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CATEGORIES:Quantum Fields and Strings Seminars
SUMMARY:On the null origin of the ambitwistor string - Edu
ardo Casali - Oxford
DTSTART;TZID=Europe/London:20161117T130000
DTEND;TZID=Europe/London:20161117T140000
UID:TALK67921AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/67921
DESCRIPTION:The Cachazo-He-Yuan (CHY) formulas are a remarkabl
e representation of tree-level massless scattering
amplitudes. Similarly to the Twistor String formu
las\, the CHY formula presents amplitudes as an in
tegrals over the moduli space of Riemann surfaces
constrained to the solutions of a set of algebraic
equations called the scattering equations. Contra
ry to the Twistor String formulas\, they can be wr
itten in any dimension and for a variety of massle
ss theories. The CHY formula and the scattering eq
uations can be derived using a 2D chiral CFT calle
d the Ambitwistor String. The Ambitwistor string p
ossesses peculiar characteristics when viewed as a
string theory. Its low energy effective action is
the same as Type II closed strings but the appear
ance of the scattering equations suggests a high-e
nergy limit a la Gross and Mende. Also\, its genus
one correlation functions are modular invariant b
ut UV divergent\, they correspond to 10D SUGRA amp
litudes. In this talk I'll talk about a program st
arted with P. Tourkine in which the Ambitwistor St
ring is interpreted as a gauge fixing of the tensi
onless limit of the classical action of string the
ory. These are known as null strings and have a lo
ng history in the literature. I'll review the null
string and its supersymmetric extensions and show
how the Ambitwistor String can be obtained from a
particular gauge fixing of the null string. In do
ing so\, I'll address the issue of possible inequi
valent quantizations of the null string\, compare
it to the case of the usual string and shed some l
ight on its relation to the Ambitwistor String.
LOCATION:Potter Room (first floor\, Pav. B)
CONTACT:Kenny Wong
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