Measurement of the Strong Coupling Constant from Inclusive Jet Production at the Tevatron $\bar pp$ Collider

TL;DR

The QCD prediction for the evolution of alpha(s) with jet transverse energy ET is tested over the range 40<ET<450 GeV using ET for the renormalization scale and the data show good agreement with QCD in the region below 250 GeV.

Abstract

We report a measurement of the strong coupling constant, $α_s(M_Z)$, extracted from inclusive jet production in $p\bar{p}$ collisions at $\sqrt{s}=$1800 GeV. The QCD prediction for the evolution of $α_s$ with jet transverse energy $E_T$ is tested over the range 40<$E_T$<450 GeV using $E_T$ for the renormalization scale. The data show good agreement with QCD in the region below 250 GeV. In the text we discuss the data-theory comparison in the region from 250 to 450 GeV. The value of $α_s$ at the mass of the $Z^0$ boson averaged over the range 40<$E_T$<250 GeV is found to be $α_s(M_{Z})= 0.1178 \pm 0.0001{(\rm stat)}^{+0.0081}_{-0.0095}{\rm (exp. syst)}$. The associated theoretical uncertainties are mainly due to the choice of renormalization scale ($^{+6%}_{-4%}$) and input parton distribution functions (5%).

Figures (3)

• Figure 1: The strong coupling constant as a function of $E_T$ for $\mu_R=E_T$ measured using cteq4m parton distributions. The shaded area shows the experimental systematic uncertainties. The curved line represents the NLO QCD prediction for the evolution of $\alpha_s(E_T)$ using $\alpha_s(M_Z)=0.1178$, the average value obtained in the region $40<E_T<250$ GeV. The $\alpha_s(M_Z)$ extracted from $\alpha_s(E_T)$ is shown in the inset along with the weighted average as the horizontal line.
• Figure 2: Experimental systematic uncertainties for $\alpha_s$ measurement (the lines are 1 standard deviation contours), with cteq4m as input PDF and $\mu_R=\mu_F=E_T$.
• Figure 3: Uncertainties in $\alpha_s(M_Z)$ due to the renormalization scale $\mu$, (a), and parton distribution functions, (b).