Breakdown of the Universality Hypothesis in Directed Abelian Sandpile Models

TL;DR

This paper demonstrates that the avalanche exponents in directed abelian sandpile models vary with interaction details, challenging the assumption of universal behavior across these models.

Contribution

It reveals that the universality hypothesis does not hold universally in directed abelian sandpile models, showing dependence on interaction specifics.

Findings

Avalanche exponents depend on interaction details.

Universality classes may not exist in these models.

Challenging previous assumptions of universal critical behavior.

Abstract

We show that in a broad class of directed abelian sandpile models that had been expected to have the same exponents as the Dhar-Ramaswamy model, the avalanche exponent depends upon the details of the interaction, calling into question the general existence of universality classes in self organized critical models.