# Heuristic Description of Perpendicular Diffusion of Energetic Particles in Astrophysical Plasmas

## TL;DR

This paper introduces a heuristic method to derive the diffusion coefficient for energetic particles diffusing perpendicularly in astrophysical plasmas, clarifying previous models and improving agreement with simulations.

## Contribution

It presents a new heuristic approach for collisionless perpendicular diffusion, deriving analytic diffusion coefficients and explaining key parameters used in prior theories.

## Key findings

- Derived analytic forms for diffusion coefficients.
- Clarified the role of parameter a^2 in diffusion models.
- Showed significant differences in formulas for certain scenarios.

## Abstract

A heuristic approach for collisionless perpendicular diffusion of energetic particles is presented. Analytic forms for the corresponding diffusion coefficient are derived. The heuristic approach presented here explains the parameter $a^2$ used in previous theories in order to achieve agreement with simulations and its relation to collisionless Rechester & Rosenbluth diffusion. The obtained results are highly relevant for applications because previously used formulas are altered significantly in certain situations.