Hi Crostophe, thank you for this wonderful tutorial.
You may want to use the more standard terms: "pre-envelope" m_+(t) = m(t) + j \hat{m}(t) (ie, the signal you currently denote as \tilde{m}(t)) "complex-envelope", \tilde{m}(t) (for the signal you currently denote as m^{bb}(t) ) thank you again for your efforts, Achilleas