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

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) acc...

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Bibliographic Details
Main Authors: Rikkert Frederix, Timea Vitos
Format: Article
Language:English
Published: SpringerOpen 2024-12-01
Series:Journal of High Energy Physics
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Online Access:https://doi.org/10.1007/JHEP12(2024)201
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Summary: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 → 4 processes to the per-mille level for 2 → 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.
ISSN:1029-8479