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K     Results: E949 Steve Kettell , BNL March 7 th , 2006

K     Results: E949 Steve Kettell , BNL March 7 th , 2006 Fourth Workshop on Mass Origin and Supersymmetry Physics. I. Motivation and Overview of K. Details of E949. Conclusions. K     Motivation.

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K     Results: E949 Steve Kettell , BNL March 7 th , 2006

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  1. K Results: E949 Steve Kettell , BNL March 7th, 2006 Fourth Workshop on Mass Origin and Supersymmetry Physics • I. Motivation and Overview of K. • Details of E949. • Conclusions.

  2. K Motivation One of the Golden Modes for study of the CKM matrix and CP violation. The rate can be calculated precisely from fundamental SM parameters (~6%), and any deviation in the measured rate will be a clear signal for new physics. • FCNC, hard GIM suppression • No long distance contribution • Hadronic Matrix element from Ke3/isospin • NNLO QCD calculation of c-quark cont. • B(K) = (0.8±0.1)10-10 hep-ph/0508165 Steve Kettell, BNL

  3. Motivation VCKM= Four very clean processes Perhaps the most incisive test of the SM picture of CP violation is to verify K from A(Bd J/ψ Κso) & B(KLπονν)/B(K+π+νν) Steve Kettell, BNL

  4. Worldwide Overview of K • E787: completed (1988-98); discovered two K events (DAR) • E949: 2002 run; approved but not funded for 50 more weeks…(DAR) • CKM: FNAL scientific approval; P5 says no (separated DIF) • Kplus: FNAL LOI for unseparated DIF (rejected: not enough protons) • LOI’s: J-PARC L-04 (DAR) and CERN E326 (unseparated DIF) • E391a aims for 0.01-0.1 KL0 events; L-05 for 1000 events • KOPIO construction start in 2005, aim for 100 KL0 events E326 Steve Kettell, BNL

  5. E787 K events PRL 88, 041803 (2002) 1998 Event Steve Kettell, BNL

  6. Outline of K Experimental Method “PNN1” “PNN2” • Problem: 3-body decay (2 missing ’s); BR<10-10 • Event signature = single K+ in, single p+ out • Basic concepts • Precise and redundant measurement of kinematics e.g. Energy (E) / Momentum (P) / Range (R) or Velocity (V) / Momentum (P) / Range (R) • PID: p-m-e decay chain and/or P/R, P/V, dE/dx… • Hermetic veto detectors (g) • Major backgrounds • K+m+n (Br=63%) • Kinematics (monochromatic) • PID: p+/m+ • K+p+p0 (Br=21%) • Kinematics (monochromatic) • Photon veto • Scattered beam particles • Timing • PID: K+/p+ Primary signal region Steve Kettell, BNL

  7. E949 Experiment BNL/FNAL/SBU/UNM, U.S.A IHEP/INR, Russia Fukui/KEK/Kyoto/NDA/Osaka, Japan TRIUMF/UA/UBC, Canada V.V. Anisimovsky1,A.V. Artamonov2, B. Bassalleck3, B. Bhuyan4, E.W. Blackmore5, D.A. Bryman6, S. Chen5, I-H. Chiang4, I.-A. Christidi7, P.S. Cooper8, M.V. Diwan4, J.S. Frank4, T. Fujiwara9, J. Hu5, A.P. Ivashkin1, D.E. Jaffe4, S. Kabe10, S.H. Kettell4, M.M. Khabibullin1, A.N. Khotjantsev1, P. Kitching11, M. Kobayashi10, T.K. Komatsubara10, A. Konaka5, A.P. Kozhevnikov2, Yu.G. Kudenko1, A. Kushnirenko8, L.G. Landsberg2, B. Lewis3, K.K. Li4, L.S. Littenberg4, J.A. Macdonald5, J. Mildenberger5, O.V. Mineev1, M. Miyajima12, K. Mizouchi9, V.A. Mukhin2, N. Muramatsu13, T. Nakano13, M. Nomachi14, T. Nomura9, T. Numao5, V.F. Obraztsov2, K. Omata10, D.I. Patalakha2, S.V. Petrenko2, R. Poutissou5, E.J. Ramberg8, G. Redlinger4, T. Sato10, T. Sekiguchi10, T. Shinkawa15, R.C. Strand4, S. Sugimoto10, Y. Tamagawa12, R. Tschirhart8, T. Tsunemi10, D.V. Vavilov2, B. Viren4, N.V. Yershov1, Y. Yoshimura10 and T. Yoshioka10 1. Institute for Nuclear Research (INR), 2. Institute for High Energy Physics (IHEP), 3. University of New Mexico (UNM), 4. Brookhaven National Laboratory (BNL), 5. TRIUMF, 6. University of British Columbia, 7. Stony Brook University, 8. Fermi National Accelerator Laboratory (FNAL), 9. Kyoto University, 10. High Energy Accelerator Research Organization (KEK), 11. Centre for Subatomic Research, University of Alberta, 12. Fukui University, 13. Research Center for Nuclear Physics (RCNP), Osaka University, 14. Osaka University, 15. National Defense Academy. Steve Kettell, BNL

  8. E949 Detector (1): Overview • More protons from the AGS (High duty factor, high stopping fraction at low |p|) • Improved photon veto (Especially important for pnn2) • Improved tracking and energy resolution • Higher rate capability from FEE/trigger/DAQ upgrades (reduced deadtime) Steve Kettell, BNL

