Measurement of the spin-density matrix elements in exclusive electroproduction of {rho}{sup o} mesons at HERA.
Exclusive electroproduction of {rho}{sup 0} mesons has been measured using the ZEUS detector at HERA in two Q(2) ranges, 0.25 lt Q(2) lt 0.85 GeV2 and 3 lt Q(2) lt 30 GeV2. The low-Q(2) data span the range 20 lt W lt 90 GeV; the high-Q(2) data cover the 40 lt W lt 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}{sup 0} 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}{sup 0} mesons from transverse photons. Measurements of the 15 combinations of spin-density matrix elements which completely define the angular distributions are presented and discussed.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 942699
- Report Number(s):
- ANL-HEP-PR-99-93; TRN: US0904212
- Journal Information:
- Eur. J. Physics C, Vol. 12, Issue 3 ; Feb. 2000; ISSN 1434-6044
- Country of Publication:
- United States
- Language:
- ENGLISH
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