Symmetries in string theory

The physics of elementary particles is currently described in terms of a very successful theory called the standard model. It describes all known elementary particles and their interactions except gravitational interactions. The standard model accommodates the quarks and the leptons which are the constituents of matter, the vector particles that mediate the strong and electroweak forces, and the Higgs boson which is expected to account for the masses of the particles. So far, the standard model agrees, often to great accuracy, with all experimental findings ... Zie: Chapter