- A quark with a charge of - 1/3 , a mass about 20 times that of the electron, and a downward spin. It is a component of protons and neutrons. See dining table at subatomic particle.
- A quark having a fractional electric cost of -1/3 and a mass about 4 to 8 MeV. Image: d
- a stable quark with a power cost of -1/3 and a mass 607 times that an electron