1. 1 M. Selen, FPCP/02 Expectation Experiments Rate Asymmetries Other Approaches Outlook CP Violation in D Meson Decays CP Violation in D Meson Decays Mats Selen, University of Illinois 2002 FPCP Meeting, University of Pennsylvania

2. 2 M. Selen, FPCP/02  ( ) ≠  Indirect CPV: Very small in charm since mixing is suppressed (i.e. good hunting ground for new physics)  ( ) ≠  Direct CPV:

3. 3 M. Selen, FPCP/02 Since this decay is Singly Cabibbo Suppressed… Direct CPV: 1) Consider D 0 →     (same for K + K  K + K      K + K   ,  ,      ,        etc  ) c u u d u d W+W+

4. 4 M. Selen, FPCP/02 c u u d u d d,s,b W+W+ Direct CPV: …we can modify it’s topology in a simple way to get a penguin: 1) Consider D 0 →     (same for K + K  K + K      K + K   ,  ,      ,        etc  )

5. 5 M. Selen, FPCP/02 c u u d u d W+W+ c u u d u d b W+W+ different weak phases different strong phases are likely We have the ingredients: Expect A CP < 10 -3 in most cases

6. 6 M. Selen, FPCP/02 2) Consider D + → K S   (also K S , K S a 1, K *      [K S        K S    D S  K S K   [K S   ] K* K   etc  ) c d s u d W+W+ d c d W+W+ s d u d Cabibbo Favored Decay Doubly Cabibbo Suppressed Decay

7. 7 M. Selen, FPCP/02 CFD DCSD Lipkin & Xing

8. 8 M. Selen, FPCP/02 ≤ 10 -3 in SM (from data) hopefully big (measurable in principle) ~5 x 10 -2 ~1 From CPV in K 0 system~ 3 x 10 -3 CFD DCSD New physics could make this much bigger Lipkin & Xing

9. 9 M. Selen, FPCP/02 Bigi & Yamamoto, Phys. Lett B349 (1995) See Lipkin & Xing, Phys. Lett B450 (1999) 3 x 10 -3 + new physics So what? D + → K S  +, K S  +, K S a 1 + … D 0 → K S  0, K S     … Should be able to see  K induced CPV with 10 7 -10 8 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 K L and K S in final state. not suppressed (big BR)

10. 10 M. Selen, FPCP/02 The usual suspects

11. 11 M. Selen, FPCP/02Comments Since D + and D  (and similarly D 0 and D 0 ) 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 + , A FB For example: where

12. 12 M. Selen, FPCP/02 These modes are “self-tagging” (no D* needed). E791  D + → K + K   +,  +,K * (892) 0  +,  +    + FOCUS  D + → K + K   +, K S K +, K S  + D + Decays

13. 13 M. Selen, FPCP/02 73710 ± 292 68607 ± 282 D+→D+→ D→D→ 7355 ± 112 D→D→ 6860 ± 110 D+→D+→

14. 14 M. Selen, FPCP/02 5080 ±110 D+→SD+→S 5518 ±110 D→SD→S 495 ±38 D+→SD+→S 454 ±42 D→SD→S

15. 15 M. Selen, FPCP/02 1031 ± 44 1265 ± 48 474 ± 25 598 ± 28 D+→D+→ 23465 ± 183 28014 ± 201 D→D→ D+→D+→ D→D→ D + →   D  →  

16. 16 M. Selen, FPCP/02 239 ± 18 291 ± 19 697 ± 42 851 ± 48 D+→D+→ D→D→ D+→D+→ D→D→

17. 17 M. Selen, FPCP/02 stat stat & syst D ± A CP Summary   FOCUSE791  SS  S  + (  )     ± 1.1 ± 0.5 SS  ± 1.5 ± 0.9  S          ± 6.0 ± 1.5  S    S    ± 6.1 ± 1.2   ± 2.9   ± 3.6      ± 5.0   ± 4.2 S+(S)S+(S)  * All analyses statistics limited. * None are background free.

