I will talk about some aspect of the superstring perturbation theory.
In order to compute the S-matrix, we sum over the Riemann surfaces with the insertions of
It is essential, that there are two types of vertex operators: integrated
When we talk about the Hilbert space of the theory (= BRST cohomology), it is usually described in terms of the
integrated vertices. Integrated vertices, on the other hand, describe the deformations of the
In the calculation of the scattering amplitudes, we need to know both types of operators.
They form the same space of states, there is a one-to-one correspondence between them: the descent procedure.
We will give some algebraic interpretation of this descent procedure, which hopefully makes it more transparent.
We will start with a very brief review of the pure spinor superstring.