N-jettiness subtractions for NNLO QCD calculations

A bstract We present a subtraction method utilizing the N -jettiness observable, T N , to perform QCD calculations for arbitrary processes at next-to-next-to-leading order (NNLO). Our method employs soft-collinear effective theory (SCET) to determine the IR singular contributions of N -jet cross sec...

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Bibliographic Details
Published in:The journal of high energy physics 2015-09, Vol.2015 (9), p.1-52, Article 58
Main Authors: Gaunt, Jonathan R., Stahlhofen, Maximilian, Tackmann, Frank J., Walsh, Jonathan R.
Format: Article
Language:English
Subjects:
Classical and Quantum Gravitation
Construction
Construction costs
Elementary Particles
Ingredients
Mathematical analysis
Mathematical models
Partons
Physics
Physics and Astronomy
Quantum chromodynamics
Quantum Field Theories
Quantum Field Theory
Quantum Physics
Regular Article - Theoretical Physics
Relativity Theory
String Theory
Subtraction
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Summary:A bstract We present a subtraction method utilizing the N -jettiness observable, T N , to perform QCD calculations for arbitrary processes at next-to-next-to-leading order (NNLO). Our method employs soft-collinear effective theory (SCET) to determine the IR singular contributions of N -jet cross sections for T N → 0, and uses these to construct suitable T N -subtractions. The construction is systematic and economic, due to being based on a physical observable. The resulting NNLO calculation is fully differential and in a form directly suitable for combining with resummation and parton showers. We explain in detail the application to processes with an arbitrary number of massless partons at lepton and hadron colliders together with the required external inputs in the form of QCD amplitudes and lower-order calculations. We provide explicit expressions for the T N -subtractions at NLO and NNLO. The required ingredients are fully known at NLO, and at NNLO for processes with two external QCD partons. The remaining NNLO ingredient for three or more external partons can be obtained numerically with existing NNLO techniques. As an example, we employ our results to obtain the NNLO rapidity spectrum for Drell-Yan and gluon-fusion Higgs production. We discuss aspects of numerical accuracy and convergence and the practical implementation. We also discuss and comment on possible extensions, such as more-differential subtractions, necessary steps for going to N 3 LO, and the treatment of massive quarks.
ISSN:1029-8479
1029-8479
DOI:10.1007/JHEP09(2015)058