EPJ Web Conf.
Volume 138, 2017XXIII International Baldin Seminar on High Energy Physics Problems Relativistic Nuclear Physics and Quantum Chromodynamics (Baldin ISHEPP XXIII)
|Number of page(s)||6|
|Section||Polarization phenomena, spin physics|
|Published online||27 March 2017|
Ratios of helicity amplitudes for exclusive ρ0 electroproduction on transversely polarized proton
National Research Centre “Kurchatov Institute”, Petersburg Nuclear Physics Institute, Russia
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Published online: 27 March 2017
Exclusive ρ0-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 GeV2 < Q2 < 7.0 GeV2, 3.0 GeV < W < 6.3 GeV, and −t′ < 0.4 GeV2. Using an unbinned maximum-likelihood method, 25 parameters are extracted. They determine the real and imaginary parts of the ratios of certain helicity amplitudes describing ρ0-meson production by a virtual photon, where the denominator is the dominant amplitude . The latter is the nucleon-helicity-non-flip amplitude, which describes the production of a longitudinal ρ0 meson by a longitudinal virtual photon. The transverse target polarization allows for the first time the extraction of ratios of a number of nucleon-helicity-flip amplitudes to . The ratios of nucleon-helicity-non-flip amplitudes are found to be in good agreement with those from the previous HERMES analysis.
© The Authors, published by EDP Sciences, 2017
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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