The production of single photons has been studiedin the reaction e+e- --> gamma+ invisible particles at centre-of-mass energies of 183~GeV and 189~GeV.A previously published analysis of events with multi-photonfinal states accompanied by missing energy has been updated with 189 GeV data.The data were collected with the DELPHI detector and correspondto integrated luminosities of about 51~pb^{-1}and 158~pb^{-1}at thetwo energies.The number of light neutrino families is measured to be2.86\pm0.13(stat)\pm0.14(syst)$. The absence ofan excess of events beyond that expected from Standard Modelprocesses is used to set limits on new physicsas described by supersymmetric and composite models.A limit on the gravitational scale is also determined
Single and multi-photon events with missing energy are analysed using data collected with the L3 det...
The production of single- and multi-photon events has been studied in the reaction e(+) e(-) --> gam...
An analysis of single and multi-photon events with missing energy is performed using data collected ...
The production of single photons has been studiedin the reaction e+e- --> gamma+ invisible particles...
The production of single photons has been studied in the reaction e+e- -> gamma + invisible particle...
The production of single photons has been studied in the reaction e+e- -> gamma + invisible particle...
The production of single photons has been studied in the reaction e(+)e(-) --> gamma +invisible part...
The production of single photons has been studied in the reaction e+e- → γ+invisible particles at ce...
DELPHIThe production of single- and multi-photon events has been studied in the reaction e+e- -> gam...
The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (ga...
The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (ga...
Single and multi-photon events with missing energy are analysed using data collected with the L3 det...
The production of single- and multi-photon events has been studied in the reaction e(+) e(-) --> gam...
An analysis of single and multi-photon events with missing energy is performed using data collected ...
The production of single photons has been studiedin the reaction e+e- --> gamma+ invisible particles...
The production of single photons has been studied in the reaction e+e- -> gamma + invisible particle...
The production of single photons has been studied in the reaction e+e- -> gamma + invisible particle...
The production of single photons has been studied in the reaction e(+)e(-) --> gamma +invisible part...
The production of single photons has been studied in the reaction e+e- → γ+invisible particles at ce...
DELPHIThe production of single- and multi-photon events has been studied in the reaction e+e- -> gam...
The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (ga...
The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (ga...
Single and multi-photon events with missing energy are analysed using data collected with the L3 det...
The production of single- and multi-photon events has been studied in the reaction e(+) e(-) --> gam...
An analysis of single and multi-photon events with missing energy is performed using data collected ...