The concepts of scattering length a and effective range
re previously introduced for low-energy scattering from a potential V(r) in a plane and in higher dimensions are extended to include a 1/r potential (strength parameter \ensuremath{\gamma}). Both a and
re have the physical significance of being equal to the radius of an equivalent hard sphere giving rise to the same O(
k0) and O(
k2) terms in the expression for the phase shift. The method used is based on the properties of the ``local scattering length'' a(r,\ensuremath{\gamma}) for the potential V(r) cut off at radius r and an ``equivalent hard-sphere radius'' a(r,k,\ensuremath{\gamma}) for wave number k\ensuremath{\ne}0. It is shown that these quantities have a smooth behavior for \ensuremath{\gamma}\ensuremath{\rightarrow}0 and for dimension n\ensuremath{\rightarrow}2.
It is shown how the concepts of scattering length and effective range, previously introduced for low-energy scattering from a potential V(r) in a plane, correspond to the well-known parameters in three dimensions. This is done by considering low-energy scattering in a general dimension n\ensuremath{\ge}2 and subsequently showing that both the n=2 and n=3 cases fit naturally in such a generalized treatment. Furthermore, our previous work is extended to long-range potentials, decreasing faster than 1/
rn+1. The method used is based on the properties of a local scattering length a(r) for the potential V(r) cut off at radius r and an equivalent hard-sphere radius a(r,k) for k\ensuremath{\ne}0. Some applications and illustrative examples are given.
Abstract Isotropic scattering in various spatial dimensions is considered for arbitrary finite-range potentials using non-relativistic effective field theory. With periodic boundary conditions, compactifications from a box to a plane and to a wire, and from a plane to a wire, are considered by matching S-matrix elements. The problem is greatly simplified by regulating the ultraviolet divergences using dimensional regularization with minimal subtraction. General relations among (all) effective-range parameters in the various dimensions are derived, and the dependence of bound states on changing dimensionality are considered. Generally, it is found that compactification binds the two-body system, even if the uncompactified system is unbound. For instance, compactification from a box to a plane gives rise to a bound state with binding momentum given by ln 1 2 ( 3 + 5 ) in units of the inverse compactification length. This binding momentum is universal in the sense that it does not depend on the two-body interaction in the box. When the two-body system in the box is at unitarity, the S-matrices of the compactified two-body system on the plane and on the wire are given exactly as universal functions of the compactification length.