Status of KTe V E 832 E Blucher

Status of KTe. V (E 832) E. Blucher, Chicago • • • Introduction E 832 Physics Results Status of Ongoing Analysis Ph. D Students Conclusions The KTe. V Collaboration: Arizona, Campinas (Brazil), Chicago, Colorado, Elmhurst, Fermilab, Osaka (Japan), Rice, Rutgers, San Paulo (Brazil), UCLA, UCSD, Virginia, Wisconsin 26 February 2003 FNAL Director's Review

KTe. V Physics Goals: E 832: / to 10 -4 E 799: rare KLdecays to 10 -11 E 832: Indirect vs. Direct CP Violation “Direct” in decay process / 0 “Indirect” from asymmetric mixing direct CP violation

KTe. V Detector KL KL + KS For EK ~ 70 Ge. V, E 832: E 799: rare decays KS: c ~ 3. 5 m KL: c ~ 2. 2 km

KTe. V Cs. I Electromagnetic Calorimeter (NIM article in preparation) E/E < 1% for E > 1 Ge. V x, y ~ 1. 2 mm (small crystals) ~ 2. 4 mm (large crystals) KL a b zab rab

KTe. V Datataking • 27 papers already published using 1996 -1997 data sample; first paper using 1999 data has been accepted for publication. • 17 Ph. Ds awarded; 16 current Ph. D students

E 832 Publications 8 Measurements of direct CP violation, CPT symmetry, and other parameters in the neutral kaon system, PRD 67, 012005 (2003). 4 A measurement of the KL charge asymmetry, PRL 88, 181601 (2002). 1 Radiative decay width measurements of neutral kaon excitations using the Primakoff effect, PRL 89, 072001 (2002). 0 A new measurement of the radiative Ke 3 branching ratio and photon spectrum, PRD 64, 112004 (2001). 8 Study of the KL direct emission vertex, PRL 86, 761 (2001). 263 Observation of direct CP violation in KS, KL decays, PRL 83, 22 (1999). 20 Measurement of the decay KL , PRL 83, 917 (1999). 24 Light gluino search for decays containing or from a neutral hadron beam at Fermilab, PRL 83, 2128 (1999). 25 Search for light gluinos via the spontaneous Appearance of pairs with an 800 Ge. V/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) KTe. V ~ 1. 6 Me. V ~ 1. 5 Me. V

Reconstructed Vertex z Distributions

0. 1% shift in E scale: ~3 cm shift in vertex; ~1 shift in

KTe. V Data / Monte Carlo Comparison

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, K 2 0 Dalitz, 3 0

Systematic Uncertainties in Re( )

KTe. V 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 KTe. V Results:

History of KS Lifetime Measurements

History of m Measurements

Re( ) and Im( ) NA 48 E 731 NA 48+KTe. V f. s. phase+CPT KTe. V E 773 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%.

KL Data / Monte Carlo Comparison (full KTe. V data sample)

Ongoing E 832 Analyses • : Re( ), Im( ), , m, S • • Diurnal variations of , l, etc. • KL e • KL Dalitz parameters • KL 0 0 Dalitz parameters • Ratios of dominant branching ratios; Vus • mass

E 832 Ph. D Students Past students: M. Barrio (Chicago) J. Graham (Chicago) V. Prasad (Chicago) P. Shawhan (Chicago) Thesis Topic KL Dalitz parameters Re( ), , m, S (96+97) Re( ), , m, S (96+97) Re( ) (1/4 96+97) Current students: S. Averitte (Rutgers) C. Bown (Chicago) A. Jansen (Chicago) M. Ronquest (UVA) E. Santos (San Paulo) J. Shields (UVA) J. Wang (Arizona) E. Worcester (Chicago) (1996+1997) Vus (full data) KL e KL (full data) KL (full data) Re( ), , , etc. (full data)

Conclusions • KTe. V 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 KTe. V 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 KTe. V 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!)