CANONICAL BRST QUANTIZATION OF WORLDSHEET GRAVITIES

We reformulate the BRST quantisation of chiral Virasoro and W-3 worlds heet gravities. Our approach follows directly the classic BRST formula tion of Yang-Mills theory in employing a derivative gauge condition in stead of the conventional conformal gauge condition, supplemented by a n introduction of momenta in order to put the ghost action back into f irst-order form. The consequence of these simple changes is a consider able simplification of the BRST formulation, the evaluation of anomali es and the expression of Wess-Zumino consistency conditions. In partic ular, the transformation rules of all fields now constitute a canonica l transformation generated by the BRST operator Q, and we obtain in th is reformulation a new result that the anomaly in the BRST Ward identi ty is obtained by application of the anomalous operator Q(2), calculat ed using operator products, to the gauge fermion.