Final answer:
The Standard Model of particle physics consists of three main categories: quarks, leptons, and bosons. Bosons are not further broken down into subcategories.
Step-by-step explanation:
In the Standard Model of particle physics, there are three main categories: quarks, leptons, and bosons. Quarks are further divided into six different flavors, while leptons are divided into three generations. Bosons are categorized into four types: gluons, photons, W and Z bosons, and the Higgs boson. Therefore, the category that is not a further breakdown is bosons.