Particle Physics II CP violation (also known as Physics of - PowerPoint PPT Presentation

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

Plan 1) Wed 12 Feb: Anti-matter + SM 2) Mon 17 Feb: CKM matrix + Unitarity Triangle 3) Wed 19 Feb: Mixing + Master eqs. + B 0 → J/ ψ K s 4) Mon 9 Mar: CP violation in B (s) decays (I) 5) Wed 11 Mar: CP violation in B (s) and K decays (II) 6) Mon 16 Mar: Rare decays + Flavour Anomalies 7) Wed 18 Mar: Exam Final Mark: Ø if (mark > 5.5) mark = max(exam, 0.85*exam + 0.15*homework) § else mark = exam § In parallel: Lectures on Flavour Physics by prof.dr. R. Fleischer Ø Niels Tuning (2)

Recap L L L L = + + SM Kinetic Higgs Yukawa + u I ⎛ ⎞ ϕ d I I I L Y ( u , d ) d ... − = + W ⎜ ⎟ i Yuk i j L L Rj ⎜ ⎟ 0 ϕ ⎝ ⎠ g g d I I I I I L u W d d W u ... µ − µ + = γ + γ + Kinetic Li Li Li L i µ µ 2 2 Diagonalize Yukawa matrix Y ij I d d ⎛ ⎞ ⎛ ⎞ – Mass terms ⎜ ⎟ ⎜ ⎟ I s V s → ⎜ ⎟ CKM ⎜ ⎟ – Quarks rotate ⎜ ⎟ ⎜ I ⎟ b b – Off diagonal terms in charged current couplings ⎝ ⎠ ⎝ ⎠ m d m u ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ ⎛ ⎞ d u L ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ( ) ( ) g g g g d s b , , m s u c t , , m c ... − = + + u Mass ⎜ s ⎟ ⎜ ⎟ ⎜ c ⎟ ⎜ ⎟ L L ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ ⎜ ⎟ m b m t W ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ ⎝ ⎠ b t R R g g ( ) ( ) L 5 * 5 u W V 1 d d W V 1 u ... µ − µ + = γ − γ + γ − γ + CKM i ij j j i j i µ µ 2 2 d,s,b L L L L = + + SM CKM Higgs Mass Niels Tuning (4)

CKM-matrix: where are the phases? • Possibility 1: simply 3 ‘ rotations ’ , and put phase on smallest: • Possibility 2: parameterize according to magnitude, in O( λ ): u W d,s,b Niels Tuning (5)

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 (6)

Meson Decays • Formalism of meson oscillations : 0 ( ) P t • Subsequent: decay P 0 à f P 0 à P 0 à f Interference ( ‘ direct ’ ) Decay Interference

Classification of CP Violating effects 1. CP violation in decay 2. CP violation in mixing 3. CP violation in interference Niels Tuning (8)

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 (9)

Remember! Niels Tuning (10)

CP violation: type 3 Niels Tuning (11)

Classification of CP Violating effects - Nr. 3: Consider f=f : If one amplitude dominates the decay, then A f = A f 3. CP violation in interference Niels Tuning (12)

Relax: B 0 � J/ Ψ K s simplifies… | λ f |=1 ΔΓ =0 Niels Tuning (13)

β s : B s 0 → J/ ψ φ : B s 0 analogue of B 0 → J/ ψ K 0 S • Replace spectator quark d à s Niels Tuning (14)

β s : B s 0 → J/ ψ φ : B s 0 analogue of B 0 → J/ ψ K 0 S Niels Tuning (15)

β s : B s 0 → J/ ψ φ : B s 0 analogue of B 0 → J/ ψ K 0 S Differences: B 0 B 0 s CKM V td V ts ΔΓ ~0 ~0.1 Final state (spin) K 0 : s=0 φ : s=1 Final state (K) K 0 mixing - Niels Tuning (16)

β s : B s 0 → J/ ψ φ V ts large, oscilations fast, need good vertex detector 3 amplitudes A ║ B 0 B 0 l=2 s CKM V td V ts A ┴ l=1 ΔΓ ~0 ~0.1 A 0 l=0 Final state (spin) K 0 : s=0 φ : s=1 Final state (K) K 0 mixing - Niels Tuning (17)

B s à J/ ψФ : B s equivalent of B à J/ ψ K s ! • The mixing phase (V td ): φ d =2 β B 0 à f B 0 à B 0 à f Wolfenstein parametrization to O ( λ 5 ): Niels Tuning (18)

B s à J/ ψФ : B s equivalent of B à J/ ψ K s ! • The mixing phase (V ts ): φ s =-2 β s B 0 à f B 0 à B 0 à f V ts - s Ф B s B s Ф s s s V ts Wolfenstein parametrization to O ( λ 5 ): Niels Tuning (19)

B s à J/ ψФ : B s equivalent of B à J/ ψ K s ! • The mixing phase (V ts ): φ s =-2 β s B 0 à f B 0 à B 0 à f V ts - s Ф B s B s Ф s s s V ts Niels Tuning (20)

Other angles Niels Tuning (21)

