# Axion vs. WIMP / Is Axion a WIMP?

What is the difference between an Axion and a WIMP?

A WIMP is just defined as a class of particles interacting via gravity and potentially via weak interaction (or a new force that is even weaker than that). Why is the Axion not a type of WIMP?

WIMPs (Weakly Interacting Massive Particles) are a class of hypothetical particles which can be dark matter candidates which most notably have masses near the $$\bf{weak}$$ scale, $$m_{\rm{wimp}} \approx \mathcal{O}(100 GeV)$$, and interact with the same strength (or less) than the weak interactions.
Axions are also hypothetical dark matter candidates with entirely different origins. They arise from spontaneous symmetry breaking and thus have very small masses, $$m_{\rm{axion}} \ll m_{\rm{wimp}}$$. They interact with through QCD and QED in very specific ways depending on the specific model of the axion.