  On the basis of an extended set of nonlinear convective RR Lyrae pulsation
models we derive the first theoretical light curves in the Gaia bands and the
corresponding intensity-weighted mean magnitudes and pulsation amplitudes. The
effects of chemical com-position on the derived Bailey diagrams in the Gaia
filters are discussed for both Fundamental and First Overtone mode pulsators.
The inferred mean magnitudes and colors are used to derive the first
theoretical Period-Wesenheit relations for RR Lyrae in the Gaia filters. The
application of the theoretical Period-Wesenheit relations for both the
Fundamental and FirstOvertone mode to Galactic RR Lyrae in the Gaia Data
Release 2 database and complementary information on individual metal
abundances, allows us to derive theoretical estimates of their individual
parallaxes. These results are compared with the astrometric solutions to
conclude that a very small offset, consistent with zero, is required in order
to reconcile the predicted distances with Gaia results.
