Tue Apr 18 11:09:39 CDT 1995
from run 1A and 1B.
The analysis is identical to the
submitted dijet search paper using
run 1A data alone.
The dijet mass spectrum
extends from 150 to 1040 GeV. Like the
inclusive jet Et spectrum, the
dijet data has a smoothly increasing
excess over QCD which becomes
most noticeable at high mass: the measured
spectrum is more energetic than QCD predicts. To search for new particles we
fit the mass spectrum
with a simple parameterization and search for bumps. On a
linear scale we observe bumps
which are fit by resonances at
200 GeV (2.4 
),
550 GeV (2.6 
), and
850 GeV (1 
).
The angular distribution of the
550 GeV bump is compatible with QCD, although it is fit optimally by
QCD + 5% signal (flat),
which is the same amount of signal as predicted by the
mass fit. The
angular distribution of
a bump-free region (400-500 GeV) is better fit by QCD alone, although it also
prefers a fit with
QCD + 3% signal.
We conclude there is currently insufficient evidence to claim a signal.
The 95% CL upper limits on signal
cross section are compared to lowest order models of new particle production
using CTEQ2L parton distributions. Where the model's cross section is higher
than the measured upper limit, we have an
excluded mass region, which we
compare to exclusions by other experiments.
This preliminary search excludes at 95% CL models of: