Analyticity of Lyapunov Exponents for Mixed Markov Quasi-Periodic Cocycles

Abstract

We study the dependence of the top Lyapunov exponent of a mixed Markov quasi-periodic cocycle on the transition probabilities. The transition matrix is assumed primitive, the Markov extension on the torus is assumed non-resonant along directed cycles, and the top Lyapunov exponent is assumed simple. We first prove the result in the irreducible case by a forward Markov transfer operator and contraction estimates uniform over the initial Markov state. The reducible case is then obtained, as in the Bernoulli argument of Bezerra-S\'anchez-Tall, by decomposing along measurable invariant sections into restricted and quotient bundle cocycles and inducting on the fiber dimension. A measurable invariant section need not admit a continuous trivialization, even when the original matrices cocycle are continuous. We therefore formulate the irreducible analytic case for essentially bounded measurable bundle cocycles with essentially bounded inverses.