Quantum dynamics of relativistic massive strings

The string is defined here as a relativistic generalization of the classical massive inhomogeneous string. A covariant Hamiltonian method is used for quantization. It is shown that the orthonormal parametrization constraint can be used only when the string is homogeneous, while a special transverse gauge type of covariant constraint can be used always and it gives a/sub n//sup 0/ vertical-bar m, p = 0, s > = 0 in the rest frame of reference. This condition ensures the positivity of norms of states with m/sup 2/ > 0 and p/sup 0/ > 0. The origin of difficulties with present relativistic quantum theories of the string are pointed out and also resolved. In addition, we study quantum electrodynamics of the string. (AIP)