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Palm tree and CKM

Palm tree and CKM. Beauty in the Standard Model and Beyond. Gabriella Sciolla (MIT). CIPANP 2006 - Puerto Rico - May 30 - June 3, 2006. Palm tree and CKM. Beauty in the Standard Model and Beyond. Gabriella Sciolla (MIT). CIPANP 2006 - Puerto Rico - May 30 - June 3, 2006.

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Palm tree and CKM

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  1. Palm tree and CKM Beauty in the Standard Model and Beyond Gabriella Sciolla (MIT) Beauty in the Standard Model and Beyond CIPANP 2006 - Puerto Rico - May 30 - June 3, 2006

  2. Palm tree and CKM Beauty in the Standard Model and Beyond Gabriella Sciolla (MIT) Beauty in the Standard Model and Beyond CIPANP 2006 - Puerto Rico - May 30 - June 3, 2006

  3. Outline • The beauty of B physics • CP violation in the B system and the Unitarity Triangle • Standard Model measurements • Sensitivity to New Physics • Measurements of CP violation in B decays • The experiments • Measurement of the angles and sides of the Unitarity Triangle • What have we learned? • Summary and conclusion Beauty in the Standard Model and Beyond

  4. CP violation • What is CP? • Why is CP violation interesting? • Crucial ingredient to explain the matter-dominated universe • A. Sakharov (1967) • CP violation is expected in the Standard Model • Until recently, one of the least tested aspect of the theory • Many new sources of CP violation Beyond the Standard Model • Sensitive to New Physics CP = C × P C: Charge Conjugation Particle  Anti-particle P: Parity Inverts space coordinates Beauty in the Standard Model and Beyond

  5. W- c b CP violation in the Standard Model • Discovered by Fitch and Cronin in 1964 in KL decays • Introduced in Standard Model in 1973 by Kobayashi and Maskawa • In KM mechanism, CP violation originates from a complex phase in the quark mixing matrix (CKM matrix) First goal of CP violation studies: Precise determination of the parameters r and h A,l (Cabibbo angle): very well measured r,h: poorly known until recently Beauty in the Standard Model and Beyond

  6. Pros and Cons of CKM Pros: • Elegant and simple explanation of CPV in SM • It is very predictive: only one CPV phase • It accommodates all experimental results • Indirect CP violation in Kpp and KLpln • Direct CP violation in Kpp • CP violation in the B system Cons:  nB/ng predicted by CKM « observed value • …by orders of magnitude!  New sources of CPV must exist besides CKM! . CP violation as a probe for New Physics: Measure CP violation in channels theoretically well understood and look for deviations w.r.t. SM expectations Beauty in the Standard Model and Beyond

  7. (r,h) a g b (0,0) (1,0) The Unitarity Triangle Unitarity of CKM implies: V†V = 1  6 unitarity conditions Of particular interest: All sides are ~ O(1)  possible to measure both sides and angles! • CP asymmetries in B meson decays measure a, b and g • Sides from semileptonic B decays, B mixing, rare B decays Beauty in the Standard Model and Beyond

  8. (r,h) a g b (0,0) (1,0) Standard Model or New Physics? Two ways of looking for New Physics: • Compare measurement of sides and angles • 2 measurements define the apex; >2 test Standard Model • All pieces of the puzzle must fit: inconsistencies mean New Physics • Measure same quantity in channels with different sensitivity to NP • E.g.: measure b in modes mediated by different decay diagrams Precision and redundancy are essential! Beauty in the Standard Model and Beyond

  9. The experiments: B factories • BaBar (SLAC) and Belle (KEK) • e+e- asymmetric collisions • .  U(4S) resonance • Advantages of the B factories • No need for bb trigger • Very clean environment: • High luminosity • Peak luminosity > 1034 cm-2s-1 • Integrated luminosity • 350/600 fb-1 (BaBar/Belle) 350/600 fb-1 (BaBar/Belle) Beauty in the Standard Model and Beyond

  10. The experiments: Tevatron experiments • CDF and D0 at Fermilab • . • Challenges of the Tevatran • Special trigger necessary for B events • High multiplicity events • Advantages of the Tevatron • Large number of B produced • L~1032 cm-2s-1 but high x-sections • Integrated luminosity: >1 fb-1 • All b hadrons are produced • BS , Lb , BC ,… Complementary to B factories Beauty in the Standard Model and Beyond

