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A fragmentation approach to jet flavor

30 Mar 2023, 11:10
20m
104AB (MSU Kellogg Center)

104AB

MSU Kellogg Center

Parallel talk WG4: QCD with Heavy Flavours and Hadronic Final States WG4

Speakers

Andrew Larkoski (UCLA) Simone Caletti

Description

An intuitive definition of the partonic flavor of a jet in quantum chromodynamics is often only well-defined in the deep ultraviolet, where the strong force becomes a free theory and a jet consists of a single parton. However, measurements are performed in the infrared, where a jet consists of numerous particles and requires an algorithmic procedure
to define their phase space boundaries. In this talk we introduce a novel and simple partonic jet flavor definition in the infrared. To connect these two regimes, we define the jet flavor to be the net flavor of the partons that lie exactly along the direction of the Winner-Take-All recombination scheme axis of the jet, which is safe to all orders under emissions of soft particles, but is not collinear safe. Collinear divergences can be absorbed into a perturbative fragmentation function that describes the evolution of the jet flavor from the ultraviolet to the infrared. The evolution equations are linear and a small modification to traditional DGLAP and we solve them to leading-logarithmic accuracy. The evolution equations exhibit fixed points in the deep infrared, we demonstrate quantitative agreement with parton shower simulations, and we present various infrared and collinear safe observables that are sensitive
to this flavor definition.

Submitted on behalf of a Collaboration? No

Primary authors

Andrew Larkoski (UCLA) Daniel Reichelt (Durham University, IPPP) Simone Caletti Prof. Simone Marzani (Università di Genova and INFN Sezione di Genova)

Presentation materials