  9. E949 Detector (2): Details Side view (cutaway) End view (top half) • 700 MeV/c K+ beam (80%) • Active target (scintillation fibers) to stop K+ • Wait at least 2ns forK+ decay • Drift chamber to measure p+ momentum • 19 layers of scintillator, Range Stack (RS) to measure E and R • Stop p+ in RS, waveform digitizer to record p+-m+-e+ decay chain • Veto photons, charged tracks over 4p(BV/BVL/Endcap/…) Renew inner 5 layers! Equip gain monitor! New! Steve Kettell, BNL

  10. Data Taking Conditions • E787 collected NK=5.91012 in 81 weeks over 5 years. • E949 proposed NK=181012 in 60 weeks over 3 years. • E949 collected NK=1.81012 in 12 weeks in 2002. • Beam conditions were less than optimal: • broken separator – more p+ less K+ • spare M.G. – lower p+ mom., worse duty factor • Detector worked very well • Smooth data taking Steve Kettell, BNL

  11. Analysis Strategy • Blind Analysis • Measure Background level with real data • To avoid bias, 1/3 of data cut development 2/3 of data background measurement • Characterize backgrounds using background functions • Likelihood Analysis Signal region“the BOX” Background sources Identify a priori. Identify at least 2 independent cuts to target each background K+ Analysis Strategy Steve Kettell, BNL

  12. Calculation of backgrounds Tag with  kinematics Photon veto Tag kinematics outside pnn box – in Kp2 peak Steve Kettell, BNL

  13. Final Sensitivity and Background • Sensitivity • Background • 30% larger acceptance,by enlarging the signalbox to lower edge ofE/P/R phase space,resulting in largerKp2 backgrounds • All the cuts fixed and BG level estimated…. Steve Kettell, BNL

  14. Open the Box • Range vs. Energy after all other cuts are applied • Box shows signal region • Single candidate in the box The 3rdK candidate Steve Kettell, BNL

  15. Branching ratio • E949 result alone: • Combine E787 and E949 results (68% CL) PRL 93, 031801 (2004) E949(02) = combined E787&E949. E949 projection with full running period. (~60 weeks) Steve Kettell, BNL

  16. Impact on Unitary Triangle • Contour in r-h plane courtesy of J. Ocariz K+p+nn  K+p+nn K+p+nn Central value off the “SM” Need more data!!  Steve Kettell, BNL

  17. Further analysis: pnn2 “PNN1” “PNN2” • More phase space than pnn1 • Less loss from p+N interactions • Probe K spectrum • Main background is Kp0 with scatter in target – loss of R and P with photons aimed at weak part of detector Steve Kettell, BNL

  18. 25 • Goal: sensitivity equal to pnn1, s/b = 1 • 2  acceptance and 5  rejection • Improved PV: new detectors at small angles • Improved algorithms to identify π+scatters in target E787 Result: 1996: PL B537, 211 (2002) 1997: PR D70, 037102 (2004) 140<pp<195 MeV/c 1 candidate event w/ expected background of 1.22 +/- 0.24 events BR(K++  ) < 22 x 10-10 Background limited, with S/N<0.2 E949 Data: E949 data is being worked on now – improved photon veto rejection will improve the limit and may allow observation of K signal. pnn2 analysis (2)

  19. Other Physics p0 rejection from 1gamma inefficiency tables. p0 rejection from real data (from pnn1 analysis.) 0 (see talk by K. Mizouchi) K (and K ) PL B623, 192 (2005) PR D72, 091102(R) (2005) • ..and from E787: • K+ • K+mn Steve Kettell, BNL

  20. K • Striking difference near the endpoint between K w/UC vs. w/oUC • Endpoint is interesting in K00 for the CP-conserving contribution to K00l+l- • E787 observed 26 events with 100<Pp+<180 MeV/c; good fit to c=1.80.6 w/UC and c=1.60.6 w/oUC. B(K:100<Pp+<180MeV/c)=(6.01.50.7)10-7 • First run of E949 should see events near endpoint w/UC • Same analysis strategy and techniques as E787/E949 K • Bkg = 0.190.07 Acc = (3.720.14) 10-4 UC Acc = (1.100.04) 10-4 w/oUC No unitarity corrections with unitarity corrections (UC) Steve Kettell, BNL

  21. K PL B623, 192 (2005) • No events are observed. • B(K:Pp+>213MeV/c)<8.310-9 (UC) • B(K:Pp+>213MeV/c)<2.310-8 • Limit in this region is 8 better than E787 • Need the rest of the scheduled E949 data for a definitive test of UC. • Same data is used to search for K (forbidden by angular momentum and gauge invariance), allowed in noncommutative theories • B(K) < 2.310-9 • Limit is 150 better than E787 All limits are (90% CL) Steve Kettell, BNL

  22. Summary & Outlook (1) • E949 has observed a 3rdK event. B(K++)=1.47 10-10 PRL 93 (2004) 031801 (SM: 0.8 10-10) • BR remains higher than expected…more data is needed! • Lower Phase space region accessible - results in 1-2 years with similar sensitivity (double E949 sensitivity). • Plans are underway to move the E949 detector to Japan Steve Kettell, BNL

  23. Summary & Outlook (2) • K++ : while E949 remains un-funded and CKM and Kplus were cancelled, E326 at CERN or a stopped J-PARC experiment look promising • KL0: while KOPIO has been cancelled, E391a has data and a future J-PARC experiment looks promising • It is clear that K remains an incisive test of the flavor structure of our physical world, whether described by the SM or new physics, and some combination of experiments should go forward! • Together K++  and KL0 provide a unique opportunity for discovery of new physics. next expt. Steve Kettell, BNL

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