Identification of a sample of e+e- -> qq Events For the Precise Measurement of Alpha_S in High Energy Electron Positron Colliders

TL;DR

This study identifies event selection criteria using PYTHIA simulations and detector modeling to enable precise measurement of the strong coupling constant alpha_s at future high-energy electron-positron colliders, with minimal systematic uncertainty.

Contribution

It proposes a set of cuts for e+e- -> qq events that reduce systematic errors in alpha_s measurement at 500 GeV colliders, based on simulation and detector modeling.

Findings

Selection cuts reduce systematic uncertainty to less than ±1%.

Methodology applicable to future collider experiments.

Supports precise alpha_s measurement at high energies.

Abstract

Based on the PYTHIA physics simulation package, and a fast simulation of the proposed detector for the Next Linear Collider, a set of cuts is identified which leads to a sample of e+e- -> qq events appropriate for the precise measurement of alpha_s in e+e- annihilation at sqrt(s) = 500 GeV/c^2. Using these cuts, the systematic uncertainty on alpha_s associated with correcting for selection cut biases and remaining non-e+e- -> qq (q ^= t) contamination is expected to be less than +/- 1%. This work was done as part of a study of the prospects for the precise measurement of alpha_s at future High Energy Physics facilities, undertaken for the 1996 Snowmass Workshop on New Directions in High Energy Physics.