Understanding the Higgs Boson: Where We Are, Where We re Going, and How To Get There

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1 Understanding the Higgs Boson: Where We Are, Where We re Going, and How To Get There Seth Zenz, Imperial College London University College London High Energy Physics Seminar

2 Foreword: Higgs Discovery I think we did it! We have a discovery. July 4, 01 S. Zenz - Higgs Seminar

3 Foreword: Higgs Discovery As a layman, we have it, but as a scientist, we have to find out what sort of Higgs boson it is. July 4, 01 S. Zenz - Higgs Seminar 3

4 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? S. Zenz - Higgs Seminar 4

5 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? 008 S. Zenz - Higgs Seminar 5

6 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? At high transverse momenta... these processes can be recovered as promising search channels for the standard model Higgs boson around 10 GeV in mass. employing state-of-the-art jet reconstruction and decomposition techniques S. Zenz - Higgs Seminar 6

7 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? employing state-of-the-art jet reconstruction and decomposition techniques S. Zenz - Higgs Seminar 7

8 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? employing state-of-the-art jet reconstruction and decomposition techniques X ZZ llqq CMS-PAS-HIG6-034 JHEP 07 (017) 001 X tt lepton+jets or fully hadronic Phys. Lett. B 777 (017) 91 X VV qqqq S. Zenz - Higgs Seminar 8

9 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? At high transverse momenta... these processes can be recovered as promising search channels for the standard model Higgs boson around 10 GeV in mass S. Zenz - Higgs Seminar 9

10 Preface: Climbing the Peaks How do we get from discovery to measurement? How do we get from ideas to finished analyses? At high transverse momenta... these processes can be recovered as promising search channels for the standard model Higgs boson around 10 GeV in mass. uses well-separated standard jets only S. Zenz - Higgs Seminar

11 Preface: Climbing the Peaks Even if we know exactly where we re going How will we get there? And what will we learn along the way? Björn Dr. Bear Penning S. Zenz - Higgs Seminar 11

12 Preface: Climbing the Peaks Even if we know exactly where we re going How will we get there? And what will we learn along the way? Phys. Rev. Lett. 10 (018) Gluon-gluon fusion! Björn Dr. Bear Penning S. Zenz - Higgs Seminar 1

13 Outline The Higgs, the Standard Model, and the Large Hadron Collider Compact Muon Solenoid detector (as an example) Higgs Properties Analysis Strategy Production and decay modes Overview of H ɣɣ (as an example) Where we are: what sort of Higgs Boson is it? Production and decay Differential measurements Where we re going: the High Luminosity LHC (05 and beyond) Analysis projections and measurements Higgs trilinear couplings How to get there, and what can we learn along the way? Measurements for Run (0158) and Run 3 (01-3) Stepping stones toward the HL-LHC S. Zenz - Higgs Seminar 13

14 Higgs in the Standard Model l l l Previously known: all Standard Model (SM) quarks, leptons, and vector bosons SM BEH Mechanism solves two possiblyseparate problems l Electroweak symmetry breaking l Fermion masses With Higgs mass known, SM predicts everything else! S. Zenz - Higgs Seminar 14

15 Large Hadron Collider l p-p, Pb-Pb, p-pb l p-p: s = 7-8 TeV, now 13 TeV, ultimately ~14 TeV l Design luminosity: ~ 34 cm - s l Run 1: l Run : LHCb CMS ATLAS ALICE S. Zenz - Higgs Seminar 15

luminosity: ~ 34 cm - s l Run 1: 7.7 33 l Run :.

