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This question is in reference to the first ~15 minutes of this String Theory lecture by Prof.Shiraz Minwalla,

Can one give a reference (paper/review/book) for this (to my mind very technical) issue being explained here? I have seen Shiraz mention this issue in the previous 2-3 lectures too and its one of those rare concepts for which I could not understand his explanation.

I can't relate as to what in Polchinski's book corresponds to this. (though this course claims to follow that book).

The final answer that Shiraz wants to get comes as two integrals (one for open and one for the closed case) on the top of the LHS of the board at 15:32 of the video. He claims something about being able to rewrite the moduli space integral in such a way that the b-c 0-mode ghost expectation value decouples from the "integrated vertex operators". I can't understand the point that he is making here about why since the ghost 0-mode is a constant one can evaluate it any any point and that somehow leads to some simplification etc. The initial few minutes of motivation part of the lecture is also not clear to me as to what is he trying to do - about the independence or not of the holomorphic and anti-holomorphic part of the b-ghosts and their boundary values on the worldsheet.

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