The baryon-meson scattering amplitude is computed within the 1/Nc
expansion of QCD, where Nc is the number of color charges. The most general
expression is obtained by accounting for explicitly the effects of the
decuplet-octet baryon mass difference and perturbative flavor SU(3) symmetry
breaking. Although the resultant expression is general enough that it can be
applied to any incoming and outgoing baryons and mesons, provided that the
Gell-Mann--Nishijima scheme is respected, results for Nπ scattering
processes are explicitly dealt with. With these, some isospin relations are
verified to be valid at the physical value Nc=3. The expressions obtained
here represent a first effort toward understanding scattering processes in the
context of the 1/Nc expansion.Comment: 87 pages, 1 figur