A new parton shower algorithm: Shower evolution, matching at leading and next-to-leading order level

TL;DR

This work introduces a Catani-Seymour dipole-based parton shower that is explicitly designed to integrate with NLO calculations. It develops a comprehensive color-flow, configuration-space formalism, and a dipole splitting framework with exact phase-space weights and a transverse-momentum evolution variable. The authors present general and practical schemes for matching shower evolution to fixed-order matrix elements, including Sudakov reweighting and CKKW-like slicing, and extend the discussion to NLO matching with dipole subtraction. The approach aims to yield Lorentz-invariant, well-controlled predictions with reduced ambiguities, enabling improved incorporation of NLO corrections in event generators, with future work planned for heavy-quark and SUSY-QCD extensions.

Abstract

In this paper we outline a new parton shower algorithm based on the Catani-Seymour dipole factorization. Our motivation is to have an algorithm which can naturally cooperate with the NLO calculations.