1 / 45

Kaon Physics: Experimental Status and Perspectives

Kaon Physics: Experimental Status and Perspectives. Marco S. Sozzi CERN and Scuola Normale Superiore, Pisa. FPCP 2003, Paris – June 5 th 2003. Outline. Re( ’/ ): the quest for direct CP violation Rare K L decays and CP violation Rare K S decays and CP violation

ocean-lambert
Télécharger la présentation

Kaon Physics: Experimental Status and Perspectives

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Kaon Physics:Experimental Status and Perspectives Marco S. Sozzi CERN and Scuola Normale Superiore, Pisa FPCP 2003, Paris – June 5th 2003 M. Sozzi - Kaon physics

  2. Outline • Re(’/): the quest for direct CP violation • Rare KL decays and CP violation • Rare KS decays and CP violation • T-odd correlations: beyond the SM • Loop-induced decays and unitarity triangle • Future projects • Conclusions ? M. Sozzi - Kaon physics

  3. Still kaons? • The “minimal” flavour-laboratory • An amazing interferometric system • Long lifetime, few decay modes, large mixing • Both mass and flavour eigenstates accessible • All kinds of CP violation present • Difficulties in linking measurements to theory (not always!) M. Sozzi - Kaon physics

  4. The Quest forDirect CP Violation Indirect CP violation in the mixing:  Direct CP violation in the decay: ’ A fascinating 30-year long enterprise: “Is CP violation a peculiarity of kaons? Is it induced by a new superweak interaction?” M. Sozzi - Kaon physics

  5. E832 (KTeV) at FNAL Double KL beams (<p>=70 GeV/c)Regenerator for KSPure CsI calorimeterTagging by event positionMC acceptance correctionMaximize statistics M. Sozzi - Kaon physics

  6. NA48 at CERN Simultaneous near/far targetsConverging beams (<p>=100 GeV/c)Liquid Kr calorimeterTagging by time-of-flightLifetime weighting to minimize acceptance correction M. Sozzi - Kaon physics

  7. = ’/results Data Taking Periods ’/ Total: 5.3M KL00 1996 NA48: ’/ ’/ Rare Rare 1997 ’/ 1998 ’/ ’/ KS Rare 1999 no spectrometer 2000 KL KS FNAL-KTeV ’/low intensity 2001 KS Total: 7.1M KL00 2002 NA48/1: KS 2003 NA48/2: K CERN-NA48 M. Sozzi - Kaon physics

  8. Ways towards direct CPV NA48:TOF tagging KTeV: MCincoherent regeneration M. Sozzi - Kaon physics

  9. Re(’/) Results 2=6.2/3 Final result (1997-2001) Half statistics (1997) Direct CP violation proved at >7 level…after 36 years! Wait for further results from KTeV and KLOE M. Sozzi - Kaon physics

  10. Date of exp. measurement Re(’/) and the SM SM theoretical predictions Exp. value Despite huge efforts, ’/ not yet computed reliablyMeasured value is roughly compatible with the SMExpect improvements from lattice M. Sozzi - Kaon physics

  11. Other kaon Parameters KTeVm = (5261  15)  106ħ s-1S = (89.65  0.07)  10-12 s+SW = (0.61 1.19)º00 += (0.39 0.50)ºIm(’/) = (22.9  29.1)  10-4 CPT NA48: S = (89.60  0.07)  10-12 s M. Sozzi - Kaon physics

  12. Semileptonic Charge Asymmetry Measure of indirect CP violation in the mixing () and limits on CPT and S=Q Preliminary NA482  108 events in 2001 run L(e) = (3.317  0.070  0.072)  10-3 KTeV3  108 events in 2001 run L(e) = (3.322  0.058  0.047)  10-3 CPT test using  data: Re(y+x/2+a) = ( 5  31)  10-6 M. Sozzi - Kaon physics

