Upsilon meson

Upsilon Meson

The Upsilon peak observed in particle collision experiments.

Quark structure of bottomonium, including the Upsilon meson.

The Upsilon meson (_) is a family of mesons formed from a bottom quark and its antiparticle, the bottom antiquark. It is a type of bottomonium, a bound state of a bottom quark and its antiquark. The Upsilon meson was first discovered in 1977 by the E288 experiment at Fermilab.

Discovery

The discovery of the Upsilon meson was a significant event in the field of particle physics. It was first observed by a team led by Leon M. Lederman at Fermilab. The team detected the Upsilon meson through its decay into a pair of muons, which produced a distinct peak in the invariant mass distribution of the muon pairs. This peak, known as the Upsilon peak, was a clear indication of a new particle.

Properties

The Upsilon meson is a neutral particle with a mass of approximately 9.46 GeV/c_. It is the lightest of the bottomonium states and has a relatively long lifetime compared to other mesons. The Upsilon meson can decay into various final states, including pairs of leptons such as muons and electrons, as well as hadrons.

Significance

The study of the Upsilon meson and other bottomonium states provides valuable insights into the strong force, one of the four fundamental forces of nature. The strong force is responsible for binding quarks together to form protons, neutrons, and other particles. By studying the properties and decay modes of the Upsilon meson, physicists can test predictions of quantum chromodynamics (QCD), the theory that describes the strong interaction.

Related pages

• Bottom quark
• Meson
• Quantum chromodynamics
• Fermilab

References

• Lederman, L. M., et al. "Observation of a Dimuon Resonance at 9.5 GeV in 400-GeV Proton-Nucleus Collisions." Physical Review Letters, vol. 39, no. 5, 1977, pp. 252-255.
• "Upsilon Meson." Particle Data Group. Retrieved from [1].

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  Upsilon meson peak
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  Quark structure of bottomonium