1 / 23

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

ena
Download Presentation

Measurement of the weak phase γ

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

  23. Back up

More Related