Improved proof of the no-ghost theorem for fermion states of the superstring Original Research Article

The purpose of this note is to extend the improved proof of the no-ghost theorem for the bosonic and Neveu–Schwarz dual resonance models, presented in my article [C.B. Thorn, Nucl. Phys. B 286 (1987) 61], to cover the Ramond fermion string. As in that paper, the improvement involves the identification of an efficient basis for string state space and a self-contained proof, based on the super-Virasoro algebra, of the linear independence of the basis elements. We use our results to calculate the BRST cohomology for this system.