1. Feasibility to Study the Bc Meson and Testing Anomalous Gauge Couplings of the Higgs Boson via Weak-Boson Scatterings at CMS CMS Group Institute of High Energy Physics, Chinese Academy of Science Guilin 2006.10.29

2. Feasibility to Study the Bc Meson at CMS

3. Outline Introduction Process & results –Production of Signal & Backgrounds –Event selection, by studying Bc signal & backgrounds –Results Summary

4. Introduction

5. Bc Meson The Bc meson is the lowest-mass bound state of a charm quark and a bottom anti-quark. It is the latest such meson predicted by the Standard Model. Because Bc meson carry flavor, it provides a new window for studying heavy-quark dynamics for the two different heavy quarks, which is very different from the window provided by quarkonium. Its mass is predicted to be And its lifetime is predicted to be between 0.4 and 0.7 ps V.V.Kiselev, PACS number:13.20.Gd,13.25.Gv, 11.55.Hx

6. TEVATRON: CDF (1998) 20 J/ψ lυ events, mass : 6.40±0.39±0.13 GeV life time : ps

7. Recent results of Bc Meson Experimental observation (CDF & D0, Tevatron) 1998 2004 2005

8. CMS Experiment CMS 2008 Large Hadron Collider

9. CMS Experiment

10. Production of Bc at LHC pp LHC (14TeV) g-g fusion

11. Adavantages of study Bc at CMS 1. Higher Collide Energy LHC: PP collider 2. Larger detector region than CDF The CMS detector has the similar structure as CDF,but it has larger detector region than CDF. CMS: eta~(-2.5,2.5) CDF: eta~(-1.0,1.0) (RUN I) eta~(-1.5,1.5) (RUN II) (Muon system) 3. A better identification ability to muons The CMS detector has a better identification ability to muons,this is more useful for the channels which include muon/muons in the final state.

12. The goal: to measure the mass and life time of Bc with a larger statistics. The first channel to look: B c → J/ψ π (J/ψ → µµ) First publication at about 1 fb -1 Goal & status

13. Process & results

14. The CMS Analysis chain MC generator HEPEVT Ntuple OSCAR Ntuple signal Ntuple minbias POOL SimHits/signal POOL SimHits/minbias POOL Digis DST ROOT Tree “data summary tape” User SimReaderRecReader 1)digitization2)reconstruction3)analysis ORCA

15. The CMS Fast Simulation MC generator HEPEVT Ntuple Ntuple POOL Simulation, Digis, and DST ROOT Tree FAMOS analysis

16. Generator of Bc signal BCVEGPY IPT, Beijing, by Chang et al. Russian package IHEP, Protvino, by Berezhnoy et al. PYTHIA BCVEGPY is used: faster agrees well with PYTHIA

17. ParticleDecay channels σ (pb) Generated (* 10 4 ) BcBc→J/ψπ (J/ψ→µµ ) 1.7815.2082 kine cut : Bc Pt≥10GeV |eta|≤2.0 Mu Pt≥4GeV |eta|≤2.2 Pion Pt≥2GeV |eta|≤2.4 About 30 1/fb Bc events were produced for efficiency study with both OSCAR/ORCA and FAMOS Another independent 1/fb Bc were produced as data OSCAR_3_7_0 ORCA_8_7_3 FAMOS_1_3_2 Bc signal

18. Backgrounds 1. Other B hadrons’ decay include J/ψ 2. Prompt J/ψ 3. ccbar→μμx 4. bbbar →μμx 5. General QCD, W+jets, Z+jets

19. Backgrounds (1,2,3) generated by CMKIN & produced by FAMOS

20. Backgrounds (4,5) CMS official production with OSCAR/ORCA Datasetσ(mb)Nevents bb→mumu+ X4.8*10 -3 100,000 QCD57.6950,000 W+jets1.56*10 -4 880,000 Z+jets3.82*10 -5 710,000

21. J/Ψ candidates: 2 muons Pt ≥ 4.0 GeV, |η|<=2.2 2 muons share the same vertex 2 muons have different charge 2 muons’ invariant mass around the J/Ψ [3.0,3.2]GeV Data Selection Selection I Bc → J/ψ π (J/ψ → µµ)

22. Pion candidate: Be not identified as a lepton Pt ≥ 2 GeV |η|<=2.4 Share the same vertex with 2 muons (J/Ψ vertex) Selection II Bc → J/ψ π (J/ψ → µµ)

23. Selection III Signal selection cuts: cos(thetasp)>0.8 thetasp: is the angle between the direction from the primary vertex to the second vertex and the direction of the reconstructed Bc momentum PDLxy >60 μm (Proper decay length) PDLxy / σ xy >2.5 P. V. S. V.

