  The MAGIC collaboration has recently reported correlated X-ray and very
high-energy gamma-ray emission from the gamma-ray binary LS I +61 303 during
~60% of one orbit. These observations suggest that the emission in these two
bands has its origin in a single particle population. We aim at improving our
understanding of the source behaviour by explaining the simultaneous X-ray and
VHE data through a radiation model. We use a model based on a one zone
population of relativistic leptonic particles assuming dominant adiabatic
losses located at the position of the compact object. The adiabatic cooling
timescale is inferred from the X-ray fluxes. The model can reproduce the
spectra and lightcurves in the X-ray and VHE bands. Adiabatic losses could be
the key ingredient to explain the X-ray and partially the VHE lightcurves. From
the best fit result, we obtain a magnetic field of B=0.2 G, a minimum
luminosity budget of ~2x10^35 erg/s and a relatively high acceleration
efficiency. In addition, our results seem to confirm that the GeV emission
detected by Fermi does not come from the same parent particle population as the
X-ray and VHE emission and the Fermi spectrum poses a constraint on the
hardness of the particle spectrum at lower energies. In the context of our
scenario, more sensitive observations would allow to constrain the inclination
angle, which could determine the nature of the compact object.
