Unitarity bounds for 4-fermion contact interactions

In this paper we consider the effect of unitarity bounds s_bs(E₁+E₂) _cms ² for the recently proposed types of nonderivative 4-fermion contact interactions. To this purpose we decompose the helicity amplitudes at c.m.s. into partial waves. The bounds are defined to hold for all reaction channels due to the same type of contact interaction. We find s_b=4/. Here is the coupling constant. The factor depends on the type of coupling and on the different cases to identify the fermions. It ranges from 1/3 to 4.