Matching NLLA+NNLO for event shape distributions

TL;DR

This paper develops a combined theoretical approach by matching NLLA with NNLO calculations for event shape distributions in electron-positron annihilation, enhancing the accuracy and reliability of QCD predictions across a broad kinematic range.

Contribution

It introduces a novel matching of NLLA with NNLO calculations, improving the precision of event shape distribution predictions in QCD.

Findings

NLLA+NNLO effects are small in the three-jet region.

The combined approach extends the reliable kinematic range.

Improves agreement with experimental data.

Abstract

We study the matching of the next-to-leading logarithmic approximation (NLLA) onto the fixed next-to-next-to-leading order (NNLO) calculation for event shape distributions in electron-positron annihilation. The resulting theoretical predictions combine all precision QCD knowledge on the distributions, and are theoretically reliable over an extended kinematical range. Compared to previously available matched NLLA+NLO and fixed order NNLO results, we observe that the effects of the combined NLLA+NNLO are small in the three-jet region, relevant for precision physics.