Measure γ : B 0 s à D s ± K -/+ : both λ f and λ f 2 + Γ ( B � f)= 2 + Γ ( B � f )= NB: In addition B s à D s ± K -/+ : both λ f and λ f Niels Tuning (22)

Measure γ : B s à D s ± K -/+ --- first one f : D s + K - V * V s cs us s s s s s * * 3 4 i i V V V V e γ e γ * * 3 2 V V V V ∝ ∝ λ λ ∝ ∝ λ λ ub ub cs cd cb cb ud us • This time | A f | ≠ |A f | , so | λ | ≠ 1 ! • In fact, not only magnitude, but also phase difference: Niels Tuning (23)

Measure γ : B s à D s ± K -/+ • B 0 s à D s - K + has phase difference ( δ - γ ): • Need B 0 s à D s + K - to disentangle δ and γ : Niels Tuning (24)

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

γ ( ) 1) B - → D 0 K - (Time integrated) 2) B s ± K +- (Time dependent) 0 → D s 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)

γ (GLW) A 1 A 2 V cb * V ub * ( ) B - → D 0 K - Relative phase: γ § D 0 K + GLW: f CP K + B + i ( ) δ − γ r e CP eigenstate: D 0 → K + K - ( ππ ) B B D 0 K +

γ (GLW) A 1 A 2 V cb * V ub * ( ) B - → D 0 K - Relative phase: γ § D 0 K + GLW: f CP K + B + i ( ) δ − γ r e CP eigenstate: D 0 → K + K - ( ππ ) B B D 0 K +

γ (GLW) D 0 K + GLW: f CP K + B + i ( ) δ − γ r e CP eigenstate: D 0 → K + K - ( ππ ) B B D 0 K +

γ (ADS) A 1 A 2 V cb * V ub * ( ) B - → D 0 K - Relative phase: γ § D 0 K + ADS: i r e δ D D B + K - π + K + i ( ) δ − γ r e B or D Cabibbo favoured: D 0 → K + π - B B D 0 K + Cabibbo allowed.

γ (ADS) A 1 A 2 V cb * V ub * ( ) B - → D 0 K - Relative phase: γ § D 0 K + ADS: i r e δ D D B + K - π + K + i ( ) δ − γ r e B or D Cabibbo favoured: D 0 → K + π - B B D 0 K + Cabibbo allowed. “Difference in suppression” “Average suppression”

γ (ADS) Suppressed mode for the B - is relatively more suppressed than for the B + … D 0 K + ADS: i r e δ D D B + K - π + K + i ( ) δ − γ r e B or D Cabibbo favoured: D 0 → K + π - B B D 0 K + BR~ 2 x 10 -7 Cabibbo allowed.

Another example of CP violation in decay 1. CP violation in decay 2. CP violation in mixing 3. CP violation in interference

CP violation in Decay? (also known as: “ direct CPV ” ) First observation of Direct CPV in B decays (2004): B A B AR B 0 K + − → π Γ −Γ B f B K B f 0 → → A − + → π = Γ CP + Γ B f B f → → hep-ex/0407057 B A B AR Phys.Rev.Lett.93:131801,2004 A 0.133 0.030 0.009 = − ± ± CP 4.2 σ HFAG: A CP = -0.098 ± 0.012 Niels Tuning (34)

CP violation in Decay? (also known as: “ direct CPV ” ) First observation of Direct CPV in B decays at LHC (2011): LHCb Γ −Γ B f B f → → A = Γ CP + Γ B f B f → → LHCb-CONF-2011-011 LHCb Niels Tuning (35)

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 (36)

Direct CP violation: Γ ( B 0 à f) ≠ Γ (B 0 à f ) CP violation if Γ ( B 0 à f) ≠ Γ (B 0 à f ) But: need 2 amplitudes à interference Amplitude 1 Amplitude 2 + 2 2 * i 4 i i 0 * i * 4 i i 2 V V e e ( B K + − ) V V e δ V V e + γ + δ δ + γ + δ Γ → π ∝ + ≈ λ + λ ≈ λ ub us tb ts ub us 2 2 0 * i * 4 i i 2 ( B K ) V V e V V e + − δ + γ + δ Γ → π ∝ + ≈ λ + λ ub us tb ts 2 2 0 * i * 4 i i 2 ( B K ) V V e V V e − + δ − γ + δ Γ → π ∝ + ≈ λ + λ ub us tb ts Only different if both δ and γ are ≠ 0 ! è Γ ( B 0 � f) ≠ Γ ( B 0 � f ) Niels Tuning (37)

Hint for new physics? B 0 à K π and B ± à K ± π 0 Redo the experiment with B ± instead of B 0 … d or u spectator quark: what ’ s the difference ?? B 0 � K π B K 0 + − → π A 0.114 0.020 Average = − ± CP 3.6 σ ? ? B + � K π B K 0 + + → π A 0.049 0.040 Average = + ± CP Niels Tuning (38)

Hint for new physics? B 0 à K π and B ± à K ± π 0 Niels Tuning (39)

Hint for new physics? B 0 à K π and B ± à K ± π 0 T (tree) C (color suppressed) P (penguin) B 0 → K + π - B + → K + π 0 Niels Tuning (40)

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