The DØ Collaboration has updated its results on the search for the evidence for Supersymmetry. Supersymmetry is an extension of the standard model which introduces a symmetry between bosons and fermions. This symmetry results in a doubling of the number of fundamental particles. For every known particle, a super-partner must exist. The super-partner has spin which differs by 1/2 from its standard model partner. Its quantum numbers are otherwise identical. A doubling of the number of particles was seen once before when anti-matter was discovered in the 1920's. We have new results on the search for the super-partners of the standard model particles participating in the strong interactions, the quarks and the gluons. These so-called squarks and gluinos have very distinctive signature when pair-produced in proton-anti-proton collisions. They can produce events with many jets and large apparent momentum inbalance in the detector (MET), or events with 2 electrons, 2 jets, and MET. A previous search in the jets and MET channel was published in our PRL and was updated in our ICHEP96 proceedings. That result used 13.5 pb-1 of data and could exclude squarks and gluinos with equal mass below 229 GeV. Our new result in this channel uses 79.2 pb-1 and can exclude equal mass squarks and gluinos below 260 GeV. Details on the new analysis can be found in our Lepton-Photon 97 proceedings. Our new result in the 2 electrons, 2 jets, and MET channel uses 92.9 pb-1 and can exclude equal mass squarks and gluinos below 267 GeV. This limit, however, has a stronger dependence on tan(beta). Details on this analysis can be found in our ICHEP96 proceedings.
Last updated: Aug. 21, 1997
 |
 |
 |
 |
The first two plots are from the di-electron analysis.
The first plots shows the 95% confidence level exclusion contour in the
M(gluino)/M(squark) plane for tan(beta)=2. The second plot shows the
exclusion contour in the SUGRA parameter space M0/M1/2. M0 is the
common mass parameter for the super-partners of the fermions
at the SUSY breaking scale. M1/2 is the common mass parameter
for the super-partners of the bosons at the SUSY breaking scale.
The next two plots are for the hadronic channel.
Postscript files are available for the 2 hadronic channel plots
here and
here.
Send questions/comments to Marc Paterno for the hadronic analysis and Naba Mondal for the di-electron analysis.