A heavy quark, also called beauty quark, about four times heavier than a proton.The bottom quark, also known as the beauty quark, is one of the six flavors of quarks in the Standard Model of particle physics. It is the second-heaviest known elementary particle, with a mass about four times that of a proton, or roughly 4.18 GeV/c². Because of its large mass, the bottom quark decays quickly and is only observed indirectly through the particles it produces, such as B mesons.
The bottom quark was discovered in 1977 by a team led by Leon Lederman at Fermilab, USA, through the observation of the Upsilon particle, a bound state of a bottom quark and its antiquark.
Bottom quarks are produced in high-energy particle collisions, such as those at the Large Hadron Collider. They are never found alone; they bind with other quarks to form composite particles called hadrons, most notably B mesons (containing a bottom quark and a lighter antiquark). These particles travel a short distance before decaying, and physicists reconstruct their paths and decay products to study the properties of the bottom quark, including its mass, spin, and interactions.
Bottom quark studies are crucial for testing the Standard Model, particularly for understanding CP violation (the asymmetry between matter and antimatter) and for searching for physics beyond the Standard Model.
The bottom quark's large mass makes it a sensitive probe for new physics, as many theoretical extensions of the Standard Model predict subtle deviations in its decay rates that experiments are currently hunting for.