Results for the CU-SeeMe Conference

Plots:

• 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
  • the peak is at the right position, justifying the use of 1.9688 GeV as the Ds mass in the 2-c fit.
  • 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.
  • the background is indeed flat, without other peaks. This results in a flat background in the 2-c chi square histogram.

• The same mass plot for the f0 pi mode. Same remarks as above.

• 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.
  • There is no enhancement towards small chi squares, ie. no signal above background. D decays don't create a fake signal.
  • 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).
  • The background is flat, not linearly rising or falling.