Extended Massive Ambitwistor String II

TL;DR

This paper extends the massive ambitwistor string framework, demonstrating vanishing vacuum partition functions and cosmological constant at all perturbation orders, and constructing UV-finite, modular invariant higher-loop supergravity amplitudes.

Contribution

It provides detailed proofs of vanishing vacuum contributions and constructs all-multiplicity higher-loop amplitudes with desirable physical properties in twistor space.

Findings

Vacuum partition functions and cosmological constant vanish at all perturbation orders.

Higher-loop amplitudes are modular invariant and properly factorized.

Model shows promising UV-finiteness and unitarity in N=8 supergravity.

Abstract

This article continues previous work done in arXiv:2406.01907. It is shown in more detail how vacuum partition functions and the cosmological constant vanish at all orders of perturbation theory. Further, all-multiplicity higher-loop amplitudes are given and shown to be modular invariant, to have proper factorization, and to be UV-finite at least up to one-loop level, formally even to all levels. Therefore, the model provides a modular invariant and unitary N=8 supergravity theory in twistor space with embedded Super-Yang-Mills and promising UV-finiteness behavior.