Interleaved Resonance Decays and Electroweak Radiation in the Vincia Parton Shower

Submission summary

 As Contributors: Rob Verheyen Preprint link: scipost_202109_00013v1 Code repository: http://pythia.org Date submitted: 2021-09-10 11:04 Submitted by: Verheyen, Rob Submitted to: SciPost Physics Academic field: Physics Specialties: High-Energy Physics - Phenomenology Approaches: Computational, Phenomenological

Abstract

We propose a framework for high-energy interactions in which resonance decays and electroweak branching processes are interleaved with the QCD evolution in a single com- mon sequence of decreasing resolution scales. The interleaved treatment of resonance decays allows for a new treatment of finite-width effects in parton showers. At scales above their offshellness (i.e., typically Q > Γ ), resonances participate explicitly as incom- ing and outgoing states in branching processes, while they are effectively “integrated out” of the description at lower scales. We implement this formalism, together with a full set of antenna functions for branching processes involving electroweak (W/Z/H) bosons in the Vincia shower module in Pythia 8.3, and study some of the consequences

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