Hydrodynamics of relativisic systems with broken continuous symmetries

We show how hydrodynamics of relativistic system with broken continuous symmetry can be constructed using the Poisson bracket technique. We illustrate the method on the example of relativistic superfluids.Comment: 3 pages; talk at DPF2000, Columbus, Ohio, August 9-12, 200

Comment on "Is There a "Most Perfect Fluid" Consistent with Quantum Field Theory?"

This is a comment on hep-th/0702136Comment: 1 page, comment on hep-th/070213

Rate of convergence for periodic homogenization of convex Hamilton-Jacobi equations in one dimension

Let $u^\varepsilon$ and $u$ be viscosity solutions of the oscillatory Hamilton-Jacobi equation and its corresponding effective equation. Given bounded, Lipschitz initial data, we present a simple proof to obtain the optimal rate of convergence $\mathcal{O}(\varepsilon)$ of $u^\varepsilon \rightarrow u$ as $\varepsilon \rightarrow 0^+$ for a large class of convex Hamiltonians $H(x,y,p)$ in one dimension. This class includes the Hamiltonians from classical mechanics with separable potential. The proof makes use of optimal control theory and a quantitative version of the ergodic theorem for periodic functions in dimension $n = 1$.Comment: 22 pages, typos corrected, references added, final accepted versio

Operator Product Expansion and Conservation Laws in Non-Relativistic Conformal Field Theories

We explore the consequences of conformal symmetry for the operator product expansions in nonrelativistic field theories. Similar to the relativistic case, the OPE coefficients of descendants are related to that of the primary. However, unlike relativistic CFTs the 3-point function of primaries is not completely specified by conformal symmetry. Here, we show that the 3-point function between operators with nonzero particle number, where (at least) one operator has the lowest dimension allowed by unitarity, is determined up to a numerical coefficient. We also look at the structure of the family tree of primaries with zero particle number and discuss the presence of conservation laws in this sector.Comment: 11 pages, 1 figure. V2 added reference