@article {1806.05156, archivePrefix = {arXiv}, eprint = {1806.05156}, primaryClass = {hep-th}, author = {David Andriot and Dimitrios Tsimpis}, title = {Laplacian spectrum on a nilmanifold, truncations and effective theories}, year = {2018}, url = {http://arxiv.org/abs/1806.05156} }