Gauge/Gravity Duality 2015

Session

Parallel Session

Apr 15, 2015, 2:20 PM

The Galileo Galilei Institute for Theoretical Physics (GGI)

58. Entanglement entropy associated to a far-from-equilibrium energy flow

Daniel Fernandez

4/15/15, 2:20 PM

The time evolution of the energy transport triggered in a strongly coupled quantum critical system by a temperature gradient is holographically related to the evolution of an asymptotically AdS black brane with a gradient in its planar horizon. A relevant observable that provides physical insight about the evolution of this system and the eventual formation of a steady state is the...

67. The local renormalization group equation in superspace

Roberto Auzzi

4/15/15, 2:20 PM

The superspace formulation of the local renormalization group equation is discussed. This is framework in which the constraints of holomorphy and R-symmetry on supersymmetric RG flows are manifest. Background fields are used to define the super-Weyl symmetry off-criticality and to derive the consistency conditions associated with this symmetry. An analog of the "a-maximization" equation,...

60. Holographic magneto-transport and strange metals

Andrea Amoretti

4/15/15, 2:50 PM

In this talk we analyze the thermo-electric transport properties of a strongly coupled, planar medium in the presence of an orthogonal magnetic field and disorder. Even though the analysis is performed within the gauge/gravity framework, we propose and argue for a possible universal relevance of the results relying on comparisons and extensions of previous hydrodynamical analyses and...

68. Looking for an on-shell regulator

Eduardo Conde Pena

4/15/15, 2:50 PM

A generic QFT without mass gap may present IR and UV divergencies, which must be regularized before making sense of them. In a Feynman diagram, one thinks of these divergencies as arising from an infinite integration region for a certain off-shell momentum. When one treats the theory purely on-shell, these divergencies must be seen (and regularized) in some other way. In this talk I present an...

69. Holographic Representation of Bulk Fields and Locality in (A)dS

Debajyoti Sarkar

4/15/15, 3:20 PM

The study of local physics in a theory of quantum gravity is an important problem. (A)dS/ CFT gives us a platform to study this issue from the CFT perspective. The construction of local bulk scalars in semiclassical limit of AdS/ CFT is well-known at order by order in 1/N perturbation. Here we discuss the recent developments on this topic and in particular describe how to extend this program...

61. Testing the membrane paradigm with holography

Natalia Pinzani Fokeeva

4/15/15, 3:20 PM

For an asymptotic observer a black hole can be replaced by a simple dissipative membrane located at a stretched horizon, i.e. a very small distance outside the horizon. In this talk I will show what are the limits of validity of such approximation scheme. In particular I will argue that it generically fails to capture massive quasinormal modes. I will also show how it instead reproduces...

70. Fermi gas formulation for D-type quivers

Benjamin Assel

4/15/15, 4:20 PM

I will explain that the exact partition function of D-type N=4 quivers SCFTs on a three-sphere coincides with the partition function of a gas of free fermions in one dimension with a non-standard Hamiltonian. I will describe briefly the mirror dual quiver theories and show that mirror symmetry is expressed as a simple canonical transformation on the density operator of the quantum mechanics....

63. Thermoelectric Conductivities at Finite Magnetic Field and the Nernst effect

Yunseok Seo

4/15/15, 4:20 PM

We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an...

66. Electron-Phonon interactions, MIT and Holographic Massive Gravity

Matteo Baggioli

4/15/15, 4:50 PM

Massive gravity is holographically dual to ''realistic'' materials with momentum relaxation. In its fully covariant formulation it in fact provides an holographic effective description for electron-phonon interactions. I will show how phonons' degrees of freedom are enconded in massive gravity and which are the interesting phenomenological features concerning the transport properties of the...

71. Scale vs. Conformal Invariance in Holography with Higher Derivative Corrections

Yegor Korovin

4/15/15, 4:50 PM

Gravitational theories with higher derivative corrections in AdS are dual to non-unitary QFTs. In particular, these may provide holographic examples of scale but not conformally invariant field theories (SFT). A distinct signature of a SFT is the non-vanishing scale anomaly R^2, which may be computed holographically. We perform a systematic near-boundary analysis of relevant gravitational...

65. Entanglement entropy in a holographic model of the Kondo effect.

Mario Flory

4/15/15, 5:20 PM

My starting point is a holographic model of the Kondo effect recently proposed by Erdmenger et. al., i.e. of a magnetic impurity interacting with a strongly coupled system. Specifically, I focus on the challenges of computing gravitational backreaction in this model, which demands a study of the Israel junction conditions. I present general results on these junction conditions, including...

72. Spontaneous Breaking of U(N) symmetry in invariant Matrix Models

Fabio Franchini

4/15/15, 5:20 PM

Matrix Models have a strong history of success in describing a variety of situations, from nuclei spectra to conduction in mesoscopic systems, from strongly interacting systems to various aspects of mathematical physics, from holographic models to supersymmetric theories in the localization limit. Traditionally, the requirement of base invariance has lead to a factorization of the eigenvalue...