# HERMES

 2017-04-2813:01 [PUBDB-2017-02102] Journal Article et al Evidence for a Single-Spin Azimuthal Asymmetry in Semi-inclusive Pion Electroproduction Physical review letters 84(18), 4047 - 4051 (2000) [10.1103/PhysRevLett.84.4047]   Restricted: PDF; 2017-04-1011:12 [PUBDB-2017-01572] Report/Journal Article Oganesian, K. A. Transversity distribution and polarized fragmentation function from semiinclusive pion electroproduction [hep-ph/0002268; DESY-99-176] The European physical journal / C 18(4), 639 - 644 (2001) [10.1007/s100520100564]   A method is discussed to determine the hitherto unknown u-quark transversity distribution from a planned HERMES measurement of a single-spin asymmetry in semi-inclusive pion electroproduction off a transversely polarized target. Assuming u-quark dominance, the measurement yields the shapes of the transversity distribution and of the ratio of a polarized and the unpolarized u-quark fragmentation functions. [...] Restricted: PDF; 2017-04-1011:10 [PUBDB-2017-01571] Report/Journal Article Oganesian, K. A. Single spin azimuthal asymmetries in the 'Reduced twist - three approximation' [DESY-00-016; hep-ph/0002091] Physics letters / B 483(1-3), 69 - 73 (2000) [10.1016/S0370-2693(00)00596-7]   We consider the single-spin azimuthal asymmetries recently measured at the HERMES experiment for charged pions produced in semi-inclusive deep inelastic scattering of leptons off longitudinally polarized protons. Guided by the experimental results and assuming a vanishing twist-2 transverse quark spin distribution in the longitudinally polarized nucleon, denoted as “reduced twist-3 approximation”, a self-consistent description of the observed single-spin asymmetries is obtained. [...] Restricted: PDF; 2017-04-1010:47 [PUBDB-2017-01569] Report/Journal Article et al The Longitudinal polarimeter at HERA [DESY-00-106; physics/0009047] Nuclear instruments & methods in physics research / A 479(2-3), 334 - 348 (2002) [10.1016/S0168-9002(01)00901-9]   The design, construction and operation of a Compton back-scattering laser polarimeter at the HERA storage ring at DESY are described. The device measures the longitudinal polarization of the electron beam between the spin rotators at the HERMES experiment with a fractional systematic uncertainty of 1.6%. [...] Restricted: PDF; 2017-04-1010:45 [PUBDB-2017-01568] Report/Journal Article et al The HERMES dual-radiator ring imaging Cherenkov detector [physics/0104033; DESY-00-190] Nuclear instruments & methods in physics research / A 479(2-3), 511 - 530 (2002) [10.1016/S0168-9002(01)00932-9]   The construction and use of a dual radiator Ring Imaging Cerenkov(RICH) detector is described. This instrument was developed for the HERMES experiment at DESY which emphasizes measurements of semi-inclusive deep-inelastic scattering. [...] Restricted: PDF; 2017-04-1010:40 [PUBDB-2017-01567] Report/Journal Article et al Exclusive leptoproduction of rho0 mesons from hydrogen at intermediate virtual photon energies [hep-ex/0004023; DESY-00-058] The European physical journal / C 17(3), 389 - 398 (2000) [10.1007/s100520000483]   Measurements of the cross section for exclusive virtual-photoproduction of rho^0 mesons from hydrogen are reported. The data were collected by the HERMES experiment using 27.5 GeV positrons incident on a hydrogen gas target in the HERA storage ring. [...] Restricted: PDF; 2017-04-1010:38 [PUBDB-2017-01566] Report/Journal Article et al The $Q^2$-dependence of the generalized Gerasimov-Drell-Hearn integral for the proton [hep-ex/0008037; DESY-00-096] Physics letters / B 494(1-2), 1 - 8 (2000) [10.1016/S0370-2693(00)01111-4]   The dependence on Q 2 (the negative square of the 4-momentum of the exchanged virtual photon) of the generalised Gerasimov–Drell–Hearn integral for the proton has been measured in the range 1.2 GeV 2 < Q 2 <12 GeV 2 by scattering longitudinally polarised positrons on a longitudinally polarised hydrogen gas target. The contributions of the nucleon-resonance and deep inelastic regions to this integral have been evaluated separately. [...] Restricted: PDF; 2017-04-1010:35 [PUBDB-2017-01565] Report/Journal Article et al Hadron formation in deep inelastic positron scattering in a nuclear environment [hep-ex/0012049; DESY-00-191] The European physical journal / C 20(3), 479 - 486 (2001) [10.1007/s100520100697]   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 \nu and the fraction z of this energy transferred to the hadron. [...] Restricted: PDF; 2017-04-1010:33 [PUBDB-2017-01564] Report/Journal Article et al Measurement of angular distributions and R = $\sigma_L$ / $\sigma_T$ in diffractive electroproduction of $\rho^0$ mesons [hep-ex/0002016; DESY-99-199] The European physical journal / C 18(2), 303 - 316 (2000) [10.1007/s100520000536]   Production and decay angular distributions were extracted from measurements of exclusive electroproduction of the rho^0(770) meson over a range in the virtual photon negative four-momentum squared 0.5< Q^2 <4 GeV^2 and the photon-nucleon invariant mass range 3.8< W <6.5 GeV. The experiment was performed with the HERMES spectrometer, using a longitudinally polarized positron beam and a ^3He gas target internal to the HERA e^{+-} storage ring. [...] Restricted: PDF; 2017-02-0215:04 [PUBDB-2017-00843] Preprint/Report et al Ratios of helicity amplitudes for exclusive $\rho^0$ electroproduction on transversely polarized protons [arXiv:1702.00345; DESY-17-017]   Exclusive $\rho^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV$^2$