DELPHI Event r064180e011653
from the 130-140 GeV Run
e+ e- ---> e+ e- Nu Nubar
From 130.4 GeV run.
The e- has 12 GeV/c momentum and is identified by a 11 GeV shower in the
HPC.
The e+ has 8 GeV/c momentum, escapes the electromagnetic calorimeters
but is identified by the 40 degree taggers.
The e+ e- system has and energy of 19 GeV and a mass of 4.6 GeV.
The detector shows nothing to balance the pair.
This event appeared in the selection of neutralino candidates.
Its most likely interpretation is as a four-fermion final state where
an initial state virtual photon gives rise to the observed electron pair
in association with a Z0 decaying to the neutrino pair.
The interpretation as e+ e- --> e+ e- e+ e- where an
electron pair disappears in the beam pipe is unlikely due to the large pt.
Shown by H.Dijkstra at the seminar on LEP 1.5 results 12/12/95.
Characteristics :
Evis = 19 GeV , Mvis = 4.6 GeV
Emiss = 111 GeV, Mmiss = 109 GeV, P_{t,miss} = 15 GeV.