Problems with the perturbative QCD interpretation of HERMES data on semi-inclusive lepto-production of pions

Abstract

A theoretical analysis has been performed of the HERMES semi-inclusive deep inelastic data on the difference between ${\pi }^{+}$ and ${\pi }^{-}$ multiplicities. It turns out that the application of a standard perturbative QCD analysis, using, as usual, isospin symmetry for the fragmentation functions, leads to a poor description of the deuteron data at small z values. If one allows a breaking of isospin invariance, a good fit to both proton and deuteron data can be achieved for all measured z, but the level of isospin violation, especially at small values of z, is simply not credible. We suspect that the problem is a consequence of using the factorized QCD treatment in a kinematic region where it is unjustified.

13 pages, 8 figures, 2 tables, a version to be published in Phys. Rev. D - Fig. 8 and corresponding discussion added, Refs 10 and 11 added, typo in Ref. 9 corrected

References in corpus (4)

• Global analysis of fragmentation functions for pions and kaons and their uncertainties
• Determination of fragmentation functions and their uncertainties
• Multiplicities of charged pions and kaons from semi-inclusive deep-inelastic scattering by the proton and the deuteron
• Towards a model independent approach to fragmentation functions

Cited by in corpus (1)

• The difference cross sections of unpolarized SIDIS with transverse momentum dependence