A renormalisation-group treatment of two-body scattering

Nonrelativistic two-body scattering by a short-ranged potential is studied using the renormalisation group. Two fixed points are identified: a trivial one and one describing systems with a bound state at zero energy. The eige nvalues of the linearised renormalisation group are used to assign a system atic power-counting to terms in the potential near each of these fixed poin ts. The expansion around the nontrivial fixed point is shown to be equivale nt to the effective-range expansion. (C) 1999 Elsevier Science B.V. All rig hts reserved.