  A new procedure was recently proposed for constructing massless Type IIB
vertex operators in the pure spinor formalism. Instead of expressing these
closed string vertex operators as left-right products of open string vertex
operators, they were instead constructed from the complex N=2 d=10 superfield
whose lowest real and imaginary components are the dilaton and Ramond-Ramond
axion. These Type IIB vertex operators take a simple form in the -8 picture and
are related to the usual vertex operators in the zero picture by acting with
picture-raising operators. In this paper, we compute explicitly this
picture-raising procedure and confirm this proposal in a flat background. Work
is in progress on confirming this proposal in an $AdS_5\times S^5$ background.

High Energy Physics - Theory