H.J. Bulten

Measurement of the Proton Spin Structure Function g1p with a Pure Hydrogen target.

Abstract A measurement of the proton spin structure function g1p(x,Q2) in deep-inelastic scattering is presented. The data were taken with the 27.6 GeV longitudinally polarised positron beam at HERA incident on a longitudinally polarised pure hydrogen gas target internal to the storage ring. The kinematic range is 0.021 ∫ 0.021 0.85 g 1 p (x) dx evaluated at Q02 of 2.5 GeV2 is 0.122±0.003(stat.)±0.010(syst.).

The flavor asymmetry of the light quark sea from semi-inclusive deep-inelastic scattering

The flavor asymmetry of the light quark sea of the nucleon is determined in the kinematic range 0.02<x<0.3 and 1 GeV^2<Q^2<10 GeV^2, for the first time from semi-inclusive deep-inelastic scattering. The quantity (dbar(x)-ubar(x))/(u(x)-d(x)) is derived from a relationship between the yields of positive and negative pions from unpolarized hydrogen and deuterium targets. The flavor asymmetry dbar-ubar is found to be non-zero and x dependent, showing an excess of dbar over ubar quarks in the proton.

Single-spin azimuthal asymmetries in electroproduction of neutral pions in semi-inclusive deep-inelastic scattering

A single-spin asymmetry in the azimuthal distribution of neutral pions relative to the lepton scattering plane has been measured for the first time in deep-inelastic scattering of positrons off longitudinally polarized protons. The analyzing power in the sinφ moment of the cross section is 0.019±0.007(stat)±0.003(syst). This result is compared to single-spin asymmetries for charged pion production measured in the same kinematic range. The π^0 asymmetry is of the same size as the π^+ asymmetry and shows a similar dependence on the relevant kinematic variables. The asymmetry is described by a phenomenological calculation based on a fragmentation function that represents sensitivity to the transverse polarization of the struck quark.

Hadron formation in deep-inelastic positron scattering in a nuclear environment.

Abstract. The influence of the nuclear medium on the production of charged hadrons in semi-inclusive deep-inelastic scattering has been studied by the HERMES experiment at DESY using a 27.5 GeV positron beam. The differential multiplicity of charged hadrons and identified charged pions from nitrogen relative to that from deuterium has been measured as a function of the virtual photon energy

The Charge form-factor of the neutron from the reaction polarized H-2(polarized e, e-prime n) p

nu

A-dependence of nuclear transparency in quasielastic A(e, ef'p) at high Q2

and the fraction z of this energy transferred to the hadron. There are observed substantial reductions of the multiplicity ratio

Determination of the deep inelastic contribution to the generalised Gerasimov-Drell-Hearn integral for the proton and neutron

R_M^{h}

Measurement of Longitudinal Spin Transfer to Lambda Hyperons in Deep Inelastic Lepton Scattering.

at low

Performance of a Polarized Deuterium Internal Target in a Medium-Energy Electron Storage Ring.

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Double-spin asymmetry in the cross section for exclusive rho(0) production in lepton-proton scattering

and at high z, both of which are well described by a gluon-bremsstrahlung model of hadronization. A significant difference of the