Direct CPV. K.Trabelsi kek.jp

Transcription

1 Direct CPV K.Trabelsi kek.jp

2 '' Theoretical issues in heavvy flavor physics'' K puzzle LP2011, Amol Dighe

3 Old puzzle Before 2004, the K π puzzle was said to be in the ratios of averaged decay rates: It is by now clear that this puzzle is disappearing and the remaining small difference can be explained by the contributions of Cʹ and PʹEW amplitudes

4 Measuring direct CPV with B K

5 Measuring direct CPV with B K Diagrams identical except for spectator quark? strong and weak phases are the same, A CP should be the same?

6 B K measurements at B- factories... σ(e+e- hadrons) [nb] energy threshold for BB production

7 B K measurements at B- factories... K ± K ± 0

8 K puzzle A K = A CP K 0 A CP K B K B K Belle Nature paper : A K = ± 4.4 Belle preliminary : A K = ± 4.0 B K 0 B K 0 A CP K ± 0 = ± ± A CP K ± = ± ± 0.007

9 K puzzle [LHCb-CONF ] B K B K A CP K ± = ± ± A K = ± NEW PHYSICS!!?

10 Contributing diagrams Tree Loop mediated

11 Contributing diagrams Tree Color- allowed tree diagram external W emission ~ A 4 e i Loop mediated

12 Contributing diagrams Tree Color-suppressed tree diagram internal W emission ~ A 4 e i from CKM factors Loop mediated from T by ~ 1/3 naively

13 Contributing diagrams Tree QCD-penguin diagram ~ A 2 from CKM factors u, c, t in the loop down by one loop dominant in K π decays Loop mediated

14 Contributing diagrams Tree EW-penguin diagram ~ A 2 from CKM factors down by one loop and weak couplings Loop mediated

15 Contributing diagrams Tree B 0 K -+ Loop mediated

16 Contributing diagrams Tree B 0 K 0 Loop mediated

17 Perturbative predictions Cheng-Wei Chiang BAS [but probably not such bad disagreement, look errors...]

18 Possible explanations Cheng-Wei Chiang BAS

19 Conclusions from... Cheng-Wei Chiang BAS

20 '' Theoretical issues in heavvy flavor physics'' LP2011, Amol Dighe

21 Contributing diagrams Tree B K 0 0 Loop mediated

22 Contributing diagrams Tree B 0 0 K 0 00 Loop mediated Important component : it has the interesting diagrams C and P EW

23 Measuring direct CPV ''Model independent '' sum rule for all four modes: [Gronau, PLB 627, 82 (2005), Atwood & Soni, PRD 58, (1998)]

24 Measuring direct CPV

25 Where else to look for direct CPV? CPV in charm provides a unique probe of New Physics sensitive to NP in the up sector SM charm physics is CP conserving to first approximation (2 generation dominance)

26 Direct CP Violation Consider CP conjugate decay amplitudes of mesons M f and M f A f T is a dominant tree-level amplitude with weak (CP violating) phase T r f is relative magnitude of subleading amplitude containing new weak phase f relative strong phase f In SM SCS D decays the subleading amplitudes are the penguins Direct CP asymmetry:

27 in charged D s decays, straightforward to measure - just the rate difference:

28 in charged D s decays, straightforward to measure - just the rate difference: D 0 's more complicated: must subtract indirect CPV contribution from time integrated CP asymmetries: The indirect CP asymmetry a ind = a m a i

29 at the B-factories: at CDF (due to cuts on proper decay times): at LHCb (due to cuts on proper decay times):

30 Where else to look for direct CPV? Remember: need (at least) two contributing amplitudes with different strong and weak phases to get CPV. Singly-Cabibbo-suppressed modes with gluonic penguin diagrams very promising Several classes of NP can contribute... but also non-negligible SM contribution Difference between A CP D 0 K K and A CP D 0 Expectation from U-spin: A dir KK = A dir Conclusion could be softened by large U-spin violation in power corrections[kagan]

31 D 0 K K, measurements Dominated by CDF, especially for D 0 K K and values consistent with zero but have opposite sign

32 Formalism so when we take A RAW f * A RAW f ' * the production and soft pion detection asymmetries will cancel. Moreover... No detector asymmetry for D 0 decays to K K,...i.e. all the D*-related production and detection effects cancel. This is why we measure the CP asymmetry difference: very robust against systematics. A CP A CP K K A CP

33 Mass spectra

34 Comparison with world average LHCb : A CP = [ 0.82 ± 0.21 stat ± 0.11 sys ] % WA : A CP = [ 0.65 ± 0.18] %

35 one order of magnitude above the naive SM expectation! New Physics? is an order of magnitude enhancement of a dir plausible in the SM? [Brod, Kagan, Zupan, arxiv: ]

36 from A.Kagan's seminar

37 from A.Kagan's seminar

38 from A.Kagan's seminar

39 from A.Kagan's seminar

40 from A.Kagan's seminar

41 My own conclusion: Don 't jump too fast to conclusion... Need more data to confirm these deviations......and look for others!

42 My own conclusion: Don 't jump too fast to conclusion... Need more data to confirm these deviations......and look for others! Unexpected doesn' t mean New Physics More penguins tomorrow, maybe NP there??