The radiation-matter transition in Jordan-Brans-Dicke theory

We study the transition from radiation domination to matter domination in Jordan-Brans-Dicke theory, in particular examining how the Hubble length at equality depends on the coupling parameter $\omega$. We consider the prospects for using high-accuracy microwave anisotropy and large-scale structure data to constrain $\omega$ more strongly than by conventional solar system gravity experiments.