  Metallicities ([Fe/H]) from low resolution spectroscopy obtained with the
Very Large Telescope (VLT) are presented for 98 RR Lyrae and 3 short period
Cepheids in the bar of the Large Magellanic Cloud. Our metal abundances have
typical errors of +/-0.17 dex. The average metallicity of the RR Lyrae stars is
[Fe/H]=-1.48 +/- 0.03 +/- 0.06 on the scale of Harris (1996). The star-to-star
scatter (0.29 dex) is larger than the observational errors, indicating a real
spread in metal abundances. The derived metallicities cover the range -2.12 <
[Fe/H] <-0.27, but there are only a few stars having [Fe/H] > -1. For the
ab-type variables we compared our spectroscopic abundances with those obtained
from the Fourier decomposition of the light curves. We find good agreement
between the two techniques, once the systematic offset of 0.2 dex between the
metallicity scales used in the two methods is taken into account. The
spectroscopic metallicities were combined with the dereddened apparent
magnitudes of the variables to derive the slope of the luminosity-metallicity
relation for the LMC RR Lyrae stars: the resulting value is 0.214 +/- 0.047
mag/dex. Finally, the 3 short period Cepheids have [Fe/H] values in the range
-2.0 < [Fe/H] <-1.5 . They are more metal-poor than typical LMC RR Lyrae stars,
thus they are more likely to be Anomalous Cepheids rather than the short period
Classical Cepheids that are being found in a number of dwarf Irregular
galaxies.
