https://doi.org/10.1140/epjc/s10052-025-14576-1
Regular Article - Theoretical Physics
Sudakov evolution without unitarity
1
School of Physics and Astronomy, Monash University, 3800, Clayton, VIC, Australia
2
School of Physics, Shandong University, 250100, Jinan, Shandong, China
Received:
7
July
2025
Accepted:
21
July
2025
Published online:
5
August
2025
We present a method for sampling singular functions defined on (nested) multiparticle phase spaces, based on a generalisation of parton-shower phase-space generation techniques. At the heart of the method are three key ingredients: (1) the Sudakov sampling by which shower-style calculations sweep across phase space in an ordered manner, from hard to soft; (2) the sequential nesting of multiparticle phase spaces; and (3) the factorisations obeyed by singular multiparton amplitudes on the edges of these phase spaces. We demonstrate a C++ implementation of the proposed algorithm, dubbed Sunshine (loosely derived from Sudakov Nesting of Hard Integrals), for hadronic Z decays, and use it to test the tree-level accuracy of the Vincia sector shower through 
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© The Author(s) 2025
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