1. Mauro Donega – WIN05 Charmless B decays at CDF Mauro Donegà Université de Genève on behalf of the CDF collaboration

2. Mauro Donega – WIN05 Outline Lot of Charmless B results… …in this talk: B  hh’ (B  PP) BR and Acp: B d  Kπ BR: B d  π π B s  KK B  VV BR first evidence: B s    B  PV BR and Acp B ±   K ±

3. Mauro Donega – WIN05 CDF LAYER 00: 1 layer of radiation-hard silicon at very small radius (1.5 cm) (expected 50 fs proper time resolution in B s  D s  ) COT: large radius (1.4 m) Drift C. 96 layers, 200ns drift time Precise P T above 400 MeV/c Precise 3D tracking in |  |<1  (1/P T ) ~ 0.1%GeV –1 ;  (hit)~150  m dE/dx info provides >1.4 sigma K/  separation above 2 GeV SVX-II + ISL: 5 + 1 (2) layers of double-side silicon (3cm < R < 30cm) Standalone 3D tracking up to |  |= 2 Very good I.P. resolution: ~30  m (~20  m with Layer00) TIME OF FLIGHT B =1.4 T TOF: ~ 100ps resolution, 2sigmaK/  separation for tracks below 1.6 GeV/c (significant improvement of B s flavor tag effectiveness)

4. Mauro Donega – WIN05 Silicon Vertex Trigger 35  m  33  m =  47  m (resolution  beam) Primary Vertex Secondary Vertex B Decay Length Lxy d = impact parameter B physics @ hadron collider : 2 leptons (rare decays, charmonium decays) 1 lepton + 1 displaced track (semileptonic decays) 2 displaced tracks : (two-body decays, multibody decays) Silicon Vertex Trigger Pt(trk) >2 GeV/c  Pt >5.5 GeV/c 100  m<IP(trk)<1 mm |  | <1

5. Mauro Donega – WIN05 B  hh’ at CDF TeVatron  all b-hadrons (B d, B s,  b …) Both B s  hh’ processes and B d  hh’ CDF is the first experiment to be sensitive to Bs  hh’ decays Physics opportunities: Counting experiments: B d  K +  - –Branching Ratio –Direct CP asymmetry With higher statistics B s  K -  + –Branching Ratio –Direct CP asymmetry Contributions from both: tree penguin

6. Mauro Donega – WIN05 B  hh’ at CDF More than counting: B s  K + K - : Lifetime measurement sample sensitive to Γ L Combined with other lifetime measurements →ΔΓ s … in the future B d   +  - →  B d  K +  - →  Time dependent CP asymmetry requires b-flavor tagging and more statistics !

7. Mauro Donega – WIN05 B  hh’ in 180 pb -1 893±47 B  hh’ events Selection cuts The only significant cut not already present in the trigger BdBd BsBs Bd kBd k Bs kkBs kk B d   Bs  kBs  k Invariant mass  hp (GeV/c 2 )

8. Mauro Donega – WIN05 Unbinned Maximum Likelihood Fit BKG fraction (float) BKG Likelihood Sum over the 4 channels Likelihood variables:

9. Mauro Donega – WIN05 Likelihood in detail KinematicsParticle Identification = fraction of events of the j th mode Signal likelihood Unbalance Momentum P(A|B)P(B) Background likelihood same structure as the signal j j j

10. Mauro Donega – WIN05 Kinematics M  B d  +  - B d  K +  - Bd  K-+Bd  K-+ Bs  K+-Bs  K+- Bs  K+K-Bs  K+K- Bs  K-+Bs  K-+  Invariant mass (  hypothesis) vs unbalance Def:  =[1–p1/p2] q1 Helps to disentangle the B d  K +  - from B s  K -  +     M 

11. Mauro Donega – WIN05 Particle Identification K/  separation: 1.4  @P T >2 GeV/c …no ev/ev PID separation This PID performance implies statistical separation of K-pi with resolution 60% of a “perfect” PID Background composition: (ad-hoc study) kaons & pions (muons)& protons & electrons Helps to disentangle B d  +  - from B s  K + K - e p k  

12. Mauro Donega – WIN05 Fit Projections

13. Mauro Donega – WIN05 B  hh’ results BR and Acp Analyzed Luminosity =180 pb -1

14. Mauro Donega – WIN05 ±0.063 ± 0.012 ±0.019 ±0.054 0.047550.0464 0.01272 0.0033 Systematic uncertainties will decrease with statistics

15. Mauro Donega – WIN05 Upper Limits ΔΓ s /Γ s = 0.12 (Standard Model) B s  KK = 100% short eigenstate (HFAG2005) BR(B d  K  ) = 18.2 x 10 -6 (PDG 2004) f s = 0.107 f d = 0.397

