Study of α_s in Z + 1 Jet and Z + 2 Jets Channels

Abstract

The QCD coupling constant (αs) is today the least accurately known of all interaction couplings in nature. The coupling runs with energy and, by convention, it is given at the Z Boson mass scale. Currently, uncertainty on the measurement of αs contributes significantly to the uncertainties in the calculations of key Standard Model (SM) decay and cross-section processes, such as the production and hadronic decay of the Higgs Boson. Hence, precise determination of this quantity is of utmost importance to the high energy physics (HEP) community. Currently, its value is extracted from a number of processes in hadron colliders. However, what has not been attempted is its estimation in ratios of cross-sections where common uncertainties cancel out. Therefore, the aim of this study is to understand observables that are sensitive to αs in the ratios of Z + n jet to Z + (n-1) jet cross-section (or differential cross-section) ratios. We will also study the observables in Z + n jet processes sensitive to αs. This study will serve as input to the precise extraction of αs from Z + n jet processes and their ratios