Analytic bound on the generalized HMWC denominator
Establish analytically the bound on the quantity D_N(k_L)=\langle\{C_{k_L},\{C_{k_L}^*,H\}\}\rangle used in the generalized Hohenberg–Mermin–Wagner–Coleman argument for one-dimensional noncompact classical fractons, and determine the range of kernels, densities, and temperatures for which the bound is valid.
References
An immediate open problem is to establish the bound in \cref{eqn:D_N_bound} analytically and determine its range of validity across kernels, densities, and temperatures.
An immediate open problem is to establish the bound in \cref{eqn:D_N_bound} analytically and determine its range of validity across kernels, densities, and temperatures. Extending the analysis to higher dimensions would also determine whether noncompact classical fractons can support an equilibrium ordered phase, and how such a phase would be related to the nonequilibrium clustered states found for compact support.