  13. KLOE at DANE (KS +())/(KS 00)= (2.236  0.003  0.015) from which (2000 data) 0  2 (48  3) BR(K   00) = (1.807  0.008  0.018)% Good prospects for rare KS decays, interferometry, new IR Peak luminosity: 81031 cm-2 s-1 in 2002Goal: 51032 cm-2 s-1500 pb-1 (1.5 109 ) collected so far M. Sozzi - Kaon physics

  14. K+e3 K0e3 K+m3 K0m3 E865 KLOE KS KLOE KL |Vus|f+(0) KLOE results Using KL-crash tagging of KS: Preliminary (2001 data) S = (1.9  1.7  0.6)  10-2 KS semileptonic charge asymmetry Re(x+) = (3.3  5.2  3.5)  10-3 S=Q in CPT-conserving amplitudes BR(KSe) = (6.81  0.12  0.10)  10-4 QM interference Vus KS KLp+p-p+p- t M. Sozzi - Kaon physics

  15. E799-II (KTeV): Rare KL decays Intense KL flux allows sensitive searches; checks of PT KLe+e- (1997, 93K events – norm. 000D): KL e+e- e+e- (1997+1999, 1K events – norm 00D0D): no CP violation found in decay plane asymmetryKLe+e-+- (1997+1999, 132 events – norm +-0D): New results expected soon with full 1997+1999 data sample:KL e+e- e+e- and KLe+e- form factors, KL +- e+e- update Preliminary BR(KL e+e-) = (10.13  0.04  0.06  0.29norm)  10-6 Preliminary BR(KL e+e-e+e-) = (4.07  0.12  0.11  0.16norm)  10-8 BR(KL e+e-  + -) = (2.69  0.24  0.12)  10-9 M. Sozzi - Kaon physics

  16. CPV inner bremsstrahlung CPC direct emission CPV direct emission Charge radius KL,S ee : why? For KL: interference gives indirect CP-violating asymmetry in the orientation of  and eedecay planes Easier access to polarization asymmetry in K  Large ( 14%) asymmetries predicted M. Sozzi - Kaon physics

  17. KL,S ee A = (13.3  1.7)% KTeV: KL [NA48:A = (14.2  3.6)%] 1.5K events BR = (3.63  0.18)  10-7 [NA48: BR = (3.08  0.2)  10-7] BR = (4.69  0.30)  10-5 NA48: KS,KL No asymmetry:A = (1.1  4.1)% M. Sozzi - Kaon physics

  18. NA48/1 – Rare KS decays First measurement of KS  031 events, 13.6 background Preliminary BR(KS  0)z>0.2 = (4.9  1.6  0.8)  10-8 30% higher than PT prediction Not yet sensitive to chiral structure of weak vertex BR(KS  ) = (2.78  0.02  0.04)  10-6 For both: first contribution at O(p4) in PTIndications of large O(p6) terms M. Sozzi - Kaon physics

  19. Signal region NA48/1 - Search for KS0e+e- Determines indirect CP-violating contribution toKL 0e+e- decay Published limit from 1999 data:BR(KS 0e+e-) < 1.410-7 (90% CL) 2001 KS run data analyzed - Result available very soon M. Sozzi - Kaon physics

  20. Search for KS30 Expectation  Im (000) sensitive to direct CPV CPLEAR (1999)Re(000) = 0.18  0.15Im(000) = 0.15  0.20 SND, Novosibirsk (1999)BR(KS30) < 1.410-5 Hadron machines: search for interference term M. Sozzi - Kaon physics

  21. NA48/1: KS30 Re(000) = (2.6  1.0  0.5)  10-2Im(000) = (3.4  1.0  1.1)  10-2 Preliminary • Data from 2000 run • Use near-target data: 6.5M 30 events • Normalize to far-target data: 155M 30 events • Correct residual acceptance difference with MC Im(000) = (1.2  0.7  1.1)  10-2 BR(KS30) < 1.410-6 (90% CL) M. Sozzi - Kaon physics

