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Particle Physics 2004 Birmingham 5 th -7 th April

Physics at the B-factories. Particle Physics 2004 Birmingham 5 th -7 th April. Adrian Bevan. Talk Outline. Current generation of B-factories CP Violation Studies: , ,  Rare Decays New Particle Searches  Physics Conclusions. The B-factories.

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Particle Physics 2004 Birmingham 5 th -7 th April

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  1. Physics at the B-factories Particle Physics 2004 Birmingham 5th-7th April Adrian Bevan

  2. Talk Outline • Current generation of B-factories • CP Violation Studies: , ,  • Rare Decays • New Particle Searches •  Physics • Conclusions

  3. The B-factories • PEP-II and KEK-B at SLAC and KEK, respectively • Collide e+ and e- with a 10.58 GeV CM energy • Detectors: BaBar and Belle • Started data taking in 1999 • 9GeV e- on 3.1GeV e+ • (4S) boost: bg=0.56

  4. (4S) off-peak • (4S) decays into B+B- or B0B0 • Cross Sections at (4S): “continuum background”

  5. IFR EMC e- SOLENOID e+ SVT DCH DIRC The Detectors BaBar Differences between BaBar and Belle are small Belle

  6. run 4 run 3 run 2 run 1 Data Samples Peak Lumi: 12×1033 cm-2 sec-1 Number of B pairs approx: 220×106 Peak Lumi: 8.16×1033 cm-2 sec-1 Number of B pairs approx: 200×106

  7. CP Violation Studies: Why is CP Violation so important? • Matter/anti-matter asymmetry in the universe • requires CP Violation •  known level of CPV is 109 times too • small for cosmology • Standard Model describes all CPV with a single • complex phase •  need to test • Flavour physics BSM has many parameters • can search indirectly for new physics and try to • (further) constrain models before the LHC

  8. CP Violation in meson decay The couplings, Vij, form a 3×3 matrix: The CKM Matrix; Wolfenstein Parameterisation: Understanding Standard Model CP Violation means accurate measurements of  and 

  9. mixing (,) (0,0) (1,0) The Unitarity Triangle SM Predicts a closed triangle with two independent phase angles:  & 

  10. Three observable interference effects: CP violation in mixing: (direct) CP violation in decay CP violation in interference of mixing and decay (Iml≠ 0) CP violation at the U(4S) time dependent effect time integrated effect – number counting time dependent effect – relevant for measuring CKM angles!

  11. Indirect CP violation S ≠ 0 Direct CP violation C ≠ 0 Analyse time evolution of B0B0system (assume DG=0):

  12. (,) (0,0) (1,0) Measurements Related to the angles of the Unitarity Triangle

  13. The CKM Angle : (Belle & BaBar) • Precision measurement of  from bccs • Perfect agreement with the SM Prediction •  Alternate measurements of  probe NP at TeV scale

  14. The CKM Angle : B0K0 • Rare Decay • loop or “pure penguin” • sensitive to new physics • measured  in this mode should agree with • So in SM:

  15. SM=+0.74 106 candidates B0K0S 3.5 deviation for S in KS Belle Claim “evidence for new physics” (from 152×106 B pairs) PRL. 91 (2003) 261602

  16. Preliminary 120 M BB B0→f KS B0→f KL BaBar Result consistent with SM B0 →  K0 hep-ex/0403026, submitted to PRL

  17. The CKM Angle : new hep-ex new result new result

  18. The CKM Angle :

  19. CP Violation in B0 →h+h-; h=r,p +Loops (penguins) W u,c,t Tree Level: •  measure eff • need to bound |eff-| (shift from loops) • different |Penguin/Tree| for different decays

  20. p+p- results for S and C Presented at LP ‘03 124×106 B pairs 152×106 B pairs 372 signal events 266 signal events LR preliminary hep-ex/0401029 -A= -0.58 0.15 0.07 = C S= 1.00 0.21 0.07 Observation of CPV Evidence for DCPV

  21.  Isospin Analysis: need B+-, +0 and 00limiting factor is B0→p0p0 124×106 B pairs • Small signal BR • qq and 0 background Significance including systematic errors = 4.2s Can’t do Isospin analysis in  without a super B factory Stuck with model dep. interpretation in  PRL 91 (2003) 241801

