It is shown that in an axial-vector field theory the axial-vector field is always accompanied by a spin-0 field which has negative metric. Therefore, the theory has problem of negative probability and unitarity is broken. The same results are found in a theory of charged vector fields which are coupled to two fermions whose masses are different. These results are applied to the SM. It is found that both Z and W fields contain spin-0 component. Their masses are mφ0 = mte28.4 = 3.78 × 1014 GeV and mφ+/- = mte27 = 9.31 × 1013 GeV respectively. A new perturbation theory of the SM is proposed. The propagators of Z and W fields in this new perturbation theory are derived in ``unitary gauge.'' A minus sign is obtained in front of the scalar part of the propagators of W and Z fields. The minus sign indicates that the scalar fields have negative metric which leads to negative probability. Therefore, the unitarity of the SM is broken at about ~ 1014 GeV.