  Bound state excitations of the spin 1/2-XYZ model are considered inside the
Bethe Ansatz framework by exploiting the equivalent Non-Linear Integral
Equations. Of course, these bound states go to the sine-Gordon breathers in the
suitable limit and therefore the scattering factors between them are explicitly
computed by inspecting the corresponding Non-Linear Integral Equations. As a
consequence, abstracting from the physical model the Zamolodchikov-Faddeev
algebra of two $n$-th elliptic breathers defines a tower of $n$-order Deformed
Virasoro Algebras, reproducing the $n=1$ case the usual well-known algebra of
Shiraishi-Kubo-Awata-Odake \cite{SKAO}.

High Energy Physics - Theory