1 BaBar & Belle: Results and Prospects Claudio Campagnari University of California Santa Barbara

2 Physics Program at the B-Factories Comprehensive investigation of CKM structure of SM –CP-Violation (CPV) a key ingredient CPV from just one phase in SM –Other measurements very important too Rare B-meson decay (but also D,  ) –Sensitive to new particles in loops –Indirect signature of new physics? B (and D and  ) decay dynamics

3 Today: Concentrate (mostly) on measurements related to the unitarity triangle

4 B-factories and the unitarity triangle       B 0  J/  K s, D * D *,… B 0  , ,.. B  ,DK,D * ,… B-mixing B  ( ,  )  B  ul B  ( , ,  )l B  cl B  D (*) l Both angles and sides of U.T. are accessible through measurements at the B-factories Both angles and sides of U.T. are accessible through measurements at the B-factories

5 Outline BaBar and Belle –Luminosity, present and future Lifetimes and mixing Sin2  results Working towards sin2  Comments on  V ub Conclusions Note: averages from Heavy Flavor Averaging Group (unless otherwise specified) Note: averages from Heavy Flavor Averaging Group (unless otherwise specified)

6 B-factories performance Belle: 132 fb -1 Record lumi: BaBar: 117 fb -1 Record lumi: Note: 100 fb -1 ~ BB pairs

7 B-factories prospects Luminosities are improving –PEPII up to ~ 2 to cm -2 sec -1 –KEKB perhaps as high as Detectors need modest upgrades to cope Should have ~500 fb -1 by , fb -1 by end of decade –Now have ~ 100 fb -1 per expt

8 Mixing and lifetimes Results based on large samples of –Fully or partially reco. hadronic decays –Fully or partially reco. D * l –Dileptons 8K events 12K events 29 fb -1

9  t Distributions  Lifetimes  t = proper time difference between the decay times of the two B-mesons  t = proper time difference between the decay times of the two B-mesons  t resolution of ~ same order of magnitude as lifetime  t resolution of ~ same order of magnitude as lifetime  0 =   psec  - =   psec

10 Adding Tagging Information  m d =   ps fb -1

11 Lifetimes results summary Belle and BaBar now dominate world averages Improvement by x2 over pre B-factory era Order 1% uncertainty on lifetimes and ratio Belle and BaBar now dominate world averages Improvement by x2 over pre B-factory era Order 1% uncertainty on lifetimes and ratio

12 } LEP+CDF § ps -1 } BaBar + Belle § ps -1 World Average § ps -1 Dominated by BaBar & Belle Partial averages from F. Ronga CKM Workshop03 Mixing results summary 3% precision!

13 Mixing and Lifetimes - Prospects Hard, precision measurements Many are based on only a fraction of the available dataset –Statistical uncertainties still significant  room for improvement Theoretical uncertainties limiting factor in ability to extract clean CKM information

14 The measurements of mixing and lifetimes provide the foundations for the time dependent CPV measurements that follow

15 General time-dependent formalism Interfering amplitudes with different CP-violating (weak) phases can give a non-zero CP asymmetry. For B 0 ! f CP : Then, when one of the interfering amplitudes is B-mixing with S C Only one decay amplitude (or all decay amp. same CKM phase): C=0 and S gives clean CKM phase information

16 Sin2  in b ! c c s Golden modes: –clean theory –“relatively easy” experiment Tree and leading penguin have same phase sin  m  t coeff. measures sin2  cleanly Not just J/  K S : –Also  ’ K S,  c1 K S,  c K S (CP=-1) –J/  K L (CP=+1) –J/  K *0 (Mixed CP)

17 1.6K events ~500 signal ev. Event Samples Clean ~2K K S sample + ~ 500 K L events with ~ 60% purity

18  t distributions and asymmetries CP=-1 CP=+1 Events with K S Events with K L

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20 Summary of sin2  in b  ccs 7.5% precision

21 Fit for cos  m  t coefficient, extract | | 5% precision consistent with | |=1 (as expected in SM) 5% precision consistent with | |=1 (as expected in SM)

22 Sin2  from other modes b ! ccd –D (*) D (*) and J/   0 penguins with different phases can be important b ! s (penguin) –  K S,  ’ K S etc sensitive to new physics in the b ! s penguin Results from these modes are very much statistics limited

23 J/   0 ~ 40 ev D * ~ 130 ev  K S ~ 36 ev  ‘ K S ~ 150 ev

24 B 0 ! J/   0 S = - sin2  if no penguin C = 0 if no penguin

25 B 0 ! D * D * Vector-Vector final state: could have CP even and odd components Both BaBar and Belle measure mostly CP even BaBar fits S and C S = § 0.43 § 0.13 C = § 0.25 § 0.09 S = sin2  if no penguin C = 0 if no penguin

26 b ! s modes B !  K S  B !  ‘ K S Same CKM structure as J/  K S u-penguin down by ~1/50 Expect S=sin2  to 5% Same CKM structure as J/  K S u-penguin down by ~1/50 Expect S=sin2  to 5% Like  K S but also u-tree Still, S~sin2  Like  K S but also u-tree Still, S~sin2 

27 b  s penguin: S coefficient (sin2  ) b  s penguin average 0.18  0.20 ~ 2.5  from ccs modes b  s penguin average 0.18  0.20 ~ 2.5  from ccs modes Expectation from J/  K S ‘

28 Sin2  prospects Sin2  in b  ccs is already a precision measurement –But still statistically limited –Will be improved Measurements in other modes will improve as  luminosity –Maybe faster, as techniques improve Improved results in the b  s modes will be particularly interesting!

