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The CP-violation experiments NA48 at CERN

The CP-violation experiments NA48 at CERN. Manfred Jeitler Institute of High Energy Physics of the Austrian Academy of Sciences RECFA meeting Innsbruck, 26 March 2004. NA48. overview. the original NA48 experiment direct CP-violation: Re e ’/ e

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The CP-violation experiments NA48 at CERN

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  1. The CP-violation experiments NA48 at CERN Manfred Jeitler Institute of High Energy Physics of the Austrian Academy of Sciences RECFA meeting Innsbruck, 26 March 2004

  2. NA48 overview • the original NA48 experiment • direct CP-violation: Re e’/e • measurements in a high-intensity KS beam • KS p0 p0 p0 • KS p0e+e- and KS p0m+m- • measurements of direct CP-violation with charged kaon beams • K    + - • future ? NA48/1 NA48/2 Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  3. p0 p0 p0 p0 KS KL p+ p+ p- p- KL KS The original aim of NA48: measuring Re e’/e e’/e 0: direct CP-violation exists ”frequent“ ”rare“ / Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  4. The neutral kaon beams of NA48 Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  5. hadron calorimeter DCH DCH magnet DCH DCH The detector of the NA48 experiment at CERN • electromagnetic liquid-krypton calorimeter for measuring p0p0-decays • spectrometer (consisting of 4 drift chambers and a magnet) and hadron calorimeter for measuring p+p--decays Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  6. The liquid-krypton calorimeter • measures decays of kaons into neutral particles: K0p0p04g • filled with 9 m3 of liquid krypton • part of trigger electronics built by HEPHY, Vienna Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  7. Re e’/e : the experimental result NA48 (13.7 ± 3.1) 10-4 (15.3 ± 2.6) 10-4 Re e’/e = (14.7 ± 2.2) 10-4 NA48 (all data) Re e’/e = (16.6 ± 1.6) 10-4 new world average Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  8. Re e’/e : the shape of the theory considering the present accuracy of calculations, there is no use to further improve measurements Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  9. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  10. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  11. NA48 pay one – take three: NA48/1 NA48/2 2003 charged kaons 2004 charged kaons ...? Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  12. CP-violation in K0S decays: KS p 0p 0p 0KS p 0e +e - and KS p 0m +m - NA48/1

  13. The high-intensity KS-beam Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  14. KS p 0p 0p 0 • CP-violating decay • no CP-conserving components such as in KS p+p-p0 • counterpart to the “classical” CP-violating decay KL p0 p0 • CP | p0p0p0 > = - | p0p0p0 > while • CP | KS> ~ CP | K1> = + | K1> • described by parameter Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  15. KS p 0p 0p 0 : the result • result consistent with zero with 5% probability • limit on branching fraction: BR(KS p0p0p0) < 1.410-6at 90% confidence level (one order of magnitude better than previous limit) Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  16. KS p 0p 0p 0 and CPT Bell-Steinberger relation Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  17. KS p 0e +e -and KS p 0m +m - Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  18. KS p 0e +e - 7 events found with a background of0.15 +0.10-0.04 Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  19. KS p 0m +m - Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  20. CP-violation in charged K decays: K    + -K    0 0 NA48/2

  21. high-precision measurement of K  (3) • measure decays of K+ and K– • direct CP-violation in K  (3) : M(u,v) 1 + gu + hu2 + kv2 Ag  (g+  g–)/(g++ g–) • measurement of the ratio R (u) dvM+(u,v)2  dvM–(u,v)2 constant • simultaneousK+ and K–beams • same acceptance, alternating magnetic field Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  22. and expected experimental accuracy asymmetry parameter Ag in K  (3) theoretical predictions Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  23. KAon BEam Spectrometer (“Micromegas” detector) Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  24. KABES: KAon BEam Spectrometer (a MICROMEGAS detector) Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  25. charged Ke4 decays K+/-p+p-e+/-n • experimental observation of quark-antiquark condensate • s-wave scattering length a00 in pp-scattering at low energy • earlier experiments statistically and systematically limited • Rosselet et al., 1977 • Brookhaven, 2001 • neutral Ke4-decay (K0L p0 p-/+ e+/- n ) was studied by the Vienna group (Laurenz Widhalm, Heinz Dibon) Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  26. future plans: K+→ p +nn • so far, three events seen at BNL (E787 and E949) • decay established but not enough statistics to check Standard Model • plans to collect ~100 events at FNAL (CKM experiment): financial difficulties • idea to use CKM’s expertise and parts of the NA48 detector at CERN SM prediction: BR(K+→ p +nn) = 7.1 ± 1.0 × 10-11 Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  27. Conclusion:NA48 has yielded an unexpectedly large amount of valuable results.....and may still continue to do so!

