26 February 2003 FNAL Director's Review Status of KTeV (E832) Introduction E832 Physics Results Status of Ongoing Analysis PhD Students Conclusions E. Blucher, Chicago The KTeV Collaboration: Arizona, Campinas (Brazil), Chicago, Colorado, Elmhurst, Fermilab, Osaka (Japan), Rice, Rutgers, San Paulo (Brazil), UCLA, UCSD, Virginia, Wisconsin

 /   0 direct CP violation  “Direct” in decay process “Indirect” from asymmetric mixing  E832: Indirect vs. Direct CP Violation KTeV Physics Goals: E832:  /  to E799: rare K L decays to

KTeV Detector K L +  K S KLKL For E K ~ 70 GeV, K S :  c  ~ 3.5m K L :  c  ~ 2.2 km E832:  E799: rare decays

KTeV CsI Electromagnetic Calorimeter rabrab zabzab a b K L      E /E 1 GeV ~ 2.4 mm (large crystals)  x,y ~ 1.2 mm (small crystals) (NIM article in preparation)

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

E832 Publications Measurements of direct CP violation, CPT symmetry, and other parameters in the neutral kaon system, PRD 67, (2003). A measurement of the K L charge asymmetry, PRL 88, (2002). Radiative decay width measurements of neutral kaon excitations using the Primakoff effect, PRL 89, (2002). A new measurement of the radiative Ke3 branching ratio and photon spectrum, PRD 64, (2001). Study of the K L      direct emission vertex, PRL 86, 761 (2001). Observation of direct CP violation in K S,K L  decays, PRL 83, 22 (1999). Measurement of the decay K L   , 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) Citations (Spires)

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)  

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

Reconstructed Vertex z Distributions

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

KTeV Data / Monte Carlo Comparison

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

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

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

Systematic Uncertainties in Re(  )

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

K L - K S Interference Downstream of Regenerator KTeV Results:

History of K S Lifetime Measurements

History of  m Measurements

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

Current  Analysis 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: p t distribution, neutral background estimate Better drift chamber performance (99) and track reconstruction: mass resolution improved by ~10%. Improvement in systematics needed to take advantage of increase in statistics. ~ ~

K L     Data / Monte Carlo Comparison (full KTeV data sample)

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

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

Conclusions KTeV results from data include: Re(  ) = (20.7  2.8)  Precise measurements of  m,  S,  + , ,  l Analysis of full data sample going well; manpower becoming a challenge. Full KTeV data sample ( ) 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.

 : Theory vs. Experiment 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!)  may soon be measured to  5%!  Theory improvement will be needed to take full advantage of this precision. Bertolini, Sozzi