Possible instability of one-step replica symmetry breaking in p-spin Ising models outside mean-field theory

TL;DR

This paper investigates the stability of one-step replica symmetry breaking in p-spin Ising models outside mean-field theory, suggesting that full replica symmetry breaking is more relevant in finite dimensions than 1RSB.

Contribution

The study introduces the analysis of two-step RSB in fully connected p-spin models and argues that FRSB is more likely than 1RSB outside mean-field limits.

Findings

2RSB state is degenerate with 1RSB but with vanishing weight

FRSB is degenerate with 1RSB in the thermodynamic limit

Finite size effects favor FRSB features outside mean-field models

Abstract

The fully-connected Ising $p$-spin model has for $p >2$ a discontinuous phase transition from the paramagnetic phase to a stable state with one-step replica symmetry breaking (1RSB). However, simulations in three dimension do not look like these mean-field results and have features more like those which would arise with full replica symmetry breaking (FRSB). To help understand how this might come about we have studied in the fully connected $p$-spin model the state of two-step replica symmetry breaking (2RSB). It has a free energy degenerate with that of 1RSB, but the weight of the additional peak in $P(q)$ vanishes. We expect that the state with full replica symmetry breaking (FRSB) is also degenerate with that of 1RSB. We suggest that finite size effects will give a non-vanishing weight to the FRSB features, as also will fluctuations about the mean-field solution. Our conclusion is that outside the fully connected model in the thermodynamic limit, FRSB is to be expected rather than 1RSB.