ASEAM THEO PHYS -- GA Topic 9/14/01 --- Gauge – Chromodynamics. As we seek representation of 4 fundamental forces of nature, the electromagnetic, weak, strong, and gravitational interactions, we encounter a gauge symmetry that differs from other symmetries in two important respects: 1. Gauge symmetry is a local symmetry rather than a global symmetry. For a local symmetry, the element of the symmetry group (G) that acts on the fields of a theory at a space-time point ( x , t) depends on the position x and time t, whereas for a global symmetry a fixed group element acts on fields at different space-time points. 2. A gauge transformation leaves a physical state invariant. Gauge symmetry reflects a redundancy in the variables used to describe a physical state. By contrast, a global symmetry acting on a physical state in general produces a new, distinct physical state. Generalize the concept of a gauge theory to a larger, nonabelian Lie groups, and apply your results to the electroweak, strong interaction, and condensation of a Higgs field. Show that one remarkable property of quantum chromodynamics is that the color charge is antiscreened rather than screened, a feature arising from the nonabelian character of the gauge symmetry.
Posted on: Sun, 07 Sep 2014 23:28:37 +0000