SUMMARY OF PHYSICS PROSPECTS FOR POLARIZED NUCLEON-NUCLEON-SCATTERINGAT HERA-(N)OVER-ARROW

The physics scope of polarized nucleon-nucleon collisions originating from an internal polarized target in the HERA proton beam is summarize d. Based on 240 pb(-1) integrated luminosity at 40 GeV c.m. energy, st atistical sensitivities are given over a wide (x(F),p(T))-range for a variety of inclusive and exclusive final states. By measuring single s pin asymmetries unique information can be obtained on higher twist con tributions and their p(T)-dependence. From double spin asymmetries in both photon and J/psi production it appears possible to measure the po larized gluon distribution in the range 0.1 less than or equal to x(gl uon) less than or equal to 0.4 with a good statistical accuracy. Drell -Yan pair production asymmetries in doubly longitudinal mode, measurab le in the mass range 3 divided by 10 GeV, allow discrimination between different parametrizations of the polarized light sea quark distribut ions. In doubly transverse mode access to the quark transversity distr ibution might become possible. Statistically significant results can b e expected in the elastic channel.