Paul Romatschke

Transport at Strong Coupling -- a Field Theory Approach

Abstract:
Transport properties are hard to calculate from the first principles for any value of the coupling. At strong coupling, it's generally considered impossible except for field theories with known gravity duals. In this talk, I will review large N approaches to simple scalar and fermion field theories and show that they allow for the determination of exact transport coefficients at strong coupling, directly from the field theory. As an example, I calculate the (large N exact) infinite coupling value of eta/s in the 3d O(N) model.