Paul M. Chesler

Conformal field theories in a periodic potential: results from holography and field theory

We study ( 2 + 1 )-dimensional conformal field theories (CFTs) with a globally conserved U(1) charge, placed in a chemical potential which is periodically modulated along the spatial direction x with zero average: μ ( x ) = V cos ( k x ) . The dynamics of such theories depends only on the dimensionless ratio V / k , and we expect that they flow in the infrared to new CFTs whose universality class changes as a function of V / k . We compute the frequency-dependent conductivity of strongly coupled CFTs using holography of the Einstein-Maxwell theory in four-dimensional anti–de Sitter space. We compare the results with the corresponding computation of weakly coupled CFTs, perturbed away from the CFT of free, massless Dirac fermions (which describes graphene at low energies). We find that the results of the two computations have significant qualitative similarities. However, differences do appear in the vicinities of an infinite discrete set of values of V / k : the universality class of the infrared CFT changes at these values in the weakly coupled theory, by the emergence of new zero modes of Dirac fermions which are remnants of local Fermi surfaces. The infrared theory changes continuously in holography, and the classical gravitational theory does not capture the physics of the discrete transition points between the infrared CFTs. We briefly note implications for a nonzero average chemical potential.

Holography and off-center collisions of localized shock waves

A bstractUsing numerical holography, we study the collision, at non-zero impact parameter, of bounded, localized distributions of energy density chosen to mimic relativistic heavy ion collisions, in strongly coupled N=4

How big are the smallest drops of quark-gluon plasma?

mathcal{N}=4

Universal hydrodynamic flow in holographic planar shock collisions

supersymmetric Yang-Mills theory. Both longitudinal and transverse dynamics in the dual field theory are properly described. Using the gravitational description, we solve 5D Einstein equations with no dimensionality reducing symmetry restrictions to find the asymptotically anti-de Sitter spacetime geometry. Implications of our results on the understanding of early stages of heavy ion collisions, including the development of transverse radial flow, are discussed.

On the evolution of jet energy and opening angle in strongly coupled plasma

Using numerical holography, we study the collision of a planar sheet of energy with a bounded localized distribution of energy. The collision, which mimics proton-nucleus collisions, produces a localized lump of debris with transverse size R∼1/T_{eff} with T_{eff} the effective temperature, and has large gradients and large transverse flow. Nevertheless, the postcollision evolution is well described by viscous hydrodynamics. Our results bolster the notion that debris produced in proton-nucleus collisions may be modeled using hydrodynamics.

Dynamical Hawking Radiation and Holographic Thermalization

A bstractUsing holographic duality, we present results for both head-on and off-center collisions of Gaussian shock waves in strongly coupled N=4

Holography and hydrodynamics in small systems

mathcal{N}=4