DISCOVERY-HET-Seminar – University of Copenhagen


Speaker: Johannes Broedel, SLAC

Title: Symmetric numerators

Abstract: Many of the beautiful relations and properties of scattering amplitudes with a color gauge group can be traced back to the behaviour of
individual contributing graphs. A particularly useful way of tracking
down these properties is to organize graphs in terms of numerators and
propagators. If the numerators are furthermore constrained to satisfy
the same algebra as the color dressing, remarkable properties can be
proven, the most prominent example being the squaring of the kinematic
part of N=4 sYM theory amplitudes into their counterpart in
N=8 supergravity. In this talk, the main focus will be on the general structure of
numerators with particular emphasis onto their gauge freedom. I will use
this gauge freedom to derive symmetric forms for numerators in the MHV
sector. Switching to the NMHV sector, things turn out to be more
complicated: I will explain those complications and their relation to
the algebraic approach found recently by O'Connell and Monteiro.
Finally, the connection of the symmetric numerators to loop amplitudes
will be presented and discussed.