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B physics from the e + e  B factories

B physics from the e + e  B factories. Paul Dauncey, Imperial College London on behalf of the BaBar Collaboration. 2007 Aspen Winter Conference on Particle Physics "New Physics at the Electroweak Scale and New Signals at Hadron Colliders”. Belle and BaBar. Belle. Both operating at U (4S)

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B physics from the e + e  B factories

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  1. B physics from the e+e B factories Paul Dauncey, Imperial College London on behalf of the BaBar Collaboration 2007 Aspen Winter Conference on Particle Physics"New Physics at the Electroweak Scale and New Signals at Hadron Colliders” B Physics from the B Factories

  2. Belle and BaBar Belle Both operating at U(4S) Belle: 8 GeV e/3.5 GeV e+ BaBar: 9 GeV e/3.1 GeV e+ Very similar detectors; main difference is in PID: BaBar: Ring-imaging Cherenkov Belle: Threshold Cherenkov and ToF BaBar B Physics from the B Factories

  3. Recorded luminosity Y(4S)BB cross section ~1nb Total > 1ab1 KEKB (Belle) PEP-II (BaBar) Total sample > 109 BB events; allows precision SM measurements B Physics from the B Factories

  4. CKM unitary matrix CKM matrix relates weak and mass eigenstates of quarks Four physical parameters; fundamental constants of the SM Complex elements allow (only source of) CP violation in SM Unitary means Wolfenstein expansion (A~0.82, l~0.23, r, h) in powers of l: Only two complex elements to this order; both small ~l3 B Physics from the B Factories

  5. Unitarity triangle Represent as “Unitarity Triangle” in complex r,h plane To O(l6), use corrected values: , Apex is B Physics from the B Factories

  6. Example of New Physics in loops B0B0 mixing bsg penguin SM SM SUSY: squark, gluino loop with soft term dd13 SUSY: squark, gluino loop with soft breaking term dd23 NP can change phase and/or amplitude of loops compared to expectations from measurements of tree processes  inconsistent r, h B Physics from the B Factories

  7. Measurements of b/f1 Phase of Vtd* B Physics from the B Factories

  8. CP violation in bccs Golden mode: B0J/yK; high rate, theoretically clean No Wolfenstein phase Two Vtd vertices Two Vtd vertices ei2b ei0 B0 J/yK ei0 B0 ei2b Measurable = relative phase = ei2b Note: true for any B0 decay with no phase from decay amplitude B Physics from the B Factories

  9. Experimental method Proper time DtDz/bgc Exclusive B meson vertex reconstruction Y(4S) boost bg ~0.5 Tag B meson flavour and vertex reconstruction Time dependent asymmetry = SCPsin(DmDt)  CCPcos(DmDt) SCP = fCP sin2b (fCP= ±1), CCP “direct” CP violation = 0 for J/yK B Physics from the B Factories

  10. Dt time-dependence BaBar preliminary, hep-ex/0607107 Belle preliminary, hep-ex/0608039 B0J/yKL B0J/yKS Dt for B0 tag  B0J/yK Dt for B0 tag  B0J/yK Background Dt asymmetry J/yKLis fCP= +1 J/yKS is fCP= 1 Belle Preliminary Belle Preliminary B0 tags B0 tags B0 tags B0 tags Dt oscillation Period = B mixing Dm Amplitude = D sin2b (Dilution D due to mistags; measured experimentally) B Physics from the B Factories

  11. World average (HFAG) Heavy Flavors Averaging Group E.Barberio et al., hep-ex/0603003 SCP= Statistics limited Consistent with zero: no evidence for NP in tree decay Precision measurement; allows comparison with other b measurements to overconstrain the SM Extracting b from sin2b has ambiguities; removed by J/yK*, D*D*KS and Dp0/h/h'/w analyses B Physics from the B Factories

  12. CP violation in bsss V*ub vertex eig E.g. B0fK + Suppressed ei0 eiD Two Vtd vertices ei2b B0 fK ei0 eiD B0 ei2b Relative phase = ei2b  ei2(b+D) Overall sin2beff  sin2b B Physics from the B Factories

  13. Theoretical estimates of SM offsets Lazzaro, ICHEP06 QCDF Short distance effect: QCDF: Beneke, PLB 620, 143 (2005) Cheng, Chua, Yang, PRD 73, 014017 (2006) pQCD: Mishima, Sanda, PRD 72, 114005 (2005) SCET: Williamson, Zupan, PRD 74, 014003 (2006) Long distance effect: Cheng, Chua, Soni, PRD 72, 014006 (2005) Mainly positive but large error, sin2beff > sin2b Small value and error, sin2beff ~ sin2b Representative theory estimates 0.0 0.2 0.1 0.1 D(sin2b/f1) sin2b experimental error B Physics from the B Factories

  14. BfKS and Bh'KS BfKS: B.F. = (4.3±0.6)×106 Even with small rates, clear CP violation observed in penguin decays BfKS Belle Preliminary Bh'KS: B.F. = (3.4±0.2)×105 BaBar Preliminary Belle Preliminary Bh'KS Belle preliminary, hep-ex/0608039 BaBar preliminary, hep-ex/0607112 BaBar preliminary, hep-ex/0609052 B Physics from the B Factories

  15. Comparison to bccs sin2b from J/yK NP? More data needed! B Physics from the B Factories

  16. Measurements of a/f2 pbg B Physics from the B Factories

  17. CP violation in charmless modes Vtd vertex eib E.g. B0p+p/r+r + V*ub vertex eig Suppressed eig ei(g+D) Two Vtd vertices ei2b p+p/r+r B0 eig ei(g+D) B0 ei2b  ei2(a+D) Relative phase = ei2(b+g) = ei2(pa) =ei2a Overall sin2aeff  sin2a B Physics from the B Factories

  18. Penguin corrections SM correction for penguin from first principles difficult Use isospin or SU(3) relations with input from data • Other pp and rr modes; p0p0, p+p0,r0r0, r+r0 Branching fractions (×106) Zupan, hep-ph/0701004 Penguin correction cleaner for rrthan pp; largest penguin contribution is in p0p0 or r0r0 Isospin SU(3) B Physics from the B Factories Amplitude Penguin/Tree

  19. Bp+pdecays BaBar preliminary; hep-ex/0607106 Belle preliminary; hep-ex/0608035 BellePreliminary B0 tags B0 tags B0 tags Direct CP B0 tags CCP  0  SCP = (1CCP2)sin2aeff B Physics from the B Factories

  20. Bpp decay results Including p+p0, p0p0isospin analysis UTFit, M.Bona et al., hep-ph/0606167 Primarily Bayesian CKMFitter, J.Charles et al., Eur.Phys.J.C41, 1 (2005) Belle and BaBar only marginally in agreement Primarily frequentist SCP= (1CCP2)sin2aeff Bayesian and frequentist interpretations give quantitively different conclusions B Physics from the B Factories

  21. Br+rdecays BaBar preliminary; hep-ex/0607098 Belle; Phys.Rev.Lett.96, 171801 (2006) Belle Direct CP consistent with zero B Physics from the B Factories

  22. Brr decay results Including r+r0, r0r0isospin analysis SCP= (1CCP2)sin2aeff Small CP violation: restricts aeff ~ 90 or 0/180 B Physics from the B Factories

  23. Overall result, including rp Other solutions disfavoured CL=0.683 Indirect:a = [100+57] Combined:a = [93+119] B Physics from the B Factories

  24. Measurements of g/f3 Phase of Vub* B Physics from the B Factories

  25. CP violation in DK modes GLW: Gronau, London, Wyler (2001) ADS: Atwood, Dunietz, Soni (1997) GGSZ: Giri, Grossman, Soffer, Zupan (2003) E.g. B+D0 /D0K+ D decays do not involve Vub or Vtd: no contribution to phase ei0 ei0 D0K+ D0/D0 CP state (GLW) D0/D0Kp+/K+p, CA/DCS (ADS) D0/D0KSp+p, Dalitz(GGSZ) B+ V*ub vertex eig D0K+ eig ei0 Relative phase = eig B±  no time dependence; extract g from rates and CP asymmetries B Physics from the B Factories

  26. The GGSZ method Look for deviations in B±D0K±plots Map out Dalitz plot from all D0 decays B+ B Belle Belle BaBar preliminary; hep-ex/0607104 Belle; Phys.Rev.D 73, 172009 (2006) B Physics from the B Factories

