A Vacuum Accumulation Solution to the Strong CP Problem
  We suggest a solution to the strong CP problem in which there are no axions involved. The superselection rule of the \theta-vacua is dynamically lifted in such a way that an infinite number of vacua are accumulated within the phenomenologically acceptable range of \theta < 10^{-9}, whereas only a measure-zero set of vacua remains outside of this interval. The general prediction is the existence of membranes to which the standard model gauge fields are coupled. These branes may be light enough for being produced at the particle accelerators in form of the resonances with a characteristic membrane spectrum. 
Gia Dvali