 Another way of understanding the Breit frame is to look at the elastic scattering formula_3.The Breit frame is defined as the frame in which formula_4.There are different occasions when Breit frame can be useful, e.g., in measuring the electromagnetic form factor of a hadron, formula_5 is the scattered hadron; while for deep inelastic scattering process, the elastically scattered parton should be considered as formula_5.