  27. Results from GGSZ method Express in terms of measurables from B± dBg 2g rB is ratio of D/D amplitudes = 0.16±0.07 dB is D/D relative (strong) phase Different rB, dB for each mode D(*)K(*) dB+g BaBar preliminary; hep-ex/0607104 Belle; PRD 73, 112009 (2006) B Physics from the B Factories

  28. Overall result Indirect:g = [59+94] Combined:g = [62+3824 ] B Physics from the B Factories

  29. Measurements of Ru Error on Ru dominated by error on |Vub| B Physics from the B Factories

  30. Semileptonic bu decays In principle, simple measurement of rate  |Vub|2 • But huge rate of semileptonic bc to remove Inclusive BXul+nl • Use high momentum lepton (“endpoint”), Xu mass (or both) • Need to correct for missing parts of spectra Exclusive B0/+p/0l+nl • Correct B+ decays for lifetime difference • Need to include form factor f+(q2=mln2) for Bp transition B Physics from the B Factories

  31. Vub inclusive summary BLNP: Lange, Neubert, Paz (2005) DGE: Anderson, Gardi (2006) LLR: Leibovich, Low, Rothstein (2006) Representative theory example (BLNP) Room for some experimental statistical improvement B Physics from the B Factories

  32. Vub exclusive summary Using theoretical form factors Measured branching fractions (all 2006) Theoretical errors dominate Experiments starting to measure form factor shape from data; allows elimination of some theory models Will still need form factor normalisation from theory B Physics from the B Factories

  33. Vub vs. sin2b/f1 Direct: sin2b/f1 = 0.67±0.03 Indirect: sin2b/f1 = 0.76±0.04 Difference: = 0.09±0.05 Not statistically significant, but… Limits amplitudes to at most ~50% of SM Model independent NP in B mixing Add new amplitude to SM  modifies b to b+fdNP B Physics from the B Factories

  34. Measurements of Rt Not covered here • B mixing; new Dms • See talk by P. Gutierrez • bsg and dg rates • See talk by S. Robertson Error on Rt dominated by error on |Vtd| B Physics from the B Factories

  35. Overall CKM agreement Frequentist Bayesian Conclusion is the same: All measurements agree with SM picture of CKM matrix within errors B Physics from the B Factories

  36. Trees versus loops Trees Loops B Physics from the B Factories

  37. Trees versus loops Trees Loops Consistent within errors B Physics from the B Factories

  38. Prospects for the future • BaBar and Belle only half way • Both aiming for around 1ab1each over next two years • Some measurements are clearly statistics limited • Sin2b/f1 bccs vs. bsss comparison • All angle measurements • Vub is mainly theory limited • Some experimental improvements possible • Theory error can be reduced but with substantial work • More data also brings new techniques and decay modes • Improvements better than N can be expected • The Tevatron and LHC may also help us out  B Physics from the B Factories

  39. Conclusions • Standard Model is in very good shape • NP must be correction, not alternative, to SM in flavour sector • Little room for any NP in trees; possible in loops • Items to watch… • Vub vs. sin2b/f1 (NP in B0 mixing loop?) • sin2b/f1 in bccs vs. bsss (NP in bsg penguin loop?) • …but neither is significant at this stage • More data will help and will come • More likely to limit NP through loops than discover it • NP in flavor sector is constrained • Flavor physics must be considered in any NP model building B Physics from the B Factories

  40. Backup slides B Physics from the B Factories

  41. Isospin analysis for pp, rr Assuming isospin symmetry between amplitudes Flipping triangles gives four-fold ambiguity in solution B Physics from the B Factories

  42. Results from GLW, ADS methods GLW CP+ No significant CP± differences CP CP+ CP ADS CP+ CP Most rates consistent with zero so few measured asymmetries AADS=0.22±0.63 B Physics from the B Factories

  43. Results from GGSZ method Express in terms of measurables from B± rB is ratio of D/D amplitudes and dB the relative (strong) phases B+ B B± difference due to g B Physics from the B Factories

  44. Angles versus sides Angles Sides Consistent B Physics from the B Factories

  45. sin2b vs. time (BaBar only) 1/N B Physics from the B Factories

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