24. 1fb -1

25. Selection IV Bc mass window (6.25, 6.55) GeV

26. Summary of the Number of Events Bc120±11 B+0.7±0.2 Bs0.1 B00.9±0.3 Prompt J/ψ0.1 QCD0.7±0.1 ΛbΛb0.1 ccbar0.01 bbbar0.01 Total Bkgs: 2.6 ± 0.4 Normalize to 1fb -1

27. Bc number uncertainty source: 1.LO only 2.color singlet only (no color-octet available) 3.Values of inputs mass of b quark, c quark ; parton distribution function (pdf).

28. Kinematic fitting Bc→J/ψπ, J/ψ→μμ Totally 3 tracks: 2 muon tracks: J/ψ mass constraint all the 3 tracks: share the same vertex

29. M(Bc): 6402.0±22.0 MeV Input:6400MeV cτ(Bc): 148.8±13.1 μm Input 150 μm

30. Systematic error source: Misalignment 1. muon momentum scale uncertainty 2. muon momentum resolution deterioration 3. vertex resolution deterioration Efficiency uncertainty Theoretical uncertainty Cuts sensitivity

31. Summary of systematic error Bc mass (MeV)Bc cτ (μm) P scale 11 0.2 P smear 10 0.8 Vertex smear / 2.4 Cuts 0.1 0.2 Efficiency / 0.1 Theoretical / 1.5 Total 14.9 3.0

32. Summary

33. With MC data, the feasibility for CMS to measure the mass and the lifetime of Bc meson was studied. The study focus on the decay channel Bc→J/ψπ. 120 events can be selected with the first 1 fb -1 data Mass resolution is estimated to be cτ resolution is corresponding to the lifetime error to be Uncertainty: effects of misalignment, theoretical uncertainty on the Bc Pt distribution, and limited Monte Carlo statistics.

34. This study had been reported for 6 times at CERN. This study had been written into 2 notes: CMS Notes & Analysis Notes And Physics TDR. The results can be available from the following website http://cmsdoc.cern.ch/doc/notes/docs/NOTE2006_118 Continue…

35. Testing Anomalous Gauge Couplings of the Higgs Boson via Weak-Boson Scatterings at CMS Outline 1. Motivation 2. Extraction of anomalous coupling constants via Neural Network 3. Study of signal and backgrounds 4. Summary & to do list

36. 1.whether there exists a sub-TeV Higgs Boson. 2. Discriminate the EWSB sector of the new physics model from that of the SM. Motivation

37. --------- p p u u d d W W W W + + + + H l + v l v + Zhang Bin and Kuang Yuping et. al. (Tsinghua Univ.) proposed a sensitive way of testing AHVVC via VV (V = W +, Z 0 ) scatterings, especially the WW scatterings at LHC and provided the matrix element level generator. It is

38. among them, fw and fww are the most sensitive ones. Hence, only fw and fww are considered.

39. To suppress backgrounds, the cuts suggested by theorists

41. Distribution of the number of events with f w Normalized to 300 fb -1 m H =115 GeV

42. For the small number of events, large fluctuation occurred. For the number of events fluctuated according Poisson distribution, the neural network can make the resolution of parameter fw better after taking the distribution of two leptons’ invariant mass as one of the inputs.

43. Extract anomalous coupling constant fw via Neural Network

44. Neural Network inputs: (1) number of events (2) distribution of the invariant mass of 2 leptons. outputs: anomalous coupling constants fw training: fw =0,1,2,3,4 evaluate: fw =1.5,2.5

45. Distribution of two leptons’ invariant mass Normalized to 300 fb -1

46. 2200 ~ 4000 960 ~ 2200 480 ~ 960 0 ~ 480 two leptons’ invariant mass (GeV) 4 3 2 1bin

