  The helix structure of the Lund string, first derived from studies devoted to
the emission of soft gluons at the end of the parton cascade, may be at the
origin of certain characteristic discrepancies observed in the low transverse
momentum region at LEP and LHC. A study of the relation between different helix
implementations and observable effects is presented. The model is extended to
cover a multiparton string topology (result of parton shower), and compared
with the experimental data. It is found that a helix-ordered string with a
regular winding (proportional to the energy density stored in the string), is
favoured by the inclusive single-particle spectra measured in the hadronic
decay of Z$^0$.
