Linked from
The 31 pages that link to Particle physics, each with the reason it gives.
ScatteringNarrower topic: Scattering applies to particles as well as to waves.
Atomic physicsNarrower topic: It probes constituents and interactions beneath the atomic scale.
GasRelated: Gas behavior arises from the motion and interactions of its constituent particles.
Outline of physicsBroader topic: It investigates matter and forces at the smallest known scales.