A new approach to dark photon

Over the past few decades, the hypothetically dark photon has been extensively studied from both phenomenological and experimental perspectives. It should be noted that the local symmetry for dark photon does not gauge the standard model Higgs scalar and chiral fermions. In this paper, we show that an artificially introduced $U(1)_X$ gauge group for dark photon and the standard model $U(1)_Y$ gauge group for hypercharge can be simultaneously born from two $U(1)_1\times U(1)_2$ gauge groups under which the standard model scalar and fermions carry the same $U(1)_1$ and $U(1)_2$ charges without causing any gauge anomalies. We further introduce a spontaneously broken mirror symmetry between the $U(1)_1$ and $U(1)_2$ gauge groups so that the $U(1)_1$ and $U(1)_2$ gauge couplings can acquire a small difference at one-loop level and hence the $U_X \times U_Y$ kinetic mixing can be highly suppressed in a natural way.