Generalized angular-order parton showers in Herwig 7

Lee, Joon-Bin; Masouminia, M. R.; Seymour, Michael H.; Yang, Un-ki

Abstract

This paper presents the inaugural investigation of beyond the Standard Model (BSM) radiation processes, framed as a generalized, process- and model-independent parton shower algorithm within Herwig 7, based on direct translations of Universal FeynRules Output (UFO) constructed via Herwig’s ufo2herwig module. Leveraging the fact that shower kinematics are dictated by the spins of involved particles, we calculate comprehensive helicity-dependent branching kernels for all feasible splittings of scalars, fermions, and vector bosons, tailored to Herwig 7’s angular-ordering (AO) parton shower algorithm. Utilizing these kernels, we derive BSM splitting functions in the quasi-collinear limit, ensuring compatibility with the Standard Model (SM) and supersymmetry (SUSY) splitting functions when analogous parameter conditions are applied. These newly derived functions have been integrated into the Herwig 7 event generator framework. Comparative analyses with fixed-order matrix element calculations show good agreement for single radiation events. Moreover, the results showcase the influence of BSM radiation at the Large Hadron Collider (LHC) and envisage its implications for future collider endeavours. This research augments our comprehension of BSM radiation effects, with significant bearings on present and prospective collider-based inquiries.

Citation

Lee, J.-B., Masouminia, M. R., Seymour, M. H., & Yang, U.-K. (2024). Generalized angular-order parton showers in Herwig 7. Journal of High Energy Physics, 2024(8), Article 64. https://doi.org/10.1007/jhep08%282024%29064

• Journal Article Type: Article
• Acceptance Date: Jun 28, 2024
• Online Publication Date: Aug 8, 2024
• Publication Date: Aug 8, 2024
• Deposit Date: Sep 4, 2024
• Publicly Available Date: Sep 4, 2024
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Electronic ISSN: 1029-8479
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2024
• Issue: 8
• Article Number: 64
• DOI: https://doi.org/10.1007/jhep08%282024%29064
• Keywords: Specific BSM Phenomenology, Electroweak Precision Physics, Parton Shower
• Public URL: https://durham-repository.worktribe.com/output/2795652