Search for Single-Photons from Radiative Production of Supersymmetric Particles or Neutrinos.
Abstract
Pair production of stable weakly interacting neutral particles in e('+)e('-) annihilation can be tagged by the observation of a single radiative photon in an otherwise invisible final state. The first such search for single unaccompanied photons is described, analyzed, and used to set limits on neutrinos and super-symmetric particles. The search was performed with the MAC detector at the PEP e('+)e(' -) storage ring at SLAC. The single-photon tagging technique exploits unique features of the general-purpose MAC detector, including total absorption calorimetry which provides highly efficient particle detection over nearly the full solid angle. The upper limit on the single-photon signal excludes with 90% confidence the existence of 17 or more light-neutrinos. The upper limit on single-photons beyond those expected from radiative production of the three known neutrinos is interpreted as a lower limit on the masses of the selectrons that are exchanged in photino pair production and the charginos that are exchanged in sneutrino pair production. Degenerate selectrons that have mass less than 47 GeV/c('2) are excluded with 90% confidence if photinos are light. The MAC search, when combined with all other reported single-photon searches, excludes with 90% confidence the existence of more than 4.8 light-neutrinos, and degenerate selectrons with mass less than 65 GeV/c('2) if photinos are light.
- Publication:
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Ph.D. Thesis
- Pub Date:
- 1986
- Bibcode:
- 1986PhDT.......102L
- Keywords:
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- Physics: Elementary Particles and High Energy