Post on 09-Jan-2016
description
Ю.Г. Куденко
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Редкие распады каонов
Дубна, 12 мая 2004
Вторые Марковские чтения Дубна-Москва, 12-13 мая 2004 г.
Институт ядерных исследований РАН
CKM матрица: K и B распады
KL
K+
CKM matrix
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- CP violating parameter
K and B decays as a test of the SM and CP-violation in the SM
KL and K+ in SM
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Br(KL0) Im(VtdVts)2 1.8•10-102A4X2(xt) 2
Br(K++) e,,,|VcdVcsXl
NL + VtdVtsX2(xt)|2 [(0 )2 + 2]
Flavor – changing neutral current decays
From isospin symmetryBr(KL0) 4.4Br(K++) 2x10-9
Theory SM
Br(KL0) = (2.6 ± 1.2)x10-11
Br(K++) = (7.7 ± 1.1)x10-11
Unitarity triangle from B and K
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Comparison of |Vtd| from K++ and Ms/ Md important test of SM
Comparison of sin2 from Br(KL0)/Br(K++) and A(BJ/Ks) definitive test of CP- violation in SM
K beyond the SM
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K beyond the SM Model Br(K 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 – 10.6C.-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+)
(Nir and Worrah, Phys. Lett. B319, 1998)Low energy SUSY, Minimal Flavor Violation,Multiple Higgs
Measurement of K+
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Region 1Region 2
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+ + 310-11 (SM)
Physics backgrounds
Only K+ + produces pions with momentum 205 MeV/c
K+
E787/E949 detector
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Method
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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
Suppression of neutrals
Average photon inefficiency 10-3 – 10-4
0 detection inefficiency 10-6 forphoton threshold = 1 MeV
GOAL: Observation of + in the momentum region211 < p <229 MeV/c
+no other detector activity
Suppresion of K K Ke3 K
Supression: 1 10-3
0 10-69
E949
E787
Region 1
Backgrounds
K
KK, K …
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Signal box
e chain
Sample pulse height every 2 ns
+ stops in RS (2cm/layer)
++ E = 4.1 MeVR 1mm = 26 ns
+ e+ Ee 53 MeV = 2.2 s
Suppression factor 10-5
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K+ acceptance
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E949 acceptance = 0.0022
Event display
K+ event
drift chamber
target
range stack
kaon pulse
T-counter
No other concidence signal in detector
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Signal
K background
Signal region
all cuts applied
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Result K+
K+ 1 + 2 (from E787) = 3
Br(K++) = (1.47 + 1.30 – 0.89) x 10-10 (hep-ex/0403036) consistent with the SM predictions0.006 < |Vtd| < 0.027 t = V
ts Vtd = A25(1--i) 0.2410-3 <|t|< 1.0810-3
analysis below Kanalysis below K peak is under waypeak is under way
Stopped kaons 1.8 1012
Total acceptance 0.22 0.02 %
Signal 1
Background 0.30 0.03
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E949
E949 + E787
Br(KL0) 5.9x10-7 (90% c.l.)
KL from kTeV
kTeV at FNAL: “pencil” KL beam
Dalitz decay mode e+e- signal: pt > 160 MeV/c
Phys.Rev.
Phys.Rev.D61:072006,2000
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KL
KEK E391a
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pencil beam high acceptance high PT for K selection
extreme photon veto efficiency photon calorimetry
Expected sensitivity of 10-9 - 10-10
KOPIO
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pK 0.7 GeV/c
flat beam
- Work in KL center of mass system using TOF- Microbunched, large angle, low energy beam - Measure photon direction- Efficient photon detection
KL at BNL
KOPIO experiment at BNL: Canada, USA, Russia (INR, IHEP), Japan, Italy, Switzerland
KOPIO detector
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= 500 sr, E = (2-3)%/E(GeV), = 20-30 mrad, z 15 cm,t 50ps/E(GeV), photon veto 18X0,, inefficiency 2x10-4
Photon and charged particle veto
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Main backgroundsKL
and KL e+
Two photons missed
charged particle missed second photon created
0 inefficiency 10-4 x 10-4 = 10-8
Br 10-3
Br 1.3x10-2
KOPIO acceptance and backgrounds
KL at the SM rate 40
KL 12.4
KL e 4.5
KL 1.7
KL e 0.02
KL 0.02
n 0.01nA X 0.2Accidentals 0.6 Total background 19.5
KOPIO goal: B/B 20% 10% at S/B = 2
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Acceptance to KL
1%
KOPIO 3D
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Conclusion and perspectives
Theory ExperimentK+ (7.7 ± 1.1)x10-11 (14.7 + 13.0 – 8.9) x 10-11
KL (2.6 ± 1.2)x10-11 5.9x10-7 (90% c.l.)
K - a useful probe of new physics
Perspectives: E949 doubles sensitivity next year final result 10 events (?) CKM at FNAL 100 events (?) KOPIO 40 events
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