Incoherent Photoproduction ofρ0Mesons From Complex Nuclei and Comparison with Vector-Dominance Predictions

Observation of a Coherence Length Effect in Exclusiveρ0Electroproduction

“…Because of the acceptance for 20 , n & 370 GeV, the three Q 2 bins measured by [8] a small ͑,3%͒ increase with l c due to the known [2] energy dependence of the r 0 N cross section. Figure 3c also shows the transparency to incoherent r 0 production measured at Cornell with 4 and 8 GeV photons [6] and by the E655 collaboration at FNAL with 470 GeV muons [8]. These results are consistent with the present data but give no indication of a variation with l c .…”

“…These errors comprise statistical and l cdependent systematic uncertainties added in quadrature; the normalization systematic uncertainty is not included, because it does not influence the l c dependence. In the absence of ISI variations, the transparency would exhibit [6] and muon (open circle) [8] beams. Because of the acceptance for 20 , n & 370 GeV, the three Q 2 bins measured by [8] a small ͑,3%͒ increase with l c due to the known [2] energy dependence of the r 0 N cross section.…”

“…The dependence of the ISI on l c can be measured explicitly in exclusive r 0 production experiments, where a single mass-namely, the r 0 mass-dominates M qq and l c [2][3][4]. Largely because of limited coverage in l c , previous experiments have not yet seen the expected l c dependence [2,6].…”

“…If the ISI and FSI amplitudes factorize from the exclusive scattering amplitude, then T A is the probability that no significant ISI or FSI occur. The transparency has been used to study the space-time dynamics of several exclusive reactions [2,[6][7][8][9]. This paper reports measurements of the nuclear transparency for exclusive incoherent r 0 electroproduction on 2 H, 3 He, and 14 N targets at Q 2 .…”

Nuclear deep-inelastic lepton scattering and coherence phenomena

“…In Fig.8.1 the rate of produced ρ 0 's is plotted against t ′ = t − t 0 , the squared momentum transfer above threshold (|t 0 | ≃ λ −2 ). At |t ′ | ≪ 0.1 GeV 2 coherent production dominates, leaving the λ (fm) [284,271]. The dashed curve shows a Glauber calculation from Ref.…”