PT Journal
AU Cui, ZF
   Ding, M
   Morgado, JM
   Raya, K
   Binosi, D
   Chang, L
   Papavassiliou, J
   Roberts, CD
   Rodriguez-Quintero, J
   Schmidt, SM
TI Concerning pion parton distributions
SO European Physical Journal A
JI Eur. Phys. J. A
PY 2022
BP 10
EP 14pp
VL 58
IS 1
DI 10.1140/epja/s10050-021-00658-7
LA English
AB 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.
ER