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

Plan Mon 5 Feb: Anti-matter + SM Wed 7 Feb: CKM matrix + Unitarity Triangle Mon 26 Feb: Mixing + Master eqs. + B0J/ψKs Wed 28 Feb: CP violation in B(s) decays (I) Mon 12 Mar: CP violation in B(s) and K decays (II) Wed 14 Mar: Rare decays + Flavour Anomalies Wed 21 Mar: Exam Final Mark: 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 Niels Tuning (2)

Recap uI W dI u W d,s,b Diagonalize Yukawa matrix Yij Mass terms Quarks rotate Off diagonal terms in charged current couplings u d,s,b W Replace the derivative with the covariant derivative introducing the force carriers: gluons, weak vector bosons and photon. The constants g_s, g and g’ are the corresponding coupling constants of the gauge particles. Niels Tuning (4) 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 d,s,b W Niels Tuning (5)

This was theory, now comes experiment We already saw how the moduli |Vij| 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: Subsequent: decay P0 f Interference P0 f P0P0 f Interference (‘direct’) Decay

Classification of CP Violating effects CP violation in decay CP violation in mixing CP violation in interference Niels Tuning (8)

2 amplitudes 2 phases Remember! Necessary ingredients for CP violation: Two (interfering) amplitudes Phase difference between amplitudes one CP conserving phase (‘strong’ phase) one CP violating phase (‘weak’ phase) 2 amplitudes 2 phases Niels Tuning (9)

Remember! 2 amplitudes 2 phases 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 Af = Af CP violation in interference Niels Tuning (12)

Relax: B0J/ΨKs simplifies… ΔΓ=0 Niels Tuning (13)

βs: Bs0 ® J/yφ : Bs0 analogue of B0 ® J/yK0S Replace spectator quark d  s Niels Tuning (14)

βs: Bs0 ® J/yφ : Bs0 analogue of B0 ® J/yK0S Niels Tuning (15)

βs: Bs0 ® J/yφ : Bs0 analogue of B0 ® J/yK0S Differences: B0 B0s CKM Vtd Vts ΔΓ ~0 ~0.1 Final state (spin) K0 : s=0 φ: s=1 Final state (K) K0 mixing - Niels Tuning (16)

βs: Bs0 ® J/yφ A║ A┴ A0 B0 B0s CKM Vtd Vts ΔΓ ~0 ~0.1 Vts large, oscilations fast, need good vertex detector A║ A0 A┴ l=2 l=1 l=0 3 amplitudes B0 B0s CKM Vtd Vts ΔΓ ~0 ~0.1 Final state (spin) K0 : s=0 φ: s=1 Final state (K) K0 mixing - Niels Tuning (17)

Bs  J/ψФ : Bs equivalent of B J/ψKs ! The mixing phase (Vtd): φd=2β B0  f B0  B0  f Wolfenstein parametrization to O(λ5): Niels Tuning (18)

Bs  J/ψФ : Bs equivalent of B J/ψKs ! The mixing phase (Vts): φs=-2βs B0  f B0  B0  f Vts - s Ф Bs Bs Ф s s s Vts Wolfenstein parametrization to O(λ5): Niels Tuning (19)

Bs  J/ψФ : Bs equivalent of B J/ψKs ! The mixing phase (Vts): φs=-2βs B0  f B0  B0  f Vts - s Ф Bs Bs Ф s s s Vts Niels Tuning (20)

Other angles Niels Tuning (21)

Measure γ: B0s  DsK-/+ : both λf and λf 2 + Γ(Bf)= 2 + Γ(B f )= NB: In addition B s  DsK-/+ : both λ f and λf Niels Tuning (22)

Measure γ: Bs  DsK-/+ --- first one f: Ds+K- This time | Af||Af|, so |λ|1 ! In fact, not only magnitude, but also phase difference: Niels Tuning (23)

Measure γ: Bs  DsK-/+ B0s  Ds-K+ has phase difference ( - ): Need B0s  Ds+K- to disentangle  and : Niels Tuning (24)

Next CP violation in decay CP violation in mixing CP violation in interference

γ B - → D0 K- (Time integrated) Bs0 → DsK+- (Time dependent) ( ) B - → D0 K- (Time integrated) Bs0 → DsK+- (Time dependent) Necessary ingredients for CP violation: Two (interfering) amplitudes Phase difference between amplitudes one CP conserving phase (‘strong’ phase) one CP violating phase (‘weak’ phase)

γ (GLW) D0K+ fCPK+ B+ GLW: CP eigenstate: D0→ K+K-(ππ) bc favoured Vub* Vcb* ( ) B- →D0K- Relative phase: γ B+ D0K+ fCPK+ bc favoured bu suppressed GLW: CP eigenstate: D0→ K+K-(ππ)

γ (GLW) D0K+ fCPK+ B+ GLW: CP eigenstate: D0→ K+K-(ππ) bc favoured Vub* Vcb* ( ) B- →D0K- Relative phase: γ B+ D0K+ fCPK+ bc favoured bu suppressed GLW: CP eigenstate: D0→ K+K-(ππ)

γ (GLW) D0K+ fCPK+ B+ GLW: CP eigenstate: D0→ K+K-(ππ) bc favoured bu suppressed GLW: CP eigenstate: D0→ K+K-(ππ)

