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Jeroen van Tilburg (Physikalisches Institut Heidelberg) On behalf of the LHCb collaboration

CP violation in the charm and beauty systems at LHCb. Jeroen van Tilburg (Physikalisches Institut Heidelberg) On behalf of the LHCb collaboration. Introduction. Focus on two new results today : Time dependent CP violation in B 0 →  +  − and B s → K + K − .

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Jeroen van Tilburg (Physikalisches Institut Heidelberg) On behalf of the LHCb collaboration

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  1. CP violation in the charm and beauty systems at LHCb Jeroen van Tilburg (Physikalisches Institut Heidelberg) On behalf of the LHCb collaboration CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  2. Introduction • Focus on two new results today: • Time dependent CP violation in B0→+− and Bs→K+K−. • Sensitive to CKM angle γ and d, s. • Effective lifetime in Bs→K+K− • Sensitive to ΔΓs and s Tree – penguin interference in B→hh’ allow to probe CKM angles Bs system Unitarity triangle ΔΓs: lifetime difference of Bs system s : mixing phase Bd system ΔΓd ~ 0 d = 2β CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  3. Time-dependent CPV in B→hh’ Time-dependent CP asymmetry where For B0→π+π−and Bs→K+K− we have Adir(γ,d,θ) Adir(γ,d’,θ’) Amix(γ,d,d,θ) Amix(γ,s,d’,θ’) ππ KK ππ KK • Assuming U-spin symmetry: d=d’ and θ=θ’ • Use d as input: extract γ and s. [Fleischer, PLB459 (1999) 306] [LHCb roadmap] Complementary to γ from pure tree decays using B→DK: ADS+GLW method. → see new nice results on AADS shown by Chris Jones yesterday. CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  4. Current experimental status Time-dependent CP asymmetry in B0→π+π− • Only B0→π+π− measurements available from B-factories • Bare agreement for direct CP violation between BaBar and Belle • Third independent measurement essential. No measurements on Bs→K+K− yet BaBar [arXiv:0807.4226] Belle [PRL 98 (2007) 211801] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  5. LHCb analysis New result! Not shown before [LHCb-CONF-2012-007] Preliminary • Data sample: • Integrated luminosity of 0.69 fb-1 • Event selection: • Common kinematics cuts for B→Kπ,B0→π+π−and Bs→K+K− • PID cuts to distinguish various final states • Decay time resolution • Use resolution from B→J/X: t=50 fs • Decay time acceptance from MC • Flavour tagging • Use OS tagging only • Use B→Kπ to calibrate efficiency and mistag rate Flavour tagging example K+ Signal Bs K+ DX B- Sign of muon tags Bs flavour at production μ- CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  6. Bd,s→K fit [LHCb-CONF-2012-007] B0→Kπ Bs→πK B0→π+π− Bs→K+K− x-feed+3-body combinatorial Extract from fit: Bd oscillation plot Bdparameters: (Constrain Bs parameters) Δmd = (0.484±0.019) ps-1 τ(B0) = (1.509±0.011) ps (only statistical errors) Agreement with WA • Tagging power: (2.3±0.1)% • Production asymmetry • AP(B0) = (-1.5±1.3)% • AP(Bs) = (-3±6)% Input to π+π−andK+K−fits. CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  7. Bd→+− fit 5359±96 events [LHCb-CONF-2012-007] B0→Kπ B0→π+π− x-feed+3-body combinatorial Input Δmd = (0.499±0.032) ps-1[LHCb-CONF-2011-010] Extract from fit: First B0→π+π−CP asymmetry measurement at hadron collider τ(B0) = (1.497±0.025) ps (only statistical error) In agreement with WA CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  8. Bs→K+K− fit 7155±97 events B0→Kπ Bs→K+K− x-feed+3-body combinatorial [LHCb-CONF-2012-007] Input ΔmsandΓsfrom LHCb measurements Extract from fit: First Bs→K+K−CP asymmetry measurement ΔΓs = (0.076±0.019) ps-1 (only statistical error) In agreement with[LHCb-PAPER-2011-021] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  9. Results (statistical correlation) B0→π+π− [LHCb-CONF-2012-007] Main systematic uncer-tainty: input on Δmd Preliminary • Adir favours BaBar result • Amix in agreement with WA CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  10. Results (statistical correlation) Bs→K+K− Main systematic uncertainties: Decay time resolution & acceptance and input on Δms [LHCb-CONF-2012-007] Preliminary [LHCB-PAPER-2011-029] • Expect: • Assuming U-spin symmetry and neglecting penguin annihilation (small) • SM prediction: • Assuming U-spin symmetry and SM predictions [LHCb roadmap] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  11. Effective lifetime in