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arXiv · 2409.12128

Leading-colour-based unweighted event generation for multi-parton tree-level processes

Rikkert Frederix·Timea Vitos
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Abstract

In this work, we revisit unweighted event generation for multi-parton tree-level processes in massless QCD. We introduce a two-step approach, in which initially unweighted events are generated at leading-colour (LC) accuracy, followed by a reweighting of these events to full-colour (FC) accuracy and applying an additional unweighting cycle. This method leverages the simple structure of LC integrands, enabling optimized phase-space parameterisations and resulting in high primary unweighting efficiencies, ranging from the percent level for $2 \to 4$ processes to the per-mille level for $2 \to 7$ processes. Given that the LC-accurate matrix elements closely approximate the FC-accurate ones, the secondary unweighting efficiencies exceed 50%. Our results suggest that this two-step approach offers an efficient alternative to direct event generation at FC accuracy.

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Rikkert Frederix, Timea Vitos. 2024-09-18. Leading-colour-based unweighted event generation for multi-parton tree-level processes. https://arxiv.org/abs/2409.12128

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