Context :

Aims : We study the star formation histories ( SFH ) and stellar populations of 213 red and 226 blue nearly face-on low surface brightness disk galaxies ( LSBGs ) , which are selected from the main galaxy sample of Sloan Digital Sky Survey ( SDSS ) Data Release Seven ( DR7 ) .
We also want to compare the stellar populations and SFH between the two groups .

Methods : The sample of both red and blue LSBGs have sufficient signal-to-noise ratio in the spectral continua .
We obtain their absorption-line indices ( e.g . Mg _ { 2 } , H \delta _ { A } ) , D _ { n } ( 4000 ) and stellar masses from the MPA/JHU catalogs to study their stellar populations and SFH .
Moreover we fit their optical spectra ( stellar absorption lines and continua ) by using the spectral synthesis code STARLIGHT on the basis of the templates of Simple Stellar Populations ( SSPs ) .

Results : We find that red LSBGs tend to be relatively older , higher metallicity , more massive and have higher surface mass density than blue LSBGs .
The D _ { n } ( 4000 ) - H \delta _ { A } plane shows that perhaps red and blue LSBGs have different SFH : blue LSBGs are more likely to be experiencing a sporadic star formation events at the present day , whereas red LSBGs are more likely to form stars continuously over the past 1-2 Gyr .
Moreover , the fraction of galaxies that experienced recent sporadic formation events decreases with increasing stellar mass .
Furthermore , two sub-samples are defined for both red and blue LSBGs : the sub-sample within the same stellar mass range of 9.5 \leq log ( M _ { \star } / M _ { \odot } ) \leq 10.3 , and the surface brightness limiting sub-sample with \mu _ { 0 } ( R ) \geq 20.7 mag arcsec ^ { -2 } .
They show consistent results with the total sample in the corresponding relationships , which confirm that our results to compare the blue and red LSBGs are robust .

Conclusions :