Measurement of Angular Distributions and R= sigma_L/sigma_T in Diffractive Electroproduction of rho^0 Mesons

Simple item page
dc.creatorHERMES Collaboration
dc.creatorAckerstaff, K.
dc.date2000-02-06
dc.date2000-10-21
dc.date.accessioned2026-07-07T12:25:50Z
dc.date.available2026-07-07T12:25:50Z
dc.descriptionProduction 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. The event sample combines rho^0 mesons produced incoherently off individual nucleons and coherently off the nucleus as a whole. The distributions in one production angle and two angles describing the rho^0 -> pi+ pi- decay yielded measurements of eight elements of the spin-density matrix, including one that had not been measured before. The results are consistent with the dominance of helicity-conserving amplitudes and natural parity exchange. The improved precision achieved at 4< W <7 GeV, in combination with other data at W>7 GeV, reveals evidence for an energy dependence in the ratio R of the longitudinal to transverse cross sections at constant Q^2.
dc.description15 pages, 15 embedded figures, LaTeX for SVJour(epj) document class Revision: Fig. 15 corrected, recent data added to Figs. 10,12,14,15; minor changes to text
dc.identifierhttps://arxiv.org/abs/hep-ex/0002016
dc.identifierhttp://arxiv.org/abs/hep-ex/0002016
dc.identifierEur.Phys.J.C18:303-316,2000
dc.identifierdoi:10.1007/s100520000536
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/214694
dc.subjectHigh Energy Physics - Experiment
dc.titleMeasurement of Angular Distributions and R= sigma_L/sigma_T in Diffractive Electroproduction of rho^0 Mesons
dc.typetext

Files

Collections

arXiv