Niels Tuning (1) Particle Physics II – CP violation (also known as “Physics of Anti-matter”) Lecture 5 N. Tuning

Plan 1)Mon 2 Feb: Anti-matter + SM 2)Wed 4 Feb: CKM matrix + Unitarity Triangle 3)Mon 9 Feb: Mixing + Master eqs. + B 0  J/ψK s 4)Wed 11 Feb:CP violation in B (s) decays (I) 5)Mon 16 Feb:CP violation in B (s) decays (II) 6)Wed 18 Feb:CP violation in K decays + Overview 7)Mon 23 Feb:Exam on part 1 (CP violation) Niels Tuning (2)  Final Mark:  if (mark > 5.5) mark = max(exam, 0.8*exam + 0.2*homework)  else mark = exam  In parallel: Lectures on Flavour Physics by prof.dr. R. Fleischer  Tuesday + Thrusday

Plan 2 x 45 min 1)Keep track of room! 1)Monday + Wednesday:  Start:9:00  9:15  End: 11:00  Werkcollege: 11:00 - ? Niels Tuning (3)

Diagonalize Yukawa matrix Y ij –Mass terms –Quarks rotate –Off diagonal terms in charged current couplings Niels Tuning (5) Recap uIuI dIdI W u d,s,b W

Niels Tuning (6) CKM-matrix: where are the phases? u d,s,b W Possibility 1: simply 3 ‘rotations’, and put phase on smallest: Possibility 2: parameterize according to magnitude, in O( λ):

This was theory, now comes experiment We already saw how the moduli |V ij | are determined Now we will work towards the measurement of the imaginary part –Parameter: η –Equivalent: angles α, β, γ. To measure this, we need the formalism of neutral meson oscillations… Niels Tuning (7)

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

CP violation: type 3 Niels Tuning (12)

λ f contains information on final state f Niels Tuning (13) Investigate 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

Niels Tuning (14) Final state f : 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 –Lets ’ s simplify … 1)For B 0 we have: 2)Since f CP = f CP we have: 3)The amplitudes | A( B 0 →J/ψK s ) | and | A(B 0 →J/ψK s ) | are equal: B0B0 B0B0 d |λ f |=1

Relax: B 0  J/ΨK s simplifies… Niels Tuning (15) |λ f |=1 ΔΓ=0

Niels Tuning (16) b d d b s d d s c J/  K0K0K0K0 B0B0B0B0 b c s d d K0K0K0K0 B0B0B0B0 c d s c b d λ f for B 0 J/K 0 S

Niels Tuning (17) λ f for B 0 J/K 0 S Theoretically clean way to measure  Clean experimental signature Branching fraction: O(10 -4 ) “Large” compared to other CP modes! Time-dependent CP asymmetry

Remember! Necessary ingredients for CP violation: 1)Two (interfering) amplitudes 2)Phase difference between amplitudes –one CP conserving phase (‘strong’ phase) –one CP violating phase (‘weak’ phase) Niels Tuning (18)

λ f contains information on final state f Niels Tuning (19) Investigate 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

β s : B s 0 J/φ : B s 0 analogue of B 0 J/K 0 S Niels Tuning (20) Replace spectator quark d  s

β s : B s 0 J/φ : B s 0 analogue of B 0 J/K 0 S Niels Tuning (21)

Remember: The “B s -triangle”: β s Niels Tuning (22) Replace d by s:

β s : B s 0 J/φ : B s 0 analogue of B 0 J/K 0 S Niels Tuning (23) Differences: B0B0 B0sB0s CKMV td V ts ΔΓ ~0~0.1 Final state (spin)K 0 : s=0 φ : s=1 Final state (K)K 0 mixing-

β s : B s 0 J/φ Niels Tuning (24) B0B0 B0sB0s CKMV td V ts ΔΓ ~0~0.1 Final state (spin)K 0 : s=0 φ : s=1 Final state (K)K 0 mixing- A║A║ A0A0 A┴A┴ l=2 l=1 l=0 3 amplitudes V ts large, oscilations fast, need good vertex detector

“Recent” excitement (5 March 2008) Niels Tuning (25)

B s  J/ψФ : B s equivalent of B  J/ψK s ! The mixing phase (V td ): φ d =2β B 0  f B 0  B 0  f Wolfenstein parametrization to O (λ 5 ): Niels Tuning (26)

B s  J/ψФ : B s equivalent of B  J/ψK s ! The mixing phase (V ts ): φ s =-2β s B 0  f B 0  B 0  f Wolfenstein parametrization to O (λ 5 ): BsBs BsBs s s s s - Ф Ф V ts Niels Tuning (27)

