Exclusive electroproduction of rho(o) mesons has been measured using the ZEUS detector at HERA in two Q(2) ranges, 0.25 < Q(2) < 0.85 GeV2 and 3 < Q(2) < 30 GeV2. The low-Q(2) data span the range 20 < W < 90 GeV; the high-Q(2) data cover the 40 < W < 120 GeV interval. Both samples extend up to four-momentum transfers of \t\ = 0.6 GeV2. The distribution in the azimuthal angle between the positron scattering plane and the rho(o) production plane shows a small but significant violation of s-channel helicity conservation, corresponding to the production of longitudinally polarised (i.e, helicity zero) rho(o) mesons from transverse photons. Measurements of the 15 combinations of spin-density matrix elements which completely define the angular distributions are presented and discussed.

Measurement of the spin-density matrix elements in exclusive electroproduction of rho(0) mesons at HERA

SACCHI, Roberto;CIRIO, Roberto;COSTA, Marco;MONACO, Vincenzo;PERONI, Cristiana;SOLANO, Ada Maria;
2000-01-01

Abstract

Exclusive electroproduction of rho(o) mesons has been measured using the ZEUS detector at HERA in two Q(2) ranges, 0.25 < Q(2) < 0.85 GeV2 and 3 < Q(2) < 30 GeV2. The low-Q(2) data span the range 20 < W < 90 GeV; the high-Q(2) data cover the 40 < W < 120 GeV interval. Both samples extend up to four-momentum transfers of \t\ = 0.6 GeV2. The distribution in the azimuthal angle between the positron scattering plane and the rho(o) production plane shows a small but significant violation of s-channel helicity conservation, corresponding to the production of longitudinally polarised (i.e, helicity zero) rho(o) mesons from transverse photons. Measurements of the 15 combinations of spin-density matrix elements which completely define the angular distributions are presented and discussed.
2000
12
393
410
http://dx.doi.org/10.1007/s100529900246
LUND MONTE-CARLO; PROTON SCATTERING; JET FRAGMENTATION; VECTOR-MESONS; E+E-PHYSICS; PHOTOPRODUCTION
J. Breitweg;S. Chekanov;M. Derrick;D. Krakauer;S. Magill;B. Musgrave;A. Pellegrino;J. Repond;R. Stanek;R. Yoshida;M. C. K.;G. Abbiendi;F. ...espandi
File in questo prodotto:
File Dimensione Formato  
fulltext.pdf

Accesso riservato

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 351.46 kB
Formato Adobe PDF
351.46 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/109715
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 78
  • ???jsp.display-item.citation.isi??? 85
social impact