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arXiv · 2504.05377

Logarithmically-accurate and positive-definite NLO shower matching

Melissa van Beekveld·Silvia Ferrario Ravasio·Jack Helliwell·Alexander Karlberg·Gavin P. Salam·Ludovic Scyboz·Alba Soto-Ontoso·Gregory Soyez·Silvia Zanoli
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Abstract

We present methods to achieve NLL+NLO accurate parton showering for processes with two coloured legs: neutral- and charged-current Drell-Yan, and Higgs production in $pp$ collisions, as well as DIS and $e^+e^-$ to jets. The methods include adaptations of existing approaches, as well as a new NLO matching scheme, ESME, that is positive-definite by construction. Our implementations of the methods within the PanScales framework yield highly competitive NLO event generation speeds. We validate the fixed-order and combined resummation accuracy with tests in the limit of small QCD coupling and briefly touch on phenomenological comparisons to standard NLO results and to Drell-Yan data. The progress reported here is an essential step towards showers with logarithmic accuracy beyond NLL for processes with incoming hadrons.

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Melissa van Beekveld, Silvia Ferrario Ravasio, Jack Helliwell, Alexander Karlberg, Gavin P. Salam, Ludovic Scyboz, Alba Soto-Ontoso, Gregory Soyez, Silvia Zanoli. 2025-04-07. Logarithmically-accurate and positive-definite NLO shower matching. https://doi.org/10.1007/jhep10(2025)038

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