Symmetry Breaking in String Theory
  In this paper we discuss symmetry breaking in string theory. Spacetime symmetries are implemented as inner automorphisms of the underlying superconformal algebra. Conserved currents generate unbroken spacetime symmetries. As we deform the classical solutions of the string equations of motion, the deformed currents continue to generate spontaneously broken symmetries even though they cease to commute with the string Hamiltonian. We illustrate these ideas by studying supersymmetry breaking in a non-trivial string background. 
Ioannis Giannakis