Search for high mass γγ resonances ine^ + e^ - to ell ^ + ell ^ - γ γ ,ν bar ν γ γ andqbar qγ γ at LEP Iat LEP I
Abstract
A search for high mass photon pairs from the processese^ + e^ - to ell ^ + ell ^ - γ γ ,e^ + e^ - to qbar qγ γ ande^ + e^ - to ν bar ν γ γ with the DELPHI detector at LEP I is reported. From a data sample containing 3.5 million hadronic Z0 decays, collected by DELPHI during the years 1991 to 1994, 79 events with two charged leptons and two isolated photons were selected with photon pair masses above 10 GeV/c2, where 76±6 events were predicted from standard sources. In the same data sample, noν bar ν γ γ candidates were found and no accumulation of events was visible for γγ masses above 10 GeV/c2 in theqbar qγ γ channel. Upper limits at 95% confidence level on the Z0 branching ratios for the three different channels were extracted from the data. In the mass region m γγ >30 GeV/c2 the limits obtained are between 3×10-6 and 4×10-6.
- Publication:
-
Zeitschrift fur Physik C Particles and Fields
- Pub Date:
- June 1996
- DOI:
- 10.1007/BF02909145
- Bibcode:
- 1996ZPhyC..72..179A