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LHCb results

LHCb results. (New Physics Search at LHCb ). Bolek Pietrzyk LAPP, Annecy, IN2P3, CNRS. SUSY 2011 August 28 – September 02, Fermilab. Flavour Physics is Important. Many of open questions in Standard Model (SM) found in flavour sector - Why are there 3 generations

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LHCb results

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  1. LHCb results (New Physics Search at LHCb) Bolek Pietrzyk LAPP, Annecy, IN2P3, CNRS SUSY 2011 August 28 – September 02, Fermilab

  2. Flavour Physics is Important Many of open questions in Standard Model (SM) found in flavour sector - Why are there 3 generations - What determines the extreme hierarchy of fermion masses? - What determines the elements of the CKM matrix? - What is the origin of CP violation (CPV)? Progress in flavour physics may help understand open questions in cosmology - SM CPV insufficient to explain matter/antimatter asymmetry , LHCb results

  3. Flavour Physics is Important Flavour physics is a proven tool of discovery: - Kaon mixing, BR(K0L→μμ) & GIM→ prediction of charm - CP violation → need for a third generation - B mixing → mass of top is very heavy - SUSY parameter space already severely constrained by e.g. b→sγ Precise studies of flavour observables are an excellent way to look for New Physics! , LHCb results

  4. LHCb Essentials CMS and LHCb are complementary , LHCb results

  5. LHCb Essentials LHCb is optimised for flavour physics. # Dedicated heavy flavour trigger - L0: hardware trigger firing on high pt hadrons and muons(~few GeV/c) - HLT: software trigger exploiting, in particular, tracking and vertexing, outputs at 3 kHz → Efficient for hadronic B and D decays, as well as leptonic channels #Very precise vertexing - VELO (planes of forward silicon) approach to within 8mm of beam #Hadron identification - Two RICHes provide good π/K separation over 2 < p < 100 GeV/c #LHCb design luminosity << maximum design luminosity of machine - LHCb already operating at (above!) design luminosity (2x1032cm-2 s-1) , LHCb results

  6. LHCb data taking LHCb collected 37 pb-1 in 2010, and so far 690 pb-1 in 2011, expect about 1 fb-1 by the end of 2011. 2011 analyses presented today use ~330 pb-1 Luminosity levelling delivers ~constant operation at 3-3.5x1032cm-2s-1 ATLAS & CMS lumi falls . off exponentially Lumi of LHCb ‘levelled’ continually , LHCb results

  7. The golden mode: Bs→μμ BR(Bs→μμ)SM = (3.2 ± 0.2) x 10-9 [A.J.Buras, arXiv:1012.1447] - Very high sensitivity to NP, eg. MSSM: - One example [O. Buchmuller et al, arXiv:0907.5568; F. Mahmoudi, arXiv: 08083144; B.C. Allanach, Comput. Phys. Commun. 143 (2002) 305-331] , LHCb results

  8. Bs→μμ : experimental context # BR Upper Limit 95% CL as of Spring 2011: - CDF (3.7 fb-1): < 4.3 x 10-8 - D0 (6.1 fb-1): < 5.1 x 10-8 - LHCb (37 pb-1): < 5.6 x 10-8 (2010 data) # Recent exciting hint from CDF (7 fb-1): - BR = 1.8+1.1-0.9 x 10-8 [arXiv:1107.2304] , LHCb results

  9. 2011 Bs→μ+μ- search with LHCb • # Strategy very similar to 2010 analysis [PLB 699 (2011) 330] • After di-μ preselection: • Build Boosted Decision Tree out of • 9 kinematical and topological variables • -Train BDT on MC, but calibrate on data: • & signal response: use B → hh decays • triggered on ‘other B’ (avoid biases!) • & background response: use sidebands , LHCb results

  10. 2011 Bs→μ+μ- search with LHCb • Invariant mass of expected signal • parameterised as crystal ball, with scale • & resolution (~25 MeV) calibrated from • data (dimuon resonances & B → hh) • Now look in a 6 x 4 grid of μ+μ- invariant • mass vs BDT output • To obtain relative BR for signal use three normalisation channels: • B+ → J/ΨK+, Bs → J/Ψφ and B0 → Kπ • – all give consistent results , LHCb results

  11. 2011 Bs→μ+μ- search with LHCb Data Combinatorial background B → hh misid background 0.1±0.1 events in each of 4 BDT bins Signal with SM BR , LHCb results

