Breit frame

In particle physics, the Breit frame (also known as infinite-momentum frame or IMF) is a frame of reference used to describe scattering experiments of the form ${\displaystyle A+B\rightarrow A+\sum C_{i}}$, that is experiments in which particle A scatters off particle B, possibly producing particles ${\displaystyle C_{i}}$ in the process.[1] The frame is defined so that the particle A has its momentum reversed in the scattering process.

Another way of understanding the Breit frame is to look at the elastic scattering ${\displaystyle A+\gamma \rightarrow A'}$. The Breit frame is defined as the frame in which ${\displaystyle {\vec {p}}_{A}+{\vec {p}}_{A'}=0}$. There are different occasions when Breit frame can be useful, e.g., in measuring the electromagnetic form factor of a hadron, ${\displaystyle A}$ is the scattered hadron; while for deep inelastic scattering process, the elastically scattered parton should be considered as ${\displaystyle A}$. It is only in the latter case the Breit frame gets related to infinite-momentum frame.

It is named after the American physicist Gregory Breit.[2]

See also

• Center-of-momentum frame
• Laboratory frame of reference

References

1. Griffiths, David (1987). Introduction to elementary particles. New York: Wiley. p. 102. ISBN 978-0-471-60386-3.
2. Hughes, Vernon; Iachello, Francesco; Kusnezov, Dimitri (2001). The Gregory Breit Centennial Symposium: Yale University, USA. Singapore River Edge, N.J: World Scientific. p. 9. ISBN 978-981-02-4553-5.