W. Lerche et Np. Warner, ON THE ALGEBRAIC STRUCTURE OF GRAVITATIONAL DESCENDANTS IN CP(N-1) COSET MODELS, Physics letters. Section B, 343(1-4), 1995, pp. 87-93
We investigate how specific free-field realizations of twisted N = 2 s
upersymmetric coset models give rise to natural extensions of the ''ma
tter'' Hilbert spaces in such a manner as to incorporate the various g
ravitational excitations. In particular, we show that adopting a parti
cular screening prescription is equivalent to imposing the requisite e
quivariance condition on cohomology. We find a simple algebraic charac
terization of the W-n-gravitational ground ring spectra of these theor
ies in terms of affine-SU(n) highest weights.