According to (8.33), the fraction z of the proton momentum carried by the struck parton in Figure 8.4 is equal to the scaling variable x if certain approximations are made. These are: the proton momentum P is much larger than its mass, that is |P| >> M; the masses and transverse momenta of the partons are negligible compared with |P| and Q²; and Q²M². Verify this starting from the relation

ω² ˆ’ k² = m² €“̃ 0,

where k is the final momentum of the struck parton, as shown in Figure 8.4, and ω and m̃ are its energy and mass, respectively. 

Figure 8.4

Transcribed Image Text:

p' zP k hadrons hadrons