Search for Quantum Gravity induced effects with PKS 2155-304 flaring period in 2006 by H.E.S.S

Highly energetic, variable and distant sources such as Active Galactic Nuclei provide a good means to evaluate effects due to the emission and the propagation of high energy photons. In this work, studies of possible energy-dependent time-lags with PKS 2155-304 light curve as measured by H.E.S.S. on 28 July 2006 (MJD 52944) are presented. The time-lags could come from the emission processes and also sign a Lorentz Symmetry breaking as predicted in some Quantum Gravity models. After a brief description of the methods in use, the latest results from two different analyses of the flare will be given.