The scaling form of the free-energy near a critical point allows for the
definition of various thermodynamical amplitudes and the determination of their
dependence on the microscopic non-universal scales. Universal quantities can be
obtained by considering special combinations of the amplitudes. Together with
the critical exponents they characterize the universality classes and may be
useful quantities for their experimental identification. We compute the
universal amplitude ratios for the Tricritical Ising Model in two dimensions by
using several theoretical methods from Perturbed Conformal Field Theory and
Scattering Integrable Quantum Field Theory. The theoretical approaches are
further supported and integrated by results coming from a numerical
determination of the energy eigenvalues and eigenvectors of the off-critical
systems in an infinite cylinder.Comment: 61 pages, Latex file, figures in a separate fil
