  We investigate the relationship between black hole mass (MBH) and Doppler
boosted emission for BL Lacertae type objects (BL Lacs) detected in the SDSS
and FIRST surveys. The synthesis of stellar population and bidimensional
decomposition methods allows us to disentangle the components of the host
galaxy from that of the nuclear black hole in their optical spectra and images,
respectively. We derive estimates of black hole masses via stellar velocity
dispersion and bulge luminosity. We find that masses delivered by both methods
are consistent within errors. There is no difference between the black hole
mass ranges for high-synchrotron peaked BL Lacs (HBL) and low-synchrotron
peaked BL Lacs (LBL). A correlation between the black-hole mass and radio,
optical and X-ray luminosity has been found at a high significance level. The
optical-continuum emission correlates with the jet luminosity as well. Besides,
X-ray and radio emission are correlated when HBLs and LBLs are considered
separately. Results presented in this work: (i) show that the black hole mass
does not decide the SED shapes of BL Lacs, (ii) confirm that X-ray and optical
emission is associated to the relativistic jet, and (iii) present evidence of a
relation between MBH and Doppler boosted emission, which among BL Lacs may be
understood as a close relation between faster jets and more massive black
holes.
