Cui, Zhu-FangDing, M.Morgado Chávez, José ManuelRaya, KhépaniBinosi, DanieleChang, L.Papavassiliou, J.Roberts, Craig D.Rodríguez Quintero, JoséSchmidt, S. M.2022-09-202022-09-202022-01Cui, Z.-F., Ding, M., Morgado, J. M., Raya, K., Binosi, D., Chang, L., Papavassiliou, J., Roberts, C. D., Rodríguez-Quintero, J., & Schmidt, S. M. (2022). Concerning pion parton distributions. In The European Physical Journal A (Vol. 58, Issue 1). Springer Science and Business Media LLC. https://doi.org/10.1140/epja/s10050-021-00658-71434-60011434-601X (electrónico)http://hdl.handle.net/10272/21167Analyses of the pion valence-quark distribution function (DF), uπ (x; ζ ), which explicitly incorporate the behaviour of the pion wave function prescribed by quantum chromodynamics (QCD), predict uπ (x 1; ζ ) ∼ (1 − x)β(ζ ), β(ζ m p) > 2, where m p is the proton mass. Nevertheless, more than forty years after the first experiment to collect data suitable for extracting the x 1 behaviour of uπ , the empirical status remains uncertain because some methods used to fit existing data return a result for uπ that violates this constraint. Such disagreement entails one of the following conclusions: the analysis concerned is incomplete; not all data being considered are a true expression of qualities intrinsic to the pion; or QCD, as it is currently understood, is not the theory of strong interactions. New, precise data are necessary before a final conclusion is possible. In developing these positions, we exploit a single proposition, viz. there is an effective charge which defines an evolution scheme for parton DFs that is all-orders exact. This proposition has numerous corollaries, which can be used to test the character of any DF, whether fitted or calculatedengAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/Deep inelastic-scatteringMuon pairsAsymptotic freedomWave-functionsQuarkNucleonMesonsModelQCDjournal article10.1140/epja/s10050-021-00658-7open access22 Física