CP eigenmodes Untagged decay time distribution: with AΔΓ(γ,s,d’,θ’) If no CPV then for CP eigenstates AΔΓ= ±1 : CP even: Bs→K+K− ΓL CP odd: Bs→ J/ f0 ΓH Effective lifetime Bs→K+K− Expand in: • Alternative way to extract ΔΓs and s • → Complementary to e.g. Bs → J/  • → No flavour tagging needed CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  12. Current picture Using effective lifetimes to constrain ΔΓs and s Fleischer, Knegjens, [arXiv:1109.5115] Including direct measurements LHCb [PLB 707 (2012)] CDF [PRD84:052012, 2011] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  13. Update on s New result. Update using 1.0 fb−1 Only shown last week at Moriond EW (P. Clarke) Bs → J/  and Bs→ J/ ππ(incl. f0) time-dependent analysis [LHCb-CONF-2012-002] Preliminary [LHCb-PAPER-2012-006] Γ = 0.6580 ± 0.0054(stat.)± 0.0066(syst.) ΔΓ = 0.116 ± 0.018(stat.) ± 0.006(syst.) s = -0.002 ± 0.083(stat.) ± 0.027(syst.) Note: Sign of ΔΓs resolved using P-wave – S-wave interference: ΔΓs> 0 [LHCb-PAPER-2011-028] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  14. Update on CP odd lifetime Analysis of Bs→ J/ ππ(incl. f0) [LHCb-PAPER-2012-006] Background Background Using f0 resonance only: Using full CP odd sample: Statistical errors only. Detailed analysis of effective lifetime in preparation. CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  15. Effective Lifetime of Bs→K+K− Previous analysis on 2010 data [PLB 707 (2012)] • Two approaches to counter lifetime biasing effects in trigger and selection • “Swimming” method (determine trigger acceptance event-by-event ) • Relative method (Bs→K+K− vs B0→K+π−) New result!!! (not shown before) [LHCb-CONF-2012-001] Preliminary Now a third method is added and shown today • Minimal lifetime bias method • No cuts on lifetime, impact parameters, etc. • Dedicated trigger line • Trigger and event selection all based on neural networks • Flat acceptance (verified on MC) • Using full 1.0 fb−1 from 2011 data set CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  16. Mass distributions Signal: Bs→K+K− Control mode: B0→K+π− B0→K+π− Bs→K+K− [LHCb-CONF-2012-001] Partially reconstructed B mesons Partially reconstructed B mesons B0→K+π− Bs→K+K− Kaon mass assigned to both final state particles • Final event selection • Use PID to isolate Bs→K+K− vs B0→K+π−. • Cut on proton ID to suppress contribution from Λ. CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  17. Lifetime fit Signal: Bs→K+K− Control mode: B0→K+π− [LHCb-CONF-2012-001] Note: Trigger needs to cut at t>0.3 ps → Fit starts at t=0.5 ps Agrees well with previous result: Agrees with WA (PDG): CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  18. Effective lifetime Bs→K+K− [LHCb-CONF-2012-001] Preliminary Final result Main systematic uncertainty from reconstruction efficiency In agreement with SM expectation: Fleischer, Knegjens, [EPJC 71 (2011) 1532] CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  19. Charm results [LHCb-PAPER-2011-023] ΔACP in D0→h+h- (CPV in decay) 0.6 fb-1 Production and detector asymmetry cancel. Signifance 3.5 First evidence of CP violation in charm sector! yCPand AГin D0→K+K- (CPV in mixing) 29 pb-1 [LHCb-PAPER-2011-032] → Combined with measurement of y gives access to CPV. LHCb is currently updating for full 1.0 fb-1 CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  20. Conclusions Time-dependent CPV in B0→π+π−and Bs→K+K−(0.7 fb-1) [LHCb-CONF-2012-007] Preliminary • B0→π+π− CP asymmetries in good agreement with world average • Amix yields first 3 evidence of time-dependent CPV at hadron collider • CP asymmetry in Bs→K+K− measured for the first time [LHCb-CONF-2012-001] Preliminary Effective lifetime in Bs→K+K−(1.0 fb-1) • Effective Bs→K+K− lifetime measured using novel technique • Minimal lifetime bias in trigger and selection using neural networks • Significant improvement over 2010 result • Analyses using different techniques in progress and expect to reduce further uncertainty. Charm results • First evidence for CP violation in charm (ΔACP) • Expect large improvement for yCP and AΓ using 2011 data. CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  21. Backup CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

  22. Time-dependent asymmetries For B0→π+π−and Bs→K+K− we have CP violation in the charm and beauty systems at LHCb, Jeroen van Tilburg

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