Definition
A B-meson is a type of subatomic particle. Specifically, it is a meson containing a bottom quark (also known as a b quark) and another quark (either up, down, strange, or charm), or their antiparticles. Mesons are composite particles made up of a quark and an antiquark. B-mesons are of interest to physicists because they provide a way to study the weak nuclear force and the properties of quarks. They are unstable and decay rapidly into other particles. They are a fundamental particle.