Kaon Kaon Experiments Experiments at KEK and J-PARC at KEK and - PowerPoint PPT Presentation

Kaon Kaon Experiments Experiments at KEK and J-PARC at KEK and J-PARC Tadashi Nomura Tadashi Nomura (Kyoto University) (Kyoto University) T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 1 1

Contents Contents  Introduction Introduction   Two Two Kaon Kaon experiments: now and future experiments: now and future   CP-violating Rare decay K CP-violating Rare decay K L π 0 0 νν  π L   νν  Results from KEK E391a (in analysis) Results from KEK E391a (in analysis)   Proposed J-PARC E14 Proposed J-PARC E14   T-violating Transverse Muon Polarization T-violating Transverse Muon Polarization  in K + in K +  0 µ + ν π 0 µ +  π ν  Results from KEK E246 (analysis completed) Results from KEK E246 (analysis completed)   Proposed J-PARC E06 Proposed J-PARC E06  T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 2 2

Motivation for Kaon Kaon experiment experiment Motivation for  Sensitivities nearly reach the SM prediction Sensitivities nearly reach the SM prediction  in extremely rare decays, which are in extremely rare decays, which are important and theoretically clean. important and theoretically clean.  K K + (|V V td |): 10 : 10 -10 in SM +  + νν νν (| td |) -10 in SM π +  π   3 candidates observed (BNL E787/E949) 3 candidates observed (BNL E787/E949)   K K L (ImV ImV td ): 10 : 10 -11 in SM π 0 0 νν νν ( td ) -11 in SM  π L    10 10 -8 ~10 -9 in experiment (KEK E391a) -8 ~10 -9 in experiment (KEK E391a)   ~10 ~10 -12 -12 at J- at J-Parc Parc  T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 3 3

Motivation for Kaon Kaon experiment experiment Motivation for  There are unexplored rooms having a There are unexplored rooms having a  possibility to be contributed from physics possibility to be contributed from physics beyond the SM. beyond the SM.  K K L 0 νν π 0  π L  (SM predict ~10 -11 ) νν (SM predict ~10 -11 )   Some models enhance branching Some models enhance branching ratio, ratio, significantly. significantly.   T-violating muon P T-violating muon P T in K K + T in +  π 0 0 µ µ + + ν  π ν (SM predict <10 (SM predict <10 -7 -7 ) )   Some models allow sizeable P Some models allow sizeable P T  T w/o conflicting other experimental constraints. w/o conflicting other experimental constraints. Act as a probe for new physics  Act as a probe for new physics  T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 4 4

K L in the Standard Model 0 νν K π 0 νν in the Standard Model  π L  W i =u,c,t V i s V *  Feature Feature i d s i d  Z ν  Z penguin and Box diagram Z penguin and Box diagram  ν V i s V *  Top in the loop, sensitive to Top in the loop, sensitive to V V td  i d i td s d  A(K A(K L )=A(K 0 -K 0 ) ∝ Im(V Im(V td ) L )=A(K 0 -K 0 ) ∝ td )  W W e, µ , τ  Small theoretical uncertainty Small theoretical uncertainty  ν ν 2 * Im( V V ) � � 0 10 ts td B ( K ) 2 . 2 10 � X ( x ) � � � � �� = � � � L t 5 � � � 11 ( 2 . 8 0 . 4 ) 10 � = ± � T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 5 5

K  beyond the SM K πνν beyond the SM  πνν  Case Minimal Flavor Violation Case Minimal Flavor Violation   Flavor symmetry breaking at very high energy Flavor symmetry breaking at very high energy  and mediated via Yukawa coupling and mediated via Yukawa coupling  Small deviation from SM in this case Small deviation from SM in this case   Case Beyond MFV Case Beyond MFV χ   New source of New source of  d L s L ~ ~ flavor symmetry breaking flavor symmetry breaking ~ u L (s) u L (d) u R at TeV TeV scale scale at  Large deviation might occur Large deviation might occur Z  ν ν T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 6 6