  22. Penguins are small in B  No observation published prior to last year  now have measurements of all modes run 1+2

  23. Preliminary Result run 1+2+3 • ~113/fb • 314 signal events Isospin analysis gives:

  24. The CKM Angle : Full Reconstruction 5207 ± 87 signal lepton kaon 25160 signal 6400 signal 4746 ± 78 signal 82/fb hep-ex/0308048 & hep-ex/0310037 (BaBar) hep-ex/0308048 (Belle) 2 of many methods under study: Full & Partial reconstruction of BD(*): sin(2+) Partial Reconstruction using 78/fb Only consider D* with l or K in other B O(50%) purity use hard pion from B decay and soft pion from D* decay. No low efficiency from D0 reconstruction  High Purity  Lower Statistics Preliminary

  25. Preliminary Combining results of both BaBar methods sin(2+) > 0.87 (68% CL) sin(2+) > 0.58 (95% CL)

  26. Only hint from Belle’s +-  Need More Data Direct CP Violation • Interference of diagrams with different strong • and weak phases • ’ in kaon system only observed manifestation

  27. (,) (0,0) (1,0) Measurements Related to Sides of the Unitarity Triangle semi-leptonic B decays

  28. Measurement of Vcb from semileptonic B decays Use model from Gambino and Uraltsev 8 parameter fit includes: |Vcb|, BR(XCe), mb and mc B(B→Xclν), |Vcb| and mb determined with precision of 2% or better! hep-ex/0403031, hep-ex/0403030 Preliminary Thanks to Henning Flaecher

  29. preliminary WMAP e.g. MSSM constraint hep-ph/0303043 (Ellis et al) excluded by th. 88×106 B pairs B →K* • Acp≤1% in SM. • SUSY can enhance to ~20% Reconstruct ~1150 signal in: Preliminary

  30. Non CP/UT physics from BaBar •  Too much physics activity to do justice to all areas: • We have work published/under study in many • areas including: • New Particle Searches • Rare B decays • Direct CP Violation Searches •  physics • lots more areas under study that I don’t have time to discuss.

  31. Last Spring from BaBar: • discovery of cs state: DsJ(2317) • evidence for Ds(2458) New Particle Searches data favour JP=0+ • revitalised charm meson spectroscopy • Belle and CLEO confirmed this discovery • led to improvement in theoretical models • State was found below DK threshold (previously assumed to be above threshold) • Now have many BDsJX branching fractions See: 2317: Phys.Rev.Lett. 90 (2003) 242001  105 citations! 2458: Phys.Rev. D69 (2004) 031101 • Ongoing work searching for Pentaquarks

  32. Belle Observe BXSll, XS=K, KS from Iwasaki’s talk at http://moriond.in2p3.fr/EW/2004/ • Rare Decay (FCNC) • Sensitive to NP • 72 Signal Events • 6.2 significance • 140/fb, 152×106 B pairs Also study where BF~7×10-7 (results available from both expts)

  33.  Physics: Overview Preliminary LFV decay searches: 91.5/fb Rare  decays  lifetime: 30/fb  = 290.8 ± 1.5stat ± 1.6syst fs signal box

  34. Conclusions • BaBar has first measurement of  from B • Belle Observes CPV in B • & sees hint of Direct CPV • Starting to test closure of the Unitarity triangle • Everything measured so far consistent with SM • Searching for New Physics at higher order: looking • closely at bs penguins: new measurements of  • Will have ~200-250/fb per experiment for ICHEP ’04 • (approx ×2-3 increase in stats over results shown)

  35. Knowledge of , from direct measurements CPV from B system is consistent with SM Constraints from:

  36. Additional Material:

  37. B0 → f0 K0 (CP even decay)

  38. cos(2) comes from interference between helicity states 104 tagged events (KS0)

  39. Preliminary • Rare Decay (FCNC) • Sensitive to NP Ali: PRD 66 034002 (2002) Ali: hep-ph/0210183 SM BF~7(1)×10-6 (ee) ~4(1)×10-6 () peaking BG component from charmonium and hadronic B decays c.f. 0.02(0.20) in SM

  40. Isospin Analysis Grossman Quinn bound Also see Charles, GLSS, Buchalla et al… 

  41. direct CPV related to a • doing analysis in region near  • Dalitz Plot analysis goal • K is self tagging • CK, SK, SK =0, CK =-1 • large expected: • ACP() & ACP(K) 804.2 ±49.2 signal events BF From Winter ’03 (82/fb)

  42. ~123106 B pairs LP ‘03 result (113 /fb) 2.4 Difficult to relate to  without DP analysis

  43. 0 0

  44. The whole picture for B-meson decay: • CP Violation in mixing: • so this is small • Direct CP Violation: • So far only seen in kaon decays • this can be a large effect in rare B decay • - Belle claim ‘evidence for’ in  decay • Indirect CP Violation – CPV in interference • Need to measure the unitarity triangle angles • , , 

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