Reported here are transverse single-spin asymmetries (A(N)) in the production of charged hadrons as a function of transverse momentum (p(T)) and Feynman-x (x(F)) in polarized p(up arrow)+ p, p(up arrow) + Al, and p(up arrow) + Au collisions at root s(NN) = 200 GeV. The measurements have been performed at forward and backward rapidity (1.4 0) in p(up arrow) + p collisions, whereas the p(up arrow)+ Al and p. thorn Au results show smaller asymmetries.
This finding provides new opportunities to investigate the origin of transverse single-spin asymmetries and a tool to study nuclear effects in p thorn A collisions.