Factorization and resummation for groomed multi-prong jet shapes

Journal Article · 21 February 2018 · Journal of High Energy Physics (Online)

DOI: https://doi.org/10.1007/JHEP02(2018)144 · OSTI ID:1463551

Larkoski, Andrew J. ^[1]; Moult, Ian ^[2]; Neill, Duff Anderson  ^[3]

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1. Reed College, Portland, OR (United States). Physics Dept.
2. Univ. of California, Berkeley, CA (United States). Berkeley Center for Theoretical Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Observables which distinguish boosted topologies from QCD jets are playing an increasingly important role at the Large Hadron Collider (LHC). These observables are often used in conjunction with jet grooming algorithms, which reduce contamination from both theoretical and experimental sources. In this paper we derive factorization formulae for groomed multi-prong substructure observables, focusing in particular on the groomed D₂ observable, which is used to identify boosted hadronic decays of electroweak bosons at the LHC. Our factorization formulae allow systematically improvable calculations of the perturbative D₂ distribution and the resummation of logarithmically enhanced terms in all regions of phase space using renormalization group evolution. They include a novel factorization for the production of a soft subjet in the presence of a grooming algorithm, in which clustering effects enter directly into the hard matching. We use these factorization formulae to draw robust conclusions of experimental relevance regarding the universality of the D₂ distribution in both e+e- and pp collisions. In particular, we show that the only process dependence is carried by the relative quark vs. gluon jet fraction in the sample, no non-global logarithms from event-wide correlations are present in the distribution, hadronization corrections are controlled by the perturbative mass of the jet, and all global color correlations are completely removed by grooming, making groomed D₂ a theoretically clean QCD observable even in the LHC environment. Lastly, we compute all ingredients to one-loop accuracy, and present numerical results at next-to-leading logarithmic accuracy for e⁺e^- collisions, comparing with parton shower Monte Carlo simulations. Results for pp collisions, as relevant for phenomenology at the LHC, are presented in a companion paper.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
• Grant/Contract Number: AC52-06NA25396
• OSTI ID: 1463551
• Alternate ID(s): OSTI ID: 22739151; OSTI ID: 1485079
• Report Number(s): LA-UR--17-29531
• Journal Information: Journal of High Energy Physics (Online), Journal Name: Journal of High Energy Physics (Online) Journal Issue: 2 Vol. 2018; ISSN 1029-8479
• Publisher: Springer BerlinCopyright Statement
• Country of Publication: United States
• Language: English