Abstract
In this thesis the exclusive electroproduction of {rho}{sup 0} mesons is analyzed using the data accumulated with the HERMES spectrometer in the years 2002-2005 by scattering the lepton beam of the HERA accelerator of the internal target of HERMES filled with transversely polarized hydrogen gas atoms. The {rho}{sup 0} production mechanism and, in a model-dependent way, the structure of the nucleon are studied by measuring the spin-density matrix elements (SDMEs), which parameterize the {rho}{sup 0} production and decay angular distribution. The decomposition of the angular distribution in terms of SDMEs was previously done for both polarized and unpolarized lepton beam and unpolarized target. Recently, the angular distribution was decomposed in terms of SDMEs also for a transversely polarized target. A first measurement of the 30 'transverse' SDMEs is reported in this thesis, yielding information on the degree of s-channel helicity conservation and natural-parity exchange in the case of a transversely polarized target. The measured SDMEs are implemented into the rhoMC Monte Carlo generator, which is currently the only one capable of fully simulating the exclusive {rho}{sup 0} production and decay for both unpolarized and polarized beam and target. The interest in SDMEs for a polarized target arose after it was
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Citation Formats
Rostomyan, Armine Armand.
Exclusive {rho}{sup 0} production at HERMES.
Germany: N. p.,
2008.
Web.
Rostomyan, Armine Armand.
Exclusive {rho}{sup 0} production at HERMES.
Germany.
Rostomyan, Armine Armand.
2008.
"Exclusive {rho}{sup 0} production at HERMES."
Germany.
@misc{etde_21125714,
title = {Exclusive {rho}{sup 0} production at HERMES}
author = {Rostomyan, Armine Armand}
abstractNote = {In this thesis the exclusive electroproduction of {rho}{sup 0} mesons is analyzed using the data accumulated with the HERMES spectrometer in the years 2002-2005 by scattering the lepton beam of the HERA accelerator of the internal target of HERMES filled with transversely polarized hydrogen gas atoms. The {rho}{sup 0} production mechanism and, in a model-dependent way, the structure of the nucleon are studied by measuring the spin-density matrix elements (SDMEs), which parameterize the {rho}{sup 0} production and decay angular distribution. The decomposition of the angular distribution in terms of SDMEs was previously done for both polarized and unpolarized lepton beam and unpolarized target. Recently, the angular distribution was decomposed in terms of SDMEs also for a transversely polarized target. A first measurement of the 30 'transverse' SDMEs is reported in this thesis, yielding information on the degree of s-channel helicity conservation and natural-parity exchange in the case of a transversely polarized target. The measured SDMEs are implemented into the rhoMC Monte Carlo generator, which is currently the only one capable of fully simulating the exclusive {rho}{sup 0} production and decay for both unpolarized and polarized beam and target. The interest in SDMEs for a polarized target arose after it was shown that at leading twist the corresponding SDMEs can be related to the azimuthal transverse target-spin asymmetry in the cross section of exclusive {rho}{sup 0} production which is sensitive to the unknown nucleon helicity-ip GPDs. Since the GPD formalism is only valid for longitudinally polarized vector mesons produced by longitudinal photons, for the first time the transverse target-spin asymmetry of longitudinally polarized {rho}{sup 0} mesons is extracted and compared to the available theoretical predictions, specically considering possible problems with next-to-leading order corrections. (orig.)}
place = {Germany}
year = {2008}
month = {Nov}
}
title = {Exclusive {rho}{sup 0} production at HERMES}
author = {Rostomyan, Armine Armand}
abstractNote = {In this thesis the exclusive electroproduction of {rho}{sup 0} mesons is analyzed using the data accumulated with the HERMES spectrometer in the years 2002-2005 by scattering the lepton beam of the HERA accelerator of the internal target of HERMES filled with transversely polarized hydrogen gas atoms. The {rho}{sup 0} production mechanism and, in a model-dependent way, the structure of the nucleon are studied by measuring the spin-density matrix elements (SDMEs), which parameterize the {rho}{sup 0} production and decay angular distribution. The decomposition of the angular distribution in terms of SDMEs was previously done for both polarized and unpolarized lepton beam and unpolarized target. Recently, the angular distribution was decomposed in terms of SDMEs also for a transversely polarized target. A first measurement of the 30 'transverse' SDMEs is reported in this thesis, yielding information on the degree of s-channel helicity conservation and natural-parity exchange in the case of a transversely polarized target. The measured SDMEs are implemented into the rhoMC Monte Carlo generator, which is currently the only one capable of fully simulating the exclusive {rho}{sup 0} production and decay for both unpolarized and polarized beam and target. The interest in SDMEs for a polarized target arose after it was shown that at leading twist the corresponding SDMEs can be related to the azimuthal transverse target-spin asymmetry in the cross section of exclusive {rho}{sup 0} production which is sensitive to the unknown nucleon helicity-ip GPDs. Since the GPD formalism is only valid for longitudinally polarized vector mesons produced by longitudinal photons, for the first time the transverse target-spin asymmetry of longitudinally polarized {rho}{sup 0} mesons is extracted and compared to the available theoretical predictions, specically considering possible problems with next-to-leading order corrections. (orig.)}
place = {Germany}
year = {2008}
month = {Nov}
}