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5. Our metric is given by δμν(μ,ν=1,2,3,) (μ, ν=1, 2, 3) andx 3=it. Naturally the introduction of a suitable mass scale is necessary and in particular we shall work in units for which a normal Reggeon trajectory (f, ϱ) slope is equal to unity. This is a natural choice, for example in dual models.