Effective predictions of event shapes: factorized, resummed and gapped angularity distributions

2009/01/31 by Andrew Hornig, Christopher Lee, Grigory Ovanesyan
Physics and Astronomy · #Effective field theory #Event (particle physics) #Factorization #High-Energy Particle Collisions Research #Jet (fluid) #Logarithm #Particle physics theoretical and experimental studies #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Renormalon #Resummation #Weierstrass factorization theorem #hep-ph

paper · pdf · doi:10.1088/1126-6708/2009/05/122

published as JHEP 0905:122,2009 · 52 pages, 13 figures, 1 table, uses JHEP3.cls. v2: comparison between SCET and QCD clarified, other minor corrections, v3: journal version, references added, minor corrections and clarifications

openalex publication_date 2009/05/29 · arxiv created 2009/06/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06

Abstract

Using soft-collinear effective theory (SCET), which provides a unified framework for factorization, resummation of logarithms, and incorporation of universal nonperturbative functions in hard-scattering QCD cross-sections, we present a new prediction of angularity distributions in e+e- annihilation. Angularities tau_a are an infinite class of event shapes which vary in their sensitivity to the substructure of jets in the final state, controlled by a continuous parameter a<2. We calculate angularity distributions for all a<1 to first order in the strong coupling alpha_s and resum large logarithms in these distributions to next-to-leading logarithmic (NLL) accuracy. Our expressions for the next-to-leading order (NLO) O(alpha_s) partonic jet and soft functions in the factorization theorem for angularity distributions are given for the first time. We employ a model for the nonperturbative soft function with a gap parameter which cancels the renormalon ambiguity in the partonic soft function. We explore the relation between the SCET approach to resummation and past approaches in QCD, and discuss the advantages of the effective theory approach. In addition, we draw from the NLO calculations of the jet and soft functions an intuitive lesson about how factorization breaks down in the effective theory as a->1.

Citations

• Power suppressed operators and gauge invariance in soft-collinear effective theory
• Enhanced Nonperturbative Effects in Jet Distributions
• Jets from massive unstable particles: Top-mass determination
• On the equivalence of soft and zero-bin subtractions
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• Evolution of the light-cone distribution function for a heavy quark
• Toward a NNLO calculation of the B¯→Xsγ decay rate with a cut on photon energy: I. Two-loop result for the soft function
• Power corrections to event shape distributions
• Experimental tests of asymptotic freedom
• Event shape–energy flow correlations
• Threshold Resummation in Momentum Space from Effective Field Theory
• Two-loop jet function and jet mass for top quarks
• Infrared Safety in Factorized Hard Scattering Cross-Sections
• Designing gapped soft functions for jet production
• Momentum flow correlations from event shapes: Factorized soft gluons and soft-collinear effective theory
• Sudakov factorization and resummation
• Charm quark mass from inclusive semileptonic B decays
• Event generation from effective field theory
• Soft-collinear factorization and zero-bin subtractions
• The back-to-back region in e+e− energy–energy correlation