B s  J/ψФ : B s equivalent of B  J/ψK s ! The mixing phase (V ts ): φ s =-2β s B 0  f B 0  B 0  f BsBs BsBs s s s s - Ф Ф V ts Niels Tuning (28)

Next: γ Niels Tuning (29)

Niels Tuning (30) CKM Angle measurements from B d,u decays Sources of phases in B d,u amplitudes* The standard techniques for the angles: *In Wolfenstein phase convention. AmplitudeRel. MagnitudeWeak phase bcbcDominant0 bubuSuppressed γ t  d ( x2, mixing)Time dependent 2β2β B 0 mixing + single b  c decay B 0 mixing + single b  u decay Interfere b  c and b  u in B ± decay. bubu tdtd

Niels Tuning (31) Determining the angle  From unitarity we have: Must interfere b  u ( c d) and b  c( u d) Expect b  u ( c s) and b  c( u s) to have the same phase, with more interference (but less events)   

Measure γ : B 0 s  D s  K -/+ : both λ f and λ  f Niels Tuning (32) NB: In addition  B s  D s  K -/+ : both  λ f and  λ  f + Γ( B  f)= + Γ( B  f )= 2 2

Break Niels Tuning (33)

Niels Tuning (34) Measure γ : B s  D s  K -/+ first one f : D s + K - This time | A f ||A f |, so | λ|  1 ! In fact, not only magnitude, but also phase difference:

Measure γ : B s  D s  K -/+ Niels Tuning (35) Need B 0 s  D s + K - to disentangle  and : B 0 s  D s - K + has phase difference ( - ):

Measure γ : B s  D s  K -/+ : in practice! 1) Signal & Backgrounds 2) Acceptance 3) Decay time resolution Time fit 4) Flavour Tagging ~ 28 0 o Expect  with ~ 28 0 precision o Improve with 2012 data o LHCb average now: 67 0  12 0  m  t  Δt Δt

Measure γ 1) Backgrounds (from mass fit) 2) Acceptance vs decay time 3) Decay time resolution Time fit 4) Flavour Tagging Zoom

Measure γ 2) Acceptance vs decay time Time fit S D C γ Im Re

Basics 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 (39)

Niels Tuning (40) Next

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

Niels Tuning (42) 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

Niels Tuning (43) LHCbLHCb CP violation in Decay? (also known as: “direct CPV”) LHCb-CONF LHCbLHCb First observation of Direct CPV in B decays at LHC (2011):

Remember! Necessary ingredients for CP violation: 1)Two (interfering) amplitudes 2)Phase difference between amplitudes –one CP conserving phase (‘strong’ phase) –one CP violating phase (‘weak’ phase) Niels Tuning (44)

Niels Tuning (45) 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 (46) 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 (47)

Hint for new physics? B 0  Kπ and B   K  π 0 Niels Tuning (48) T (tree) C (color suppressed) P (penguin) B 0 →K + π - B + →K + π 0

B s 0 → K + π − First CP violation in B s 0 system B s 0 → K + π − Historical? History: 1964: Discovery of CPV with K 0 (Prize 1980) 2001: Discovery of CPV with B 0 (Prize 2008) 2013: Discovery of CPV with B 0 s Bs0→K+π−Bs0→K+π−Bs0→K+π−Bs0→K+π− Bs0→K−π+Bs0→K−π+Bs0→K−π+Bs0→K−π+

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

Niels Tuning (51) 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 (52) (limit on) CP violation in B 0 mixing Look for a like-sign asymmetry: As expected, no asymmetry is observed…

Remember! Necessary ingredients for CP violation: 1)Two (interfering) amplitudes 2)Phase difference between amplitudes –one CP conserving phase (‘strong’ phase) –one CP violating phase (‘weak’ phase) Niels Tuning (53)

CP violation in B s 0 Mixing?? Niels Tuning (54) D0 Coll., Phys.Rev.D82:032001, arXiv: b s s b “Box” diagram: ΔB=2 φ s SM ~ 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 (57)

Niels Tuning (58) 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 (59) + 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 (60) + e -iφ Amplitude 2 Amplitude 1

Niels Tuning (61) Penguin diagrams Nucl. Phys. B131:

Penguins?? Niels Tuning (62) The original penguin:A real penguin:Our penguin:

Funny Niels Tuning (63) Super Penguin: Penguin T-shirt: Flying Penguin Dead Penguin

Niels Tuning (64) 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 (65) 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