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Measurement of the weak phase γ

Measurement of the weak phase γ. K.Akiba – UFRJ On behalf of the LHCb Collaboration. CP Violation and CKM. CKM mixing matrix Mass  Weak eigenstates Unitary Complex  CP Violation. Wolfenstein parametrization. Unitarity. CP Violation and CKM. CKM mixing matrix

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Measurement of the weak phase γ

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  1. Measurement of the weak phase γ K.Akiba – UFRJ On behalf of the LHCb Collaboration

  2. CP Violation and CKM • CKM mixing matrix • MassWeak eigenstates • Unitary • Complex  CP Violation Wolfensteinparametrization Unitarity Kazu Akiba

  3. CP Violation and CKM • CKM mixing matrix • MassWeak eigenstates • Unitary • Complex  CP Violation α Wolfensteinparametrization γ β Unitarity Kazu Akiba

  4. Standard CP Violation Unitarity Triangle Constrained by all the CKM related measurements CKMfitter Group (J. Charles et al.), Eur. Phys. J. C41, 1-131 (2005) Kazu Akiba

  5. The importance of γ Least precisely measured of the angles.(|Vub|<< 1) Direct measurements: 66 ± 12 ° (CKM Fitter 2012) (-100.8 or 79.1) ± 9.2 °(UTFit post-Moriond 2012) Kazu Akiba

  6. How to measure γ • It’s a phase  Interference. • Needs bu transitions; Rare. • Mainly 2 methods with tree level diagrams. • Time independent: B(u,d)  D(*)K(*) • Time dependent: BsDsK • Requirements: • A large sample of B mesons • An excellent K / p identification • Precise vertex reconstruction (time meas. And BG suppr.) Kazu Akiba

  7. The LHCb Experiment RICH2 TT Si Outer Tracker straw Tubes ECAL HCAL Magnet Zoom in the vertex region VELO&PU Si Open during injection Closes for physics Muon MWPCGEM Inner Tracker Si + Trigger Hard & Soft RICH1 Large Hadron Collider beauty Experiment for CP violation and Rare B Decays. KazuAkiba 7

  8. BD0K : Time independent γ (+ππ) → f • Where f can be: Kπ, KK, ππ, Kπππ, Ksππ, KsKK, Kππ0 … → f (+ππ) → f Kazu Akiba

  9. Gronau, London, Wyler (GLW) [Phys. Lett. B 253, 483 (1991), Phys. Lett. B 265, 172 (1991)] • Interference with D on a CP eigenstate: f = h+ h- ,rD=1 • Summarized in 2 observables, but 3 unknowns: • Similarly, B0 and K*0 can be used. Kazu Akiba

  10. Attwood, Dunietz, Soni (ADS) Phys.Rev.Lett. 78 (1997) 3257, axiv:hep-ph/9612433 • Interference with D through Cabibbofavoured and supressed modes: f = K+π- , rD≈ 0.06 (rD=Γ(D0->K+π-)/Γ(D0->K-π+)) • Need external input on δDKπ and rD. • Combined with GLW can provide a measurement of γ Kazu Akiba

  11. LHCb Results B(KK)D h (GLW) BDK , BDπ, BDh+BG, ΛbΛc h (dashed) Difference in reconstructed candidates for different B charges Mis-ID πK Mis-ID Kπ ACP+ = 0.145±0.032±0.010 Kazu Akiba Phys. Lett. B Vol 712, Issue 3, 2012,, 203–212

  12. LHCb Results B(ππ)D h (GLW) BDK , BDπ, BDh+BG, ΛbΛc h (dashed) Difference in reconstructed candidates for different B charges Mis-ID πK Mis-ID Kπ RCP+ = 1.07±0.038±0.012 Kazu Akiba Phys. Lett. B Vol 712, Issue 3, 2012,, 203–212

  13. LHCb Results B(hh')D h (ADS) BDK , BDπ, BDh+BG, ΛbΛc h (dashed) Favoured modes Difference in reconstructed candidates for different B charges Mis-ID πK Mis-ID Kπ AADS(π)= (0.143±0.062±0.011) AADS(K)= (-0.52±0.15±0.02) Kazu Akiba Phys. Lett. B Vol 712, Issue 3, 2012,, 203–212

  14. LHCb Results B(h'h)D h (ADS) RADS(K)= (1.52±0.20±0.04)% Suppressed modes B( B±→[π±K+]DK± ) ≈ (2.2 ± 0.3)×10−7 (10 σ) observation Bs->D0Kπ Mis-ID Kπ Mis-ID πK RADS(π) = (0.410±0.025±0.005)% 2σ higher than previous measurements Phys. Lett. B Vol 712, Issue 3, 2012,, 203–212 Kazu Akiba

  15. Global picture ADS/GLW (Kπ)Dπ B Factories still dominate most of the results but LHCb comes in with most precise measurements… Kazu Akiba

  16. Global picture ADS/GLW (Kπ)DK B Factories still dominate most of the results but LHCb comes in with most precise measurements… Kazu Akiba

  17. Global picture ADS/GLW (hh)DK B Factories still dominate most of the results but LHCb comes in with most precise measurements… Kazu Akiba

  18. Giri, Grossman, Soffer, Zupan (GGSZ) Phys.Rev. D68 (2003) 054018, arXiv:hep-ph/0303187 • Uses the same kind of interference but with a three-body final state B (Ks π π)DKand perform a Dalitz Analysis • Complementary to the previous methods, gives independent information on rB,δBγ. • No results fromLHCb just yet… Kazu Akiba

  19. Effects on γ • ADS/GLW do not provide unambiguous solution to γ • The precision of the newest measurements does not translate directly to precision on γ. • LHCb gives more precise constraints on rB Kazu Akiba

  20. BsDsK: Time dependent γ • The Two diagrams interfere directly through the same final state  time dependent analysis reveals γ-φs , where φsis the phase in the mixing. • Requires a good proper time calibration and tagging (BsDsπ). • Method unique to LHCb! Kazu Akiba

  21. BsDsK: towards a γ measurement • Good proper time resolution • ~50 ps (measured with Dsπ) • Well controlled tagging • εD2 = (3.2 ±0.8) % (OS only) • More from SST. • Milestones measurements • Δms = 17.63 ±0.11 ± 0.02 1/ps[arXiv:1112.4311]) • BF (Bs DsK) = (1.90 ±0.12(stat) ±0.13 (sys)+0.12-0.14 (fd/fs) ) [arXiv:1204.1237] • Basic ingredients ate there: • Time dependent analysis • Flavour tagging • Reconstruction and PID. Kazu Akiba

  22. Conclusions • Decays of BDh offer a rich programme to measure the CKM phase γ. • Main decay modes already measured • 10 σ observation of suppressed ADS modes • 5.8 σ measurements of CP violation B->DK modes combined • More and unique analyses to come • B0->D0K*0 modes to offer more information on GLW+ADS • Time dependent BsDsKway to measure γ • Multiple methods in LHCb can be combined for a best precision on γ! Kazu Akiba

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