  11. a The angle b g b b The measurements Beauty in the Standard Model and Beyond

  12. e+ Flavor tagging Q=(30.5  0.5)% BfCPexclusive reconstruction Dz~bgc Dt Precise Dt determination How to measure the CP asymmetry . e- B0 e- U(4S) m+ B0 p+ p- m- Beauty in the Standard Model and Beyond

  13. CP violation at the B factories (hf) mixing decay • When only one diagram contributes to the final state, |l|=1 ACP(t) = ± Iml sin(Dmt) (CP violation in interference between mixing and decays in B0 ) Beauty in the Standard Model and Beyond

  14. h a g b r CP violation in B0 decays: sin2b For some modes, Iml is directly and simply related to the angles of the Unitarity Triangle. Example: B0J/YKS: the “golden mode” • Theoretically clean • Experimentally clean • Relatively large BF (~10-4) ACP(t) = sin2b sinDmt Beauty in the Standard Model and Beyond

  15. sin(2b) = 0.685 ± 0.032 WA EPS 2005 The golden mode for sin2b:sin2b in B0 J/y KS Belle 386 fb-1 B0J/y KS(p+p-) Belle 386 fb-1 Dt[ps] Belle 386 fb-1 mES[GeV/c2] sin(2b)= 0.652 ± 0.039± 0.020 Beauty in the Standard Model and Beyond Dt[ps]

  16. 95% CL from sides Unitarity Triangle constraints sin2b vs indirect UT constraints: very good agreement! • New Physics does not show up in the golden mode SM reference • Compare with sin2b in independent modes with different sensitivity to NP h r CKM mechanism is the dominant source of CPV at low energies Beauty in the Standard Model and Beyond

  17. NP SM The key to New Physics: The Penguin Modes Decays dominated by gluonic penguin diagrams • The typical example: B0fKS • No tree level contributions: theoretically clean • SM predicts: ACP(t) = sin2b sin(Dmt) • Impact of New Physics could be significant • New particles could participate in the loop  new CPV phases • Low branching fractions (10-5) • Measure ACP in as many bsqq penguins as possible! • φ K0, K+ K− KS,η′ KS, KS π0, KS KS KS, ω KS,f0(980) KS Beauty in the Standard Model and Beyond

  18. The golden penguin: B0fK0 B0fKS Belle 386 fb-1 N(fKs)=180 ± 16 Belle 386 fb-1 Belle 386 fb-1 B0fKL Belle 386 fb-1 Beauty in the Standard Model and Beyond

  19. The silver penguin: B0h’KS Larger BF ~ 6 x 10-5 but theoretically slightly less clean than fKS BaBar 210 fb-1 BaBar 210 fb-1 Sη′Ks = 0.30± 0.14±0.02 Cη′Ks = −0.21±0.10±0.02 BaBar 210 fb-1 Beauty in the Standard Model and Beyond

  20. “sin2b” in penguins J/yKS BaBar + Belle average • A trend is visible • although each measurement is compatible with J/YKS… • Most significant shift in h’KS • ~2.1s • Naïve average: 0.50±0.06 • ~2.5s Penguin modes Golden mode … statistical errors still large… Beauty in the Standard Model and Beyond

  21. a The angle a g a b The measurements Beauty in the Standard Model and Beyond

  22. Tree Penguin sin2a in B0r+r- • Tree diagram dominates • Relatively large Branching Fraction • B(B0 → r+r-) = (25.2 ± 3.7 )×10-6 • Penguin contribution small • B(B0 → r0r0) < 1.1×10-6 (90%C.L.) • Vector-vector final state: is CP defined? • In principle admixture of CP+ and CP- eigentastes… ACP(t) = sin2a sinDmt Beauty in the Standard Model and Beyond

  23. BaBar 210 fb-1 Is CP defined in B0r+r-? • Vector-vector final state • 3 possible L states • Measure fraction of longitudinal polarization in angular analysis ~ 100% longitudinally polarized  CP even eigenstate Beauty in the Standard Model and Beyond

