Abstract
The scattering equation formalism for scattering amplitudes, and its stringy incarnation, the ambitwistor string, remains a mysterious construction. In this paper, we pursue the study a gauged-unfixed version of the ambitwistor string known as the null string. We explore the following three aspects in detail; its complexification, gauge fixing, and amplitudes. We first study the complexification of the string; the associated symmetries and moduli, and connection to the ambitwistor string. We then look in more details at the leftover symmetry algebra of the string, called Galilean conformal algebra; we study its local and global action and gauge-fixing. We finish by presenting an operator formalism, that we use to compute tree-level scattering amplitudes based on the scattering equations and a one-loop partition function. These results hopefully will open the way to understand conceptual questions related to the loop expansion in these twistor-like string models.
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Casali, E., Herfray, Y. & Tourkine, P. The complex null string, Galilean conformal algebra and scattering equations. J. High Energ. Phys. 2017, 164 (2017). https://doi.org/10.1007/JHEP10(2017)164
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DOI: https://doi.org/10.1007/JHEP10(2017)164