  22. CPT Test From KS30 Bell-Steinberger relation (unitarity) connects indirect CPT violation  to CP-violating decays Largest contribution to the error from f = 30After NA48/1: Im() = (1.2  3.0)  10-5 Preliminary Assuming no CPT violation in the decay: m(K0)  m(K0) = (1.7  4.2)  10-19 GeV/c2 M. Sozzi - Kaon physics

  23. KEK E246: T-violation in K+ 0 Search for PT() orthogonal to () decay planeFSI in SM give PT < 10-5: probe of New Physics 660 MeV/c kaons stopped in absorber Combined result from 8.3M decays (1996-2000): PT() = (-1.12  2.17  0.9)  10-3 LOI to reach 10-4 accuracy at J-PARC M. Sozzi - Kaon physics

  24. NA48/2 – Kdecays 0º prod. angle 60 GeV/c 5% Beam spectrometer New simultaneous K+ and K- narrow band beamKaon momentum spectrometer M. Sozzi - Kaon physics

  25. NA48/2 – Kphysics • Search for direct CP violation in K  + and 00Dalitz plot slope asymmetries: (g/2g)  210-4 (SM, SUSY: 10-4 to 10-6) Exploit “double ratio” cancellations • Precise measurement of  interaction in Ke4 decays (>106) (a00)  0.01 • Rare K decays and CP violation • 1011K decays expected Currently taking data M. Sozzi - Kaon physics

  26. OKA @ Protvino - K New RF-separated beam at U-70 PS in construction15 GeV/c kaons, alternating K+ or K-Magnetic detector evolved from ISTRA+, GAMSIn preparation, expected 2004Measurement of 3 Dalitz plot asymmetries @ 1 10-4T-odd correlations, search for New Physics in Kl2 decays M. Sozzi - Kaon physics

  27. HyperCP: K  Main goal: CP violation in hyperon decaysCollected large samples of K decays K : FCNC GIM-suppressed loopsDominated by long-distance effects Preliminary BR(K ) = (9.8  1.0  0.5)  10-8 From 1997 statistics (1/5): A(K ) = 0.02  0.11  0.04 M. Sozzi - Kaon physics

  28. The golden modes: K   FCNC, loop-induced,GIM-suppressed in SMSensitive to New Physics MOREOVER:No long-range contributionsQCD corrections under controlSingle Heff operator with matrix element linked to Ke3 BUT:BR  10-11, unconstrained kinematics, huge backgrounds Dedicated efforts required! M. Sozzi - Kaon physics

  29. Kaons and the unitarity triangle • Comparison to B constraints (10% on BR): • Errors on , Vtd:better from B • Errors on , sin2:similar to B-factories • Error on t:always better from K A. Buras, hep-ph/9905437 M. Sozzi - Kaon physics

  30. The rare decays KL0l+l- Three contributions: 1) CP-conserving through KL0**estimate from KL  0 (KTeV/NA48 disagreement?) 2) Indirect CP-violating through KS 0l+l-Not suppressed, unlike the  case: measure from KS 0l+l- (NA48 for e+e- ) 3) “Direct” CP-violating, short-distance, reliably predicted and interfering with (2): BR=4.310-12 (e+e-), 0.910-12 (+-). (3) is smaller by  5 for the +- case “Greenlee” background KLl+l-: BR=610-7 (e+e-), 1 10-7 (+-) M. Sozzi - Kaon physics

  31. KL0e+e Exp. Limits from KTeV (90% CL): BR(KL 0e+e-) < 2.810-10BR(KL 0+-) < 3.810-10 Measured BR 10-12 Measurement requires accurate background subtraction BR(Direct CPV) 10-12 L. Littenberg, hep-ex/0212005 expected M. Sozzi - Kaon physics

