  The false-positive probability (FPP) of Kepler transiting candidates is a key
value for statistical studies of candidate properties. A previous investigation
of the stellar population in the Kepler field has provided an estimate for the
FPP of less than 5% for most of the candidates. We report here the results of
our radial velocity observations on a sample of 46 Kepler candidates with a
transit depth greater than 0.4%, orbital period less than 25 days and host star
brighter than Kepler magnitude 14.7. We used the SOPHIE spectrograph mounted on
the 1.93-m telescope at the Observatoire de Haute-Provence to establish the
nature of the transiting candidates. In this sample, we found five undiluted
eclipsing binaries, two brown dwarfs, six diluted eclipsing binaries, and nine
new transiting planets that complement the 11 already published planets. The
remaining 13 candidates were not followed-up or remain unsolved due to photon
noise limitation or lack of observations. From these results we computed the
FPP for Kepler close-in giant candidates to be 34.8% \pm 6.5%. We aimed to
investigate the variation of the FPP for giant candidates with the longer
orbital periods and found that it should be constant for orbital periods
between 10 and 200 days. This significant disagrees with the previous
estimates. We discuss the reasons for this discrepancy and the possible
extension of this work toward smaller planet candidates. Finally, taking the
false-positive rate into account, we refined the occurrence rate of hot
jupiters from the Kepler data.
