B^- Mesons are subatomic particles made up of a bottom quark and an anti-up quark. They are part of the larger family of particles known as mesons, which are composed of a quark and an antiquark. B^- mesons are unstable and typically decay into lighter particles, such as pions and kaons, through weak interactions. These mesons play a crucial role in studying CP violation, which helps physicists understand the differences between matter and antimatter. The properties and behaviors of B^- mesons are essential for exploring the fundamental forces of nature and the evolution of the universe.