2008/01/31 by C. Bauer, Christian W. Bauer, Frank J. Tackmann +1
Mathematics · Physics and Astronomy · #Algorithm #Computer science #Event (particle physics) #Event generator #High-Energy Particle Collisions Research #Large Hadron Collider #Logarithm #Matching (statistics) #Mathematical analysis #Mathematics #Merge (version control) #Parallel computing #Particle physics #Particle physics theoretical and experimental studies #Parton #Parton shower #Phase space #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Quantum mechanics #Resummation #hep-ph
paper · pdf · doi:10.1088/1126-6708/2008/12/010
published as JHEP 0812:010,2008 · 60 pages, 22 figures, v2: corrected typos, added references
arxiv created 2008/09/05 · openalex publication_date 2008/12/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We show how many contemporary issues in event generation can be recast in terms of partonic calculations with a matching scale. This framework is called GenEvA, and a key ingredient is a new notion of phase space which avoids the problem of phase space double-counting by construction and includes a built-in definition of a matching scale. This matching scale can be used to smoothly merge any partonic calculation with a parton shower. The best partonic calculation for a given region of phase space can be determined through physics considerations alone, independent of the algorithmic details of the merging. As an explicit example, we construct a positive-weight partonic calculation for e+e- -> n jets at next-to-leading order (NLO) with leading-logarithmic (LL) resummation. We improve on the NLO/LL result by adding additional higher-multiplicity tree-level (LO) calculations to obtain a merged NLO/LO/LL result. These results are implemented using a new phase space generator introduced in a companion paper [arXiv:0801.4028].