16 Large Hadron Collider l p-p, Pb-Pb, p-pb l p-p: s = 7-8 TeV, now 13 TeV, ultimately ~14 TeV l Design luminosity: ~ 34 cm - s l Run 1: l Run : LHCb CMS ATLAS ALICE S. Zenz - Higgs Seminar 16

17 Compact Muon Solenoid S. Zenz - Higgs Seminar 17

18 Object Reconstruction in CMS S. Zenz - Higgs Seminar 18

19 Luminosity S. Zenz - Higgs Seminar 19

20 SM Higgs Boson Production σ(pp H+X) [pb] 1 pp H (NNLO+NNLL QCD + NLO EW) pp qqh (NNLO QCD + NLO EW) pp WH (NNLO QCD + NLO EW) pp ZH (NNLO QCD + NLO EW) pp bbh (NNLO and NLO QCD) Production LHC HIGGS XS WG 014 ggh tth pp tth (NLO QCD) M H = 15 GeV MSTW s [TeV] VBF VH Illustration: FNAL S. Zenz - Higgs Seminar 0

21 Higgs Decay Modes σ(pp H+X) [pb] pp H (NNLO+NNLL QCD + NLO EW) pp qqh (NNLO QCD + NLO EW) Production LHC HIGGS XS WG pp WH (NNLO QCD + NLO EW) pp ZH (NNLO QCD + NLO EW) pp bbh (NNLO and NLO QCD) pp tth (NLO QCD) = 15 GeV MSTW s [TeV] M H Decay S. Zenz - Higgs Seminar 1

22 Higgs Channels: Analysis l l Complete detector signature created by the Higgs decay and the decay products of particles from the production process Which analyses are possible? l Rate of detector signature l Rate of backgrounds l Tools for background rejection S. Zenz - Higgs Seminar

H ɣɣ Overview Maximize Signal-to-Background using mass: m γγ = E1E(1 - cosδα) Some photons have better energy resolutions than others Barrel Well-contained Avoid cracks in detector

23 H ɣɣ Overview Maximize Signal-to-Background using mass: m γγ = E1E(1 - cosδα) Some photons have better energy resolutions than others Barrel Well-contained Avoid cracks in detector Categorize events by resolution to maximize Signal-to-Background CMS-PAS-HIG5-005 Best Run 1 Category σ = 1.05 GeV Worst Category σ =.6 GeV Eur. Phys. J. C 74 (014) 3076 S. Zenz - Higgs Seminar 3

24 H ɣɣ Categorization Events/ CMS Preliminary 35.9 fb (13TeV) Data Simulation background jet jet γ jet γ γ MC stat. uncert. SM H γγ, m =15 GeV H ggh VBF VH tth Events / CMS Preliminary 35.9 fb (13 TeV) Data Sidebands VBF (m =15 GeV) H ggh (m =15 GeV) H 4 3 CMS-PAS-HIG Transformed score of the diphoton BDT Transformed score of the VBF Combined BDT Classifier BDT s independent of m ɣɣ fit in next step S. Zenz - Higgs Seminar 4

25 H ɣɣ Categorization CMS Preliminary H γγ 35.9 fb (13 TeV) Untagged 0 ggh VBF tth bbh thq thw WH hadronic WH leptonic ZH hadronic ZH leptonic 45.8 expected events σeff σhm S/(S+B) Untagged 1 Untagged Untagged 3 VBF 0 VBF 1 VBF tth Hadronic tth Leptonic ZH Leptonic WH Leptonic VH LeptonicLoose VH Hadronic VH MET expected events expected events 6.1 expected events.0 expected events 8.6 expected events 7.8 expected events 5.8 expected events 3.8 expected events 0.5 expected events 3.6 expected events.8 expected events 9.7 expected events 4. expected events Signal Fraction (%) Width (GeV) S/(S+B) in ± σeff Classifier BDT s independent of m ɣɣ fit in next step S. Zenz - Higgs Seminar 5

26 -- Signal extraction Events / GeV CMS Preliminary H γγ m H =15.4 GeV, µ= fb (13 TeV) Untagged 0 Data S+B fit B component ±1 σ ± σ Events / GeV CMS Preliminary H γγ m H =15.4 GeV, µ= fb (13 TeV) Untagged 3 Data S+B fit B component ±1 σ ± σ Events / GeV CMS Preliminary H γγ m H =15.4 GeV, µ= fb (13 TeV) VBF Tag 0 Data S+B fit B component ±1 σ ± σ Events / GeV B component subtracted CMS Preliminary H γγ m H =15.4 GeV, µ=1.16 m γγ (GeV) 35.9 fb (13 TeV) tth Leptonic Tag Data S+B fit B component ±1 σ ± σ Events / GeV B component subtracted CMS Preliminary H γγ m H =15.4 GeV, µ=1.16 m γγ (GeV) 35.9 fb (13 TeV) VHMetTag Data S+B fit B component ±1 σ ± σ Events / GeV 0 8 B component subtracted (GeV) CMS Preliminary H γγ m H =15.4 GeV, µ=1.16 m γγ 35.9 fb (13 TeV) ZHLeptonicTag Data S+B fit B component ±1 σ ± σ B component subtracted (GeV) m γγ B component subtracted m γγ (GeV) 0 4 B component subtracted m γγ (GeV) S. Zenz - Higgs Seminar 6

