Status of KTeV (E832)

1. Status of KTeV (E832) E. Blucher, Chicago • Introduction • E832 Physics Results • Status of Ongoing Analysis • PhD Students • Conclusions The KTeV Collaboration: Arizona, Campinas (Brazil), Chicago, Colorado, Elmhurst, Fermilab, Osaka (Japan), Rice, Rutgers, San Paulo (Brazil), UCLA, UCSD, Virginia, Wisconsin FNAL Director's Review

2. KTeV Physics Goals: E832:/ to 10-4 E799:rare KLdecays to 10-11 E832: Indirect vs. Direct CP Violation  “Indirect” from asymmetric mixing “Direct” in decay process  /   0 direct CP violation

3. KTeV Detector KL E832:  E799: rare decays KL + KS KS: c ~ 3.5m KL: c ~ 2.2 km For EK ~ 70 GeV,

4. KTeV CsI Electromagnetic Calorimeter (NIM article in preparation) E/E < 1% for E > 1 GeV x,y ~ 1.2 mm (small crystals) ~ 2.4 mm (large crystals) KL a rab b zab

5. KTeV Datataking • 27 papers already published using 1996-1997 • data sample; first paper using 1999 data • has been accepted for publication. • 17 PhDs awarded; 16 current PhD students

6. E832 Publications Measurements of direct CP violation, CPT symmetry, and other parameters in the neutral kaon system, PRD 67, 012005 (2003). A measurement of the KL charge asymmetry, PRL 88, 181601 (2002). Radiative decay width measurements of neutral kaon excitations using the Primakoff effect, PRL 89, 072001 (2002). A new measurement of the radiative Ke3 branching ratio and photon spectrum, PRD 64, 112004 (2001). Study of the KL direct emission vertex, PRL 86, 761 (2001). Observation of direct CP violation in KS,KL decays, PRL 83, 22 (1999). Measurement of the decay KL, PRL 83, 917 (1999). Light gluino search for decays containing  or  from a neutral hadron beam at Fermilab, PRL 83, 2128 (1999). Search for light gluinos via the spontaneous Appearance of  pairs with an 800 GeV/c proton beam at Fermilab, PRL 79, 4083 (1997). 8 4 1 0 8 263 20 24 25 Citations (Spires)

7. Semileptonic Charge Asymmetry Semileptonic decays obey s= Q rule. World Ave. L = (3.30  0.07)  Expectation from K with only indirect CP violation: (3.32  0.03) 

8. (before background subtraction) Reconstructed K Mass Distributions KTeV  ~ 1.6 MeV  ~ 1.5 MeV

9. Reconstructed Vertex z Distributions

10. 0.1% shift in E scale: ~3 cm shift in vertex; ~1 shift in 

11. KTeV Data / Monte Carlo Comparison

12. Calorimeter Energy Scale Final energy scale adjustment based on regenerator edge. Energy scale depends on PK. Applying an energy-independent scale shifts Re() by -0.5 compared to nominal method.

13. Calorimeter Energy Scale Final energy scale adjustment based on regenerator edge.

14. Cross Checks of Energy Scale Check E scale with different modes: K, K*KS, hadronic 2 production, K20 Dalitz, 30

15. Systematic Uncertainties in Re()

16. KTeV Result: Re() = (20.7  1.5(stat)  2.4(syst))  10-4 = (20.7  2.8)  10-4 World ave. Re()= (16.6  6)   (confidence level = 10%)

17. KL - KS Interference Downstream of Regenerator KTeV Results:

18. History of KS Lifetime Measurements

19. History of m Measurements

20. Re() and Im() NA48 E731 NA48+KTeV f.s. phase+CPT KTeV E773 2 contours (  Im())

21. Current  Analysis ~ ~ Improvement in systematics needed to take advantage of increase in statistics. • Full treatment of photon angles in simulation and reconstruction: E scale, E nonlinearity • Better treatment of nearby and overlapping clusters: E scale, E nonlinearity • Better modeling of fringe field: calorimeter calibration, E nonlinearity • Improved drift chamber alignment: calorimeter calibration, E nonlinearity • Improved simulation of delta rays: pt distribution, neutral background estimate • Better drift chamber performance (99) and track reconstruction: mass resolution improved by ~10%.

22. KLData / Monte Carlo Comparison (full KTeV data sample)

23. Ongoing E832 Analyses • : Re(), Im() ( ), , m, S •  • Diurnal variations of , l, etc. • KL • KL • KL • KLe • KL Dalitz parameters • KL00 Dalitz parameters • Ratios of dominant branching ratios; Vus •  mass

24. E832 PhD Students Past students:Thesis Topic M. Barrio (Chicago) KL Dalitz parameters J. Graham (Chicago) Re(), , m, S (96+97) V. Prasad (Chicago) Re(), , m, S (96+97) P. Shawhan (Chicago) Re() (1/4 96+97) Current students: S. Averitte (Rutgers)  (1996+1997) C. Bown (Chicago)  A. Jansen (Chicago) Vus M. Ronquest (UVA)  (full data) E. Santos (San Paulo) KLe J. Shields (UVA) KL (full data) J. Wang (Arizona) KL (full data) E. Worcester (Chicago) Re(), , , etc.(full data)

25. Conclusions • KTeV results from 1996+1997 data include: Re() = (20.7  2.8)  10-4 Precise measurements of m, S, +, , l • Analysis of full data sample going well; manpower becoming a challenge. • Full KTeV data sample (96+97+99) will reduce the statistical error on  to ~ 1  104;  significant work will be required to reduce systematic error to similar level. • We are also working on broad range of non- topics. • We rely on continued operations support from computing division for KTeV hardware and PC farms.

26. : Theory vs. Experiment  may soon be measured to 5%!  Theory improvement will be needed to take full advantage of this precision. Bertolini, Sozzi There is some optimism that next round(s) of lattice efforts could reach 10% level. Two recent lattice calculations (with similar approximations) find small, negative values for . Re()=( (RBC Collaboration) (stat. error only!)