Continuum limits of sparse coupling patterns

TL;DR

This paper introduces lattice systems with sparse couplings that, in the continuum limit, interpolate between real and p-adic smoothness, revealing new dimensions and smoothness properties influenced by a spectral exponent.

Contribution

The study demonstrates how simple lattice models with sparse couplings can exhibit continuum limits that interpolate between real and p-adic geometries based on a spectral parameter.

Findings

Continuum limits interpolate between real and p-adic smoothness.

Emergence of real or p-adic dimensions depending on spectral exponent.

Holder continuity conditions quantify the smoothness of Green's functions.

Abstract

We exhibit simple lattice systems, motivated by recently proposed cold atom experiments, whose continuum limits interpolate between real and $p$-adic smoothness as a spectral exponent is varied. A real spatial dimension emerges in the continuum limit if the spectral exponent is negative, while a $p$-adic extra dimension emerges if the spectral exponent is positive. We demonstrate Holder continuity conditions, both in momentum space and in position space, which quantify how smooth or ragged the two-point Green's function is as a function of the spectral exponent. The underlying discrete dynamics of our model is defined in terms of a Gaussian partition function as a classical statistical mechanical lattice model. The couplings between lattice sites are sparse in the sense that as the number of sites becomes large, a vanishing fraction of them couple to one another. This sparseness property is useful for possible experimental realizations of related systems.