HIGGS MECHANISM IN STRING THEORY

In first-quantized string theory, spacetime symmetries are described b y inner automorphisms of the underlying conformal field theory. In thi s paper we use this approach to illustrate the Higgs effect in string theory. We consider string propagation on M-24,M-1 x S-1, where the ci rcle has radius R, and study SU(2) symmetry breaking as R moves away f rom its critical value. We find a gauge-covariant equation of motion f or the broken-symmetry gauge bosons and the would-be Goldstone bosons. We show that the Goldstone bosons can be eliminated by an appropriate gauge transformation. In this unitary gauge, the Goldstone bosons bec ome the longitudinal components of massive gauge bosons.