γ (ADS) D0K+ B+ ADS: K-π+K+ B or D Cabibbo favoured: D0→ K+π- Vub* Vcb* ( ) B- →D0K- Relative phase: γ B+ D0K+ bc favoured bu suppressed K-π+K+ Cabibbo supp. Cabibbo allowed. ADS: B or D Cabibbo favoured: D0→ K+π-

γ (ADS) D0K+ B+ ADS: K-π+K+ B or D Cabibbo favoured: D0→ K+π- Vub* Vcb* ( ) B- →D0K- Relative phase: γ B+ D0K+ bc favoured bu suppressed K-π+K+ Cabibbo supp. Cabibbo allowed. ADS: B or D Cabibbo favoured: D0→ K+π- “Difference in suppression” “Average suppression”

γ (ADS) D0K+ B+ ADS: K-π+K+ B or D Cabibbo favoured: D0→ K+π- Suppressed mode for the B- is relatively more suppressed than for the B+… B+ D0K+ bc favoured K-π+K+ Cabibbo supp. Cabibbo allowed. bu suppressed ADS: B or D Cabibbo favoured: D0→ K+π- BR~ 2 x 10-7

Another example of CP violation in decay CP violation in mixing CP violation in interference

CP violation in Decay? (also known as: “direct CPV”) First observation of Direct CPV in B decays (2004): BABAR hep-ex/0407057 Phys.Rev.Lett.93:131801,2004 4.2s BABAR HFAG: ACP = -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 LHCb-CONF-2011-011 LHCb Niels Tuning (35)

2 amplitudes 2 phases Remember! Necessary ingredients for CP violation: Two (interfering) amplitudes Phase difference between amplitudes one CP conserving phase (‘strong’ phase) one CP violating phase (‘weak’ phase) 2 amplitudes 2 phases Niels Tuning (36)

Direct CP violation: Γ( B0 f) ≠ Γ(B0f ) CP violation if Γ( B0 f) ≠ Γ(B0f ) But: need 2 amplitudes  interference Amplitude 1 Amplitude 2 + Only different if both δ and γ are ≠0 !  Γ( B0 f) ≠ Γ( B0f ) Niels Tuning (37)

Hint for new physics? B0Kπ and BKπ0 Redo the experiment with B instead of B0… d or u spectator quark: what’s the difference ?? B0Kπ Average 3.6s ? B+Kπ Average Niels Tuning (38)

Hint for new physics? B0Kπ and BKπ0 Niels Tuning (39)

Hint for new physics? B0Kπ and BKπ0 T (tree) C (color suppressed) P (penguin) B0→K+π- B+→K+π0 Niels Tuning (40)

Next CP violation in decay CP violation in mixing CP violation in interference

CP violation in Mixing? (also known as: “indirect CPV”: ε≠0 in K-system) Look for like-sign lepton pairs: t=0 t Decay gVcb* gVcb Niels Tuning (42)

(limit on) CP violation in B0 mixing Look for a like-sign asymmetry: As expected, no asymmetry is observed… Niels Tuning (43)

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

CP violation in Bs0 Mixing?? D0 Coll., Phys.Rev.D82:032001,2010. arXiv:1005.2757 CP violation in Bs0 Mixing?? b s “Box” diagram: ΔB=2 φsSM ~ 0.004 φsSMM ~ 0.04 Niels Tuning (45)

CP violation from Semi-leptonic decays SM: P(B0s→B0s) = P(B0s←B0s) DØ: P(B0s→B0s) ≠ P(B0s←B0s) ? 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(B0s→B0s) = P(B0s←B0s) DØ: P(B0s→B0s) ≠ P(B0s←B0s) ? B0s→Ds±X0μν

More β… Niels Tuning (48)

Other ways of measuring sin2β Need interference of bc transition and B0 –B0 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 Niels Tuning (49)

CP in interference with BφKs Same as B0J/ψKs : Interference between B0→fCP and B0→B0→fCP For example: B0→J/ΨKs and B0→B0→ J/ΨKs For example: B0→φKs and B0→B0→ φKs Amplitude 1 Amplitude 2 + e-iφ Niels Tuning (50)

CP in interference with BφKs: what is different?? Same as B0J/ψKs : Interference between B0→fCP and B0→B0→fCP For example: B0→J/ΨKs and B0→B0→ J/ΨKs For example: B0→φKs and B0→B0→ φKs Amplitude 1 Amplitude 2 + e-iφ Niels Tuning (51)

Penguin diagrams Nucl. Phys. B131:285 1977 Niels Tuning (52)

Penguins?? The original penguin: A real penguin: Our penguin: Niels Tuning (53)

Funny Flying Penguin Dead Penguin Penguin T-shirt: Super Penguin: Niels Tuning (54)

 The “b-s penguin” Asymmetry in SM B0J/ψKS B0φKS b s μ “Penguin” diagram: ΔB=1 … 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 Niels Tuning (55)

? Hint for new physics?? B J/ψ Ks φ Ks B sin2β sin2βpeng g,b,…? ~~ d c s φ Ks B s b d t ? g,b,…? ~~ sin2βbccs = 0.68 ± 0.03 sin2βpeng = 0.52 ± 0.05 sin2β sin2βpeng Niels Tuning (56) S.T’Jampens, CKM fitter, Beauty2006

Kaons… K1, K2, KL, KS, K+, K-, K0 Different notation: confusing! Smaller CP violating effects But historically important! Concepts same as in B-system, so you have a chance to understand… Niels Tuning (58)