Kaon experiments in Japan experiments in Japan Kaon  KEK-PS had provided good opportunities KEK-PS had provided good opportunities  to study Kaon Kaon decays. decays. Sensitivities were Sensitivities were to study limited by statistics. limited by statistics.  Now, we are lucky we can get a new, Now, we are lucky we can get a new,  world’ ’s brightest proton synchrotron here s brightest proton synchrotron here world in Japan. J-PARC at Tokai in Japan.  J-PARC at Tokai  Too good to miss !! Too good to miss !! T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 7 7

K L experiments K νν experiments 0 νν π 0  π L  KEK E391a  KEK E391a  in analysis  in analysis  J-PARC E14  J-PARC E14  stage1 approval  stage1 approval  T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 8 8

Challenges in K L 0 νν Challenges in K π 0  π L  νν measurement measurement  Extremely small branching ratio (~10 Extremely small branching ratio (~10 -11 ) -11 )   Many backgrounds from major decay modes: Many backgrounds from major decay modes:  K L (~0.2), K L (~10 -3 ), ,… … K 0 π 0 π 0 (~0.2), K 0 π 0 (~10 -3 ) π 0 π 0 π 0 π 0 π 0  π  π L  L   All neutral particles, 3-body decay All neutral particles, 3-body decay   Less stringent kinematical constraint Less stringent kinematical constraint   Impossible to reconstruct K Impossible to reconstruct K L invariant mass L invariant mass   Impossible to reconstruct Impossible to reconstruct π 0 mass mass w/o assuming vertex w/o assuming vertex π 0  How to identify “ “the decay the decay” ” ? ? How to identify T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 9 9

- Current K L experiment : KEK E391a - - Current K 0 νν νν experiment : KEK E391a -  π π 0 L  KEK E391a E391a KEK  Detect 2 Detect 2 γ & Require no other particles ) & Require no other particles ( π 2 γ γ ( 0   2 γ ) π 0  Veto counters Calorimeter γ γ K L •Clean, narrow beam “Pencil” beam (8cm @ CsI) •High vacuum 10 -5 Pa Detectors in vacuum (0.1 Pa) T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 10 10

- Current K L experiment : KEK E391a - - Current K 0 νν νν experiment : KEK E391a -  π π 0 L  E391a Analysis Method E391a Analysis Method  Event Reconstruction Event Reconstruction  (1) Find 2 clusters (1) Find 2 clusters (2) Calculate Z vertex on beam axis (2) Calculate Z vertex on beam axis assuming M(2 γ )=M( π ) assuming M(2 γ )=M( π 0 0 ) (3) Calculate π transverse momentum P T (3) Calculate 0 transverse momentum P π 0 T Considering Q-value, Signal: higher PT BG : low PT T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 11 11

- Current K L experiment : KEK E391a - - Current K 0 νν νν experiment : KEK E391a -  π π 0 L  KEK E391a Dataset E391a Dataset KEK  Run I Run I Feb 04 - Jul 04 Feb 04 - Jul 04   Suffer BG due to Suffer BG due to “ “membrane problem membrane problem” ”   First result published with 1week (10%) data First result published with 1week (10%) data   Run II Run II Mar 05 - Apr 05 Mar 05 - Apr 05   Fix Fix “ “membrane problem membrane problem” ”   Preliminary result with 1/3 data Preliminary result with 1/3 data   Run III Run III Nov 05 - Dec 05 Nov 05 - Dec 05   New BA (in-beam PV: New BA (in-beam PV: PWO+Quartz PWO+Quartz sandwich) sandwich)  T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 12 12

- Current K L experiment : KEK E391a - - Current K 0 νν νν experiment : KEK E391a -  π π 0 L  Result from Run I 1week Result from Run I 1week  Establish our basic Establish our basic  analysis method analysis method  No event in the box No event in the box   Set a upper limit: Set a upper limit:  Br < 2.1 x 10 -7 Br < 2.1 x 10 -7 published in Phys. Rev. D74, 051105 (2006) T. Nomura (Kyoto U.) The 6th KEK Topical Conference, February 6-8, 2007 The 6th KEK Topical Conference, February 6-8, 2007 T. Nomura (Kyoto U.) 13 13