Proof of the local REM conjecture for number partitioning II: growing energy scales

Abstract

We continue our analysis of the number partitioning problem with $n$ weights chosen i.i.d. from some fixed probability distribution with density $\rho$. In Part I of this work, we established the so-called local REM conjecture of Bauke, Franz and Mertens. Namely, we showed that, as $n\to \infty$, the suitably rescaled energy spectrum above some {\it fixed} scale $\alpha$ tends to a Poisson process with density one, and the partitions corresponding to these energies become asymptotically uncorrelated. In this part, we analyze the number partitioning problem for energy scales ${\alpha }_n$ that grow with $n$, and show that the local REM conjecture holds as long as $n^{-1/4}{\alpha }_n\to 0$, and fails if ${\alpha }_n$ grows like $\kappa n^{1/4}$ with $\kappa >0$. We also consider the SK-spin glass model, and show that it has an analogous threshold: the local REM conjecture holds for energies of order $o(n)$, and fails if the energies grow like $\kappa n$ with $\kappa >0$.

42 pages