Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions

TL;DR

This paper compares various algorithms for merging matrix elements with parton showers in hadronic collisions, highlighting similarities and differences across implementations at Tevatron and LHC.

Contribution

It provides a comparative analysis of CKKW and MLM merging schemes across different generators and cascades, revealing key differences and similarities.

Findings

Similar results across methods but with notable differences

Impact of implementation choices on merging accuracy

Guidance for selecting merging schemes in collider simulations

Abstract

We compare different procedures for combining fixed-order tree-level matrix-element generators with parton showers. We use the case of W-production at the Tevatron and the LHC to compare different implementations of the so-called CKKW and MLM schemes using different matrix-element generators and different parton cascades. We find that although similar results are obtained in all cases, there are important differences.