Electron-Pair Production in 158 AGeV/c Pb-Au Collisions from CERES

The CERES experiment is devoted to the measurement of low-mass electron pairs in proton and ion-induced collisions at the Super Proton Synchrotron accelerator. The main goal of the CERES experiment is to investigate modifications of hadron properties in hot and dense nuclear matter. A significant enhancement of dilepton pair yield with respect to expectations based on hadron decays was observed in the mass range 0.25~$<~$m_ee~<~0.7~GeV/c². This fascinating result can only be described by models invoking in-medium modifications of the $\rho$ meson. To distinguish between different theoretical explanations of the enhancement the experiment was upgraded in 1998 by the addition of a radial TPC to improve the mass resolution in the vector meson region. In this thesis, the analysis of the data sample taken in 2000 in 158~A~GeV/c Pb-Au collisions with the upgraded experimental setup is presented. The observed enhancement of the e⁺e^- pairs confirms previous results of CERES. The data, compared to the theoretical calculations based on dropping $\rho$ mass approach and in-medium $\rho$ spectral function modifications, favor the latter.

Level thesis:degree_level

thesis.doctoral

Grantor dc:publisher

Universität Heidelberg

Year

2006

Author dc:creator

• Yurevich, Sergey

Contributors dc:contributor

• Stachel, Johanna

Repository record source_url

http://www.ub.uni-heidelberg.de/archiv/6558

OAI identifier oai:identifier

oai:archiv.ub.uni-heidelberg.de:6558