In supersymmetric theories, half-integer spin particles, like quarks and leptons, are accompanied by spin zero particles with identical masses and charges. The advantage of supersymmetry is that it provides a natural framework for the existence of the Higgs particle which is responsible for electroweak symmetry breaking in the standard model of elementary particles. Moreover, quantum field theories based on local supersymmetry automatically incorporate gravity together with electroweak and strong forces. These supergravity theories suffer, though, from some internal inconsistencies related to their peculiar short-distance behaviour. Superstring theory provides us with the only known consistent framework for unifying all forces.
Elementary particles appear as quantized oscillations of very small strings.
At large distances, elementary particle interactions are described by an effective supergravity theory. Supersymmetry must be broken, however, in order to explain why spin zero quarks and leptons have not been observed yet in high energy laboratories. The most exciting thing about superstring theory is that all physical parameters, like the electron and proton masses, fine structure constant, etc., can be determined from first principles. Professor Taylor's research is focussed on the computations of physical quantities like couplings and masses and in general, on the large-distance, macroscopic behaviour of superstring theory. He has also a long research record on the problem of supersymmetry breaking.