The back-to-back region in e^+e^- energy--energy correlation

TL;DR

Problem: precise extraction of the strong coupling from the energy–energy correlation in e+e− collisions in the back-to-back region, where large logarithms require resummation. Method: develop NNLL resummation for EEC by deriving B^(2), assemble g1,g2,g3, and perform NNLL+NLO matching to fixed order, plus a phenomenological assessment including hadronization effects. Contributions: analytic determination of B^(2), robust NNLL+NLO predictions, and detailed comparison with LEP/SLC data demonstrating the critical role of hadronization in obtaining alpha_s(MZ) consistent with the world average. Impact: provides a reliable framework for α_s extraction from EEC and clarifies discrepancies with earlier analyses due to resummation details and hadronization modeling.

Abstract

We consider the back-to-back region in the energy--energy correlation in e^+e^- collisions. We present the explicit expression of the O(as^2) logarithmically enhanced contributions up to next-to-next-to-leading logarithmic accuracy. We study the impact of the results in a detailed comparison with precise LEP and SLC data. We find that, when hadronization effects are taken into account as is customarily done in QCD analysis in e^+e^- annihilations, the extracted value of as(M_Z) is in good agreement with the current world average.

Figures (8)

• Figure 1: Results to NLL+LO accuracy.
• Figure 2: Results to NLL+LO accuracy: scale dependence.
• Figure 3: Results to NNLL+NLO accuracy.
• Figure 4: Results to NNLL+NLO accuracy: scale dependence.
• Figure 5: NNLL+NLO results in the full $\chi$ range