Exclusive Pomeron- and Odderon induced photoproduction of omega- and f2 mesons at HERA

The topics of this thesis are the analyses of exclusive photoproduction of $omega$- and f₂-mesons at mean $gp$ centre of mass energies of $langle Wangleapprox 200$ GeV at HERA. The former process is thought to be induced by photon-Pomeron interactions, and its cross section is measured to be $sigma(gpoomega p)=(1.3 pm 0.2(ext{stat}) pm 0.2(ext{syst})),muext{b}$, where the decay $omegaopigao3gamma$ is used to analyse the events. The diffractive slope $b$ describing the exponential fall of $ds/d|t|proptoexp(-b|t|)$ is measured by analysing the acceptance corrected differential distribution $d N/d|t|$. The value found for this parameter amounts to b=(10.7pm 1.1(ext{stat})pm 2.0(ext{syst})),ext{GeV}^-2. The corrected differential cross section $ds/d|t|$ is also found to be in accordance with the prediction of the Stochastic Vacuum Model for ho⁰-photoproduction scaled by a factor of $2/9$. The decay angular distributions d N/dcosvartheta^* and d N/dvarphi^* are found to be compatible with $s$-channel helicity conservation. The predictions of the Stochastic Vacuum Model for Odderon induced f₂-photoproduction of $21$ nb cannot be confirmed, but a $95$ confidence level upper limit on the cross section of sigma(gpo f₂X)<12.4,ext{nb} is given. The contributions of the f₂ are looked for in the $pipi$ mass spectrum, where the f₂ is thought to contribute via its decay f₂opipio4gamma.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2001

Author dc:creator

• Berndt, Thomas

Contributors dc:contributor

• Meier, Karl-Heiz

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/1878

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:1878