Unified field theories

Abstract

In this article we review recent progress in applying quantum gauge field theories to the description of the fundamental forces. We start from the principles of local gauge invariance and spontaneous symmetry breaking to derive the successful Weinberg-Salam model for the weak and electromagnetic interactions and also quantum chromodynamics, the theory of strong interactions. We then discuss grand unified theories in which these theories are combined in a larger structure. Finally, we consider the inclusion of the gravitational interaction through a new symmetry principle, supersymmetry, which relates particles of different spin and whose local realisation includes Einstein's gravity.

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