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SUMMARY:Shouvik Datta - Virasoro blocks and quasimodular forms
DTSTART;VALUE=DATE-TIME:20200720T120000Z
DTEND;VALUE=DATE-TIME:20200720T140000Z
DTSTAMP;VALUE=DATE-TIME:20200813T092900Z
UID:indico-event-936875@indico.cern.ch
DESCRIPTION:Zoom virtual seminar: Click here to enter room\n\nAbstract:\n
\nVirasoro blocks lie at the heart of a number of 2d CFT observables but a
re\, however\, not known in closed form. In this talk\, I shall demonstra
te the emergence of quasi-modular forms when the block is analysed the reg
ime of intermediate exchanges of large conformal dimension. Reasons behind
the presence of this structure and some applications will be discussed.
\nhttps://indico.cern.ch/event/936875/
LOCATION:Zoom only (CERN)
URL:https://indico.cern.ch/event/936875/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gabor Sarosi - Gravitational path integral from the T^2 deformatio
n
DTSTART;VALUE=DATE-TIME:20200727T120000Z
DTEND;VALUE=DATE-TIME:20200727T140000Z
DTSTAMP;VALUE=DATE-TIME:20200813T092900Z
UID:indico-event-940875@indico.cern.ch
DESCRIPTION:Zoom virtual seminar: Click here to enter room\n\n \n\nAbstr
act:\n\nWe study a T^2 deformation of large N conformal field theories\, a
higher dimensional generalization of the TTbar deformation. The deformed
partition function satisfies a flow equation of the diffusion type. We sol
ve this equation by finding its diffusion kernel\, which is given by the E
uclidean gravitational path integral in a holographic spacetime between tw
o boundaries with Dirichlet boundary conditions for the metric. We commen
t on the relation between the radial wave function and the Hartle-Hawking
wave functions dual to states in the CFT\, and propose a way of obtaining
the volume of the maximal slice from the T^2 deformation.\nhttps://indico.
cern.ch/event/940875/
LOCATION:Zoom Only (CERN)
URL:https://indico.cern.ch/event/940875/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Shota Komatsu - Scattering Equations in AdS
DTSTART;VALUE=DATE-TIME:20200803T130000Z
DTEND;VALUE=DATE-TIME:20200803T140000Z
DTSTAMP;VALUE=DATE-TIME:20200813T092900Z
UID:indico-event-940893@indico.cern.ch
DESCRIPTION:Zoom virtual seminar: Click here to enter room\n\n \n\n \n\
nAbstract: \n\nI discuss a bosonic ambitwistor string theory in AdS spac
e. Even though the theory is anomalous at the quantum level\, one can neve
rtheless use it in the classical limit to derive a novel formula for corre
lation functions of boundary CFT operators in arbitrary space-time dimensi
ons. The resulting construction can be treated as a natural extension of t
he CHY formalism for the flat-space S-matrix\, as it similarly expresses t
ree-level amplitudes in AdS as integrals over the moduli space of Riemann
spheres with punctures. These integrals localize on an operator-valued ver
sion of scattering equations\, which can be derived from the ambitwistor s
tring action on a coset manifold. As a testing ground for this formalism I
focus on the simplest case of ambitwistor string coupled to two current a
lgebras\, which gives bi-adjoint scalar correlators in AdS. I will then sh
ow that it reproduces tree level Witten diagram computations to all multi
plicity\, and discuss a connection to quantum integrable systems\; the Ga
udin model and an elliptic deformation of the Calogero-Sutherland model.\n
https://indico.cern.ch/event/940893/
LOCATION:Zoom Only (CERN)
URL:https://indico.cern.ch/event/940893/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Yikun Jiang + Yiming Chen - Special JC on Islands
DTSTART;VALUE=DATE-TIME:20200810T130000Z
DTEND;VALUE=DATE-TIME:20200810T150000Z
DTSTAMP;VALUE=DATE-TIME:20200813T092900Z
UID:indico-event-944849@indico.cern.ch
DESCRIPTION:Zoom virtual seminar: Click here to enter room\n\n \n\nSpeci
al JC on islands in cosmological settings and bra-ket wormholes.\n\n \n\n
Speaker 1: Yikun Jiang 15:00-15:45\n\nTitle: Islands in cosmology\n\nAbs
tract: A quantum extremal island suggests that a region of spacetime is en
coded in the quantum state of another system\, like the encoding of the bl
ack hole interior in Hawking radiation. We study conditions for islands to
appear in general spacetimes. They must violate Bekenstein's area bound i
n a precise sense\, and the boundary of an island must satisfy several oth
er information-theoretic inequalities. These conditions combine to impose
very strong restrictions\, which we apply to cosmological models. Using th
ese conditions as guidance\, we find several examples of islands in crunch
ing universes. In this talk\, I will mainly focus on the example of four-d
imensional FRW cosmology with radiation and a negative cosmological consta
nt entangled with an auxiliary non-gravitational Minkowski spacetime in th
e thermofield double state\, where an island appears near the turning poi
nt when the geometry begins to recollapse. If time permits\, I will also b
riefly explain our results for islands in two-dimensional models of JT gra
vity in de Sitter spacetime. The talk will be based on work: 2008.01022 wi
th Thomas Hartman and Edgar Shaghoulian.\n\n \n\nSpeaker 2: Yiming Chen 1
5:45-16:30\n\nTitle: Bra-ket wormholes in gravitationally prepared states\
n\nAbstract: In this talk I will discuss states prepared by Euclidean AdS_
2 evolution or Lorentzian dS_2 evolution in JT gravity. We probe the prope
rties of the states mainly using the gravitational fine grained entropy fo
rmula. In such computations\, I will argue that it is both natural and nec
essary to consider wormholes that connect the bra and the ket. I will disc
uss some interesting features of these bra-ket wormholes.\nhttps://indico.
cern.ch/event/944849/
LOCATION:Zoom only (CERN)
URL:https://indico.cern.ch/event/944849/
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