Gauging

  1. gauge a finte group/discrete symmetry
    ~discrete Fourier transformation of the partition function Z(T,J): theory T with global p-form symmetry G(p) and associated BG currents Jp+1,
    Z(T/G(p),J^d−p−1)∼∑Jp+1∈Hp+1(Md,G(p))e2πi(J^,J)Z(T,Jp+1)
    where e2πi(B^,B) is coupling the dual theory T/G(p) to the current of J (or a pairing between J∈Hp+1(Md,G(p)) and J^=⋆J∈Hd−p−1(Md,G^(d−p−2))≃Hp+1, Poincare duality) and is the weight in the Fourier transform.
    The dual symmetry G^(d−p−2) is a d−p−2-form symmetry, the Pontryagin dual of G: G^=Hom(G,U(1)). It provides a explicit expression for the p-form symmetry generator: (just charges for the p-form one)
    Dd−p−1=exp(i∫Md−p−1J^d−p−1)
    which acts on/links with p-dim operators. Its own generator is given by (Mp+1,Jp+1).
  2. gauge a continuous symmetry
    eg. Maxwell in 4d
    ⋆Je(2)=ie2⋆F(2)=ie2DAD,⋆Jm(2)=12πF(2)

ref: [2305.18296] ICTP Lectures on (Non-)Invertible Generalized SymmetriesP24