27 Beyond Discovery -- Events / GeV CMS H γγ Preliminary m H =15.4 GeV, µ= fb All categories Data S+B fit B component ±1 σ ± σ (13 TeV) 600 B component subtracted m γγ (GeV) In 01, discovering the Higgs required a sophisticated simultaneous fit of all decay and production modes across entire experiments Now we can just add up one decay mode naively and see a clear peak Or we can apply our sophisticated fits to measure the properties of the Higgs boson S. Zenz - Higgs Seminar 7

28 Outline The Higgs, the Standard Model, and the Large Hadron Collider Compact Muon Solenoid detector (as an example) Higgs Properties Analysis Strategy Production and decay modes Overview of H ɣɣ (as an example) Where we are: what sort of Higgs Boson is it? Production and decay Differential measurements Where we re going: the High Luminosity LHC (05 and beyond) Analysis projections and measurements Higgs trilinear couplings How to get there, and what can we learn along the way? Measurements for Run (0158) and Run 3 (01-3) Stepping stones toward the HL-LHC S. Zenz - Higgs Seminar 8

29 H ɣɣ Run Results (so far) µ ggh µ VBF µ tth µ VH ggh VBF tth CMS Preliminary H γγ CMS Preliminary H γγ Combined ± 1σ Per process ± 1σ µ=µ SM µ = 1.16 combined 0.14 profiled m H profiled m H 35.9 fb (13 TeV) µ 35.9 fb (13 TeV) Per process ± 1σ SM Prediction κ f κ g CMS CMS Best Fit 1σ σ SM Preliminary m H profiled Preliminary 35.9 fb ( κ V 35.9 fb (13 m H profiled Best Fit 1σ σ SM TeV) TeV) q(κ V,κ f ) q(κ γ,κ g ) WH leptonic ZH leptonic VH hadronic σ proc / σ theo κ γ 4 0 S. Zenz - Higgs Seminar 9

30 Fiducial and differential With simplified resolution classification, we can also bin H ɣɣ events in event shape variables Further test of SM predictions (fb/gev) γγ dσ fid /dp T Ratio to amc@nlo + HX CMS Preliminary 35.9 fb (13TeV) H γ γ Data LHC HXSWG YR4, m =15.09 GeV H ggh amc@nlo + HX ggh POWHEG + HX HX amc@nlo γ γ ) dp γ γ (p T T fid σ.5 γγ p [GeV] T γ γ p T (GeV) (fb) dσ fid /dn j 3 Ratio to amc@nlo + HX CMS-PAS-HIG7-015 CMS Preliminary 35.9 fb (13TeV) H γ γ Data LHC HXSWG YR4, m =15.09 GeV H ggh amc@nlo + HX ggh POWHEG + HX HX amc@nlo N j ( η <.5) j N j ( η <.5) j CMS-PAS-HIG6-00 S. Zenz - Higgs Seminar 30

31 SM: The Whole Picture tth ZH WH VBF ggh γγ ZZ WW ττ bb γγ ZZ WW ττ γγ ZZ WW bb γγ ZZ WW bb γγ ZZ WW ττ bb CMS Preliminary 35.9 fb (13 TeV) Observed 1σ interval µ f i CMS-PAS-HIG7-031 S. Zenz - Higgs Seminar 31

