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Heavy Flavors

Heavy Flavors. Sheldon Stone, Syracuse University. Introduction. “Heavy” flavors, defined as b & c quarks, not t, which is heavier, as the top doesn’t live long enough to form a meson and just decays ~100% directly to b quarks (In England we have “Heavy” flavo u rs)

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Heavy Flavors

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  1. Heavy Flavors Sheldon Stone, Syracuse University The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  2. Introduction • “Heavy” flavors, defined as b & c quarks, not t, which is heavier, as the top doesn’t live long enough to form a meson and just decays ~100% directly to b quarks (In England we have “Heavy” flavours) • Charm is interesting in several special areas, but I will concentrate on b’s • First I will discuss some specific b phenomenology and then point out why these studies are extremely important and interesting The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  3. Some B Meson Decay Diagrams • a) is dominant • b) is “color suppressed” • a) & b) are called “tree” level diagrams The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  4. The Standard Model • Theoretical Background • Physical States in the Standard Model • The gauge bosons: W±, g & Zo and the Higgs Ho • Lagrangian for charged current weak decays • Where The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  5. The CKM Matrix • Unitary with 9*2 numbers  4 independent parameters • Many ways to write down matrix in terms of these parameters The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  6. The Basics: Quark Mixing & the CKM Matrix d s b mass u c m a s s t • A, l, r and h are in the Standard Model fundamental constants of nature like G, or aEM • h multiplies i and is responsible for CP violation • We know l=0.22 (Vus), A~0.8; constraints on r & h The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  7. Best measured in Bs decays The 6 CKM Triangles • From Unitarity • “ds” - indicates rows or columns used • There are 4 independent phases: b, g, c, c (a can be substituted for g or b, as a+b+g=p) c c g b a Area of each  = A2l6h, the Jarlskog Invariant The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  8. |Vcb| • Both Vcb & Vub can be determined using diagram (a) when W-→-n • Can use either inclusive decays B→X-n, with B~10%or exclusive B→D*-n with B~6% • |Vcb|=(41.96±0.23±0.35±0.59)x10-3 inclusive (see Kowalewski ICHEP 2006) Very well based theoretically (HQET) • Note difference is 2.6x10-3, much larger than quoted theoretical errors! The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  9. |Vub| • This is much more difficult because the b→u rate is so much smaller than b→c • Inclusive decays are studied with severe cuts to reduce b→u background • |Vub|=(4.49±0.19±0.27)x10-3 • For exclusive decays use B→p-n (in principle also r -n) Again difference between inclusive & exclusive The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  10. Measurements of Bo & BS mixing