16. Mauro Donega – WIN05 B  VV B  PV u,c,t W     BsBs B+B+ g or  _ b->sss pure penguin amplitude B s    B ±   K ± New Physics has a chance to compete! ( B   K*: “B   K* polarization discrepancy B s    is the B s counterpart of B d   K* Unexpected result (3  effect) from sin(2  ) measure from penguin dominated modes) Measuring angular distribution of decay products determine polarization amplitudes and their relative phases through interference effects: CP violation ΔΓ s …

17. Mauro Donega – WIN05 B s    A blind analysis was performed in anticipation of a small signal rate. Normalize rate using another B s  VV decay: B s  J/   : NO production ratio of B s vs B d (f s /f d ) one   K + K - in the final state some systematic on efficiency cancel sizeable rate Separate optimization for Signal and Normalization sample Cuts optimized checking which of The tracks fired the trigger M(kk  ) GeV/c 2 M(kk) GeV/c 2

18. Mauro Donega – WIN05 Bs   Bs    BR = (14 +6 -5 (stat) ± 2(syst) ± 5 (BR))  10 -5 From PDG * From MC B s    signal * BR(  needs to be rescaled for f s /f d From Data First observation

19. Mauro Donega – WIN05 Yield and A CP (B ±   K ± )  mass Extended unbinned maximum likelihood fit to : M KKK M  helicity angle dE/dx from COT Helicity angle Measure at the same time: N(B ±   K ± ) A CP (B ±   K ± ) + disentangle signal from B ±  f 0 K ±, B ±  K *0 , B u,d   X and combinatorial background kaons pions B u,d   X B ±  K *0  B±f0K±B±f0K± comb ID Normalization: B ±  J/  K ± Extended unbinned maximum L M  M  k

20. Mauro Donega – WIN05 B ±   K ± Results B ±  J/  K ± B ±   K ± NBNB 439 ± 2247.0 ± 8.4 PDG 2004 Babar/Belle results with ~100 fb -1 Analyzed L =180 pb -1 +PDG BR(B ±  J/  K ± )

21. Mauro Donega – WIN05 B  hh’ perspectives B  hh’ the future: Higher precision BR(B s  KK) B s  KK lifetime: ΔΓ s Precision Acp(B d  Kπ) (eventually1%) B s  Kπ BR and direct Acp Tagged time-dependent measurements further ahead: Acp parameters for B d and B s CDF “the present”: Next round with ~360 pb -1 Better tracking Improved PID 180 pb-1 360 pb-1

22. Mauro Donega – WIN05 B  VV perspective With dataset now on tape new B s modes should be visible (B s  K *0 K *0, B s   ): Need significantly more statistics to perform CP measurements (…full Run II) Measure “untagged” quantities with B s   and B d   K*events: And other charmless decays are currently under study: B d(s)  K        V 0 (as  b    )

23. Mauro Donega – WIN05 Conclusions CDF is giving important contribution in the field of the charmless B decays and remains the only player in the B s fully hadronic decays New analysis with improved tracking and PID are already in the pipeline Significant improvement of the TeVatron performance Mon, 23 May 2005 first fb -1 was exceeded (delivered luminosity ~600 pb -1 on tape) Higher level of precision is at the door !

24. Mauro Donega – WIN05

25. TeVatron 1 fb -1 delivered

26. Mauro Donega – WIN05 Imbalance - Momentum pp  Monte Carlo Binned ML fit pp  Signal BCKG

27. Mauro Donega – WIN05 Systematics a) Mass resolution: the mass resolution is input from MC. It is rescaled to match the D 0 resolution on data, vary the the rescale factor of ±10% and repeat the fit. b) dE/dx correlation: repeat the fit using the correlation shape extracted in the sample of kaons and pions from “mixed-events”: e.g. one meson from an event, the other from the subsequent event. Quote the difference wrt the central value. c) dE/dx shapes for e and p: repeat the fit assigning to the electrons and protons all 4 combinations of dE/dx shapes (ep)= (  /  K/KK/K  ). Quote the maximum difference wrt the central fit.

28. Mauro Donega – WIN05 Systematics (cont’d) d) input masses: the fit is done on data in which the recipe used for mass measurement at CDF II was applied. Input masses in the kinematics pdf are those measured by CDF II. Repeat the fit varying M(B d ) and M(B s ) within their statistical uncertainties (0.92 and 1.29 MeV/c 2 ). Quote the differences wrt the central fit e) Background model: the fit assumes mass spectrum of bckg = exp + C. Repeat the fit with p 1,p 2,p 3 and quote the difference wrt central value

29. Mauro Donega – WIN05 Systematics (cont’d) f) Different p-spectra for bckg components: central fit assumes the same momentum distribution for e/pi/K/p of background. Reweight each term of the bckg p.d.f. according to linear fits of populations vs momentum plots.

