KTeV e'/e plots
Updated Oct. 4, 2011.
[e'/e Results]
"Precise Measurements of Direct CP Violation, CPT Symmetry, and Other Parameters
in the Neutral Kaon System"

kaon_params.eps,
kaon_params.pdf
Fig.1: Diagram of CP violating kaon parameters. For this illustration, the epsilon parameter has the central value measured by KTeV and the value of epsilon' is scaled by a factor of 50. Although they appear distinct in this diagram, note that phi+ and phi00 are consistent with each other within experimental errors.


ktev_plan.eps,
ktev_plan.pdf
Fig.2: Schematic of the KTeV detector. Note that the vertical and horizontal scales are different.


regdiagram.eps,
regdiagram.pdf
Fig.3: Diagram of the regenerator. (a) Layout of the 85 regenerator modules, including the leadscintillator module. (b) Zoomed diagram of the leadscintillator regenerator module. The PMTs above and below are not shown. The thickness of each lead (scintillator) piece is 5.6 (4.0) mm. The transverse dimension is 100 mm, and is not drawn with the same scale as the zaxis. The kaon beam enters from the left. The arrows indicate the location and +1sigma uncertainty of the effective upstream edges for reconstructed K >pi0pi0 and K>pi+pi decays for 1999 data.


dccell.eps,
dccell.pdf
Fig.4: Diagram of drift chamber geometry showing six field wires (open circles) around each sense wire (solid dots). The solid lines illustrate the hexagonal cell geometry; they do not represent any physical detector element. The vertical dashed lines are separated by 6.35 mm and are used to define the track separation cut described in Sec. III B 2.


csilayout.eps,
csilayout.pdf
Fig.5: Beamline view of the KTeV CsI calorimeter, showing the 868 larger outer crystals and the 2232 smaller inner crystals. Each beam hole size is 15 × 15 cm2 and the two beam hole centers are separated by 0.3 m. The positive z direction is into the page.


prdke3shwr.eps,
prdke3shwr.pdf
Fig.6: DataMC comparison of fraction of energy in each of the 49 CsI crystals in an electron shower. (a) The fraction of energy in each of the 49 CsI crystals in electron showers for data. (b) KTeV03 data/MC ratio. (c) Current data/MC ratio.


resolution.eps,
resolution.pdf
Fig.7: Dependence of drift chamber position resolution on position within the cell. D is the distance from the sense wire. Crosses represent the measured central values and uncertainties of the resolution in bins of D and the line represents a polynomial fit to the data. This fit is used in the simulation to parameterize the position dependence of the position resolution.


mass_ch_all.eps,
mass_ch_all.pdf
Fig.8: pi+pi invariant mass distribution for K>pi+pi candidate events in the vacuum (left) and regenerator (right) beams. The data distribution is shown as dots, the K>pi+pi(gamma) signal MC (MC Sig) is shown as dotted histogram and the sum of signal and background MC is shown as a solid histogram.


pt_ch_all.eps,
pt_ch_all.pdf
Fig.9: pt2 distribution for K>pi+pi candidate events in the vacuum (left) and regenerator (right) beams. The data distribution is shown as dots, the K>pi+pi(gamma) signal MC (MC Sig) is shown as dotted histogram and the sum of signal and background MC is shown as a solid histogram.


resfinal.eps,
resfinal.pdf
Fig.10: Ke3 electrons after all corrections. (a) E/p for 1.5 x 10^{8} electrons. (b) Energy resolution. The fine curve shows the momentum resolution function that has been subtracted from the E/p resolution to find the energy resolution.


datmc_ring.eps,
datmc_ring.pdf
Fig.11: K>pi0pi0 RING distributions for data and signal MC in the vacuum (left) and regenerator (right) beams. The dashed line indicates our cut.


datmc_mass.eps,
datmc_mass.pdf
Fig.12: K>pi0pi0 m_{pi0pi0} distributions for data and signal MC in the vacuum (left) and regenerator (right) beams. The dashed lines indicate our cuts.


regedge.eps,
regedge.pdf
Fig.13: Regenerator beam K>pi0pi0 z vertex distribution near the regenerator for 1999 data nd Monte Carlo. (a) Uncorrected data. (b) Data with energy scale correction applied.


regedge_oldvnew.eps,
regedge_oldvnew.pdf
Fig.14: Change in the final energy scale adjustument relative to KTeV03. The dashed line represents no dataMC mismatch. The y axis on the right side of the plot shows the dataMC z vertex shift in meters.


escale_prd08.eps,
escale_prd08.pdf
Fig.15: Energy scale tests at the regenerator and vacuum window. The difference between the reconstructed z positions for data and MC is plotted for K>pi0pi0 events, and for hadronically produced pi0pi0 pairs at the regenerator and the downstream detector elements. The solid point at the re generator edge is the K>pi0pi0 sample; there is no difference between data and MC by construction. The open point at the regenerator edge is the average shift of the hadronic regenerator samples for all three datasets. The points at the vacuum window are the shifts for the downstream hadronic events for each dataset separately. The shaded region shows the range of dataMC shifts covered by the total systematic uncertainty from the energy scale. For reference, the dataMC shift at the vacuum window from KTeV03 is also plotted.


