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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,
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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
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
KTeV Detector KL E832: E799: rare decays KL + KS KS: c ~ 3.5m KL: c ~ 2.2 km For EK ~ 70 GeV,
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
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
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)
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)
(before background subtraction) Reconstructed K Mass Distributions KTeV ~ 1.6 MeV ~ 1.5 MeV
0.1% shift in E scale: ~3 cm shift in vertex; ~1 shift in
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.
Calorimeter Energy Scale Final energy scale adjustment based on regenerator edge.
Cross Checks of Energy Scale Check E scale with different modes: K, K*KS, hadronic 2 production, K20 Dalitz, 30
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%)
KL - KS Interference Downstream of Regenerator KTeV Results:
Re() and Im() NA48 E731 NA48+KTeV f.s. phase+CPT KTeV E773 2 contours ( Im())
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%.
KLData / Monte Carlo Comparison (full KTeV data sample)
Ongoing E832 Analyses • : Re(), Im() ( ), , m, S • • Diurnal variations of , l, etc. • KL • KL • KL • KLe • KL Dalitz parameters • KL00 Dalitz parameters • Ratios of dominant branching ratios; Vus • mass
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) KLe J. Shields (UVA) KL (full data) J. Wang (Arizona) KL (full data) E. Worcester (Chicago) Re(), , , etc.(full data)
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 ~ 1 104; 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 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!)