47. Evaluated f w = 1.5

48. Evaluated f w = 2.5

49. Study of signal and backgrounds

50. Reconstruction results of the Signal

51. channels SigmaEvents/300 fb -1 Obtained via Grid job or reconstructed by myself WZ 3l4.4E-10 (mb)13200040000 ZZ 4l1.6E-11 (mb)480040000 Z 0 t t 4l + X1.7 (fb)5101000 W + t t 3l + X3.0 (fb)9001000 t t 4l + X1.25E-9 (mb)375000121000 Zbb_4l+(njets)2E-11 (mb)6000129000 Zbb_cc_4l+(njets)8E-12 (mb)24003000 ZWjets_leptonic2.6E-9 (mb)78000050000 ZZjets_leptonic1.5E-10 (mb)45000100000 Backgrounds _ _ _

52. Comparison of the Signal & Backgrounds after the basic Cuts —2 lepton’s invariant mass and tagging jet’s pt (Taking WZ→3 l as example)

56. No background of the channels listed in the table can exits, after adding all cuts suggested by theorists to the backgrounds with the limited statistics. so we suggest to relax the cuts in order to get more signal events, which is what we will to do. channels Sigmabackground events Obtained via Grid job WZ 3l4.4E-10 (mb)040000 ZZ 4l1.6E-11 (mb)040000 Z t t 4l+X1.7 (fb)01000 Wt t 3l+X3 (fb)01000 t t 4l + X1.25E-9 (mb)0121000 Zbb_4l+(njets)2E-11 (mb)0129000 Zbb_cc 4l+(njets)8E-12 (mb)03000 ZWjets_leptonic2.6E-9 (mb)050000 ZZjets_leptonic1.5E-10 (mb)0100000

57. Summary Extracting anomalous coupling constant fw via Neural Network, we can get more sensitivity results using the number of events & invariant mass of 2 leptons than that using the number of events only on the theory. After studying the signal and backgrounds, using the cuts we can cut off all the backgrounds considered with limited number of events available.

58. To do list Further study of signal and backgrounds, then find out the best proper cuts. Try other ways to fix the anomalous coupling constants.

59. The End Thanks !

60. Backup slides

61. Cross section comparison Bc vs other B σ (other B) =1000 σ ( Bc) LHC vs TEVATRON 20 times larger H.C. Chang X.G. Wu Pt cut (GeV)0550100 TEVATRON/LHC6.3%5.2%1.0%0.3 %

62. 1. Bc → J/Ψlν(J/Ψ → l + l - ) Bc→J/ψµν(J/ψ→µµ) Bc→J/ψeν(J/ψ→µµ) Bc→J/ψµν(J/ψ→ee) Bc→J/ψeν(J/ψ→ee) 2. Bc→J/Ψπ(J/Ψ→l+ l-) Bc→J/ψπ(J/ψ→µµ) Bc→J/ψπ(J/ψ→ee) Bc decay and interface with OSCAR: Force Bc to decay with the final states we need and interface with OSCAR (Implemented within SIMUB ) SIMUB is one of CMS Supported generator packages,which is dedicated for simulation of B-meson production and decays. http://cmsdoc.cern.ch/~shulga/SIMUB/SIMUB.htmlhttp://cmsdoc.cern.ch/~shulga/SIMUB/SIMUB.html G.M. Chen S.H. Zhang IHEP Beijing A.A. Belkov S. Shulga JINR Dubna (Russia)

63. Number decay channelsBranch RatioNev σ(pb)after Kine cut 5110B0 → JPsi + K00.08%17000016.040 5111B0 → JPsi + K0*0.14%29000028.288 5112B0 → chi_c1 + K00.19%12000011.192 5113B0 → chi_c1+ K0 *0.25%15000014.808 Background of Bc→J/ψπ (J/ψ→µµ) from B0 channelsBranch Ratio JPsi → mu+ mu-5.88% chi_c1 → JPsi + γ31.6% K0* → Random K- Pi+ K0 Pi0 K0 γ 66.5% 33.3% 0.2% Kinematic cuts at generator llevel Mu: pt ≥ 4.0GeV |eta| ≤ 2.4 K : pt ≥ 2.0GeV |eta| ≤ 2.7 More than 10 fb -1 bkg from B0 were produced

64. Number decay channelsBranch Ratio Nev σ(pb) after kine cut 5210B+ → JPsi + K+0.08%17000016.056 5211B+ → JPsi + K+*0.14%29000028.611 5212B+ → chi_c1 + K+0.19%12000011.150 5213B+ → chi_c1+ K+*0.25%15000014.921 Background of Bc→J/ψπ (J/ψ→µµ) from B+ channelsBranch Ratio JPsi → mu+ mu-5.88% chi_c1 → JPsi + γ31.6% K+* → Random K0 Pi+ K+ Pi0 K+ γ 66.6% 33.3% 0.1% Kine cut: Mu: pt ≥ 4.0GeV |eta| ≤ 2.4 K : pt ≥ 2.0GeV |eta| ≤ 2.7 More than 10 fb -1 bkg from B+ were produced

