bquarks
The bottom quark, also known as the b quark or beauty quark, is a fundamental particle in the Standard Model. It is a third-generation down-type quark with electric charge −1/3 e and spin 1/2. Its mass is about 4.18 GeV/c^2 in the MSbar scheme, making it the heaviest quark typically produced as a bound state in high-energy experiments. Like other quarks, it carries color charge and participates in the strong interaction, but its most distinctive role arises from weak decays that change flavor.
Because of confinement, quarks are never observed free in nature. A bottom quark appears in hadrons such
The bottom quark was established experimentally in 1977 with the discovery of bottomonium resonances, the Υ family.