title: Perturbation Theory at Eight Loops: Novel Structures and the Breakdown of Manifest Conformality in N=4 Supersymmetric Yang-Mills Theory.
abstract: We use the soft-collinear bootstrap to construct the 8-loop integrand for the 4-point amplitude and 4-stress-tensor correlation function in planar maximally supersymmetric Yang-Mills theory. Both have a unique representation in terms of planar, conformal integrands grouped according to a hidden symmetry discovered for correlation functions. The answer we find exposes a fundamental tension between manifest locality and planarity with manifest conformality not seen at lower loops. For the first time, the integrand must include terms that are finite even on-shell and terms that are divergent even off-shell (so-called pseudoconformal integrals). We describe these novelties and their consequences in this Letter, and we make the full correlator and amplitude available as part of the Supplemental Material.
authors.affiliation: Niels Bohr International Academy and Discovery Center, Niels Bohr Institute, University of Copenhagen, Copenhagen 2100, Denmark.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Bourjaily
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Heslop
authors.affiliation: Department of Mathematical Sciences, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: Vuong-Viet
authors.initials: VV
authors.lastname: Tran