“…The strategy for constructing invariant measures on compact manifolds, as inspired by [15] initially for a NLS, refined by Bourgain in [2], [3] and then followed by many authors (we mention at least [16], [19], and [20]), basically relies on applying a frequency truncation to reduce to a finite dimensional system, exploiting conservation of Lebesgue measure, which is a consequence of Liouville Theorem, and then proving uniform probabilistic estimates to remove truncates. The non compact case represents instead a much more challenging problem and not so many results are available in literature (see [1], [4], [12], [21], [8] and references therein); this represent in fact a very active branch of research.…”