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

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

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)

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

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

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

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

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

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

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

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)

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

Niels Tuning (12) B A B AR CP violation in Decay? (also known as: “direct CPV”) HFAG: hep-ex/0407057 Phys.Rev.Lett.93:131801,2004 4.2  B A B AR First observation of Direct CPV in B decays (2004): A CP = -0.098 ± 0.012

Niels Tuning (13) LHCbLHCb CP violation in Decay? (also known as: “direct CPV”) LHCb-CONF-2011-011LHCbLHCb First observation of Direct CPV in B decays at LHC (2011):

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

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

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

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

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

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

CP violation in B s 0 Mixing?? Niels Tuning (20) D0 Coll., Phys.Rev.D82:032001, 2010. arXiv:1005.2757 b s s b “Box” diagram: ΔB=2 φ s SM ~ 0.004 φ s SM M ~ 0.04

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

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

More β… Niels Tuning (23)

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

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

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

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

Niels Tuning (28) Penguin diagrams Nucl. Phys. B131:285 1977

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

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

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

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

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 ±0.04 0.67 ±0.02

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 …

Niels Tuning (35) New physics??

Break Niels Tuning (36)

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)

Niels Tuning (38) New physics??

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 )

Present knowledge of unitarity triangle Niels Tuning (40)

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

Present knowledge of unitarity triangle

I) sin 2 β

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

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

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 | = 0.090 ± 0.025 –V ub is of order sin( c ) 3 [= 0.01]

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

Present knowledge of unitarity triangle Niels Tuning (48)

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 )

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

Niels Tuning (51) More hints for new physics? 6) V ub : 2.9 σ ?? BR(B + →τυ)=1.68 ± 0.31 10 -4 Predicted: 0.764± 0.087 10 -4 (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 ?

A.Buras, Beauty2011: Niels Tuning (52)

A.Buras, Beauty2011: Niels Tuning (53)

Standard Model: 25 free parameters Strong interaction:  s (m Z )  0.117 e   = 1 2 3 neutrino mixing (4) Electro-weak interaction:  e (0)  1/137.036 m W  80.42 GeV m Z  91.188 GeV m H >114.3 GeV Elementary particle masses (MeV): m e  0.51099890 m   105.658357 m   1777.0 m u  3 m c  1200 m t  174000 m d  7 m s  120 m b  4300 m < 0.000003 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)

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

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

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

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)

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)

Backup Niels Tuning (60)

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

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

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)

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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