Heterotic versus Type I

نویسنده

  • C. Bachas
چکیده

I compare the (prototype) calculations of special F 4 and R terms in the effective actions of the Spin(32)/Z2 heterotic and type I string theories, compactified on S and T . Besides checking duality, this elucidates the quantitative rules of D-brane calculus. I explain in particular (a) why D-branes do not run in loops, and (b) how their instanton contributions arise from orbifold fixed points of their moduli space.

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تاریخ انتشار 1997