(Giacomo Vianello, Nicola Omodei,Vahe' Petrosian)
Very surprisingly the analysis of the LAT lightcurves shows the presence of breaks (Omodei et al. 2012), providing a possible difficulty for the synchrotron models. The Swift Satellite provides a rapid follow up of the afterglows in several wavelengths, that reveals even a more complex behavior of the lightcurves. In fact, a large number of afterglows are considerably deviating from the broken power-law seen in the past (OBrien et al. 2006, Sakamoto et al. 2007), and in a significant fraction of GRBs, a ``Steep--Flat--Steep" trend (Tagliaferri et al. 2005, Nousek et al. 2006) shows the existence of a plateau lasting from hundreds to a few thousands seconds (Willingale et al. 2007; Dainotti et al. 2008,2010). The presence of the plateu emission in the X-ray band, whose nature remains still a mystery, arises a natural question: whether or not the late flattening seen in the $gamma$-ray emission is the beginning of the same plateau seen in X-ray. The plateau emission observed in BAT+XRT gives a fundamental tool to understand if the $gamma$-ray and the X-ray emissions are correlated and if the breaks we see in these two bands are achromatic. Another important question is whether the mechanism that powers the plateau in X-rays is the same as in $gamma$-rays.We will test for a handful of LAT lightcurves consistent with the X-ray plateaus if they obey the closure relations.