30. Mauro Donega – WIN05 Systematics (cont’d) g) B lifetimes: relative kinematics efficiencies depend on the lifetime assumed in MC. Re-evaluate efficiencies after simultaneous shift of B s lifetime (+1  ) and B d (-1  ) and viceversa.  is the PDG2004 uncertainty. Quote difference wrt central value h) Isolation efficiency: has a ~ 10% from measurement on data. Re-evaluate the efficiency at +/- 1  and quote difference wrt central value i) MC statistics: kinematics efficiencies have statistical error. Re-evaluate them at +/- 1  and quote difference wrt the central fit.

31. Mauro Donega – WIN05 Systematics (cont’d) l) Charge asymmetry: assess +/-25% of the 10% charge- asymmetry effect studied in the published D 0 analysis m) XFT bias correction: the correction function have uncertainties. Stretch (push) K/  discrepancy shifting simultaneously the correction coefficients by 1 , reevaluate the correction, and quote differences wrt the central fit n) p T (B) spectrum: B s and B d spectra are different, in principle, but use MC with an “average” spectrum. Created an additional “shrunk” spectrum by shifting by –1% each entry in the p T (B) histogram used in central fit. Extract weights from the ratio of the two spectra, apply to MC events; re-evaluate the relative efficiencies.

32. Mauro Donega – WIN05 Systematics (cont’d) o) ΔΓ s /Γ s : Standard Model predicts ~ 0.12±0.06 and B s → K + K - to be dominated by the short-lived component. We derive the systematic uncertainties from these assumptions by varying ΔΓs/Γs from 0.06 to 0.18, re- evaluating the relative efficiencies and quoting the differences wrt the central fit.

33. Mauro Donega – WIN05 Systematic uncertainties will decrease with statistics

34. Mauro Donega – WIN05 Measure sin(2  ) using golden charmonium modes (i.e. B d  J/  K S 0 )from mixing induced time dependent CP asymmetry Hint of discrepancy with SM in b  s penguin decays Unexpected result (3  effect) when measuring sin(2  ) from penguin dominated modes B 0   K 0 and B 0   ’K 0 theorethically clean!

35. Mauro Donega – WIN05 B   background Due to the large width of K* and to its value close to mφ we get in our Bs signal window a reflection from Bd  J/ψ K* for Bs  J/ψ φ and from Bd  φ K* for Bs  φφ We get an estimate of this contribution by evaluating from MC the efficiency of reconstructing a Bd  J/ψ K* event as Bs  J/ψ φ and from the measured BRs and fs/fd. As a cross-check we can evaluate the contribution from the sidebands subtracted mass spectrum of the φ meson, in which the only remaining source of background comes from the Bd  J/ψ K* reflection that doesn’t enter the Bs sidebands region

36. Mauro Donega – WIN05 BR(B s    ) systematics Systematic error dominated by normalization mode BR uncertainty and already similar in size to the statistical error Theory uncertainty on polarization very conservative (vary longitudinal fraction in 20 % to 80% range as suggested by A. Kagan)  s uncertainty based on the preferred theory value of:  s /  s = 0.12 ± 0.06 BR is rather on the low side respect to QCDF (2.5  ) 1.4 vs 3.7 E-5 Source Relative error on BR Trigger efficiency3.3 % J/  yield and efficiency 8.4% Background subtraction 5.4% B s   polarization 3.8% B s  J/  polarization 1.4%  s uncertainty 0.6% J/  and  BR 2.1% Sub Total11 % BR(J/  ) 35% Total37%

37. Mauro Donega – WIN05 BR(B ±   K ± ) systematics Systematic error on BR dominated by fit uncertainty and acceptance correction, largely below statistical uncertainty A CP systematic is largely statistical in nature, intrinsic systematic below 0.01 Comparable to B-factory experiments Source Relative error on BR Trigger efficiency3.3 % J/  yield and eff. 4.0% Efficiency Ratio3.6% B ±   K ± fit syst. 3.0% J/  and  BR 2.1% B ±   K ± BR 0.4% Total7.4 % Source error on Acp B ±   K ± fit syst. +0.034 -0.020 Charge asymmetry±0.005

38. Mauro Donega – WIN05 Further B s modes Rich harvest of interesting B s  VV decays (Li,Lu,Yang hep-ph/0309136) Only the  0 -less shown in the table here Measure them all! –K *+ K *- /K *0 anti-K *0 untagged angular analysis gives  (with SU(2) assumptions) (Fleisher,Duniets) –   dominated by Electro Weak Penguin (insight in to the B   K puzzle!) DecayBR(10 -6 ) BR/BR(  ) (including daugher BR) K*    0.530.11 K* + K* - 1.940.008  1.030.16 K* 0 anti-K* 0 2.610.35 K*   0.140.014  13.11 Pure penguin bsbs bdbd Trigger efficiency not included (but expected very similar)