  Closed analytical expressions for scattering intensity and other global
structure factors are derived for a new solvable model of polydisperse sticky
hard spheres. The starting point is the exact solution of the ``mean spherical
approximation'' for hard core plus Yukawa potentials, in the limit of infinite
amplitude and vanishing range of the attractive tail, with their product
remaining constant. The choice of factorizable coupling (stickiness) parameters
in the Yukawa term yields a simpler ``dyadic structure'' in the Fourier
transform of the Baxter factor correlation function $q_{ij}(r)$, with a
remarkable simplification in all structure functions with respect to previous
works. The effect of size and stickiness polydispersity is analyzed and
numerical results are presented for two particular versions of the model: i)
when all polydisperse particles have a single, size-independent, stickiness
parameter, and ii) when the stickiness parameters are proportional to the
diameters. The existence of two different regimes for the average structure
factor, respectively above and below a generalized Boyle temperature which
depends on size polydispersity, is recognized and discussed. Because of its
analycity and simplicity, the model may be useful in the interpretation of
small-angle scattering experimental data for polydisperse colloidal fluids of
neutral particles with surface adhesion.
