Fields also transform under representations of the Lorentz group SO ( 1 , 3 ) , or more generally its spin group Spin ( 1 , 3 ) which can be identified with SL ( 2 , C ) due to an exceptional isomorphism. Examples include scalar fields, commonly denoted ϕ ϕ , which transform in the trivial representation, vector fields A μ μ (strictly, this might be more accurately labelled a covector field), which transforms as a 4-vector, and spinor fields ψ ψ α α such as Dirac or Weyl spinors which transform in representations of SL ( 2 , C ) . A right-handed Weyl spinor transforms in the fundamental representation, C 2 , of SL ( 2 , C ) .