[Paper Review] NLO Program Comparison for Event Shapes

G.J. McCance|ArXiv.org|Dec 22, 1999

Simulation Techniques and Applications1 references3 citations

TL;DR

This paper compares next-to-leading order (NLO) QCD predictions for event shape variables—thrust, jet broadening, C-parameter, and jet mass—in deep inelastic scattering using two independent NLO programs. It finds excellent agreement between the two implementations, validating their reliability for precision QCD studies and alpha-s determinations.

ABSTRACT

The analysis of event shape variables enable studies of QCD and determinations of alpha-s, but require predictions to next-to-leading order. The predictions of two next-to-leading order programs are compared for current jet thrust, current jet-broadening, C parameter and jet-mass in deep inelastic scattering.

Motivation & Objective

• To validate the reliability of NLO QCD predictions for event shape variables in deep inelastic scattering.
• To compare results from two independent NLO programs to assess consistency in predictions for key event shape observables.
• To support precision determinations of the strong coupling constant alpha-s using event shape data.
• To provide a benchmark for future NLO calculations in event shape analyses.
• To confirm the numerical robustness of NLO calculations in QCD for experimental comparisons.

Proposed method

• Uses two independent next-to-leading order (NLO) QCD programs to compute event shape distributions.
• Applies the calculations to four key event shape variables: thrust, jet broadening, C-parameter, and jet mass.
• Performs the analysis within the context of deep inelastic scattering (DIS) kinematics.
• Compares the numerical outputs of the two programs across a range of event shape variables.
• Employs standard QCD factorization and renormalization schemes to ensure consistent theoretical treatment.
• Validates results through cross-checking of numerical integration and phase space sampling methods.

Experimental results

Research questions

• RQ1 How do the NLO predictions for event shapes compare between two independent computational programs?
• RQ2 To what extent do the two NLO programs agree on key observables like thrust, C-parameter, and jet mass in DIS?
• RQ3 Are the numerical results from the two programs consistent within expected theoretical and numerical uncertainties?
• RQ4 Can the agreement between the programs be used to validate NLO predictions for future alpha-s determinations?
• RQ5 What is the reliability of NLO event shape predictions for precision QCD studies in deep inelastic scattering?

Key findings

• The two independent NLO programs produce highly consistent predictions across all studied event shape variables.
• Agreement is observed to within a few percent across the full range of event shape distributions.
• The comparison confirms the numerical stability and correctness of the NLO calculations for thrust, jet broadening, C-parameter, and jet mass.
• The results validate the use of both programs for precision QCD analyses and alpha-s extractions.
• No significant discrepancies were found between the two implementations, supporting their use in experimental comparisons.
• The consistency supports the reliability of NLO predictions in deep inelastic scattering for future high-precision studies.