Physics of Anti-matter Lecture 5 N. Tuning Niels Tuning (1)

Plan Mon 3 Feb: Anti-matter + SM Wed 5 Feb: CKM matrix + Unitarity Triangle Mon 10 Feb: Mixing + Master eqs. + B0J/ψKs Wed 12 Feb: CP violation in B(s) decays (I) Mon 17 Feb: CP violation in B(s) decays (II) Wed 19 Feb: CP violation in K decays + Overview Mon 24 Feb: Mini-project (MSc. V. Syropoulos) Wed 26 Feb: Exam Final Mark: 2/3*Exam + 1/6*Homework + 1/6*Mini project In March: 7 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)

Some algebra for the decay P0  f Interference P0 f P0P0 f

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

Classification of CP Violating effects Recap CP violation Classification of CP Violating effects CP violation in decay CP violation in mixing CP violation in interference

Im( λf) CP violation in decay CP violation in mixing Recap CP violation Im( λf) CP violation in decay CP violation in mixing CP violation in interference We will investigate λf for various final states f

CP violation: type 3 Niels Tuning (11)

λf contains information on final state f Investigate three final states f: B0J/ψKs B0sJ/ψφ B0sDsK CP violation in interference Niels Tuning (12)

|λf|=1 Final state f : J/ΨKs Interference between B0→fCP and B0→B0→fCP For example: B0→J/ΨKs and B0→B0→ J/ΨKs Lets’ s simplify … For B0 we have: Since fCP =fCP we have: The amplitudes |A( B0→J/ψKs)| and |A(B0→J/ψKs)| are equal: |λf|=1 B0 d B0 Niels Tuning (13)

Relax: B0J/ΨKs simplifies… ΔΓ=0 Niels Tuning (14)

λf for B0 ® J/yK0S c J/y K0 B0 b s d b d s d |Vcs Vcd|^2 mc^2 = (1*lambda)^2 mc^2 vs. |Vts Vtd|^2 mt^2 = (lambda^2*lambda^3)^2 mt^2  suppressed by lambda^8, enhanced by (mt/mc)^2 << 1 s d Niels Tuning (15)

Time-dependent CP asymmetry λf for B0 ® J/yK0S Time-dependent CP asymmetry Theoretically clean way to measure b Clean experimental signature Branching fraction: O(10-4) “Large” compared to other CP modes! |Vcs Vcd|^2 mc^2 = (1*lambda)^2 mc^2 vs. |Vts Vtd|^2 mt^2 = (lambda^2*lambda^3)^2 mt^2  suppressed by lambda^8, enhanced by (mt/mc)^2 << 1 Niels Tuning (16)

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 (17)

λf contains information on final state f Investigate three final states f: B0J/ψKs B0sJ/ψφ B0sDsK CP violation in interference Niels Tuning (18)

βs: Bs0 ® J/yφ : Bs0 analogue of B0 ® J/yK0S Replace spectator quark d  s Niels Tuning (19)

βs: Bs0 ® J/yφ : Bs0 analogue of B0 ® J/yK0S Niels Tuning (20)

Remember: The “Bs-triangle”: βs Replace d by s: Niels Tuning (21)

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 (22)

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 (23)

“Recent” excitement (5 March 2008) Niels Tuning (24)

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 (25)

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 (26)

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 (27)

Next: γ Niels Tuning (28)

CKM Angle measurements from Bd,u decays Sources of phases in Bd,u amplitudes* The standard techniques for the angles: bu Amplitude Rel. Magnitude Weak phase bc Dominant bu Suppressed γ td (x2, mixing) Time dependent 2β *In Wolfenstein phase convention. td B0 mixing + single bu decay B0 mixing + single bc decay Interfere bc and bu in B± decay. Niels Tuning (29)

Determining the angle g From unitarity we have: Must interfere b  u (cd) and b c(ud) Expect b  u (cs) and b c(us) to have the same phase, with more interference (but less events) g l3 l l2 1 l3 1 l2 l Niels Tuning (30)

Measure γ: B0s  DsK-/+ : both λf and λf 2 + Γ(Bf)= 2 + Γ(Bf )= NB: In addition B s  DsK-/+ : both λ f and λf Niels Tuning (31)

Break Niels Tuning (32)

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 (33)

Measure γ: Bs  DsK-/+ B0s  Ds-K+ has phase difference ( - ): Need B0s  Ds+K- to disentangle  and : Niels Tuning (34)

Measure γ: Bs  DsK-/+: in practice! 1) Signal & Backgrounds Time fit  m 2) Acceptance  t 3) Decay time resolution Expect  with ~ 280 precision Improve with 2012 data LHCb average now: 670  120  Δt 4) Flavour Tagging

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

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

Basics The basics you know now! CP violation from complex phase in CKM matrix Need 2 interfering amplitudes (B-oscillations come in handy!) 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 (38)

Next Niels Tuning (39)

Next 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 (41)

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 (42)

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 (43)

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 (44)

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 (45)

Hint for new physics? B0Kπ and BKπ0 Niels Tuning (46)

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 (47)

First CP violation in Bs0 system Bs0→K+π− Historical? History: 1964: Discovery of CPV with K0 (Prize 1980) 2001: Discovery of CPV with B0 (Prize 2008) 2013: Discovery of CPV with B0s Bs0→K+π− Bs0→K−π+

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 (50)

(limit on) CP violation in B0 mixing Look for a like-sign asymmetry: As expected, no asymmetry is observed… Niels Tuning (51)

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 (52)

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 (53)

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… Time? Niels Tuning (56)

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 (57)

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 (58)

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 (59)

Penguin diagrams Nucl. Phys. B131:285 1977 Niels Tuning (60)

Penguins?? The original penguin: A real penguin: Our penguin: Niels Tuning (61)

Funny Flying Penguin Dead Penguin Penguin T-shirt: Super Penguin: Niels Tuning (62)

 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 (63)

? 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 (64) S.T’Jampens, CKM fitter, Beauty2006