Schrödinger group
https://arxiv.org/pdf/hep-th/9910025.pdf
https://arxiv.org/pdf/0706.3746.pdf
https://arxiv.org/abs/0806.2867 and https://arxiv.org/abs/0804.4053 and https://arxiv.org/abs/0804.3972 and https://inspirehep.net/literature/790118 and https://inspirehep.net/literature/804143