  We report the discovery of distant RR Lyrae stars, including the most distant
known in the Milky Way, using data taken in the $g-$band with the Dark Energy
Camera as part of the High cadence Transient Survey (HiTS; 2014 campaign). We
detect a total of 173 RR Lyrae stars over a ~120 deg^2 area, including both
known RR Lyrae and new detections. The heliocentric distances d_H of the full
sample range from 9 to >200 kpc, with 18 of them beyond 90 kpc. We identify
three sub-groups of RR Lyrae as members of known systems: the Sextans dwarf
spheroidal galaxy, for which we report 46 new discoveries, and the ultra-faint
dwarf galaxies Leo IV and Leo V. Following an MCMC methodology, we fit
spherical and ellipsoidal profiles of the form rho(R) ~ R^n to the radial
density distribution of RR Lyrae in the Galactic halo. The best fit corresponds
to the spherical case, for which we obtain a simple power-law index of
n=-4.17^{+0.18}_{-0.20}, consistent with recent studies made with samples
covering shorter distances. The pulsational properties of the outermost RR
Lyrae in the sample (d_H>90 kpc) differ from the ones in the halo population at
closer distances. The distribution of the stars in a Period-Amplitude diagram
suggest they belong to Oosterhoff-intermediate or Oosterhoff II groups, similar
to what is found in the ultra-faint dwarf satellites around the Milky Way. The
new distant stars discovered represent an important addition to the few
existing tracers of the Milky Way potential in the outer halo.
