Triangle Seminars
Tuesday, 18 Nov 2014
tba
Tomasz Lukowski
(Oxford)
Wednesday, 19 Nov 2014
Higher spins, entanglement and Wilson lines
📍 London
Juan Jottar
(ETH (Zurich))
Abstract:
We discuss entanglement and Renyi entropies in two-dimensional conformal field theories with extended symmetry algebras of W-type, in the semiclassical (large-c) limit. From the CFT perspective, the computation of these non-local observables involves the study of semiclassical conformal blocks in theories with additional conserved currents beyond the stress tensor. From an AdS perspective, the problem can be tackled using recent holographic proposals in terms of Wilson lines in the dual three-dimensional higher spin theories. We discuss non-trivial examples exhibiting the agreement between bulk and boundary computations.
We discuss entanglement and Renyi entropies in two-dimensional conformal field theories with extended symmetry algebras of W-type, in the semiclassical (large-c) limit. From the CFT perspective, the computation of these non-local observables involves the study of semiclassical conformal blocks in theories with additional conserved currents beyond the stress tensor. From an AdS perspective, the problem can be tackled using recent holographic proposals in terms of Wilson lines in the dual three-dimensional higher spin theories. We discuss non-trivial examples exhibiting the agreement between bulk and boundary computations.
Posted by: KCL
Striped phase in holographic d-wave superconductor
Alexander Krikun
(Nordita)
Abstract:
In its most general formulation the gauge/string duality may be used to build models of various strongly coupled systems in condensed matter. One of these is high-temperature d-wave superconductor. The holographic model of d-wave superconductor includes the dynamics of spin-2 charged field on top of the curved AdS geometry. In the probe approximation the model may be formulated consistently and exhibits a number of interesting physical phenomena. The important task is to classify all possible ground states of the model, which will correspond to the various phases of the dual system, and study the resulting phase diagram. In this talk I will discuss the recently found ground state which exhibits the stripes of charge density, violates the translation symmetry spontaneously and may be associated with the pseudogap state in high-Tc superconductors.
In its most general formulation the gauge/string duality may be used to build models of various strongly coupled systems in condensed matter. One of these is high-temperature d-wave superconductor. The holographic model of d-wave superconductor includes the dynamics of spin-2 charged field on top of the curved AdS geometry. In the probe approximation the model may be formulated consistently and exhibits a number of interesting physical phenomena. The important task is to classify all possible ground states of the model, which will correspond to the various phases of the dual system, and study the resulting phase diagram. In this talk I will discuss the recently found ground state which exhibits the stripes of charge density, violates the translation symmetry spontaneously and may be associated with the pseudogap state in high-Tc superconductors.
Posted by: IC
Form factors, Anomalous Dimensions and the Dilatation Operator of N=4 SYM Theory
Matthias Wilhelm
(Humboldt)
Abstract:
We study the form factor of a generic gauge-invariant local
composite operator in N=4 SYM theory. At tree-level and for a minimal
number of external fields, the form factor exactly realises the
spin-chain picture of N=4 SYM theory in the language of scattering
amplitudes. Via generalised unitarity, we obtain the cut-constructible
part of the one-loop correction to the minimal form factor of a
generic operator. Its UV divergence yields the complete one-loop
dilatation operator of the theory. We also compute the complete
two-loop correction to the two-point form factor of the Konishi
operator via unitarity and obtain the two-loop Konishi anomalous
dimensions from it. For the Konishi operator as well as other
non-protected operators, important subtleties arise which require an
extension of the method of unitarity.
Moreover, since the inclusion of non-protected operators into the
action renders it formally non-supersymmetric, the form factors of
these operators share many features with quantities in QCD, such as
the occurrence of rational terms. The talk is based on the recent
works 1410.6309 and 1410.8485.
We study the form factor of a generic gauge-invariant local
composite operator in N=4 SYM theory. At tree-level and for a minimal
number of external fields, the form factor exactly realises the
spin-chain picture of N=4 SYM theory in the language of scattering
amplitudes. Via generalised unitarity, we obtain the cut-constructible
part of the one-loop correction to the minimal form factor of a
generic operator. Its UV divergence yields the complete one-loop
dilatation operator of the theory. We also compute the complete
two-loop correction to the two-point form factor of the Konishi
operator via unitarity and obtain the two-loop Konishi anomalous
dimensions from it. For the Konishi operator as well as other
non-protected operators, important subtleties arise which require an
extension of the method of unitarity.
Moreover, since the inclusion of non-protected operators into the
action renders it formally non-supersymmetric, the form factors of
these operators share many features with quantities in QCD, such as
the occurrence of rational terms. The talk is based on the recent
works 1410.6309 and 1410.8485.
Posted by: QMW