Spin asymmetry in muon-proton deep inelastic scattering on a transversely-polarized target

Abstract We measured the spin asymmetry in the scattering of 100 GeV longitudinally-polarized muons on transversely polarized protons. The asymmetry was found to be compatible with zero in the kinematic range 0.006 x Q 2 2 . From this result we derive the upper limits for the virtual photon-proton asymmetry A 2 , and for the spin structure function g 2 . For x 2 is significantly smaller than its positivity limit √R .