History of the Kaon Meson Particle

A Kaon belongs to the meson family. Mesons consist of two quarks, a quark and antiquark. This family is also bosons because they have an integral spin. For the Kaons (K⁺, K^--, K^o, anti K^o ), these particles are composed of a strange quark and either an up or down quark.

In 1947, George Rochester and Clifford Butler from the University of Manchester were investigating cosmic rays in a cloud chamber. They found a particle that decayed in the form of a letter "V". The physicists called this particle a V-meson, a cousin to the pion (p).

Two years later, Cecil Powellis was conducting research with meson particles. His results led to the tau-meson, which decays to p⁺p^-. This meson was a "V" particle. However, in 1952 physicists realized the tau-meson and the theta-meson were different states of the same particle.

That year the tau-meson was renamed as K^o and the theta-meson became L^o (neutral lambda). The KTeV project focuses on two-types of Kaons, K_L (Kaon long) and K_S (Kaon short).

More specifically, the experiment studies the decay rate of the K_L (Kaon long) particle in K_L and K_S (Kaon short). If you look at the right end of the diagram, you can see in the pure K_L beam K_L decays into three particles. However, at times, K_L decays into K_s. You can see this by looking a little to the left of the K_L decay you were observing.

Why are scientists so inquisitive about a particle sometimes decaying into three particles or two particles? Answer: The study of neutral Kaon particle decays has the potential to gain understanding into the universe.

Below is a chart of four Kaons that exist:

The Kaon Chart

Matter & Antimatter

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