18. 18 M. Selen, FPCP/02 D 0 Decays Use D* decays to tag D 0 flavor: E791  D 0 → K + K ,  +  , K   +    + FOCUS  D 0 → K + K ,  +   CLEO  D 0 → K + K ,  +  , K S  0, K S K S,  0  0

19. 19 M. Selen, FPCP/02 333±21 276±20 149±17 194±18 7198±95 6075±87

20. 20 M. Selen, FPCP/02 1707±53 1623±47 606±31 571±33 19633 ±149 18501 ±144

21. 21 M. Selen, FPCP/02 2463±65 930±37 9099±151

22. 22 M. Selen, FPCP/02 810±89 65±14

23. 23 M. Selen, FPCP/02 stat stat & syst D 0 A CP Summary  CLEOFOCUSE791  SS SSSS        ± 2.2 ± 0.8   ± 3.2 ± 0.8 SS  ± 1.3   ± 4.8  S  ± 19   ± 2.2 ± 1.5   ± 3.9 ± 2.5   ± 4.9 ± 1.2   ± 7.8 ± 2.5 * All analyses statistics limited. * None are background free.

24. 24 M. Selen, FPCP/02 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  D 0 → K   +   (Published last year).  D 0 → K S  +    (Preliminary results).  D 0 →    +   (soon…)  D 0 →  S  0   (soon…).

25. 25 M. Selen, FPCP/02 D0D0 KK   D0D0 KK   Y   KK D0D0 X D0D0 KK   Z D0→D0→

26. 26 M. Selen, FPCP/02 ResonanceFit FractionPhase   (770)  0.788  0.023 0 (fixed)  K  (892)  0.161  0.010163  4  K  (892)  0.127  0.0100  4   (1700)  0.057  0.011171  7  K   (1430)  0.041  0.009166  7  K   (1430)  0.033  0.00956  7  K  (1680)  0.013  0.004103  11  Non-res 0.075  0.01131  7 We are sensitive to the amplitude and phase of something with BR ~ 10 -3. (Show Movie)

27. 27 M. Selen, FPCP/02 Fit D 0 and D 0 Dalitz Plots separately and look for asymmetries: Find A CP = 0.031  0.086 (Not an optimized ACP analysis)

28. 28 M. Selen, FPCP/02 Almost no background D0→SD0→S Fit D 0 and D 0 samples separately writing with PRELIMINARY:

29. 29 M. Selen, FPCP/02 E791 and FOCUS  Working on A CP 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 A CP search modes).  ~ 1.5 million D s D s 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 10 9 reconstructed charm events.  COMPASS ? Others ? BES Outlook (is interesting) E791       CLEO      

30. 30 M. Selen, FPCP/02 Extra Slides…

31. 31 M. Selen, FPCP/02 Observing this is evidence of CP At the  ”(3770) e+e+ ee  ++ K+K+  e + e    ”  D 0 D 0 J PC = 1  i.e. CP+ Suppose both D 0 ’s decay to CP eigestates f 1 and f 2 : These can NOT have the same CP : CP(f 1 f 2 ) = CP(f 1 ) CP(f 2 ) (-1) l = CP  +  (since l = 1) CPV through quantum coherence at CLEO-c Sensitivity to this will be at the ~1% level

32. 32 M. Selen, FPCP/02 D 0 →        A CP Fits

33. 33 M. Selen, FPCP/02 E791 references:  Phys. Lett. B403 (1997) 377  Phys. Lett. B421 (1998) 405 FOCUS references:  Phys. Lett. B491 (2000) 232  Phys. Rev. Lett. 88 (2002) 041602 CLEO references:  Phys. Rev. D63 (2001) 071101  Phys. Rev. D65 (2002) 092001  T. J. Bergfeld (Ph.D. Thesis, UIUC) Theory references:  Buchella et. al., Phys. Rev. D51 (1995)  Burdman hep-ph/9407378  Bigi & Yamamoto, Phys. Lett B349 (1995)  Lipkin & Xing, Phys. Lett B450 (1999)