Using the sample of radio selected BL Lacertae objects ( RBLs ) and X-ray selected BL Lacertae objects ( XBLs ) presented by Sambruna et al .
( 1996 ) , we calculated the luminosities of radio , optical and X-ray of each source and made the statistical analysis among the luminosities at different wave-bands , broad-band spectral indices from radio to X-ray ( \alpha _ { rx } ) and peak frequencies ( \nu _ { p } ) .
Our results are as follows : ( i ) there is a positive correlation between radio luminosity L _ { r } and \alpha _ { rx } and a negative correlation between L _ { r } and \nu _ { p } .
High-energy peak BL Lacs ( HBLs ) and low-energy peak BL Lacs ( LBLs ) can be distinguished very well , the dividing lines are probably those of \log { L _ { r } } = 43.25 ( erg/sec ) and \alpha _ { rx } > ( or \leq ) 0.75 for L _ { r } - \alpha _ { rx } plot and those of \log { L _ { r } } \leq 43.25 ( erg/sec ) and \log { \nu _ { p } } > 14.7 for the L _ { r } - \nu _ { p } plot ; ( ii ) there is a weak positive correlation between optical luminosity L _ { o } and \alpha _ { rx } and a negatively weak correlation between L _ { o } and \nu _ { p } ; ( iii ) there is no correlation between X-ray luminosity L _ { X } and \alpha _ { rx } or between L _ { X } and \nu _ { p } .
From our analysis , we find that synchrotron radiation is the main X-ray radiation mechanism for HBLs while inverse Compton scattering for LBLs .