Notes

(1) cf., the frequency spectrum of bremsstrahlung from an instantaneously accelerated classical electric charge.

(2) Unknown subleading log terms may, as always, lead to different effective for different processes: the effective here is essentially a free parameter.

(3) In QED, radiation emitted sufficiently late could not be resolved by any practical detector.

(4) After many progressively more contorted analytical attacks, investigations of QCD showers finally turned to Monte Carlo techniques [6] which continue to prove fruitful [7]. Perhaps similar development may be traced in QCD showers.

(5) Explicit calculation of the leading log part of fig. 2b without summing over the initial parton spin gives eq. (2).

(6) The possibility of this dissection to is revealed by the identity

where is the gluon fractional energy and the quark fractions.

(7) The equality of the integrated cross sections to in the two gauges with their corresponding identifications (quark fractions satisfying ; gluon fraction 3) is manifest from

(8) In reality, we apply only the cut , and introduce no further cuts.

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