65. Number decay channelsBranch Ratio Nev σ(pb) after kine cut 5310Bs → JPsi + phi0.14%300002.215 5311Bs → JPsi + eta0.04%400003.198 5312Bs → JPsi + eta’0.04%300002.968 5313Bs → chi_c1+ eta0.1%300002.064 5314Bs → chi_c1+ eta’0.09%200001.738 5315Bs → chi_c1+ phi0.25%300002.583 Background of Bc→J/ψπ (J/ψ→µµ) from Bs channelsBranch Ratio JPsi → mu+ mu-5.88% phi → K+ K-48.9% chi_c1 → JPsi + γ31.6% eta → Random 1 eta’ → Random 1 Kine cut Mu: pt ≥ 4.0GeV |eta| ≤ 2.4 K : pt ≥ 2.0GeV |eta| ≤ 2.7 More than 10 fb -1 bkg from Bs were produced

66. Background of Bc→J/ψπ (J/ψ→µµ) from Λ 0 b Number decay channelsBranch RatioNsel σ(pb) after kine cut 51220Lambda_b0 → JPsi + Lambda0 0.22%13000012.797 51221 Lambda_b0 → chi_c1+ Lambda0 0.44%700006.642 channelsBranch Ratio JPsi → mu+ mu-5.88% chi_c1 → JPsi + γ31.6% Lambda0 → Random Kine cut Mu: pt ≥ 4.0GeV |eta| ≤ 2.4 More than 10 fb -1 bkg from Λ b were produced

67. Number decay channelsBranch RatioN(sel) σ(pb) after kine cut 4430g (γ) + g (γ) → JPsi Chi_c0 Chi_c1 Chi_c2 5.88% 0.7% * 5.88% 31.6% * 5.88% 13.5% * 5.88% 10000 40000 180000 0.440 0.794 3.902 17.553 4431g (q) + g (q) → c cbar + g (q) 5.88%260000217.57 Background of Bc→J/ψπ (J/ψ→µµ) from prompt J/ ψ Kine cut: Mu: pt ≥ 4.0GeV |eta| ≤ 2.4 channelsBranch Ratio JPsi → mu+ mu-5.88% chi_c0 → JPsi + γ0.7% chi_c1 → JPsi + γ31.6% chi_c2 → JPsi + γ13.5% More than 10 fb -1 bkg from 4430 were produced. Only 1 fb -1 events from Channel 4431

68. (1) PYTHIA

69. (2) PYTHIA

70. Backgound estimation None of the QCD, W+jets, Z+jets, ccbar and bbbar passed the selection. As the number of events produced is less than one 1/fb, the number of background events from these samples will be estimated step by step

71. QCD background estimation selection efficiency 1. two muons pT>4GeV, |η|<2.2 ε(2μ) 2.J/ψreconctruction same vertex, mass(μμ) : (3.0,3.2) ε(rec) 3. Final cuts Lxy/σ>2.5, PDL>60μm cos(thesp)>0.8 mass(J/ψ,π): (6.25, 6.55) ε(prompt) The total efficiency is ε(2μ)*ε(rec)* ε(prompt)

72. Dataset σ(mb)No. of events getted using Grid No. of Single Mu (>= 1 Mu) No. of Double Mu (>= 2Mu) jm03b_qcd_0_1555.222399910 0 jm03b_qcd_15_201.5000644999122 1 jm03b_qcd_20_300.64173389999461 4 jm03b_qcd_30_500.15592992997933 12 jm03b_qcd_50_800.020938831989934382 126 jm03b_qcd_80_1200.002949713900003408 147 jm03b_qcd_120_1700.000499656700003872 248 jm03b_qcd_170_2300.000100995400003130 247 jm03b_qcd_230_3002.3855*10 -5 500004963 453 jm03b_qcd_300_3806.39108*10 -6 24398331873 3769 jm03b_qcd_380_4701.88967*10 -6 5000744 111 Kine cut: Mu: pt ≥ 4.0GeV |eta| ≤ 2.2 ε(2μ) can be estimated from QCD samples

