Photon Events with Missing Energy in e+e- Collisions at sqrt{s} = 130 to 209 GeV

TL;DR

This study analyzed photon events with missing energy in electron-positron collisions at energies between 130 and 209 GeV, testing the Standard Model and searching for new physics phenomena.

Contribution

It provides a comprehensive search for new physics in photon events with missing energy, combining data across multiple energies and testing various beyond-Standard-Model theories.

Findings

Number of neutrino families consistent with three

No excess events beyond Standard Model predictions

Set limits on non-standard neutrino interactions

Abstract

The production of single- and multi-photon events has been studied in the reaction e+e- -> gamma (gamma) + invisible particles. The data collected with the DELPHI detector during the years 1999 and 2000 at centre-of-mass energies between 191 GeV and 209 GeV was combined with earlier data to search for phenomena beyond the Standard Model. The measured number of light neutrino families was consistent with three and the absence of an excess of events beyond that predicted by the Standard Model processes was used to set limits on new physics. Both model-independent searches and searches for new processes predicted by supersymmetric and extra-dimensional models have been made. Limits on new non-standard model interactions between neutrinos and electrons were also determined.