A BMS-invariant free fermion model

We used the Cartan formalism to construct fermionic models that are compatible with Galilean or Carrollian symmetry and rigid scaling symmetry. The free Carrollian fermion model exhibits conformal Carrollian symmetry which is isomorphic to the asymptotic symmetries for flat spacetime in three dimensions, namely the BMS$_3$ symmetry. We performed canonical quantization to this free BMS fermion model, discussed both the highest weight vacuum and the induced vacuum, calculated the correlation functions and the torus partition function. Finally we constructed $\mathcal N=2$ supersymmetric theories by combining the free fermion model and the free scalar model.