  32. BNL E787: K+ + Theoretical prediction in the SM:BR(K+ +) = 7.2 10-11with small ( 7%) uncertainty Stopped K, redundant measurementsDetection of e chainMomentum region between  and  peaks Final result: 2 events (0.15 bkg.) BR(K+ +) = 1.56+1.750.82 10-10 Improved successor BNL E949 ran in 2002 M. Sozzi - Kaon physics

  33. Future: CKM at FNAL In-flight measurementRF-separated 22 GeV/c K+ beamRedundant measurements to overconstrain kinematics(spectrometers + RICHs)Progress on RF-cavities, photon vetos, straws in vacuumGoal: 100 SM events in 2 years (S/B  10)Data taking in 2007 M. Sozzi - Kaon physics

  34. KL 0 No CP-conserving termIndirect CP-violating term negligibleTheoretical prediction within the SM:BR(KL 0) = 2.710-11With tiny ( 2%) uncertainty Model independent bound Current KTeV limit:BR(KL 0) < 5.9 10-7 (90% CL)Using 0  e+e- decay M. Sozzi - Kaon physics

  35. KEK E391a: KL 0 Pilot project at KEK-PS2 GeV/c “pencil” beam: PT cut against 00to reduce veto requirement to 10-4Double decay chamber, 10% acceptance“Engineering run” in fall 2002:CsI calibration, KL00, 000First data run in 2004 (4 months) M. Sozzi - Kaon physics

  36. KL 0 at J-PARC J-PARC schedule: physics start in 200850 GeV (30-40 at start) 21014p/3.42 s 2 beam lines foreseen in K-hall2 GeV/c KL (1.1109/pulse)16% acceptanceGoal: 1000 SM events M. Sozzi - Kaon physics

  37. KOPIO at BNL : KL 0 800 MeV/c microbunched kaon beam Pb-scint. veto system (10-4) complemented by:KL momentum from TOF direction from pre-radiator(wires+scint. layers)“Pancake” beam M. Sozzi - Kaon physics

  38. KOPIO at BNL Several feasibility results achieved:Beam bunching performance proved (280 ns, goal: 200 ns)25 mrad resolution with preradiatorVeto efficiency performancesConstruction from 2006 Expect 40 SM events (S/B  2) M. Sozzi - Kaon physics

  39. How is kaon physics? CERN: NA48 (KL) NA48/1 (KS) analysis, NA48/2 (K) running FNAL: KTeV (KL) and HyperCP (K) analysis, CKM (K+) in preparation BNL: E949 (K+) analysis, KOPIO (KL) in preparation KEK: E246 (K+) analysis, E391a (KL) ready to run Frascati: KLOE (KL,S, K) running, upgrades? Protvino: OKA (K) in preparation Novosibirsk: VEPP-2000 machine (KL,S, K) in preparation J-PARC: Neutral K beam line foreseen Alive and kicking! M. Sozzi - Kaon physics

  40. Conclusions? Once upon a time, kaons delivered many surprises and precious insight… … they are still doing so today, and they will in the near future! CPV M. Sozzi - Kaon physics

  41. Spare slides M. Sozzi - Kaon physics

  42. KL ee KTeV: KL A = (13.3  1.7)% BR = (3.63 0.18)  10-7 Large CP-violating asymmetry seen M. Sozzi - Kaon physics

  43. KS ee NA48: KS A = (-1.1  4.1)% First measurement BR = (4.69 0.30)  10-5 No asymmetry for KS M. Sozzi - Kaon physics

  44. KTeV limits on KL 0 BR(KL 0) < 5.9 10-7 (90% CL)Using 0  e+e- decay(0.12 events bkg.) BR(KL 0) < 1.6 10-6 (90% CL)Using 0   decay(3.7 events bkg.) M. Sozzi - Kaon physics

  45. KTeV: ’/ improvements Several improvements in the analysis to reduce systematic errors: DCH simulation, alignment, reconstruction Use of angles and improvements for overlapping showers in CsI reconstruction Stat. Error  110-4 M. Sozzi - Kaon physics

More Related