A search for high mass photon pairs from the processes e(+)e(-) --> l(+)l(-)gamma gamma, e(+)e(-) --> <q(q)over bar gamma gamma> and e(+)e(-) --> nu nu gamma gamma with the DELPHI detector at LEP I is reported. From a data sample containing 3.5 million hadronic Z(0) 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/c(2), where 76 +/- 6 events were predicted from standard sources. In the same data sample, no <nu(nu)over bar gamma gamma> candidates were found and no accumulation of events was visible for gamma gamma masses above 10 GeVlc2 in the q<q(q)over bar gamma gamma> channel. Upper limits at 95% confidence level on the Z(0) branching ratios for the three different channels were extracted from the data. In the mass region m(gamma gamma) > 30 CeV/c(2) the limits obtained are between 3x10(-6) and 4x10(-6).
|Data di pubblicazione:||1996|
|Titolo:||Search for high mass gamma gamma resonances in e(+)e(-)->l(+)l(-)gamma gamma, nu(nu)over-bar-gamma gamma and q(q)over-bar-gamma gamma at LEP I|
|Rivista:||ZEITSCHRIFT FÜR PHYSIK. C, PARTICLES AND FIELDS|
|Digital Object Identifier (DOI):||10.1007/s002880050236|
|Codice identificativo ISI:||WOS:A1996VP22100002|
|Parole Chiave:||DELPHI; photon pairs; fragmentation; branching ratio|
|Appare nelle tipologie:||Articolo su Rivista|