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
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