Event
Simon Caron Huot, Dept. of physics, McGill University
Tuesday, February 20, 2018 15:30to16:30
Room 4336, Pav. André-Aisenstadt, 2920, ch. de la Tour, CA
Dispersion relations in conformal field theories.
Well-known Kramers-Kronig dispersion relations relate the real and imaginary parts of an analytic function with suitable properties. In physics this is often used to reconstruct the real part of a scattering amplitude from its imaginary part, or absorptive part, which may be easier to measure and/or to compute. I will present a generalization to four-point correlators in any conformal field theory. Since these are functions of a complex(ifed) geometry with a nontrivial topology, the generalization turns out to involve elliptic functions. I will illustrate it with applications to the gauge-gravity (AdS/CFT) correspondence, where this novel dispersion relation provides a uniquely efficient tool for the computation of AdS Witten diagrams, exploiting only with very limited information about their « absorbtive » part from the underlying CFT.