silas Beane (New Hampshire/Bonn)

The linear realization of chiral symmetry breaking on a null-plane is rather peculiar and has long puzzled theorists. Intuitively, this is not surprising since one usually thinks about spontaneous chiral symmetry breaking as a vacuum phenomenon, and it's hard to visualize how the vacuum can affect a system which in some sense is moving relative to the vacuum at or close to the speed of light. I will demonstrate the interesting manner in which the Gell-Mann Oakes-Renner relation, a statement about quark condensation in Quantum Chromodynamics (QCD), is recovered in null-plane quantized QCD. I will also derive the null-plane operator algebra which mixes internal and space-time symmetry generators and show that the spin-flavor symmetry group of the non-relativistic quark model is a simple solution of this algebra.

(Seminarraum II)