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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