Single-spin asymmetries for pions and charged kaons are measured in semi-inclusive deep-inelastic scattering of positrons and electrons off a transversely nuclear-polarized hydrogen target. The dependence of the cross section on the azimuthal angles of the target polarization (phi s) and the produced hadron (phi) is found to have a substantial sin(phi +phi s) modulation for the production of pi(+), pi(-) and K(+). This Fourier component can be interpreted in terms of non-zero transversity distribution functions and non-zero favored and disfavored Collins fragmentation functions with opposite sign. For pi(0) and K(-) production the amplitude of this Fourier component is consistent with zero.
Effects of transversity in deep-inelastic scattering by polarized protons
BACCHETTA, ALESSANDRO;
2010-01-01
Abstract
Single-spin asymmetries for pions and charged kaons are measured in semi-inclusive deep-inelastic scattering of positrons and electrons off a transversely nuclear-polarized hydrogen target. The dependence of the cross section on the azimuthal angles of the target polarization (phi s) and the produced hadron (phi) is found to have a substantial sin(phi +phi s) modulation for the production of pi(+), pi(-) and K(+). This Fourier component can be interpreted in terms of non-zero transversity distribution functions and non-zero favored and disfavored Collins fragmentation functions with opposite sign. For pi(0) and K(-) production the amplitude of this Fourier component is consistent with zero.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.