  24. CP asymmetry in B0→ r+r- BaBar 210 fb-1 BaBar 210 fb-1 BaBar 210 fb-1 Beauty in the Standard Model and Beyond

  25. Average of BaBar and Belle r cfr: CKM fit Combined constraints on a Beauty in the Standard Model and Beyond

  26. a The angle g g g b The measurements Beauty in the Standard Model and Beyond

  27. The angle g • . Cabibbo allowed Cabibbo and color suppressed NB: only tree diagrams: 100% Standard Model Beauty in the Standard Model and Beyond

  28. Currently most sensitive g from B → DK • GWL (Gronau, Wyler, London) • D  CP eigenstate • Theoretically clean • Small interference: needs more data • ADS (Atwood, Dunietz, Soni) • is doubly Cabibbo suppressed • Larger interference • Needs more data • Dalitz method (Giri, Grossman, Soffer, Zupan) • Exploits interference pattern in Dalitz plot in DKSp+p- • Combines many modes  statistical advantage • Small systematics due to Dalitz model D0KSp+p- Beauty in the Standard Model and Beyond See talk by M. Verderi

  29. Summary of g measurements • Direct measurement on g: • BaBar + Belle, all methods combined • Indirect constraints: UTFit Beauty in the Standard Model and Beyond

  30. a g b The left side: Rb NB: b is the best measured quantity in the Unitarity Triangle  precise measurement of Rb is needed for accurate tests of SM Beauty in the Standard Model and Beyond

  31. l n Hadron level Semileptonic B Decays n • Sensitive to hadronic effects • Theory error not negligible • Prob(bc)/Prob(bu)~50 • Vcbprecisely measured (2%) • Vub is the challenge Parton level l Beauty in the Standard Model and Beyond

  32. Inclusive B  Xu l n Exclusive B  p l n Two approaches to Vub Inclusive B  Xuln • Hadronic final state is not specified • bc l n background is suppressed using kinematical variables • Partial rate is measured  theoretical uncertainties ~5% l- l- l Exclusive B  p ln • Better S/B but lower branching fraction (10-4) • Needs form factor calculation from Lattice QCD  uncertainty of ~ 12% Beauty in the Standard Model and Beyond

  33. |Vub| from Inclusive B Xu l n Close collaboration between theorists and experimentalists led to c.f.r.: precision on b: 5.5% Precision on Vub: 7.4% World Average 4.45  0.33 c2/dof = 5.5/6 Beauty in the Standard Model and Beyond

  34. a g b The last side of the triangle: Rt Beauty in the Standard Model and Beyond

  35. The measurement of Rt • Bs/Bd oscillations • Theory error <5% • Dmd is precisely measured • But Bs mixing is very hard… a g b Beauty in the Standard Model and Beyond

  36. History of BS mixing • 6 experiments, > 10 years of work • Then early this Spring… • D0: double sided limit on DmS • CDF: first observation of BS mixing Dec 2005 Beauty in the Standard Model and Beyond

  37. Flavor tagging QSST~4% QOST~1% Time reconstruction s(ct)~26-70 mm Reconstruction of BS decay in hadronic or SL modes BS mixing at the Tevatron • . • . • . • . Talk on Fri by Matthew Jones Beauty in the Standard Model and Beyond

  38. BsμDs: 5601±102 D0 result • . • . • . • . 17 < Dms < 21 ps-1 @ 90% CL assuming Gaussian errors Most probable value of Dms = 19 ps-1 Beauty in the Standard Model and Beyond

  39. CDF result 3,700 events • Probability of random fluctuation: ~0.5% Beauty in the Standard Model and Beyond

  40. Impact of DmS on Unitarity Triangle Beauty in the Standard Model and Beyond

  41. Conclusion • Standard Model: precision • Tremendous improvement in r and h • Precision ~ 0.05 • First quantitative test of CPV in SM • CKM is the dominant source of CPV • New Physics: redundancy • Sides vs angles in agreement with SM • First signs of NP in sin2b in penguins? • More statistics will help: • Analyzed: ~500 fb-1 • Available: ~1 ab-1 • By 2008: > 2 ab-1 . CP-conserving measurements BaBar+Belle CP-violating measurements Beauty in the Standard Model and Beyond

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