The bottom quark, also called the beauty quark, is a third-generation quark in the Standard Model. It is much heavier than the up and down quarks that make up protons and neutrons—about four to five times heavier than a proton.
Key features of the bottom quark:
- It has a charge of –1/3, like the down and strange quarks.
- It does not exist freely in nature but forms composite particles called bottom hadrons (such as B mesons and bottom baryons).
- These particles are unstable and decay via the weak force, often through complex processes that involve transitions to charm or up quarks.
Because of its longer lifetime (relative to other heavy quarks) and distinctive decay signatures, the bottom quark plays a central role in flavor physics, especially in:
- Studying CP violation, which helps explain the matter-antimatter imbalance in the universe.
- Testing the Standard Model’s accuracy, particularly through precision measurements at experiments like those at CERN’s LHCb detector.
- Searching for signs of new physics, including rare decays that could point to particles beyond the Standard Model.
The bottom quark’s rich decay behavior and manageable lifespan make it an ideal subject for detailed investigation into the deeper symmetries and possible extensions of known physics.