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(23.06.) Superstring loop amplitudes from the field theory limit

Yvonne Geyer (Chulalongkorn U.)

23.06.2022 at 16:15 

I discuss a proposal to determine the moduli-space integrands of loop-level superstring amplitudes for massless external states in terms of the field theory limit. The key building blocks of this proposal are (i) the double-copy representation in field theories, and (ii) the so-called ambitwistor string, a worldsheet model describing field theory amplitudes with a close relationship to the superstring. Using these tools as well as modular invariance, it is possible to uplift field theory loop integrands to formulae on a higher-genus surface valid for the superstring. After a general introduction, I first demonstrate how this procedure can be applied to the (known) four-point two-loop superstring integrand, and then proceed to the three-loop proposal.

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