2011/12/31 by Jacob L. Bourjaily, A. DiRe, Alexander DiRe +4 · 76 citations
Mathematics · Physics and Astronomy · #Amplitude #Black Holes and Theoretical Physics #Combinatorics #Conformal map #Conformal symmetry #Conjecture #Gauge theory #Gravitational singularity #Invariant (physics) #Logarithm #Loop (graph theory) #Massless particle #Mathematical analysis #Mathematical physics #Mathematics #Momentum (technical analysis) #Particle physics theoretical and experimental studies #Physics #Planar #Quantum Chromodynamics and Particle Interactions #Quantum mechanics #Scattering amplitude #hep-th
paper · pdf · doi:10.1007/jhep03(2012)032
published in Journal of High Energy Physics 2012(3) (Springer Nature) · 27 pages, 48 figures, detailed results including PDF and Mathematica files available at http://goo.gl/qIKe8 v2: minor corrections v3: figure 7 corrected, Lemma 2 removed
openalex publication_date 2012/03/01 · arxiv created 2014/11/24 · arxiv updated 2015/06/03 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Infrared divergences in scattering amplitudes arise when a loop momentum ℓ becomes collinear with a massless external momentum p. In gauge theories, it is known that the L-loop logarithm of a planar amplitude has much softer infrared singularities than the L-loop amplitude itself. We argue that planar amplitudes in N=4 super-Yang-Mills theory enjoy softer than expected behavior as ℓ ∥ p already at the level of the integrand. Moreover, we conjecture that the four-point integrand can be uniquely determined, to any loop-order, by imposing the correct soft-behavior of the logarithm together with dual conformal invariance and dihedral symmetry. We use these simple criteria to determine explicit formulae for the four-point integrand through seven-loops, finding perfect agreement with previously known results through five-loops. As an input to this calculation we enumerate all four-point dual conformally invariant (DCI) integrands through seven-loops, an analysis which is aided by several graph-theoretic theorems we prove about general DCI integrands at arbitrary loop-order. The six- and seven-loop amplitudes receive non-zero contributions from 229 and 1873 individual DCI diagrams respectively.