  12. 2011 Bs→μ+μ- search with LHCb Mmm=5.357 GeV, B mom. 58.16 GeV, transverse mom. 3.5 GeV, lifetime 3.52 ps, flighting pass 1.15 cm , LHCb results

  13. Bs→μ+μ- LHCb preliminary limit Compute limits using frequentist CLs method and LHCb combined result for fs/fd = 3.745 +-0.295 LHCb-CONF-2011-034 BackgdonlyBackgd + SM signal Expected limit at 95% (90%) C.L. 1.0 (0.8) x 10-8 1.5 (1.2) x 10-8 Observed limit at 95% (90%) C.L. 1.6 (1.3) x 10-8 p-value of bckgdonlyhypothesis 14% Observed limit at 95% (90%) C.L. 1.5 (1.2) x 10-8 (5 – 4 x SM) when combined with 2010 result , LHCb results

  14. B0→K*l+l- Many observables exist in B0→K*l+l- to probe helicity structure of any New Physics... ...in particular, forward-backward asymmetry (AFB) of lepton system as a function of lepton invariant mass (q2). , LHCb results

  15. B0→K*l+l-: experimental context Results from CDF & B-factories show intriguing behaviour at low q2 : C7=‐C7SM SM , LHCb results

  16. B0→K*μ+μ-: event selection Select events using Boosted Decision Tree from sample of 309 pb-1 Veto decays in J/Ψ and Ψ(2S) resonance regions 303 signal events after mass cut Measure in 6 q2 bins: Simultaneous fit of 1D projections of helicity angles of kaon & lepton •differential branching fraction, dΓ/dq2 } Performance of fit validated on MC and B0→J/ΨK* decays •longitudinal polarisation, FL •AFB , LHCb results

  17. AFB in B0→K*μ+μ- Systematic uncertainties are small, and generally statistics limited. C. Bobeth et al. [arXiv:1105.0376v2] LHCb-CONF-2011-039 Data are consistent with the SM predictions at present sensitivity and indicate for the first time that the asymmetry is changing sign as predicted by the SM. , LHCb results

  18. AFB in B0→K*μ+μ- arXiv:1108.0695 , LHCb results

  19. CP-violation in Bs mixing Interference between mixing and decay gives rise to CP violating phase 𝜙𝑠=𝜙𝑀 −2 𝜙𝐷 final state is mixture of CP even and CP odd eigenstates (P—VV decay) Described by three polarization amplitudes: 𝐴⊥ (CP-odd) 𝐴0 ,𝐴∥ (CP-even) Final states described by three angles: Ω={𝜑,𝜃,𝜓} 𝜙𝐷 [SM −0.0363 ± 0.0017 rad] 𝐵𝑠 𝐽/Ψ Φ −𝜙𝐷 𝜙𝑀 𝐵𝑠 , LHCb results

  20. 𝜙𝑠: experimental context 𝜙𝑠=𝜙𝑀 −2 𝜙𝐷 SM prediction: −0.0363 ± 0.0017 rad [CKMfitter, Eur. Phys. J. C41 (2005)] D0 / EPS 2011 Conference / S.Burdin CDF Public Note 10206 LHCb measurement with 2010 data: 757 ± 28 signal candidates , LHCb results

  21. Bs→ J/yf m J/y L = 337 pb-1 8276 ± 94 signal candidates (10x more than in 2010) S/B ~ 11 in 3𝜎 mass window Perform unbinned maximum likelihood fit in mass, proper time, transversity angles OS tagger optimized and calibrated on 2011 data using 𝐵+→ 𝐽/Ψ 𝐾+, 𝐵0 → 𝐽/Ψ 𝐾∗ and 𝐵0→ 𝐷∗-𝜇+𝜈𝜇 𝜖𝐷𝑒𝑓𝑓2 = 2.08 ± 0.17 ± 0.37% m- Bs f K K , LHCb results

  22. Bs→ J/yf Systematic uncertainties are small, and generally statistics limited. LHCb-CONF-2011-049 Standard Model [𝜙𝑠 CKMfitter, Eur. Phys. J. C41 (2005)] (ΔΓ𝑠 Lenz, Nierste, JHEP 0706 (2007) 072) 𝜙𝑠 = 0.13 ± 0.18 (𝑠𝑡𝑎) ± 0.07 (𝑠𝑦𝑠) rad ΔΓ𝑠 = 0.123 ± 0.029 (𝑠𝑡𝑎𝑡) ± 0.008 (𝑠𝑦𝑠) 𝑝𝑠-1 Γ𝑠 = 0.656 ± 0.009 (𝑠𝑡𝑎) ± 0.008 (𝑠𝑦𝑠) 𝑝𝑠-1 , LHCb results

