Down quarks (sometimes written as a "d") are very small particles that help make up many larger particles, like protons and neutrons. Down quarks have a charge of -1/3. Since Down quarks are fermions (which means that no two of them can exist in the same space at the same time), they have a spin of 1/2. Down quarks are the second lightest quark, the first being up quarks.
The antiparticle of a Down quark is a Down antiquark, or simply an antidown.
|Particles in Physics|
|Elementary:||Fermions:||Quarks: up – down – strange – charm – bottom – top
Leptons: electron – muon – tau – neutrinos
|Bosons:||Gauge bosons: photon – W and Z bosons – gluons|
|Composite:||Hadrons:||Baryons: proton – neutron – hyperon|
|Mesons: pion – kaon – J/ψ|
|Atomic nuclei – Atoms – Molecules|
|Hypothetical:||Higgs boson – Graviton – Tachyon|