29 Sin2  In the absence of penguins, sin2  from B 0 !  +  - asymmetry BR of B 0 ! K +  - and B + !  +  0 tell us that interference between P and T is large In principle isospin analysis of  +  -,  +  0, and  0  0 allows for clean extraction of  In practice  0  0 very hard b dd u d u ++ -- B0B0 b dd d u u -- ++ t B0B0

30 B ! hh Branching Ratios (x ) Averages from J. Olsen, CKM Workshop 2003

31 Time dependent fits to  +  - 78 fb -1 ~ 106 events 84 fb -1 ~ 160 events

32  +  - Fit Results Belle rules out CP conservation (C=S=0) at 99.93% C.L. BaBar is still consistent with C=S=0 The discrepancy is at ~  level Belle rules out CP conservation (C=S=0) at 99.93% C.L. BaBar is still consistent with C=S=0 The discrepancy is at ~  level SC

33 Sin2  from   from full, time dependent, tagged, Dalitz plot analysis of  +  -  0 Hard analysis For starters, BaBar –Quasi two body analysis, only  +  - and  -  + –Also  + K - and  - K + –BF(B 0   K)= (7.3  1.3  1.3) –BF(B 0   )= (22.6  1.8  2.2) 10 -6

34 ~ 430 events A CP = § 0.08 § 0.03 Ã time integrated term C = 0.36 § 0.18 § 0.04 S = 0.19 § 0.24 §  CPV effect first step towards full Dalitz analysis B   

35 Sin2  - Prospects Clean extraction without theoretical assumptions will be hard If B 0   0  0 very small, bounds on sin2  could become quite useful We will most likely see CPV (maybe we are already seeing it) –but we will have a hard time disentangling the weak phases

36 What can we say about  ? B !  vs K  –From tree-penguin interference –Needs some theo assumptions B ! DK –Theoretically clean –Interference between b  u(cd) and b  c(ud) B  D (*)  D (*)  D (*) a 1 –Theoretically clean –Sin(2  +  )

37 B  DK B - b u u u s c D 0   B - b s D0D0  u c Information on  through interference in final states common to D 0 and D 0 (e.g. , KK..) Several variants on the market prospects look a little brighter, as color suppression not as large as previously thought Measurements of various BR done or in progress First asymmetry measurements uu V ub ~ e i 

38  from B  DK, an example D  is CP-odd or CP-even neutral D combination with strong phase

39 DK DD D  K + K -,  +  - D  K S  0, K s , K S , K S , K S  ‘ no useful constraints yet no useful constraints yet

40  - Prospects Many methods, many theoretically clean Problems: –Need a lot of luminosity! –Often methods have ambiguities ,  + 45 o,  + 90 o, etc. Will need to combine many channels It will be a long and arduous journey We are taking the first steps –Many more B  D (*) K (*) modes have been/are being measured Not sure where we will end up –But it should be fun

41 V ub from b  u l Two complementary approaches Reconstructed exclusive states –B   l B   l B   l B   l –Theoretical uncertainties –Lattice could eventually come to the rescue Inclusive b  u l –Theoretically cleaner –Experimenters make cuts into phase space  introduce theoretical uncertainties

42 V ub : Exclusive Decays Branching ratios: BaBar, Belle, Cleo General agreement Working to combine into single V ub Typical individual measurement   |V ub | ~ 20%

43 Exclusive Branching Ratios Compilation from Gibbons, CKM Workshop 2003 x 10 -4

44 E(lepton) M 2 (X) E(X) q 2 (l ) From Muheim, CKM Workshop 2003: Blue lines indicate b  c l regions From Muheim, CKM Workshop 2003: Blue lines indicate b  c l regions Inclusive decays: b  u l X=hadronic syst in b  X l

45 b  u l : new expt. technique Fully reconstruct one B Then look only at what’s left –Reduce combinatorics –Know momentum vector of recoil Important for kinematic reconstruction –Reduce continuum B recoil B reco D*  Y(4S) l

46 S/B~0.3 M ES [GeV] Lepton p l >1.0 GeV/c S/B ~ 2.5 B  D (*) n  Efficiency only 0.4% But statistics are OK M(X) reconstruction Belle, similar technique with B  D (*) l B  D (*) n  Efficiency only 0.4% But statistics are OK M(X) reconstruction Belle, similar technique with B  D (*) l M X < 1.55 GeV Signal 167 ± 21 events

47 b  u l inclusive: summary Individual measurements in agreement ~ 15-20% uncertainty each improvement on LEP Individual measurements in agreement ~ 15-20% uncertainty each improvement on LEP

48 V ub Summary Much progress is being made Very active area, both theory and experiment Lattice improvements soon Want to go well below 10% uncertainty for Unitarity Triangle constraints

49 Conclusions The B-factories have gone through a very successful first three years Today I showed you only a small fraction of their physics program, there is much more We are looking forward to increases in luminosity, eventually x10-20 more data The SM is still alive and well, but we’ll continue poking at it

50 THE END