Antenna Showers with One-Loop Matrix Elements

Understand

We consider the probability for a colour-singlet qqbar pair to emit a gluon, in strongly and smoothly ordered antenna showers.

• We expand to second order in alphaS and compare to the second-order QCD matrix elements for Z -> 3 jets, neglecting terms suppressed by 1/NC^2.
• We give a prescription that corrects the shower to the matrix-element result at this order for both soft and hard emissions, thereby explicitly reducing its dependence on evolution- and renormalization-scale choices.
• We confirm that the choice of pT for both of these scales absorbs all logarithms through order alphaS^2, and contrast this with various alternatives.