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Niels Tuning (1) Lectures on B-physics 19-20 April 2011 Vrije Universiteit Brussel N. Tuning.

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Presentation on theme: "Niels Tuning (1) Lectures on B-physics 19-20 April 2011 Vrije Universiteit Brussel N. Tuning."— Presentation transcript:

1 Niels Tuning (1) Lectures on B-physics April 2011 Vrije Universiteit Brussel N. Tuning

2 Menu TimeTopic Lecture 114:00-15:00C, P, CP and the Standard Model 15:30-16:30CKM matrix Lecture 210:00-10:45Flavour mixing in B-decays 11:00-11:45CP Violation in B-decays 12:00 -12:45CP Violation in B/K-decays Lecture 314:00-14:45New Physics? 15:00-15:45Unitarity Triangle Niels Tuning (2)

3 Some algebra for the decay P 0  f Interference P0 fP0 fP 0  P 0  f

4 Meson Decays Formalism of meson oscillations: Subsequent: decay Interference(‘direct’) Decay Recap osc + decays

5 Classification of CP Violating effects 1.CP violation in decay 2.CP violation in mixing 3.CP violation in interference Recap CP violation

6 Im( λ f ) 1.CP violation in decay 2.CP violation in mixing 3.CP violation in interference We will investigate λ f for various final states f Recap CP violation

7 λ f contains information on final state f Niels Tuning (7) Recap CP in B Investigated three final states f B 0  J/ψK s B 0 s  J/ψφ B 0 s  D s K 3.CP violation in interference

8 λ f contains information on final state f Niels Tuning (8) B 0 s  J/ψφ 3.CP violation in interference Recap CP in B

9 β s : B s 0 J/φ : B s 0 analogue of B 0 J/K 0 S Niels Tuning (9) Recap CP in B

10 Last hour or so: The basics you know now! 1.CP violation from complex phase in CKM matrix 2.Need 2 interfering amplitudes (B-oscillations come in handy!) 3.Higher order diagrams sensitive to New Physics Next: (Direct) CP violation in decay CP violation in mixing (we already saw this with the kaons: ε≠0, or |q/p|≠1 ) Penguins The unitarity triangle Niels Tuning (10)

11 Next 1.CP violation in decay 2.CP violation in mixing 3.CP violation in interference

12 Niels Tuning (12) B A B AR CP violation in Decay? (also known as: “direct CPV”) HFAG: hep-ex/ Phys.Rev.Lett.93:131801,  B A B AR First observation of Direct CPV in B decays (2004): A CP = ± 0.012

13 Niels Tuning (13) LHCbLHCb CP violation in Decay? (also known as: “direct CPV”) LHCb-CONF LHCbLHCb First observation of Direct CPV in B decays at LHC (2011):

14 Niels Tuning (14) Direct CP violation: Γ( B 0  f) ≠ Γ(B 0  f ) Only different if both δ and γ are ≠0 !  Γ( B 0  f) ≠ Γ(B 0  f ) CP violation if Γ( B 0  f) ≠ Γ(B 0  f ) But: need 2 amplitudes  interference Amplitude 1 + Amplitude 2

15 Niels Tuning (15) Hint for new physics? B 0  Kπ and B   K  π 0 Average 3.6  Average Redo the experiment with B  instead of B 0 … d or u spectator quark: what’s the difference ?? B0KπB0Kπ B+KπB+Kπ

16 Hint for new physics? B 0  Kπ and B   K  π 0 Niels Tuning (16)

17 Next 1.CP violation in decay 2.CP violation in mixing 3.CP violation in interference

18 Niels Tuning (18) CP violation in Mixing? (also known as: “indirect CPV”: ε≠0 in K-system) gV cb * gV cb t=0 t ? Look for like-sign lepton pairs: Decay

19 Niels Tuning (19) (limit on) CP violation in B 0 mixing Look for a like-sign asymmetry: As expected, no asymmetry is observed…

20 CP violation in B s 0 Mixing?? Niels Tuning (20) D0 Coll., Phys.Rev.D82:032001, arXiv: b s s b “Box” diagram: ΔB=2 φ s SM ~ φ s SM M ~ 0.04

21 CP violation from Semi-leptonic decays SM: P(B 0 s →  B 0 s ) = P(B 0 s ←  B 0 s ) DØ: P(B 0 s →  B 0 s ) ≠ P(B 0 s ←  B 0 s ) b → Xμ - ν, b → Xμ + ν b → b → Xμ + ν, b → b → Xμ - ν  Compare events with like-sign μμ  Two methods:  Measure asymmetry of events with 1 muon  Measure asymmetry of events with 2 muons ? Switching magnet polarity helps in reducing systematics But…:  Decays in flight, e.g. K→μ  K + /K - asymmetry