  11. Bo-Bo Mixing • Bo can transform to Bo, like neutral K’s • The eigenstates of flavor, degenerate in pure QCD mix under the weak interactions. Let QM basis be {|1>,|2>} {|Bo>,|Bo>}, then The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  12. Mixing Measurements • Diagonalizing we have Dm= mBH-mBL=2|M12|, DG~0 • R= prob BoBo/ prob BoBo • First seen by ARGUS • P(BoBo)= 0.5Ge-Gt•[1+cos(Dmt)] • Must “tag” the flavor of the of the decaying B at t=0 using the other B The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  13. Dmd Measurements • Dmd average 0.507±0.004 ps-1 • Accuracy better than 1% The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  14. Bd Mixing in the Standard Model • Relation between B mixing & CKM elements: • F is a known function, hQCD~0.8 • BB and fB are currently determined only theoretically • in principle, fB can be measured, but its very difficult, need to measure B-l-n • Current best hope is Lattice QCD The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  15. Bs Mixing in the Standard Model • Measurement of Bs mixing provides the ratio of Vtd/Vts which gives the same essential information as Bd mixing alone, but with much better control of theory parameters • |Vtd|2=A2l4[(1-r)2+h2] • |Vtd|2/ |Vts|2=[(1-r)2+h2] • Circle in (r,h) plane centered at (1,0) • To relate constraints on CKM matrix in terms of say r & h need to use theoretical estimates of x=fBs2BBs/ fBd2BBd The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  16. for 95% cl limit 3.7 s effect A CDF Measurement of Dms • P(BSBS)=0.5X GSe-GSt[1+cos(DmSt)] • It is useful to analyze the data as a function of a test frequency w • g(t)=0.5 GS e-GSt[1+Acos(wt)] • CDF: • D0 90% cl bounds 21>DmS>17 ps-1 The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  17. Constraint on r - h plane • Need to use theory value for • Using both Vub/Vcb & B mixing • In principle, could measure fB|Vub|using B-t-n, but difficult: Belle “discovery” was “corrected” & Vub error is significant, so use D decays See http://ckmfitter.in2p3.fr/ The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  18. In general for all pseudoscalars: Calculate, or measure if VQq is known Leptonic Decays: D(s)+n _ c and q can annihilate, probability is  to wave function overlap Diagram: or cs (s) The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  19. CLEO-c K-p+ p+ K-p+ p+ p0 Ksp+p+ p- Ksp+ Ksp+p0 K-K+ p+ Measuring Charm at Threshold • DD production at threshold: used by Mark III, and more recently by CLEO-c and BES-II. • Unique event properties • Only DD not DDx produced • Ease of B measurements using "double tags“ • BA = # of A/# of D's • Beam Constrained Mass The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  20. Data have 50 signal events in 281 pb-1 CLEO-c Measurement of fD+ • To find signal, look for events consistent with one m+ track opposite a D- tag with a missing n • Compute • Find The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  21. mn +tn signal line shape K0p+ 100 events 400 MeV DS+→m+n + t+n, t→p+n • DS+→m+n + t+n, t→p+n Sum contains 100 m+n + t+n events for MM2 <0.2 GeV2 • Also, DS+→t+n, t→e+nn • Weighted Average: fDs=280.1±11.6±6.0 MeV, the systematic error is mostly uncorrelated between the measurements • Thus fDs/fD+=1.26±0.11±0.03 (CLEO-c) The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  22. Comparisons with Theory • CLEO-c data are consistent with most models, more precision needed, for both The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  23. Measurements of CP Violating Angles

  24. See Bigi & Sanda “CP Violation,” Cambridge Formalism of CP Violation • CP Eigenstates: • Because of mixing mass eigenstates are a superposition of a|Bo>+b|Bo> that obey the Schrödinger equation The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  25. Bo CP Formalism II • For CP not being conserved, instead of B1 & B2 • CP is violated if q/p  1 • Time dependence is given by The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  26. Bo CP Formalism III • This leads to the time evolution of flavor amplitudes as • Dm=mH-mL, G GL GH (true for Bd, not necessarily for Bs) • Probability of a Bo decay is given by <Bo(t)|Bo(t)*> & is pure exponential in the absence of CP violation The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  27. CP violation using CP eigenstates • CPV requires the interference of two amplitudes. We use the direct decay for one amplitude and mixing for the other one • Define • A=<f|H|Bo> • A=<f|H|Bo> • |A/A|1 is evidence of CP violation in the decay amplitude (“direct” CPV) • With mixing included, we have CPV if The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  28. CP V using CP eigenstates II • CP asymmetry • for |q/p| = 1 • When there is only one decay amplitude, l=1 then • Time integrated good luck, maximum is –0.5 The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  29. h b 0 1 r CPV using CP eigenstates III • For Bd, • Now need to add A/A • for J/y Ks: The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  30. Ambiguities • Suppose we measure sin(2b) using yKs, what does that tell us about b? • Ans: 4 fold ambiguity- b, p/2-b, p+b, 3p/2-b • Only reason h>0, is Bk>0 from theory, and related theoretical interpretation of e The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  31. B Kinematics at the Y(4S)(Babar & Belle) Asymmetric e+e- machines at Y(4S) The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006 From Abe

