  Aims. The aim of this work is the study of the planet-metallicity and the
planet-stellar mass correlations for M dwarfs from the HARPS GTO M dwarf
subsample
  Methods. We use a new method that takes advantage of the HARPS
high-resolution spectra to increase the precision of metallicity, using
previous photometric calibrations of [Fe/H] and effective temperature as
starting values.
  Results. In this work we use our new calibration (rms = 0.08 dex) to study
the planet-metallicity relation of our sample. The well-known correlation for
Giant planet FGKM hosts with metallicity is present. Regarding Neptunians and
smaller hosts no correlation is found but there is a hint that an
anti-correlation with [Fe/H] may exist. We combined our sample with the
California Planet Survey late-K and M-type dwarf sample to increase our
statistics but found no new trends. We fitted a power law to the frequency
histogram of the Jovian hosts for our sample and for the combined sample, f_p =
C10^\alpha[Fe/H], using two different approaches: a direct bin fitting and a
bayesian fitting procedure. We obtained a value for C between 0.02 and 0.04 and
for \alpha between 1.26 and 2.94.
  Regarding stellar mass, an hypothetical correlation with planets was
discovered, but was found to be the result of a detection bias.
