Collider Physics

Most of our knowledge of the elementary particles and their interactions comes from experiments performed at accelerators and colliders. In fixed target experiments primary particle beams (e.g., e ⁻, p, ion) from an accelerator collide with a fixed macroscopic target. They have the advantage of high relative fluxes because of the target density. They can also generate secondary beams of particles or antiparticles produced directly in the primary collision, by subsequent decays, or by radiation. These may be unstable or neutral, and include mesons, hyperons, e ⁺, μ ^±, ν, https://www.w3.org/1998/Math/MathML"> ν ¯ https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315170626/2130fe5e-77bd-49fa-b8c1-fbaea94dfb59/content/equ_2274.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> , and γ. Colliders have the complementary advantage of allowing higher center of mass energies. For example, in the CERN and SLAC e ⁺ e ⁻ experiments at the Z-pole each beam had an energy of M_Z /2 ∼ 45 GeV, while the production of a Z utilizing an e ⁺ beam scattering from atomic electrons would require https://www.w3.org/1998/Math/MathML"> E e + ~ M Z 2 / 2 m e ~ 8 × 10 6 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315170626/2130fe5e-77bd-49fa-b8c1-fbaea94dfb59/content/equ_2275.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> GeV!