Appendix A

Three-jet Kinematics

We define the momenta for three-jet production as in fig. 4, and work, as always, in the N center of mass system. We take to be the c.m.s. energy in the N collision, so that (ignoring the proton mass)

[ Figure 4 ] The kinematics of three-jet production in N collisions. 1 is the initial parton; 2 the initial while 3 and 4 are the final state partons. The final state ''diquark'' (fragments of the nucleon) is not labeled in the figure.

For the subprocess, we define the kinematic invariants

and we take the angle between and the direction to be . is the fraction of the nucleon's momentum carried by the incoming parton . We assume here that has no component transverse to . Then one finds

and are obtained by replacing in eq. (A.3) with . In the limit , (A.3) reduces to

The energy of the remnants of the nucleon (`diquark') after the ejection of momentum is

The fractional energies of the three final particles (which are all taken to be massless) are therefore:

In terms of these, one finds, for example,

For , this becomes , and for ,

previous  l   next