  32. B0 J/y KS 0 _ B0 tag B0 tag _ _ B0 tag B0 tag Asym. =-xCPsin2bsinDmDt Fit to Dt Distributions B0 tag • resolution, wrong tags B0 tag The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  33. 2006: BaBar + Belle From Hazumi ICHEP 2006 The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  34. b (not sin2b) measurements Preliminary B0gD*+D*-Ks Time-dependent Dalitz analysis (T.Browder, A. Datta et al. 2000)  cos2b > 0 (94%CL, model-dependent) B0gDh0 (h0 = p0 etc.) Time-dependent Dalitz analysis  cos2b > 0 Belle: 98.3%CL (hep-ex/0605023, accepted by PRL) BaBar 87% CL (BABAR-CONF06/017) The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  35. CPV in Charmless B Decays • Can have both tree & loop diagrams in p+p- (or r+r-) • The weak phase in the tree graph is g. The weak phase in the Penguin is different. Therefore, the Penguin can (and does) mess up CP via mixing in p+p- • Penguin is unmasked by evidence of popo Penguin Tree The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  36. CPV in Br+r- • First done by BaBar confirmed by Belle • Not a CP eigenstate, but final state is almost fully longitudinally polarized • fL=0.978+0.024+0.015 (BaBar) • However, Penguin pollution revealed at 3s level (BaBar): • B(roro)=( 1.2±0.4±0.3)x10-6 • B(r+r-)=(23.5±2.2±4.1)x10-6 -0.013 The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  37. Add B→rp→p+p-po Dalitz plot analyses suggested by Snyder & Quinn CPV in Br+r- II • Constraints on a The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  38. Results on a The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  39. g: B±DoK± decays, Do Ksp+p- • Can have CPV in B decays Just need two interfering amplitudes • For the B- decay: A(B-DoK-)AB A(B-DoK-)ABrBei(dB-g) • Use modes where the Do is indistinguishable from the Do. Then use Daltiz plot analysis to find gsee A. Giri et al., [hep-ph/0303187] The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  40. BaBar g from BDoK-, Do Ksp+p- d2 ln L/d2 sensitivity • Belle first saw a • clear difference • Now data show a smaller effect The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  41. Poor Constraints on g See http://www.utfit.org/ The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  42. Putting It All Together: Status • Global fit using all available inputs • eK is from CP violation in Ko system The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  43. Reasons for Further B Physics Studies There is New Physics out there: Standard Model is violated by the Baryon Asymmetry of Universe & by Dark Matter I will show that B physics will be crucial towards interpreting New Physics found at the LHC

  44. The Enigma of Baryogenesis • When the Universe began, the Big Bang, there was an equal amount of matter & antimatter • Now we have most matter. How did it happen? • Sakharov criteria • Baryon (B) number violation • Departure from thermal equilibrium • C & CP violation The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  45. Sakharov Criteria All Satisfied • B is violated in Electroweak theory at high temperature, B-L is conserved (need quantum tunneling, powerfully suppressed at low T) • Non-thermal equilibrium is provided by electroweak phase transition • C & CP are violated by weak interactions.However the violation is too small! • nB-nB/ng = ~6x10-10, while SM can provide only ~10-20 • Therefore, there must be new physics The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  46. Dark Matter • Discovered by Zwicky in 1933 by measuring rotation curves of galaxies in the Coma cluster • Also gravitational lensing of galaxy clusters • Is dark matter composed of • Supersymmetric particles? The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  47. The Hierarchy Problem • Physics at the Planck scale ~1019 GeV is much larger than at the ~100-1000 TeV electroweak scale, requires delicate cancellations between fundamental quantities and quantum corrections. • New Physics is needed to solve this problem The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  48. Loop Diagrams - Penguins Effects of New Particles on B Decays These decays are suppressed, so New Particles can show enhanced effects

  49. BsJ/yh • Contributions to direct CP violating decay B-fK- vs B+fK+ Asym=(MW/msquark)2sin(fm), ~0 in SM MSSM Measurements, from Hinchcliff & Kersting (hep-ph/0003090) • Contributions to Bs mixing CP asymmetry  0.1sinfmcosfAsin(Dmst), ~10 x SM The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

  50. Supersymmetry • Supersymmetry contains squarks and sleptons. • Squark mass matrixes contain information on SUSY breaking mechanisms &/or GUT scale interactions. • Quark flavor changing neutral current processes, e.g. BS or D0 mixing, are sensitive to the off-diagonal elements of the squark mass matrix. The Hadron Collider Physics Summer Schools, Fermilab August 9-18, 2006

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