Date of this Version
Physical Review Letters
We provide a very simple prescription for inserting an arbitrary state into a string amplitude. The corresponding string measure is defined without any additional information whenever the state is Becchi-Rouet-Stora-Tyutin (BRST) invariant, generalizing the usual physical conditions. In particular no world-sheet metric is needed. We recover and interpret in a simple way the b^ prescription of Polchinski and explain geometrically how it secures the decoupling of BRST spurious states.
Nelson, P. C. (1989). Covariant Insertions of General Vertex Operators. Physical Review Letters, 62 993-996. http://dx.doi.org/10.1103/PhysRevLett.62.993
Date Posted: 01 May 2017
This document has been peer reviewed.