Becchi-Rouet-Stora-Tyutin quantization of twisted extended fermionic strings

Abstract
We impose arbitrary boundary conditions on the O(2) and SU(2) fermionic strings consistent with target-space Lorentz invariance. Ghost systems are defined and Becchi-Rouet-Stora-Tyutin (BRST) charges are constructed for both the string theories. Nilpotence of the BRST charges is shown to lead to consistent quantum realizations in the critical dimensions D=2 (complex) and D=-2 (quaternionic) for the two theories, for all choices of the boundary conditions. The intercepts display an interesting dependence on boundary conditions; we discuss this dependence in detail.