Measurement of elasticρ 0 photoproduction at HERA

Diffractive photoproduction of ψ(2S) mesons at HERA

“…This has indeed been confirmed in photoproduction in the HERA energy range, where e.g. b ρ 0 > b J/ψ was measured [13,14]. Since the radius of the ψ(2S) meson is approximately a factor of two larger than that of the J/ψ meson one might naively expect a steeper t dependence.…”

Diffractive Electroproduction of ρ Mesons

“…Processes of real photon interactions with hadrons are also dominated by soft pomeron exchange [2]. Measurements of the elastic photoproduction cross section for [3,4], [5] and [6] indicate that the cross sections behave like 0.22 which is consistent with the soft pomeron exchange. By contrast the electoproduction of vector mesons [7][8][9] has a steep increase with energy.…”

“…Others introduced in the photon-vector meson vertex using a phenomenological 2 dependence [20]. The total cross section is then written as * → ( 2 , ) = ( 2 ) * → ( ) (3) where ( 2 ) involves the 2 dependence of the cross section, while the energy behavior of the vector meson electroproduction cross section * → ( ) is given by. ( 2 ) can be either fixed by the experiment or using a vertex function given .…”

A New Measurement of Exclusive Ρ° Photoproduction at Hera

“…• has been extensively studied in the last 40 years, first in fixed target experiments 1 , and more recently in the ep collider experiments H1 2 and ZEUS 3,4,5,6 at HERA, where the γp CMS energy W reaches values of up to 300 GeV. At large W values, Regge phenomenology describes the diffractive scattering as being mediated by the dominating exchange of the Pomeron trajectory, α P (t) = α P,0 + α ′ P · t. The values α P,0 = 1.08 − 1.10 and α ′ P = 0.25 GeV −2 were determined from global fits to hadron-hadron scattering data 7,8,9 .…”