Higher-order contagion processes in 1.99 dimensions

Abstract: Higher-order interactions have recently emerged as a promising framework for describing new dynamical phenomena in heterogeneous contagion processes. However, a fundamental open question is how to understand their contribution in the eyes of the physics of critical phenomena. Based on mesoscopic field-theoretic Langevin descriptions, we show that: (i) pairwise mechanisms as facilitation or thresholding are formally equivalent to higher-order ones, (ii) pairwise interactions at coarse-grained scales govern the higher-order contact process and, (iii) classical Imry-Ma arguments hold for networks with low spectral dimension. In short, we demonstrate that classical field theories, grounded on model symmetries and/or network dimensionality, still capture the nature of the phase transition, also predicting finite-size effects in real and synthetic networks.