Determination of the strong-coupling constant from the Z-boson transverse-momentum distribution

The strong-coupling constant is determined from the low-momentum region of the transverse-momentum dis-tribution of Z bosons produced through the Drell-Yan pro-cess, using predictions at third order in perturbative QCD. The analysis employs a measurement performed in proton -antiproton collisions at a centre-of-mass energy of root s = 1.96 TeV with the CDF experiment. The determined value of the strong coupling at the reference scale corresponding to the Z-boson mass is alpha S(mZ) = 0.1191( -0.0016)(+0.0013).