We remark that the high energy gauge boson scattering processes involving two-body initial and final states, satisfy certain selection rules described as helicity conservation of the gauge boson amplitudes (GBHC). These rules are valid at Born level, as well as at the level of the leading and sub-leading 1-loop logarithmic corrections, in both the Standard Model (SM) and the Minimal Supersymmetric Standard Model (MSSM). A "fermionic equivalence" theorem is also proved, which suggests that GBHC is valid at all orders in MSSM at sufficiently high energies, where the mass suppressed contributions are neglected.PACS numbers: 11.30.Pb, 12.15.Lk † Work supported by the European Union under contract HPRN-CT-2000-00149. Many people may have noticed that at high energy where masses are neglected, twobody processes involving transverse gauge bosons (V = gluon, photon, Z, W ± ) satisfy certain selection rules implying asymptotic helicity conservation in the s-channel. This can easily be seen at Born level in either the Standard Model (SM) or its renormalizable SUSY extensions; e.g. the Minimal Supersymmetric Standard Model (MSSM). For example, considering the processes V λ V + V ′ λ V ′ → A λ A + A ′ λ A ′ , and computing the diagrams of Fig.1 corresponding to A, A ′ beings scalars, one observes that the high energy helicity amplitudes F λ V λ V ′ λ A λ A ′ vanish for λ V = λ V ′ ; while for the fermion production case of Fig.2, the vanishing of the high energy amplitudes is guaranteed whenever either of the relations λ V = λ V ′ or λ A = λ A ′ is satisfied. Correspondingly, the amplitudes for the crossed processA vanish when λ V = −λ V ′ for the case of Fig.1; or when either of the relations λ V = −λ V ′ or λ A = −λ A ′ is satisfied for the fermion case of Fig.2.Similar asymptotic rules also exist for the purely gauge helicity amplitudes F λ 1 λ 2 λ 3 λ 4 of the processes V 1λ 1 V 2λ 2 → V 3λ 3 V 4λ 4 involving four gauge bosons. Thus, it has been observed in [1] that these amplitudes satisfy asymptoticallyat the Born level, in either SM or MSSM. Consequently, only the helicity amplitudes satisfying λ 1 + λ 2 = λ 3 + λ 4 can survive asymptotically, at this level. These properties of gauge boson helicity conservation (GBHC), are a priori different and complementary to the well-known fermion helicity conservation in processes involving external fermions. The later is an essentially kinematical consequence of the fermionic vertices in SM or MSSM, valid at a diagram by diagram basis, provided that the energy is sufficient high, so that all masses can be neglected 1 .GBHC though, referring specifically to the external gauge boson helicities, is more subtle. Contrary to the fermionic case, detail cancellation among the contributions of various diagrams must take place, before GBHC is established. This can be seen from the Born processes described by Figs.1 or 2, where the asymptotic vanishing of the helicity amplitudes for λ V = λ V ′ is established through the occurrence of "large gauge cancellations" among the V f...
