  An analysis has been made of the present situation with the high energy
hadron-nucleus and nucleus-nucleus interaction models. As is already known
there are inconsistencies in the interpretation of experimental data on the
primary mass composition, which appear when different EAS components are used
for the analyses, even for the same experiment. In the absence of obvious
experimental defects, there is a clear need for an improvement to the existing
models; we argue that the most promising way is to introduce two effects which
should be present in nucleus-nucleus collisions and have not been allowed for
before. These are: a few percent energy transfer into the EAS electromagnetic
component due to electron-positron pair production or electromagnetic radiation
of quark-gluon plasma and a small slow-down of the cascading process in its
initial stages associated with the extended lifetime of excited nuclear
fragments. The latter process displaces the shower maximum deeper into the
atmosphere.
