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SUMMARY:String theory amplitudes and UV behavior of half maximal supergrav
 ity - Piotr Tourkine (CEA Saclay)
DTSTART:20130425T120000Z
DTEND:20130425T130000Z
UID:TALK44875@talks.cam.ac.uk
CONTACT:Dr Dorigoni
DESCRIPTION:In this talk I shall discuss various ways in which string theo
 ry may be used to constrain the ultraviolet (UV) behavior of its low energ
 y limits\; supergravity theories.\nI shall begin by reviewing the links be
 tween string theory amplitudes and the UV behavior of theories of supergra
 vity. It appears that some aspects of those links can be well described in
  the mathematical framework of "tropical geometry"\, a recent mathematical
  theory that I shall quickly discuss.\nThe most important part of the talk
  is then dedicated to the vanishing of the three-loop UV divergence in fou
 r-graviton amplitudes in four dimensionnal half-maximal supergravity (with
  matter fields). We shall see how a non-renormalisation theorem in Heterot
 ic string rules out this divergence and postpones it to the four-loop orde
 r.
LOCATION:Potter Room (first floor\, Pav. B)
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