Rho production by virtual photons
Creators
- 1. Glasgow Univ. (UK)
Description
The reaction γp → pπ+π- (virtual photons) was studied in the W, Q2 region 1.3 - 2.8 GeV, 0.3 - 1.4 GeV2 using the streamer chamber at DESY. A detailed analysis of rho production via γp → rho p is presented. Near threshold rho production has peripheral and non-peripheral contributions of comparable magnitude. At higher energies (W < 2 GeV) the peripheral component is dominant. The Q2 dependence of sigma(γp → rho p) follows that of the rho propagator as predicted by VDM. The slope of drho/dt at < Q2 >= 0.4 and 0.8 GeV2 is within errors equal to its value at Q2 = 0. The overall shape of the rho0 is t-dependent as in photoproduction, but is independent of Q2. The decay angular distribution shows that longitudinal rhos dominate in the threshold region. At higher energies transverse rhos are dominant. Rho production by transverse photons proceeds almost exclusively by natural parity exchange. (orig./BJ)
Availability note (English)
MF available from INIS under the Report Number.Abstract (German)
Die Reaktion γp → pπ+π- (virtuelle Photonen) wurde im W, Q2 Bereich 1,3 - 2,8 GeV, 0,3 - 1,4 GeV2 mit der DESY-Streamerkammer untersucht. Es wird eine detaillierte Analyse der Rho-Produktion ueber γp → Rho p vorgelegt. In Schwellennaehe besitzt die Rho-Produktion periphere und nicht-periphere Anteile vergleichbarer Groesse. Bei hoeheren Energien (W > 2 GeV) ueberwiegt die periphere Komponente. Die Q2-Abhaengigkeit von Sigma(γp → Rho p) folgt der des durch VDM vorhergesagten Rho-Propagators. Der Abfall von dsigma/dt bei < Q2 >= 0,4 und 0,8 GeV2 ist innerhalb des Fehlerbereichs gleich dem Wert bei Q2 = 0. Der Gesamtverlauf von rho ist wie bei der Photoproduktion t-abhaengig, von Q2 aber unabhaengig. Die Zerfallswinkelverteilung zeit, dass die longitudinalen Rhos im Schwellenbereich vorherrschen waehrend bei hoeheren Energien die transversalen dominieren. Die Rho-Produktion durch transversale Photonen geht fast ausschliesslich durch natuerlichen Paritaetsaustausch vor sich. (orig./BJ)
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Additional details
Publishing Information
- Imprint Pagination
- 33 p.
- Report number
- DESY--76/17
INIS
- Country of Publication
- Germany
- Country of Input or Organization
- Germany
- INIS RN
- 7269936
- Subject category
- S72: PHYSICS OF ELEMENTARY PARTICLES AND FIELDS;
- Descriptors DEI
- ANGULAR DISTRIBUTION; ELECTRON-PROTON INTERACTIONS; ELECTROPRODUCTION; ENERGY DEPENDENCE; GEV RANGE 01-10; HELICITY; INTEGRAL CROSS SECTIONS; MASS SPECTRA; PARTICLE DECAY; PHOTOPRODUCTION; PIONS MINUS; PIONS PLUS; PROTONS; RHO-765 RESONANCES; TOTAL CROSS SECTIONS
- Descriptors DEC
- ANTIMATTER; ANTIMESONS; ANTIPARTICLES; BARYONS; BASIC INTERACTIONS; BOSONS; CATIONS; CHARGED PARTICLES; CROSS SECTIONS; DECAY; DISTRIBUTION; ELECTROMAGNETIC INTERACTIONS; ELECTRON-NUCLEON INTERACTIONS; ELEMENTARY PARTICLES; ENERGY RANGE; FERMIONS; GEV RANGE; HADRONS; HYDROGEN IONS; HYDROGEN IONS 1 PLUS; INTERACTIONS; IONS; LEPTON-BARYON INTERACTIONS; LEPTON-HADRON INTERACTIONS; LEPTON-NUCLEON INTERACTIONS; MATTER; MESON RESONANCES; MESONS; NUCLEONS; PARTICLE INTERACTIONS; PARTICLE PRODUCTION; PARTICLE PROPERTIES; PIONS; PSEUDOSCALAR ANTIMESONS; PSEUDOSCALAR MESONS; RESONANCE PARTICLES; SPECTRA
Optional Information
- Notes
- 17 figs.; 8 tabs.; 23 refs.