22 CP violation from Semi-leptonic decays SM: P(B 0 s →  B 0 s ) = P(B 0 s ←  B 0 s ) DØ: P(B 0 s →  B 0 s ) ≠ P(B 0 s ←  B 0 s ) ? B 0 s → D s ± X 0 μν

23 More β… Niels Tuning (23)

24 Next 1.CP violation in decay 2.CP violation in mixing 3.CP violation in interference

25 Niels Tuning (25) Other ways of measuring sin2β Need interference of b  c transition and B 0 –B 0 mixing Let’s look at other b  c decays to CP eigenstates: All these decay amplitudes have the same phase (in the Wolfenstein parameterization) so they (should) measure the same CP violation

26 CP in interference with B  φK s Same as B 0  J/ψK s : Interference between B 0 → f CP and B 0 → B 0 → f CP –For example: B 0 → J/ΨK s and B 0 → B 0 → J/ΨK s –For example: B 0 → φ K s and B 0 → B 0 → φ K s Niels Tuning (26) + e -iφ Amplitude 2 Amplitude 1

27 CP in interference with B  φK s : what is different?? Same as B 0  J/ψK s : Interference between B 0 → f CP and B 0 → B 0 → f CP –For example: B 0 → J/ΨK s and B 0 → B 0 → J/ΨK s –For example: B 0 → φ K s and B 0 → B 0 → φ K s Niels Tuning (27) + e -iφ Amplitude 2 Amplitude 1

28 Niels Tuning (28) Penguin diagrams Nucl. Phys. B131:

29 Penguins?? Niels Tuning (29) The original penguin:A real penguin:Our penguin:

30 Funny Niels Tuning (30) Super Penguin: Penguin T-shirt: Flying Penguin Dead Penguin

31 Niels Tuning (31) The “b-s penguin” B 0  J/ψK S B0φKSB0φKS  … unless there is new physics! New particles (also heavy) can show up in loops: –Can affect the branching ratio –And can introduce additional phase and affect the asymmetry Asymmetry in SM b s μ μ “Penguin” diagram: ΔB=1

32 Niels Tuning (32) Hint for new physics?? sin2β sin2 β b  ccs = 0.68 ± 0.03 sin2β peng B J/ψ KsKs b d c c s d φ KsKs B s b d d s t s ? sin2 β peng = 0.52 ± 0.05 g,b,…? ~~ S.T’Jampens, CKM fitter, Beauty2006

33 Niels Tuning (33) Smaller than b  ccs in most penguin modes Smaller than b  ccs in most penguin modes deviation between b  sqq and b  ccs disappeared over time… deviation between b  sqq and b  ccs disappeared over time… Hint for new physics? β with b  s Penguins 0.64 ± ±0.02

34 Niels Tuning (34) Why bother with all this? CKM matrix has origin in L Yukawa  Intricately related to quark massed… Both quark masses and CKM elements show intriguing hierarchy There is a whole industry of theorist trying to postdict the CKM matrix based on arguments on the mass matrix in L Yukawa …

35 Niels Tuning (35) New physics??

36 Break Niels Tuning (36)

37 Menu TimeTopic Lecture 114:00-15:00C, P, CP and the Standard Model 15:30-16:30CKM matrix Lecture 210:00-10:45Flavour mixing in B-decays 11:00-11:45CP Violation in B-decays 12:00 -12:45CP Violation in B/K-decays Lecture 314:00-14:45Unitarity Triangle 15:00-15:45New Physics? Niels Tuning (37)

38 Niels Tuning (38) New physics??

39 Niels Tuning (39) Hints for new physics? φ KsKs B s b d d s t s g,b,…? ~~ 1) sin2β≠sin2β ? 4 th generation, t’ ? 3) β s ≠0.04 ? 2) A CP (B 0  K + π - )≠A CP (B +  K + π 0 ) ? 4) P(B 0 s →  B 0 s ) ≠ P(B 0 s ←  B 0 s )

