Systematic Study of Low-mass Electron Pair Production in P{be and P{au Collisions at 450 Gev/c

Abstract

In a joint eeort the CERES/NA45 and TAPS collaborations have measured low-mass electron pairs in p{Be and p{Au collisions at 450 GeV/c at the CERN SPS. In the range covered up to 1.5 GeV/c 2 the mass spectra from p{Be and p{Au collisions are well explained by electron pairs from decays of neutral mesons. For p{Au our result is new. For p{Be, the simultaneously measured electron pairs and photons served as a direct measure of the Dalitz decay contribution to the inclusive pair spectrum in which instrumental uncertainties are highly reduced. We connrm the earlier nding of HELIOS-1 with signiicantly reduced systematic uncertainties of 23% in the mass range below 450 MeV/c 2 , and of 28% in the mass range above 750 MeV/c 2 at 90% conndence limit. Any unconventional source of electron pairs is limited by these error margins as the percentage fraction of the hadronic contribution.

Cite this paper

@inproceedings{Averbeck2007SystematicSO, title={Systematic Study of Low-mass Electron Pair Production in P\{be and P\{au Collisions at 450 Gev/c}, author={Ralf Averbeck and Facundo Ballester and Juan Diaz and A. Drees and U. Faschingbauer and J. L. Ferrero and P . - A . Fischer and Radim Novotn{\'y} and Luiz Henrique Olsen}, year={2007} }