  We calculate the physical mass and the width of the sigma meson by
considering that it couples in vacuum to two virtual pions. The mass is
calculated by using the spectral function, and we find that it is about 600MeV.
In addition, we obtained the value of 250MeV for the width of its spectral
function. The value obtained for the mass, is in an excellent agreement with
that reported in the Particle data Book for the sigma meson, which is also
named f0(600). This result also shows that the sigma meson can be considered as
a two pion resonance.