73. ε(rec) estimation Using ccbar→μμx sample total: 210,000 The number of events pass 2 muon selection: 147778, reconstructed J/ψ: 192 ε(rec)= (1.3±0.1) × 10 -3

74. ε(prompt) estimation Using prompt J/ψ sample The number of events pass the above selection is 434,566 Enlarge the mass window from (6.25,6.55) to (5.0,8.0), 27 events obtained assuming random distribution of the 27 events ε(prompt)=(6.55-6.25)/(8-5)*27/434566= (6.2±1.2) × 10 -6

75. Prompt J/ψ

76. Datasetσ(mb)ε(2 mu)Total εN 1fb-1 jm03b_qcd_0_1555.22(1.736256 ±0.17363)e-7 (1.40157 ±0.19937)e-15 0.077 ±0.011 jm03b_qcd_15_201.50006(7.35045 ±0.06025)e-6 (5.93353 ±0.29930)e-14 0.089 ±0.004 jm03b_qcd_20_300.641733(4.444494 ±2.222247)e-5 (3.58775 ±1.04850)e-13 0.230 ±0.067 jm03b_qcd_30_500.155929(1.290364 ±0.372496)e-4 (1.04161 ±0.13080)e-12 0.162 ±0.020 jm03b_qcd_50_800.02093883(6.331881 ±0.56409)e-4 (5.11131 ±0.25650)e-12 0.107 ±0.005 jm03b_qcd_80_1200.002949713(1.633333 ±0.134715)e-3 (1.31848 ±0.06467)e-11 0.039 ±0.002 ε(JPsi →Bkg) = (6.2±1.2 ) ×10 -6 ε(2mu→JPsi) = (1.3±0.1) × 10 -3 QCD background contribution

77. Datasetσ(mb)ε(2 mu)Total εN 1fb-1 jm03b_Wjets_0_201.110015*10 -4 (5.13333 ±0.5850)e-4 (4.14380 ±0.22887)e-12 (4.5997 ±0.2541)e-4 jm03b_Wjets_20_502.729528*10 -5 (1.4350 ±0.08471)e-3 (1.15838 ±0.05297)e-11 (3.1618 ±0.1446)e-4 jm03b_Wjets_50_851.006911*10 -5 (2.880 ±0.120)e-3 (2.32483 ±0.10225)e-11 (2.34090 ±0.1030)e-4 jm03b_Wjets_85_1506.30697*10 -6 (4.4650 ±0.149416)e-3 (3.60430 ±0.15630)e-11 (2.2732 ±0.0986)e-4 jm03b_Wjets_150_2501.20248*10 -6 (7.740 ±0.27821)e-3 (6.24799 ±0.27202)e-11 (7.5131 ±0.3271)e-5 jm03b_Wjets_250_4002.632455*10 -7 (1.123333 ±0.061192)e-2 (9.0679 ±0.40713)e-11 (2.3871 ±0.1072)e-5 ε(JPsi →Bkg) = (6.213095±1.19571 ) ×10 -6 ε(2mu→JPsi) = (1.299246±0.093765) × 10 -3 W+Jets has none

78. Muon momentum scale uncertainty Δ(1/pT)=0.0005/GeV (Albert De Roeck) Bc mass changes by 11 MeV cτ changes by 0.2 μm

79. Muon momentum resolution I. Belotelov et al CMS note 2006/017 Muon momentum were smeared according to This result Mass: 11 MeV Ctau: 0.8μm

80. Vertex resolution P. Vanlaer et al, CMS note 2006/029 Primary Vertex : x, y: smear 5.7μm, z:3.7μm Second Vertex: x, y: smear 12.4 μ m, z: 11.4μm cτ: 2.4 μ m

81. Cuts sensitivity Momentum cuts changed by one σ Other cuts changed by 10% mass: 0.1 MeV cτ : 0.2 μm

82. Efficiency uncertainty To estimate the efficiency uncertainty sqrt(N) events subtracted, efficiency recalculated cτ: 0.1 μm

83. Theoretical uncertainty Bc events were reweighted according the their Bc pT, so that the Bc pT distribution agrees with Gouz’s distribution cτ: 2.4μm

84. Muon momentum resolution CMS 1/fb: Mass: 22.0(fit) ±14.9(syst) MeV lifetime: 0.044(fit) ±0.010(syst) ps

85. Outlook (Real data 2008) J/ψ+ 1track will be selected as a control sample B + → J/ψ+K + will be used to estimate the Bc efficiency J/ψ peak side band will be used for the Bc background estimation