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Expectation Experiments Rate Asymmetries Other Approaches Outlook

CP Violation in D Meson Decays Mats Selen, University of Illinois 2002 FPCP Meeting, University of Pennsylvania. Expectation Experiments Rate Asymmetries Other Approaches Outlook. Indirect CPV:. G ( ) ≠ G( ).

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Expectation Experiments Rate Asymmetries Other Approaches Outlook

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  1. CP Violation in D Meson DecaysMats Selen, University of Illinois2002 FPCP Meeting, University of Pennsylvania • Expectation • Experiments • Rate Asymmetries • Other Approaches • Outlook

  2. Indirect CPV: G( ) ≠ G( ) Very small in charm since mixing is suppressed(i.e. good hunting ground for new physics) Direct CPV: G( ) ≠ G( )

  3. Since this decay isSingly Cabibbo Suppressed… d u u W+ Direct CPV: 1) Consider D0 → p+p- (same for K+K-, K+K-p+,K+K-p0, fp+, p+p-p+, p+p-p0, etc...) u c d

  4. u W+ c d d,s,b u d u Direct CPV: 1) Consider D0 → p+p- (same for K+K-, K+K-p+,K+K-p0, fp+, p+p-p+, p+p-p0, etc...) …we can modify it’stopology in a simpleway to get a penguin:

  5. u c d differentstrongphases are likely u d d u u u u c W+ W+ b d We have the ingredients: differentweakphases Expect ACP< 10-3in most cases

  6. u W+ c s d d d d s d 2) Consider D+ → KSp+ (also KSr, KSa1,K*0p+,[KSp0]K*p+,KSp0, DSKSK-, [KSp0]K*K-, etc...) CabibboFavoredDecay d W+ DoublyCabibboSuppressedDecay c u

  7. CFD DCSD Lipkin& Xing

  8. ~5x10-2 CFD DCSD Lipkin& Xing From CPV in K0 system~ 3x10-3 ~1 hopefully big(measurablein principle) ≤ 10-3in SM(from data) New physics couldmake this much bigger

  9. 3x10-3 + new physics So what? • D+ → KSp+, KSr+, KSa1+… • D0 → KSp0, KSp+p- … • Should be able to see dK induced CPV with 107-108 reconstructed D events. • - This is in the ballpark for CLEO-c/Belle/BaBar • New physics could make this asymmetry much bigger by increasing weak (and strong) phase differences. • - If seen, this can be studied using a suite of decays involving KL and KS in final state. not suppressed (big BR) See Lipkin & Xing, Phys. Lett B450 (1999) Bigi & Yamamoto, Phys. Lett B349 (1995)

  10. E791 The usual suspects CLEO

  11. Comments For example: where • Since D+ and D- (and similarly D0 and D0) are not produced in equal numbers in FOCUS and E791, these experiments normalize all asymmetries to some known Cabibbo favored mode. • e+e- experiments need to worry about, A+-, AFB

  12. D+ Decays • These modes are “self-tagging” (no D* needed). • E791 • D+→ K+K-p+, fp+ ,K*(892)0p+, p+p-p+ • FOCUS • D+→ K+K-p+, KSK+, KSp+

  13. D-→K+K-p- D+→K-K+p+ 7355 ± 112 6860 ± 110 D-→K+p-p- D+→K-p+p+ 73710 ± 292 68607 ± 282

  14. D-→KSK- D+→KSK+ D+→KSp+ D-→KSp- 454 ±42 495 ±38 5080 ±110 5518 ±110

  15. D+→K-p+p+ D-→K+p-p- E791 23465± 183 28014± 201 D-→K+K-p- D-→fp- D+→K-K+p+ D+→fp+ 474± 25 598± 28 1265± 48 1031± 44

  16. E791 D-→K*K-p- D+→K*K+p+ D-→p+p-p- D+→p-p+p+ 697± 42 851± 48 239± 18 291± 19

  17. D± ACPSummary stat stat & syst FOCUS E791 K-K+p+ KSp+ KSK+(Kpp) KSK+(KSp+) K-K+p+ fp+ K*K+ p+p-p+ * All analyses statistics limited. * None are background free.

  18. D0 Decays • Use D* decays to tag D0 flavor: • E791 • D0→ K+K-, p+p-, K-p+p-p+ • FOCUS • D0→ K+K-, p+p- • CLEO • D0→ K+K-, p+p-, KSp0, KSKS, p0p0

  19. 6075±87 7198±95 E791 276±20 333±21 194±18 149±17

  20. 19633±149 18501±144 1623±47 1707±53 606±31 571±33

  21. CLEO 2463±65 9099±151 930±37

  22. CLEO 810±89 65±14

  23. stat stat & syst D0 ACPSummary CLEO FOCUS E791 K+K- p+p- KSp0 KSKS K+K- p+p- p0p0 K+K- p+p- * All analyses statistics limited. * None are background free.

  24. Other Promising Approaches • Look for CPV in Dalitz Plots: • Analyze D and D samples separately • Any differences in amplitudes & phases is an indication of CPV. • Work under way by several groups. • Examples from CLEO • D0→ K-p+p0 (Published last year). • D0→ KS p+p-(Preliminary results). • D0→ p-p+p0 (soon…) • D0→ KSp0p0 (soon…).

  25. p0 p0 Y p+ p+ D0 D0 K- K- K- X p+ D0 p0 p0 Z K- D0 p+ CLEO D0→K-p+p0

  26. CLEO (Show Movie) We are sensitive to the amplitude and phase of something with BR ~ 10-3.

  27. Fit D0 and D0 Dalitz Plots separately and look for asymmetries: CLEO Find ACP= 0.0310.086 (Not an optimized ACP analysis)

  28. CLEO D0→KSp+p- Fit D0 and D0 samples separately Almost nobackground writing with PRELIMINARY:

  29. Outlook (is interesting) • E791 and FOCUS • Working on ACP analyses (for example Dalitz plots). • CLEO-c • Still working on analyses using CLEO-II, II.V and III data. • CLEO-c will turn on in about a year. • ~30 million DD events (and new ACP search modes). • ~ 1.5 million DsDs events • B Factories • In the next 5 (?) years Belle and BaBar will accumulate ~100 times the integrated luminosity that CLEO has at the (4S). • Improve on present CLEO limits by at least a factor of 10. • Hadron Machines • CDF & D0 are getting into the game. • BTeV (& LHC-b ?) could have 109 reconstructed charm events. • COMPASS ? Others ? • BES E791 K-p+p+ CLEO p-p+p0

  30. Extra Slides…

  31. CPV through quantum coherence at CLEO-c At the ”(3770) Observing this is evidence of CP CP(f1 f2) = CP(f1) CP(f2) (-1)l = CP- K+ + - (since l = 1) K- e- e+ p- p+ e+e- ”  D0D0 JPC = 1-- i.e. CP+ Suppose both D0’s decay to CP eigestates f1 and f2: These can NOT have the same CP : Sensitivity to this will be at the ~1% level

  32. CLEO D0→K-p+p0ACP Fits

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