@Article{Cui_etal2022, author="Cui, Z. F. and Ding, M. and Morgado, J. M. and Raya, K. and Binosi, D. and Chang, L. and Papavassiliou, J. and Roberts, C. D. and Rodriguez-Quintero, J. and Schmidt, S. M.", title="Concerning pion parton distributions", journal="European Physical Journal A", year="2022", publisher="Springer", volume="58", number="1", pages="10--14pp", abstract="Analyses of the pion valence-quark distribution function (DF), u(pi) (x; sigma), which explicitly incorporate the behaviour of the pion wave function prescribed by quantum chromodynamics (QCD), predict u(pi) (x similar or equal to 1; sigma) similar to (1 -- x)(beta(sigma)), beta(sigma greater than or similar to m(p)) > 2, where mp is the proton mass. Nevertheless, more than forty years after the first experiment to collect data suitable for extracting the x similar or equal to 1 behaviour of up, the empirical status remains uncertain because some methods used to fit existing data return a result for up 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 calculated.", optnote="WOS:000746605900001", optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=5083), last updated on Mon, 31 Jan 2022 08:16:21 +0000", issn="1434-6001", doi="10.1140/epja/s10050-021-00658-7", opturl="https://arxiv.org/abs/2112.09210", opturl="https://doi.org/10.1140/epja/s10050-021-00658-7", language="English" }