Scale Invariant Scattering in 2D.

For a non-relativistic scale invariant system in two spatial dimensions, the quantum scattering amplitude f() is given as a dispersion relation, with a simple closed form for Im f() as well as the integrated cross-section / Im f(= 0). For fixed 6= 0, the ~ ! 0 classical limit is straightforward to obtain. [ABSTRACT FROM AUTHOR]