  23. Bs→ J/yf This is NOT an official accurate overlay!! – only an “artist’s view” , LHCb results

  24. Bs→ J/yf0(980) Feb. 1, 2011 – LHCb: “1st observation of Bs→ J/ψ f0(980) decays“ [arXiv:1102.0206] f0 is a scalar with an ss component but decays predominatly into π+π- , LHCb results

  25. Bs→ J/yf0(980) Bs→J/ψππ • 2011 data • Nsig = 1428 ± 47 events • 365 ± 22 after tagging • εD2 = 2.13% • The f0(980) signal region • looks pure scalar • purely CP odd • no angular analysis • required B0→J/ψKπ B0→J/ψππ Bs→J/ψ η’,φ B+→J/ψπ , LHCb results

  26. Bs→ J/yf0(980) LHCb-CONF-2011-051 • ϕs = -0.44 ± 0.44(stat.) ± 0.02(syst.) , LHCb results

  27. J/yf and J/yf0(980) combination 𝜙𝑠 = 0.13 ± 0.18 (𝑠𝑡𝑎) ± 0.07 (𝑠𝑦𝑠) rad ϕs = -0.44 ± 0.44(stat.) ± 0.02(syst.) pleriminary simple combination Φs = 0.03 ± 0.16(stat) ± 0.07(syst) rad SM Φs = −0.036 ± 0.002 LHCb-CONF-2011-056 , LHCb results

  28. Δms: experimental context • # CDF (2006): • - Δ𝑚𝑠 = 17.77 ± 0.10 (𝑠𝑡𝑎𝑡) ± 0.07 (𝑠𝑦𝑠𝑡) • 5,600 fully and 3,100 partially reconstructed • hadronic 𝐵𝑠0, 61,500 semileptonic 𝐵𝑠0 • - s𝑡 = 87 fs (fully rec. hadr.) • - 𝜀𝐷2 = 3.7 % (hadr., OST+SST) • # LHCb (2010): • - Δ𝑚𝑠 = 17.63 ± 0.11 (𝑠𝑡𝑎𝑡) ± 0.03 (𝑠𝑦𝑠𝑡) • - 1381 signal candidates • - s𝑡 = 44 fs • - 𝜀𝐷2 = (3.8 ± 2.8) % (OST only) , LHCb results

  29. Δms: LHCb 2011 data # LHCb, 2011 data 341 pb-1 Δ𝑚𝑠 = 17.725 ± 0.041 (𝑠𝑡𝑎𝑡) ± 0.025 (𝑠𝑦𝑠𝑡) - 9189 signal candidates - 𝜀𝐷2 = (3.2 ± 08) % (OST) - 𝜀𝐷2 = (1.2 ± 04) % (SST) , LHCb results

  30. CP violation … is easy B0 B0 B0S B0S , LHCb results

  31. Summary • - LHCb at LHC is making precise measurements • - Hints for strong signs of NP from other experiments are not confirmed • - LHCb results presented here are in agreement with the SM prediction, but … • -There is still a lot of room for NP • - At the end of 2011 we should have about 3 times more data and improved analyses • Excellent prospects for excellent results • at Moriond 2012 , LHCb results

  32. Backup slides

  33. Bs→μ+μ- CMS search (1.14 fb-1 ) # No significant excess seen Barrel Endcap B→hh # Compute limits using frequentist CLs method and PDG fs/fd = 0.282 ±0.037 Expected limit at 95% (90%) C.L. 1.8 x 10-8 (including SM signal) Observed limit at 95% (90%) C.L. 1.9 (1.6) x 10-8 , LHCb results

  34. Bs→μ+μ- combination A preliminary CMS-LHCb combination on BR(Bs→μ+μ-) has been performed, using the CLs approach, & taking LHCb value of fs/fd as common input Observed limit at 95% (90%) C.L. 1.1 (0.9) x 10-8 3.4 times the expected SM value CMS + LHCb preliminary CDF hint is not confirmed , LHCb results

  35. Like-sign di-muon asymmetry D0 observes 3 s deviation from the SM LHC is a pp-collider, not a ppbar-collider , LHCb results

  36. LHCb detector , LHCb results

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