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Bottom quark

physical science Maturity 7-9 Next article →

The bottom quark is a tiny part of our world. Some people call it the beauty quark. It is also known as the b quark. This particle is an elementary particle of the third generation. It is a very heavy quark with a charge of -e. Scientists find it very important for understanding how the universe works.

This quark works in a very special way. It has an exceptionally low rate of transition. This means it does not change into lighter quarks very easily. It almost always comes from a top quark decay. It is also a frequent decay product of the Higgs boson. Most bottom particles live for about 10 to the power of -12 seconds. This makes them live longer than charmed particles.

Scientists first thought of this quark in 1973. Two physicists named Makoto Kobayashi and Toshihide Maskawa described it. They used it to explain something called CP violation. Haim Harari introduced the name "bottom" in 1975. In 1977, a team at Fermilab found the first evidence. Leon M. Lederman led this E288 experiment team. They saw bottomonium decay into pairs of muons.

The bottom quark has a very large mass. Its mass is about four times the mass of a proton. This is much larger than common light quarks. Because it is heavy and stays around, it is easy to spot. Scientists use a special technique called B-tagging to find it. This helps them identify the particles in big collisions. The discovery was later confirmed at the DORIS collider at DESY.

We can see bottom quarks in many different groups. These groups are called hadrons. Some are called B mesons and contain an up or down quark. Others are called B_cs mesons with a charm or strange quark. There are also bottomonium states like the upsilon meson. These are made of a bottom quark and its antiparticle. Scientists study these in experiments like BaBar, Belle, and LHCb.

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