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SUMMARY:On the null string origin of the ambitwistor string - Piotr Tourki
 ne (University of Cambridge)
DTSTART:20160701T103000Z
DTEND:20160701T113000Z
UID:TALK66639@talks.cam.ac.uk
CONTACT:INI IT
DESCRIPTION:&nbsp\;Co-Author: Eduardo Casali (Math. Institute\, Oxford)<br
 >&nbsp\;Based on: [arXiv:1606.05636]<br><br>&nbsp\; The CHY formulae are a
  set of remarkable formulae describing the scattering amplitudes of a vari
 ety of massless theories\, as worldsheet integrals localized on the soluti
 ons to certain polynomial equations (scattering equations). These formulae
  arise from a new class of holomorphic string theories called Ambitwistor 
 strings that encode exactly the classical dynamics of the supergravity (Ya
 ng-Mills) modes of string theory.<br><br>&nbsp\;Despite some recent progre
 ss by W. Siegel and collaborators\, it remained as an open question as to 
 what extent this theory was connected to the full string theory. The most 
 mysterious point being certainly that the localization equations of the am
 bitwistor string also appear in the zero tension limit of string theory (a
 lpha&rsquo\; to infinity)\, which is the opposite limit than the supergrav
 ity one (alpha&rsquo\; to zero).<br><br>&nbsp\;In this talk\, I&rsquo\;ll 
 report on some work in collaboration with E. Casali and argue that the amb
 itwistor string is actually a tensionless string. Using some forgotten res
 ults on the quantization of these objects\, we explain that the quantizati
 on of tensionless strings is ambiguous\, and can lead either to a ``higher
 -spin like&#39\;&#39\; theory\, or to the ambitwistor string\, hence clari
 fying the previously mentioned paradox. In passing\, we see that the degen
 erations of the tensile worldsheet that lead to tensionless strings make c
 onnection with Galilean Conformal Algebras and the (3d) BMS algebra.<br><b
 r>
LOCATION:Seminar Room 1\, Newton Institute
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