Why $\alpha_s$ Cannot be Determined from Hadronic Processes without Simultaneously Determining the Parton Distributions
Abstract
We show that any determination of the strong coupling $\alpha_s$ from a process which depends on parton distributions, such as hadronic processes or deepinelastic scattering, generally does not lead to a correct result unless the parton distributions (PDFs) are determined simultaneously along with $\alpha_s$. We establish the result by first showing an explicit example, and then arguing that the example is representative of a generic situation which we explain using models for the shape of equal $\chi^2$ contours in the joint space of $\alpha_s$ and the PDF parameters.
 Publication:

arXiv eprints
 Pub Date:
 January 2020
 arXiv:
 arXiv:2001.04986
 Bibcode:
 2020arXiv200104986F
 Keywords:

 High Energy Physics  Phenomenology;
 High Energy Physics  Experiment
 EPrint:
 13 pages, 6 figures