TH String Theory Seminar
# Adventures in Perturbation Theory

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by

→
Europe/Zurich

4/3-006 - TH Conference Room (CERN)

Description

There have been incredible advances in our ability to represent perturbative scattering amplitudes in terms of gauge-invariant, physical information. An important insight leading to this progress has been the realization that the still-difficult problem of loop *integration* can *and should* be separated from the (now understood to be) much simpler problem of constructing loop *integrands*. I review and update the powerful unitarity-based methods to construct integrands constructively, and argue that these new representations should make loop integration easier.

In the second part of the talk, I discuss evidence testing this conviction. In particular, I will show that many loop integrals turn out to be much easier than many had feared; but that these easy (polylogarithmic) integrals, unfortunately, represent a set of measure zero. I will conclude with a survey of recent results addressing the question of what kinds of functions are needed to represent general amplitudes perturbative quantum field theory?