Triangle Seminars
Monday, 25 Nov 2013
Cubic-interaction-induced deformations of higher-spin symmetries
Euihun Joung
(Scuola Normale Superiore)
Abstract:
The deformations of higher-spin symmetries induced by cubic interactions of symmetric massless bosonic fields are analyzed within the metric-like formalism. In particular, we identify a class of couplings which leave the gauge algebra Abelian but deform one (out of three) gauge transformation, and another class of couplings which deform all three gauge transformations in (A)dS but only two in the flat-space limit. The former class is related to higher-spin algebra multiplets (representations of the global algebra). The latter class is what makes (A)dS a distinguished background for higher-spin interactions and includes in particular the gravitational interactions of higher-spin fields, retrospectively accounting for the Fradkin-Vasiliev solution to the Aragone-Deser problem.
The deformations of higher-spin symmetries induced by cubic interactions of symmetric massless bosonic fields are analyzed within the metric-like formalism. In particular, we identify a class of couplings which leave the gauge algebra Abelian but deform one (out of three) gauge transformation, and another class of couplings which deform all three gauge transformations in (A)dS but only two in the flat-space limit. The former class is related to higher-spin algebra multiplets (representations of the global algebra). The latter class is what makes (A)dS a distinguished background for higher-spin interactions and includes in particular the gravitational interactions of higher-spin fields, retrospectively accounting for the Fradkin-Vasiliev solution to the Aragone-Deser problem.
Posted by: IC
Tuesday, 26 Nov 2013
TBA
Reinhold Egger
(Düsseldorf)
Wednesday, 27 Nov 2013
Lecture on Higher-spin symmetry
📍 London
Nicolas Boulanger
(Mons)
Coarse-grained entropy and causality in AdS/CFT
William Kelly
(UCSB)
Abstract:
While the emergence of bulk locality in AdS/CFT is not fully understood, progress has been made towards understanding how pieces of the bulk geometry are encoded in subregions of the CFT. Recently, Hubeny and Rangamani have proposed that a modification of the Ryu-Takayanagi entropy called the 'causal holographic information' (so called because extremal surfaces are replaced with causal boundaries) quantifies the minimum information needed to reconstruct certain causally defined bulk regions. I will argue that the boundary dual of the causal holographic information is a coarse-grained entropy which tracks the one-point functions in the associated boundary domain of dependence. The talk will focus on the motivation and evidence for this conjecture as well the prospects for future precision tests.
While the emergence of bulk locality in AdS/CFT is not fully understood, progress has been made towards understanding how pieces of the bulk geometry are encoded in subregions of the CFT. Recently, Hubeny and Rangamani have proposed that a modification of the Ryu-Takayanagi entropy called the 'causal holographic information' (so called because extremal surfaces are replaced with causal boundaries) quantifies the minimum information needed to reconstruct certain causally defined bulk regions. I will argue that the boundary dual of the causal holographic information is a coarse-grained entropy which tracks the one-point functions in the associated boundary domain of dependence. The talk will focus on the motivation and evidence for this conjecture as well the prospects for future precision tests.
Posted by: IC
Friday, 29 Nov 2013
Probes of Entanglement in Extremal Reissner-Nordstrom AdS
Sebastian Fischetti
(UCSB)
Abstract:
We holographically study the entanglement between two CFTs in a thermofield double state at nonzero chemical potential. In the bulk, this entanglement corresponds to entanglement between the two exterior regions of a Reissner-Nordstrom AdS black hole. We will make use of two probes: thermo-mutual information and two-point correlators of scalar operators. In particular, in the zero-temperature limit the entropy density of the black hole remains finite, while neutral correlators and the mutual information of finite regions vanish, implying that these are not good probes of entanglement at zero temperature. However, the correlators of electrically charged scalar operators can be made to remain finite. We comment on the time evolutions of these quantities and other possible applications.
We holographically study the entanglement between two CFTs in a thermofield double state at nonzero chemical potential. In the bulk, this entanglement corresponds to entanglement between the two exterior regions of a Reissner-Nordstrom AdS black hole. We will make use of two probes: thermo-mutual information and two-point correlators of scalar operators. In particular, in the zero-temperature limit the entropy density of the black hole remains finite, while neutral correlators and the mutual information of finite regions vanish, implying that these are not good probes of entanglement at zero temperature. However, the correlators of electrically charged scalar operators can be made to remain finite. We comment on the time evolutions of these quantities and other possible applications.
Posted by: IC