In a joint effort 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 pair inclusive pair spectrum in which instrumental uncertainties are highly reduced. We confirm the earlier finding of HELIOS-1 with significantly 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% confidence limit. Any unconventional source of electron pairs is limited by these error margins as the percentage fraction of the hadronic contribution.
Systematic study of low-mass electron pair production in p-Be and p-Au collisions at 450 GeV/c
GATTI, EMILIO;SAMPIETRO, MARCO;
1998-01-01
Abstract
In a joint effort 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 pair inclusive pair spectrum in which instrumental uncertainties are highly reduced. We confirm the earlier finding of HELIOS-1 with significantly 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% confidence limit. Any unconventional source of electron pairs is limited by these error margins as the percentage fraction of the hadronic contribution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
