Correlation between Spectral Index and Doppler Factor for a Sample of Fermi Blazars

Relativistic beaming effect is important for blazars. In a very recent work, γ-ray Doppler factors were calculated for a sample of Fermi blazars (Fan et al. 2013). In this work, we investigated the correlation between the Doppler factor and the effective spectral index, α OX, and found an anticorrelation between them.