  28. backup

  29. KS p0p0p0 • special interest: test of CPT invariance • if CPT is conserved • and there are no transitions to I = 3, or to nonsymmetric I = 1 states: • A1 : I=1 amplitude • real part fixed by CPT • imaginary part sensitive to direct CP-violation • Bell-Steinberger relation • connects CPT violating phase d with h parameters via unitarity: Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  30. KS p0p0p0 : the approach • time evolution of KL,S p0p0p0 I3p0 (t) ~ e-GLt + KL decay “dilution” D is momentum dependent • look for interference term | h000 |2e-GSt + KS decay 2 D(p) (Re (h000 ) cos Dmt – Im (h000 ) sin Dmt) e-(GS+ GL)t / 2 KL – KS interference term Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  31. NA48/1: preliminary result for h 000 Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  32. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  33. CP-violation: indirect / direct ? • CP-violation first seen in KLpp decays (1964) • KL and KS are mixtures of CP-eigenstates K1 and K2 • KL = K2 + e K1 • KS = K1 + e K2 • mixing responsible for most of the observed CP-violation • parameter e • known since long ago • see Michele Veltri’s talk for new measurement by NA48 • but longstanding question: is there “direct” CP-violation? • K2pp ?? • parameter e’ • small effect  need high-precision measurement ! Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  34. the NA48 approach to measuring Re e’/e • almost collinear neutral kaon beams (KL and KS ) • same decay volume •  take all 4 modes at same time and place ! • “weighting” of KL decay events with KS lifetime • eliminate acceptance effects in first order • reduce systematic effects at expense of statistics • distinguish KL and KS by “tagging” protons to “KS target” • “second experiment” in 2001 • new drift chambers • different spill structure and instantaneous beam intensity • different beam energy Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  35. rare decays at NA48 • “KL”-beam: • KL p+ p- e+ e- indirect CP-violation • KL p+/- e-/+ p0 n form factors, pp – phase shifts, chiral perturbation theory • KL p0 g g CP-conserving contribution in KL  e+ e- p0 • KL  e+ e- g form factors • KL  e+ e- g g background for KL  e+ e- p0 • KL  e+e- e+e- CP-eigenvalue of KL • “KS”-beam: • X0L p0X0 mass • X0L g non-leptonic weak interaction • X0S0 g • L0p p-transversal L-polarization Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  36. KS / KL p0p0p0interference dependence of interference on f000 (phase of h000 ) Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  37. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  38. Dalitz decays: p0 ge+e- KS p0 e+e- Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  39. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  40. Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  41. Kl3 decays and Vus • test of CKM unitarity • |Vud|2 + |Vus|2 + |Vub|2 = 0.9957  0.002 : deviation from unity • |Vus| contributes nearly 30% of uncertainty • |Vus| calculated from G(Ke3) and G(Km3) • K  p0en and K  p0mn • precise measurement will improve CKM unitarity test Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

  42. charged kaon decays: the NA48 approach • cancellation of systematic effects is essential • adapt NA48’s proven concept: simultaneous, collinear beams • use same detector without major modifications • beam particles are charged  measure their momentum ! Manfred Jeitler, Institute of High Energy Physics, Vienna: The NA48 experimentInnsbruck, 26 March 2004

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