Test of the Flavour Independence of alpha_s using Next-to-Leading Order Calculations for Heavy Quarks

TL;DR

This paper tests whether the strong coupling constant alpha_s is flavor-independent by analyzing heavy quark events at LEP, finding results consistent with flavor independence within uncertainties.

Contribution

It provides a novel experimental test of alpha_s flavor independence using NLO calculations and event shape observables for charm and bottom quarks.

Findings

Alpha_s ratios for charm and bottom to light quarks are close to 1.

Results are consistent with flavor independence of alpha_s.

Uncertainties are quantified for each measurement.

Abstract

We present a test of the flavour independence of the strong coupling constant for charm and bottom quarks with respect to light (uds) quarks, based on a hadronic event sample obtained with the OPAL detector at LEP. Five observables related to global event shapes were used to measure alpha_s in three flavour tagged samples (uds, c and b). The event shape distributions were fitted by Order(alpha_s**2) calculations of jet production taking into account mass effects for the c and b quarks. We find: = 0.997 +- 0.038(stat.) +- 0.030(syst.) +- 0.012(theory) and = 0.993 +- 0.008(stat.) +- 0.006(syst.) +- 0.011(theory) for the ratios alpha_s(charm)/alpha_s(uds) and alpha_s(b)/alpha_s(uds) respectively.