The first calculation of fractional jets
Name
Bertolini-2015-The first calculatio.pdf
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1.09 MB
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Checksum (MD5)
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Author(s)
Bertolini, Daniele
Thaler, Jesse
Walsh, Jonathan R.
Date Issued
May 2015
Journal
Journal of High Energy Physics
Publisher
Springer-Verlag
Citation
Bertolini, Daniele, Jesse Thaler, and Jonathan R. Walsh. “The First Calculation of Fractional Jets.” J. High Energ. Phys. 2015, no. 5 (May 2015).
Version
Final published version
Abstract
In collider physics, jet algorithms are a ubiquitous tool for clustering particles into discrete jet objects. Event shapes offer an alternative way to characterize jets, and one can define a jet multiplicity event shape, which can take on fractional values, using the framework of “jets without jets”. In this paper, we perform the first analytic studies of fractional jet multiplicity Ñ [subscript jet] in the context of e [superscript +] e [superscript −] collisions. We use fixed-order QCD to understand the Ñ [subscript jet] cross section at order α [2 over s], and we introduce a candidate factorization theorem to capture certain higher-order effects. The resulting distributions have a hybrid jet algorithm/event shape behavior which agrees with parton shower Monte Carlo generators. The Ñ [subscript jet] observable does not satisfy ordinary soft-collinear factorization, and the Ñ [subscript jet] cross section exhibits a number of unique features, including the absence of collinear logarithms and the presence of soft logarithms that are purely non-global. Additionally, we find novel divergences connected to the energy sharing between emissions, which are reminiscent of rapidity divergences encountered in other applications. Given these interesting properties of fractional jet multiplicity, we advocate for future measurements and calculations of Ñ [subscript jet] at hadron colliders like the LHC.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1007/JHEP05(2015)008
