Extraction of the strong coupling αs(mZ) from a combined NNLO analysis of inclusive electroweak boson cross sections at hadron colliders

Abstract

The inclusive cross sections of W + , W − , and Z boson production from 34 different measurements performed in proton-(anti)proton collisions at center-of-mass energies √ s = 1.8-13 TeV, are compared to perturbative QCD calculations at next-to-nextto-leading-order (NNLO) accuracy with four sets of parton distributions functions (CT14, HERAPDF2.0, MMHT14, and NNPDF3.0 PDFs) and varying values of the strong coupling constant at the Z mass pole, α s (m Z ). The data-theory agreement is good within the experimental and theoretical uncertainties, with the CT14 and MMHT14 parton densities providing the most overall consistent description of all cross section data. A value of α s (m Z ) = 0.1188 +0.0019 −0.0013 is extracted from a combined fit of the 28 experimental LHC measurements to the corresponding NNLO theoretical predictions obtained with the MMHT14 PDF set, which provides the most robust and stable QCD coupling extraction of this analysis.

Determination of the strong coupling constant αS(mZ) from measurements of inclusive W± and Z boson production cross sections in proton-proton collisions at $$ \sqrt{\mathrm{s}} $$ = 7 and 8 TeV

“…The impact of such a change is not significant in the final results, as observed by comparing the numbers in table 8 and those in the bottom-right columns of table 9. Further similar tests and cross-checks have been carried out in a recent α S (m Z ) extraction that exploits all the LHC electroweak boson data [40] with the same approach used here, which confirm these conclusions. All these systematic tests indicate that HERAPDF2.0 and NNPDF3.0 have larger variations when changing the ingredients of the combination, but for CT14 and MMHT14 the final α S (m Z ) values extracted are reasonably robust within the quoted uncertainties.…”

Experimental QCD summary (ICHEP 2020)

“…1, right) [13,14]. Such measurements have been further combined with 22 other similar ATLAS and LHCb results to derive a value of α s (m Z ) = 0.1188 +0.0019 −0.0013 with a competitive 1.3% uncertainty [15].…”

BLUE: Combining correlated estimates of physics observables within ROOT using the Best Linear Unbiased Estimate method

“…In addition to the LHC collaborations, the software has been used by the PHENIX [11] and STAR [12] collaborations and in a combination of the strong coupling constant α s from many results in Ref. [13]. Further examples of the software usage are described in the manual listed in Table 1.…”