Ю.Г. Куденко 1 Редкие распады каонов Дубна, 12 мая 2004 Вторые Марковские чтения Дубна-Москва, мая 2004 г. Институт ядерных исследований РАН CKM матрица: K   и B распады K L    K +   

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

K L     and K +    in SM 3 Br(K L  0 )  Im(V td V  ts ) 2   2 A 4 X 2 (x t )   2 Br(K +  + )   e,, ,  |V cd V  cs X l NL + V td V  ts X 2 (x t )| 2  [(  0   ) 2 +  2 ] Flavor – changing neutral current decays From isospin symmetry Br(K L  0 )  4.4Br(K +  + )  2x10 -9 Theory SM Br(K L  0 ) = (2.6 ± 1.2)x Br(K +  + ) = (7.7 ± 1.1)x10 -11

Unitarity triangle from B and K 4 Comparison of |V td | from K +  + and  M s /  M d important test of SM Comparison of sin2  from Br(K L  0 )/Br(K +  + ) and A(B  J/  K s ) definitive test of CP- violation in SM

K   beyond the SM 5 K   beyond the SM Model Br(K   x A.Buras, hep-ph/ review SM and beyond G.Isidori, hep-ph/ SUSY  27 (K + ),  40 (K 0 ) T.Yanir, hep-ph/ th generation of fermions  60 (K + ),  400 (K 0 ) M.S.Chanowitz, hep-ph/ SU(2) L x SU(2) R Higgs 2.8 – 10.6 C.-H.Chen, hep-ph/ SUSY gluino exchange 15 (K + ) A.Buras et al., hep-ph/ non-SM 30(K 0 )/7.7(K + ) H.G.He, G.Valencia, hep-ph/ right-handed Z ’ 14(K 0 )/15(K + ) (Nir and Worrah, Phys. Lett. B319, 1998) Low energy SUSY, Minimal Flavor Violation, Multiple Higgs

Measurement of K +    6 Region 1 Region 2 Decay BR PID  veto kinematics K +   +  K +   K +   +  K +   +  K +  e +  K +   +  -  K +   +  3  (SM) Physics backgrounds Only K +   + produces pions with momentum  205 MeV/c K +   

E787/E949 detector 7

Method 8 Experimental method 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  –  0 detection inefficiency  for photon threshold = 1 MeV GOAL: Observation of  + in the momentum region 211 < p  <229 MeV/c + no other detector activity Suppresion of K  K  K e3 K  Supression: 1    0  E949 E787 Region 1

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

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

K +    acceptance 12 E949 acceptance =

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

Signal K  background Signal region all cuts applied 14

Result K +    K +    (from E787) = 3 Br(K +  + ) = ( – 0.89) x ( hep-ex/ ) consistent with the SM predictions < |V td | < t = V  ts  V td = A 2 5 (1-  -i  ) 0.24  <| t |< 1.08  analysis below K  peak is under way analysis below K  peak is under way Stopped kaons 1.8  Total acceptance 0.22  0.02 % Signal 1 Background 0.30  E949 E949 + E787

Br(K L  0 )  5.9x10 -7 (90% c.l.) K L     from kTeV kTeV at FNAL: “pencil” K L beam Dalitz decay mode    e + e -  signal: p t > 160 MeV/c Phys.Rev. Phys.Rev.D61:072006, K L   

KEK E391a 17 pencil beam high acceptance high P T for K  selection extreme photon veto efficiency photon calorimetry Expected sensitivity of

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

KOPIO detector 19  = 500  sr,  E = (2-3)%/  E(GeV),   = mrad,  z  15 cm,  t  50ps/  E(GeV), photon veto  18X 0,,  inefficiency  2x10 -4

Photon and charged particle veto 20 Main backgrounds K L       and K L    e +   Two photons missed charged particle missed second photon created  0 inefficiency  x = Br  Br  1.3x10 -2

KOPIO acceptance and backgrounds K L    at the SM rate 40 K L      12.4 K L    e   4.5 K L        1.7 K L    e  0.02 K L    0.02     n  0.01 n A    X  0.2 Accidentals 0.6 Total background 19.5 KOPIO goal:  B/B  20%    10% at S/B = 2 21 Acceptance to K L     1%

KOPIO 3D 22

Conclusion and perspectives Theory Experiment K +     (7.7 ± 1.1)x ( – 8.9) x K L     (2.6 ± 1.2)x  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 23