Results for the CU-SeeMe Conference
Plots:
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Going a step backwards from the 2-c fit, I made plots of the 1-c fitmass
for the Phi pi and Kstar K mode. They show that
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the peak is at the right position, justifying the use of 1.9688 GeV as the
Ds mass in the 2-c fit.
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the sigma of the peak is approx. 3.5 MeV (same as in Bruce's thesis).
My histograms of the 2-c chi square go from 0 to 20, so the range in the
mass plot is 1.9688 GeV +- sqrt(20)*3.5 MeV = [1.953 ... 1.984].
This range is so small that the background can be approximated as a constant.
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the background is indeed flat, without other peaks.
This results in a flat background
in the 2-c chi square histogram.
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The same mass plot for the f0 pi mode. Same remarks
as above.
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2-c chi square histograms for the Ds mass sideband.
I used the 1.94 GeV as the mass of the Ds in the 2-c fit, and made the
same cuts. The first plot is for the Phi pi mode, the second for the
Kstar K mode.
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There is no enhancement towards small chi squares, ie. no signal above
background. D decays don't create a fake signal.
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With the signal absent,
the background shape under the signal region can be directly observed.
It can be extrapolated from the background region (chi sq. .gt. 10).
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The background is flat, not linearly rising or falling.