vacwinjunk.eps,
vacwinjunk.pdf
Fig.16: zvertex distributions of pi0pi0 pairs produced hadronically in downstream detector elements for 1999 data. Data (dots) and MC that is shifted 1.06 cm downstream ot match the data (histogram).


nonlin1.eps,
nonlin1.pdf
Fig.17: Comparisons of the reconstructed kaon mass vs (a) zvertex, (b) kaon energy, (c) minimum cluster separation, and (d) photon angle for 1999 data (circles) and MC (stars). The values plotted are the difference between the reconstructed kaon mass for each bin and the PDG kaon mass.


nonlin2.eps,
nonlin2.pdf
Fig.18: Effect of 0.1%/100 GeV distortion on MK vs EK for 1999 data. The values ploteed are teh difference between the reconstructed kaon mass for each bin and the PDG kaon mass.


vtxz.eps,
vtxz.pdf
Fig.19: (a) Comparison of teh vacuum beam z distributions for data (dots) and MC (histogram). (b) The datatoMC ratios are fit to a line, and the zslopes (see text) are shown. All distributions are for the full data sample and used in this analysis.


attenraw.eps,
attenraw.pdf
Fig.20: Ratio of KL>pi+pipi0 deay rates in teh regenerator to vacuum beam as a function of a kaon momentum. The uncertainty on the slope is statistical uncertainty of teh measurement.


eperuns.eps,
eperuns.pdf
Fig.21: Re(e'/e) in subsets of data samples. All points are statistically independent. The dashed line indicates the value of Re(e'/e) for the full data sample.


epechecks.eps,
epechecks.pdf
Fig.22: Re(e'/e) consistency with beam intensity, regenerator position, magnet polarity, and track bend. The intensity subsets are for the 1999 data only. Releft and regright refer to the positoin of the regenerator beam in the detector. These subsets are for teh full data sample. Mag+ and Mag are the magnet polarity and in/out are the bend of the two tracks inthe magnet. In each of these subsets the K>pi0pi0 sample is common to both fits; the errors are estimated by taking the quadrature difference with the error for the full dataset. The dashed lines indicate the value of Re(e'/e) in the appropriate full data sample.


epepbins.eps,
epepbins.pdf
Fig.23: (a) Re(e'/e) and (b) f(70 GeV/c) in 10 GeV/c momentum bins. All points are statistically independent. The dashed lines indicate the values for the full data sample.


eperesultprd.eps,
eperesultprd.pdf
Fig.24 Final KTeV result for Re(e'/e) and comparisons with previous measurements from E731[16], NA31[17], and NA48[19]. The new world average for Re(e'/e) is also shown.


swdmts_full.eps,
swdmts_full.pdf
Fig.25: Delta chi2 = 1 contours of total uncertainty for (a) Delta m  tauS, (b) phi_{epsilon}  Delta m and (c) tauS  phi_{epsilon}. Large ellipses correspond to the zbinned fit without CPT invariance assumption. Dashed lines corresond to phi_{epsilon} = phi_{SW} CPT constraint. Smaller ellipses are obtained after applying this constraint.


reim.eps,
reim.pdf
Fig.26: Delta chi2 = 1 contour for Re(e'/e) vs Im(e'/e) as measured by KTeV compared to the measurment of pipi phase shifts and the CPT invariance expectation.


dgdm.eps,
dgdm.pdf
Fig.27: Allowed region at 95% C.L. for Delta M, Delta Gamma.


screening.eps,
screening.pdf
Fig.28: Kaon momentum dependence of screening corrections to (a:) the magnitude and (b:) the phase of f(p), for various models from [38]. The magnitude of each correction is defined to be 1 at 70 GeV/c.


screening_fit.eps,
screening_fit.pdf
Fig.29: Kaon momentum dependence of (a:) ratio of f(p) from the fits using elastic (solid line) and inelastic factorized (dashed line) screening corrections to f^{P}(p) from the fit using no screening corrections; (b:) arg(f(p)) from the fits with elastic (solid line), inelastic (dashed line) screening corrections and with no screening corrections (dotted line).


darphi.eps,
darphi.pdf
Fig.30: Kaon momentum dependence of (a:) ratio of f(p) from the fit using inelastic factorized screening corrections (dashed line) and from the AR fit (dots with error bars) to f^{P}(p) from the fit using no screening correction; (b:) arg(f(p)) for the DAR fit (solid line), the phase fit (dots with error bars) and the fit using inelastic factorized screening model (dashed line). The phase fit is fixed to the DAR value for 70 GeV/c < p < 80 GeV/c momentum bin as indicated by the arrow.

Send corrections to Taku Yamanaka.