Yang-Mills theories in four space-time dimensions possess a hidden integrability symmetry and their effective dynamics in several important limits is described by Heisenberg sl(2;R) and sl(2;C) spin chains. A distinguished feature of these models is that their quantum space is infinite-dimensional and Bethe Ansatz is not always applicable. I will review a progress in solving the noncompact spin chains using the method of Baxter Q-operator.