A real-variable construction with applications to BMO-Teichm\"uller theory

With the use of real-variable techniques, we construct a weight function $\omega$ on the interval $[0, 2\pi)$ that is doubling and satisfies $\log \omega$ is a BMO function, but which is not a Muckenhoupt weight ($A_\infty$). Applications to the BMO-Teichm\"uller space and the space of chord-arc curves are considered.