40 Present knowledge of unitarity triangle Niels Tuning (40)

41 “The” Unitarity triangle We can visualize the CKM-constraints in () plane

42 Present knowledge of unitarity triangle

43 I) sin 2 β

44 II) ε and the unitarity triangle: box diagram Im(z 2 )=Im( (Rez+iImz) 2 )=2RezImz

45 II) ε and the unitarity triangle ρ Niels Tuning (45)

46 III.) |V ub | / |V cb | Measurement of V ub –Compare decay rates of B 0  D *- l + and B 0   - l + –Ratio proportional to (V ub /V cb) 2 –|V ub /V cb | = ± –V ub is of order sin( c ) 3 [= 0.01]

47 IV.) Δm d and Δm s Δm depends on V td V ts constraints hadronic uncertainties

48 Present knowledge of unitarity triangle Niels Tuning (48)

49 Niels Tuning (49) Hints for new physics? φ KsKs B s b d d s t s g,b,…? ~~ 1) sin2β≠sin2β ? 4 th generation, t’ ? 3) β s ≠0.04 ? 2) A CP (B 0  K + π - )≠A CP (B +  K + π 0 ) ? 4) P(B 0 s →  B 0 s ) ≠ P(B 0 s ←  B 0 s )

50 Niels Tuning (50) More hints for new physics? 5) ε K ?  Treatment of errors…  Input from Lattice QCD B K  Strong dependence on V cb

51 Niels Tuning (51) More hints for new physics? 6) V ub : 2.9 σ ?? BR(B + →τυ)=1.68 ± Predicted: 0.764± (If f Bd off, then B Bd needs to be off too, to make Δm d agree) | V ub | from B→τν From: H.Lacker, and A.Buras, Beauty2011, Amsterdam | V ub | from fit |V ub | avg from semi-lep ?

52 A.Buras, Beauty2011: Niels Tuning (52)

53 A.Buras, Beauty2011: Niels Tuning (53)

54 Standard Model: 25 free parameters Strong interaction:  s (m Z )  e   = neutrino mixing (4) Electro-weak interaction:  e (0)  1/ m W  GeV m Z  GeV m H >114.3 GeV Elementary particle masses (MeV): m e  m   m   m u  3 m c  1200 m t  m d  7 m s  120 m b  4300 m < m < 0.19 m < 18.2 ee u’ d’ s’ = udsuds quark mixing (4) V ij q V ij l m H >114.3 GeV CMS LHCb Niels Tuning (54)

55 The CKM matrix Couplings of the charged current: Wolfenstein parametrization: Magnitude:Complex phases: b WW u gV ub Niels Tuning (55)

56 The CKM matrix Couplings of the charged current: Wolfenstein parametrization Magnitude:Complex phases: 1) 2) 3) Niels Tuning (56)

57 Complex phases: The CKM matrix Couplings of the charged current: Wolfenstein parametrization: Magnitude:

58 Remember the following: CP violation is discovered in the K-system CP violation is naturally included if there are 3 generations or more –3x3 unitary matrix has 1 free complex parameter CP violation manifests itself as a complex phase in the CKM matrix The CKM matrix gives the strengths and phases of the weak couplings CP violation is apparent in experiments/processes with 2 interfering amplitudes with different strong and weak phase –Often using “mixing” to get the 2 nd decay process Flavour physics is powerful for finding new physics in loops! –Complementary to Atlas/CMS Niels Tuning (58)

59 Remember the following: CP violation is discovered in the K-system CP violation is naturally included if there are 3 generations or more –3x3 unitary matrix has 1 free complex parameter CP violation manifests itself as a complex phase in the CKM matrix The CKM matrix gives the strengths and phases of the weak couplings CP violation is apparent in experiments/processes with 2 interfering amplitudes with different strong and weak phase –Often using “mixing” to get the 2 nd decay process Flavour physics is powerful for finding new physics in loops! –Complementary to Atlas/CMS Niels Tuning (59)

60 Backup Niels Tuning (60)

61 SLAC: LINAC + PEPII PEP-II accelerator schematic and tunnel view LER HER Linac

62 Coherent Time Evolution at the  S  B-Flavor Tagging Exclusive B Meson Reconstruction PEP-2 (SLAC) Vertexing & Time Difference Determination Niels Tuning (62)

63 LHCb: the Detector p T of B-hadron η of B-hadron High cross section LHC energy B s produced in large quantities Large acceptance b’s produced forward Small multiple scattering Large boost of b’s Trigger ↓ Low p T Leptons + hadrons (MUON, CALO) Particle identification (RICH)

64 The well known triangle: γ α β γβ q W q’V q’q CP phases: Measure the CKM triangle to unprecedented precision Measure very small Branching Ratios Measuring the Quark Couplings Niels Tuning (64)


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