https://doi.org/10.1140/epjc/s10052-020-7748-6
Regular Article - Theoretical Physics
Why 
cannot be determined from hadronic processes without simultaneously determining the parton distributions
1
Tif Lab, Dipartimento di Fisica, INFN, Sezione di Milano, Università di Milano, Via Celoria 16, 20133, Milan, Italy
2
Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK
* e-mail: stefano.forte@mi.infn.it
Received:
17
January
2020
Accepted:
16
February
2020
Published online:
28
February
2020
We show that any determination of the strong coupling from a process which depends on parton distributions, such as hadronic processes or deep-inelastic scattering, generally does not lead to a correct result unless the parton distributions (PDFs) are determined simultaneously along with . 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 
contours in the joint space of and the PDF parameters.
© The Author(s), 2020
