Bottom quark
| Composition | elementary particle |
|---|---|
| Statistics | fermionic |
| Family | quark |
| Generation | third |
| Interactions | strong, weak, electromagnetic, gravity |
| Symbol | b |
| Antiparticle | bottom antiquark (b) |
| Theorized | Makoto Kobayashi and Toshihide Maskawa (1973) |
| Discovered | Leon M. Lederman et al. (1977) |
| Mass | 4.18+0.04 −0.03 GeV/c2 (MS scheme) 4.65+0.03 −0.03 GeV/c2 (1S scheme) |
| Decays into | charm quark or up quark |
| Electric charge | −1/3 e |
| Color charge | yes |
| Spin | 1/2 ħ |
| Weak isospin | LH: −+1/2, RH: 0 |
| Weak hypercharge | LH: 1/3, RH: −+2/3 |
The bottom quark, beauty quark, or b quark, is an elementary particle of the third generation. It is a heavy quark with a charge of −1/3 e.
All quarks are described in a similar way by electroweak interaction and quantum chromodynamics, but the bottom quark has exceptionally low rates of transition to lower-mass quarks. The bottom quark is also notable because it is a product in almost all top quark decays, and is a frequent decay product of the Higgs boson.