Abstract
We consider the probability for a colour-singlet \( q\overline{q} \) pair to emit a gluon, in strongly and smoothly ordered antenna showers. We expand to second order in α s and compare to the second-order QCD matrix elements for Z → 3 jets, neglecting terms suppressed by \( {1 \left/ {{N_C^2}} \right.} \). 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 p ⊥ for both of these scales absorbs all logarithms through \( \mathcal{O}\left( {\alpha_s^2} \right) \), and contrast this with various alternatives. We include these corrections in the vincia shower generator and study the impact on LEP event-shape and fragmentation observables. An uncertainty estimate is provided for each event, in the form of a vector of alternative weights.
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Hartgring, L., Laenen, E. & Skands, P. Antenna showers with one-loop matrix elements. J. High Energ. Phys. 2013, 127 (2013). https://doi.org/10.1007/JHEP10(2013)127
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DOI: https://doi.org/10.1007/JHEP10(2013)127