Calculations with off-shell matrix elements, TMD parton densities and TMD parton showers

• Published in: The European physical journal. C, Particles and fields Vol. 78; no. 2; pp. 137 - 8
• Main Authors: Bury, Marcin, van Hameren, Andreas, Jung, Hannes, Kutak, Krzysztof, Sapeta, Sebastian, Serino, Mirko
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2018; Springer; Springer Nature B.V; SpringerOpen
• Subjects: Astronomy; Astrophysics and Cosmology; Density; Elementary Particles; Energy consumption; Hadrons; Heavy Ions; Mathematical analysis; Measurement Science and Instrumentation; Nuclear Energy; Nuclear Physics; Partons; Physics; Physics and Astronomy; Quantum Field Theories; Quantum Field Theory; Regular - Theoretical Physics; Regular Article - Theoretical Physics; Showers; String Theory
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s10052-018-5642-2

A new calculation using off-shell matrix elements with TMD parton densities supplemented with a newly developed initial state TMD parton shower is described. The calculation is based on the KaTie package for an automated calculation of the partonic process in high-energy factorization, making use of TMD parton densities implemented in TMDlib. The partonic events are stored in an LHE file, similar to the conventional LHE files, but now containing the transverse momenta of the initial partons. The LHE files are read in by the Cascade package for the full TMD parton shower, final state shower and hadronization from Pythia where events in HEPMC format are produced. We have determined a full set of TMD parton densities and developed an initial state TMD parton shower, including all flavors following the TMD distribution. As an example of application we have calculated the azimuthal de-correlation of high p t dijets as measured at the LHC and found very good agreement with the measurement when including initial state TMD parton showers together with conventional final state parton showers and hadronization.