  We present a general self-consistent lepto/hadronic jet model for the
non-thermal electromagnetic emission of microquasars. The model is applied to
the low-mass microquasar (LMMQ) GX 339-4 and predicts its high-energy features.
We assume that both leptons and hadrons are accelerated up to relativistic
energies by diffusive shock acceleration, and calculate their contribution to
the electromagnetic spectrum through all main radiative processes. The
radiative contribution of secondary particles (pions, muons and
electron-positron pairs) is included. We use a set of simultaneous observations
in radio and X-rays to constrain the model parameters and find the best fit to
the data. We obtain different spectral energy distributions that can explain
the observations, and make predictions for the high-energy emission.
Observations with gamma-ray instruments like Fermi can be used to test the
model and determine the proton content of the jets. Finally, we estimate the
positron injection in the surrounding medium. Our findings support the
suggested association between LMMQs and the observed distribution of the 511
keV line flux observed by INTEGRAL.
