About the AT line in Replica Symmetry Breaking assumption for spin glasses

Replica Symmetry Breaking is a fascinating phenomenon of spin glasses model which could have consequences also in other field of studies. Although there are several studies regarding the stability between the Replica Symmetric and first step of Replica Symmetry Breaking approximations, we do not have results for the following steps (apart from that one by Gardner for P-spin glasses in 1985). This is link to the fact that the classic method, based from the work by De Almeida and Thoules (from which the critical stability line takes its name), is difficult to be generalise for the next assumptions. In this paper we devise a new straightforward method inspired to the work by Toninelli in 2002 to recover the critical line in order to inspect the stability between the second step of Replica Symmetry Breaking and the first one. Moreover, we generalise to Kth step, with K finite.