KTeV KL>pi^{0}pi^{0}pi^{0} plots
Updated August 18, 2008
[KL>pi^{0}pi^{0}pi^{0} Dalitz Plot Results]

xydal_model.eps,
xydal_model.pdf
FIG.1: Expected deviation from K_{L}>pi^{0}pi^{0}pi^{0} phasespace based on (a) h_{000} = 0.005 and no contribution from rescattering, and (b) K_{L}>pi^{+}pi^{}pi^{0} with rescattering as calculated by Cabibbo and Isidori [6], with h_{000} = 0. The intensity scales are slightly different to better illustrate the relateive shapes.


detector.eps,
detector.pdf
FIG.2: Plan view of the KTeV (E832) detector. The evacuated decay volume ends with a thin vacuum window at Z=159m. Only decays from the vacuum beam are used to measure h_{000}.


csilayout.eps,
csilayout.pdf
FIG.3: Layout of CsI calorimeter. The two neutral beams go through the 15 x 15 cm^{2} beam holes (into page) shown by the two inner squares. The fiducial cut, indicated by the dark lines, rejects K_{L}>pi^{+}pi^{}pi^{0} decays in which any photon hits a crystal adjacent to a beam hole or at the outer boundary.


m3pi0.eps,
m3pi0.pdf
FIG.4: (a) Invariant pi^{0}pi^{0}pi^{0} mass with all selection requirements except for the pi^{0}pi^{0}pi^{0}mass and chi_{E}^{2}. The pi^{0}pi^{0}pi^{0} mass resolution (from Gaussian fit) is 0.94 MeV/c^{2}. (b) shows chi_{E}^{2} distribution with all other selection requirements; last bin includes all events with chi_{E}^{2} > 200. Dots are data and the histogram is MC. Vertical arrows show the selection requirements.


xydal_data.eps,
xydal_data.pdf
FIG.5: Dalitz plot density, Y_{D} vs. X_{D}, for 68.3. million K_{L}>pi^{0}pi^{0}pi^{0} decays in the KTeV data sample after all selection requirements. the colorscale at right shows the number of events in each 0.05 x 0.05 pixel. The reconstruction resolution on X_{D} and Y_{D} is sigma ~ 0.01 as determined by the MC; the box in the lowerleft corner shows 10 sigma x 10sigma for illustration.


m2p0rsq.eps,
m2p0rsq.pdf
FIG.6: For the 68.3 million K_{L}>pi^{0}pi^{0}pi^{0} in the KTeV sample, projected Dalitz distributions are shown for (a) R_{D}^{2} and (b) m^{min}_{pi}0_{pi}0. The average reconstruciton resolution determined by the simulation is sigma(R_{D}^{2} ~ 0.014 and sigma (min m_{pi}0_{pi}0) ~ 0.3MeV/c^{0}: these resolution are indicated by a 10 sigma marker on each plot. The data/MC (phasespace) ratio is shown as a function of (c) R_{D}^{2} and (d) m^{min}_{pi}0_{pi}0 (points with eror bars). The solid curve is the prediction from our best fit h_{000} The dashed curve is the prediction using h_{000} (PDG06) = (5.0 + 1.4) x 10^{3}. The arrow in (d) shows the selection requirements m^{min}_{pi}0_{pi}0 > 0.274 GeV/c^{2}. Note that previous analysis [4,5] ignored rescattering and excluded R_{D}^{2} > 1.9; the corresponding data/MC ratio was assumed to be a straight line with slope of 0.005.


crosschecks.eps,
crosschecks.pdf
FIG.7: Crosscheck measurement of h_{000}: datataking years (96,97,99), left and right vacuum beams (L,R), and min/max photonenergy ratio (E_{gamma}^{min}/ E_{gamma}^{max}) as discussed in the text. Measurements with each category (between vertical lines) are statistically independent. Error bars reflect the statistical uncertainties from the data and MC samples.


m2p0rsq_2d.eps,
m2p0rsq_2d.pdf
FIG.8: Same as Fig.6cd, except a_{0}a_{2} is floated in the fit instead of fixed to the NA48 value.

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