21 research outputs found
Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target
Single-spin asymmetries in the semi-inclusive production of charged pions in
deep-inelastic scattering from transversely and longitudinally polarized proton
targets are combined to evaluate the subleading-twist contribution to the
longitudinal case. This contribution is significantly positive for (\pi^+)
mesons and dominates the asymmetries on a longitudinally polarized target
previously measured by \hermes. The subleading-twist contribution for (\pi^-)
mesons is found to be small
Measurement of single-spin azimuthal asymmetries in semi-inclusive electroproduction of pions and kaons on a longitudinally polarised deuterium target
Single-spin asymmetries have been measured for semi-inclusive
electroproduction of , , and mesons in
deep-inelastic scattering off a longitudinally polarised deuterium target. The
asymmetries appear in the distribution of the hadrons in the azimuthal angle
around the virtual photon direction, relative to the lepton scattering
plane. The corresponding analysing powers in the moment of the
cross section are for ,
for ,
for and for . The moments are
compatible with zero for all particles.Comment: Revised version shortened 9 pages, 3 tables, 7 figure
Quark fragmentation to , , , and in the nuclear environment
The influence of the nuclear medium on lepto-production of hadrons was
studied in the HERMES experiment at DESY in semi-inclusive deep-inelastic
scattering of 27.6 GeV positrons off deuterium, nitrogen and krypton targets.
The differential multiplicity for krypton relative to that of deuterium has
been measured for the first time for various identified hadrons (,
, , , , and ) as a function of the virtual
photon energy , the fraction of this energy transferred to the hadron,
and the hadron transverse momentum squared . The multiplicity ratio is
strongly reduced in the nuclear medium at low and high , with
significant differences among the various hadrons. The distribution of the
hadron transverse momentum is broadened towards high in the nuclear
medium, in a manner resembling the Cronin effect previously observed in
collisions of heavy ions and protons with nuclei.Comment: 8 pages, 5 figure