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Ю.Г. Куденко

Вторые Марковские чтения Дубна-Москва, 12-13 мая 2004 г. Редкие распады каонов. Ю.Г. Куденко. Институт ядерных исследований РАН. CKM матрица : K  pnn и B распады K L  p 0 nn K +  p + nn. Дубна , 12 мая 2004. 1. CKM matrix.

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Ю.Г. Куденко

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  1. Вторые Марковские чтения Дубна-Москва, 12-13 мая 2004 г. Редкие распады каонов Ю.Г. Куденко Институт ядерных исследований РАН CKM матрица: K pnn и B распады KL p0nn K+  p+nn Дубна, 12 мая 2004 1

  2. CKM matrix K and B decays as a test of the SM and CP-violation in the SM  - CP violating parameter 2

  3. KL p0nn and K+  p+nn in SM Flavor – changing neutral current decays Br(KL0)  Im(VtdVts)2  1.8•10-102A4X2(xt)  2 Br(K++)  e,,,|VcdVcsXlNL + VtdVtsX2(xt)|2  [(0  )2 + 2] From isospin symmetry Br(KL0)  4.4Br(K++)  2x10-9 Theory SM Br(KL0) = (2.6 ± 1.2)x10-11 Br(K++) = (7.7 ± 1.1)x10-11 3

  4. Unitarity triangle from B and K Comparison of |Vtd|fromK++ and Ms/ Mdimportant test of SM Comparison of sin2fromBr(KL0)/Br(K++) and A(BJ/Ks) definitive test of CP- violation in SM 4

  5. K pnnbeyond the SM (Nir and Worrah, Phys. Lett. B319, 1998) Low energy SUSY, Minimal Flavor Violation, Multiple Higgs K  pnn beyond the SM Model Br(K  pnn) x 1011 A.Buras, hep-ph/0109197 review SM and beyond G.Isidori, hep-ph/0101121 SUSY  27 (K+),  40 (K0) T.Yanir, hep-ph/0205073 4th generation of fermions  60 (K+),  400 (K0) M.S.Chanowitz, hep-ph/9905478 SU(2)Lx SU(2)R Higgs 2.8 – 10.6 C.-H.Chen, hep-ph/0202188 SUSY gluino exchange 15 (K+) A.Buras et al., hep-ph/0402112 non-SM 30(K0)/7.7(K+) H.G.He, G.Valencia, hep-ph/0404229 right-handed Z’ 14(K0)/15(K+) 5

  6. K+  p+nn Measurement of K+  p+nn Physics backgrounds Decay BR PID veto kinematics K+  +0 0.21 - ++ + K+  + 0.63 + - + K+  + 0.005 + + - K+  +0 0.032 + ++ - K+  e+0 0.048 + ++ - K+  +- + 0.056 - + ++ K+  +  310-11 (SM) Region 1 Region 2 Only K+  + produces pions with momentum  205 MeV/c 6

  7. E787/E949 detector 7

  8. Method Experimental method • - 700 MeV/c K+ beam /K  1/3 • stop K+ in active target • delay 2 ns for K+ decay • momentum measurement in drift chamber • p/p  2.5 % • measurement of range R and energy E • in target and range stack RS • stop + in range stack • detection +  +  e+ chain in RS • veto photons and charge particles 8

  9. Suppression of neutrals GOAL:Observation of + in the momentum region 211 < p <229 MeV/c + no other detector activity Average photon inefficiency  10-3 – 10-4 Suppresion of K K Ke3K E949 Region 1 E787 0 detection inefficiency 10-6 for photon threshold = 1 MeV Supression: 1  10-3 0  10-6 9

  10. Backgrounds K, K … K Signal box K 10

  11.     e chain Suppression factor 10-5 Sample pulse height every 2 ns +stops in RS (2cm/layer) ++E = 4.1 MeV R  1mm  = 26 ns +  e+ Ee  53 MeV  = 2.2 s 11

  12. K+  p+nn acceptance E949 acceptance = 0.0022 12

  13. Event display No other concidence signal in detector K+  p+nn event range stack    T-counter drift chamber kaon pulse target 13

  14. Signal all cuts applied Signal region K background 14

  15. ResultK+  p+nn E949 Stopped kaons 1.8  1012 Total acceptance 0.22  0.02 % Signal 1 Background 0.30  0.03 E949 + E787 K+  p+nn1 + 2 (from E787) = 3 Br(K++) = (1.47 + 1.30 – 0.89) x 10-10 (hep-ex/0403036) consistent with the SM predictions 0.006 < |Vtd| < 0.027 t = VtsVtd = A25(1--i) 0.2410-3 <|t|<1.0810-3 analysis below K peak is under way 15

  16. KL p0nn from kTeV KL p0nn kTeV at FNAL: “pencil” KL beam Dalitz decay mode p0  e+e-  signal: pt > 160 MeV/c Phys.Rev. Br(KL0)  5.9x10-7 (90% c.l.) Phys.Rev.D61:072006,2000 16

  17. KEK E391a Expected sensitivity of 10-9 - 10-10 pencil beam high acceptance high PT forK selection extreme photon veto efficiency photon calorimetry 17

  18. KOPIO KOPIO experiment at BNL: Canada, USA, Russia (INR, IHEP), Japan, Italy, Switzerland - Work in KL center of mass system using TOF - Microbunched, large angle, low energy beam - Measure photon direction - Efficient photon detection KL p0nn at BNL pK 0.7 GeV/c flat beam 18

  19. KOPIO detector = 500 sr, E = (2-3)%/E(GeV),  = 20-30 mrad, z  15 cm, t  50ps/E(GeV), photon veto  18X0,,  inefficiency  2x10-4 19

  20. Photon and charged particle veto Main backgrounds KL p0 p0and KL p- e+ng Br  10-3 Br  1.3x10-2 Two photons missed charged particle missed second photon created 0 inefficiency  10-4 x 10-4 = 10-8 20

  21. KOPIO acceptance and backgrounds • KL p0nn at the SM rate 40 • KL p0 p0 12.4 • KL pe 4.5 • KL p+ p-p0 1.7 • KL pe 0.02 • KL   0.02 •  p0 n 0.01 nA p0 X 0.2 Accidentals 0.6 Total background 19.5 Acceptance toKL p0nn 1% KOPIO goal: B/B  20%    10% at S/B = 2 21

  22. KOPIO 3D 22

  23. Conclusion and perspectives K pnn - a useful probe of new physics Theory Experiment K+  p+nn (7.7 ± 1.1)x10-11 (14.7 + 13.0 – 8.9) x 10-11 KL p0nn (2.6 ± 1.2)x10-11  5.9x10-7 (90% c.l.) Perspectives:E949 doubles sensitivity next year final result 10 events (?) CKM at FNAL 100 events (?) KOPIO 40 events 23

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