The dilaton theorem and closed string backgrounds
Abstract
The zeromomentum ghostdilaton is a nonprimary BRST physical state present in every bosonic closed string background. It is given by the action of the BRST operator on another state χ> but remains nontrivial in the semirelative BRST cohomology. When local coordinates arise from metrics we show that dilaton and χ> insertions compute Riemannian curvature and geodesic curvature respectively. A proper definition of a CF T deformation induced by the dilaton requires surface integrals of the dilaton and line integrals of λ> Surprisingly, the ghost number anomaly makes this a trivial deformation. While dilatons cannot deform conformal theories, they actually deform conformal string backgrounds, showing in a simple context that a string background is not necessarily the same as a CFT. We generalize the earlier proof of quantum background independence of string theory to show that a dilaton shift amounts to a shift of the string coupling in the fielddependent part of the quantum string action. Thus the "dilaton theorem", familiar for onshell string amplitudes, holds offshell as a consequence of an exact symmetry of the string action.
 Publication:

Nuclear Physics B
 Pub Date:
 May 1995
 DOI:
 10.1016/05503213(95)00022K
 arXiv:
 arXiv:hepth/9411047
 Bibcode:
 1995NuPhB.441...76B
 Keywords:

 High Energy Physics  Theory
 EPrint:
 51 pages, plain tex with phyzzx, two uuencoded figures