32 By Production and Decay µ ggh CMS Preliminary 35.9 fb (13 TeV) Observed ±1σ (stat. sys.) ±1σ (sys.) ±σ γ γ µ CMS Preliminary 35.9 fb (13 TeV) Observed ±1σ (stat. sys.) ±1σ (sys.) ±σ µ VBF µ WH µ ZZ µ ZH µ tth µ WW µ ττ µ µ bb Parameter value Parameter value S. Zenz - Higgs Seminar 3

33 Benchmark Model Fits CMS Preliminary 35.9 fb (13 TeV) CMS Preliminary 35.9 fb (13 TeV) Observed 1σ interval κ F κ Z σ interval κ W 1.5 κ t κ τ 1 κ b κ g 0.5 H bb H ZZ H ττ H γγ Best fit SM expected κ γ H WW Combined 1 σ region σ region B inv κ V B undet Parameter value S. Zenz - Higgs Seminar 33

ATLAS-CMS Run 1Combination Phys. Rev. Lett. 114 (015) 191803 J. High Energy Phys.

34 ATLAS-CMS Run 1Combination Phys. Rev. Lett. 114 (015) J. High Energy Phys. 08 (016) 045 For the word s best Higgs measurements, use all available data from the LHC! Which mass uncertainty is not like the others? S. Zenz - Higgs Seminar 34

35 Outline The Higgs, the Standard Model, and the Large Hadron Collider Compact Muon Solenoid detector (as an example) Higgs Properties Analysis Strategy Production and decay modes Overview of H ɣɣ (as an example) Where we are: what sort of Higgs Boson is it? Production and decay Differential measurements Where we re going: the High Luminosity LHC (05 and beyond) Analysis projections and measurements Higgs trilinear couplings How to get there, and what can we learn along the way? Measurements for Run (0158) and Run 3 (01-3) Stepping stones toward the HL-LHC S. Zenz - Higgs Seminar 35

36 The HL-LHC High luminosity LHC will collect up to 3000 fb starting in 05 Critical challenge: maintaining performance with 140 pileup arxiv: High pileup run: 78 reconstructed vertices S. Zenz - Higgs Seminar 36

37 H ɣɣ at HL-LHC CMS-PAS-FTR6-00 Extremely precise H ɣɣ HL-LHC fiducial cross section projection we can do very finely binned differential measurements S. Zenz - Higgs Seminar 37

38 Di-Higgs Events/(1.0 GeV) Grav. m X = 300 GeV VH(γγ) Data CMS Preliminary 35.9 fb (13 TeV) Rad. m X = 600 GeV SM HH (x5000) VBF H(γγ) ggh(γγ) Stat. Uncert. bbh(γγ) tth(γγ) Events/(3.0 GeV) 8 = 300 GeV VH(γγ) Data CMS Preliminary 35.9 fb (13 TeV) Grav. m X Rad. m X = 600 GeV SM HH (x5000) VBF H(γγ) ggh(γγ) Stat. Uncert. bbh(γγ) tth(γγ) M(γγ) [GeV] 1 With 016 data, HH bbɣɣ cross section limit (95% CL) less than 19. times the SM 3000 fb is about the right amount of data to measure the SM prediction! M(jj) [GeV] σ(pp HH) B(HH bbγ γ) [fb] CMS Preliminary 35.9 fb (13 TeV) pp HH bbγγ c g = c g = c = 0 Observed 95% C.L. limit Expected 95% C.L. limit Expected ± 1σ Expected ± σ CMS-PAS-HIG7-008 = 1) Theory Prediction (κ t = ) Theory Prediction (κ t κ λ /κ t S. Zenz - Higgs Seminar 38

39 Higgs Trilinear coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions F Maltoni, D Pagani, A Shivaji, X Zhao Eur. Phys. J. C (017) 77: 887 S. Zenz - Higgs Seminar 39

40 Higgs Trilinear coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions F Maltoni, D Pagani, A Shivaji, X Zhao Eur. Phys. J. C (017) 77: 887 S. Zenz - Higgs Seminar 40

41 Higgs Trilinear coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions F Maltoni, D Pagani, A Shivaji, X Zhao Eur. Phys. J. C (017) 77: 887 S. Zenz - Higgs Seminar 41

42 Higgs Trilinear Coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions What if we combine these constraints with di-higgs searches, or even do a broader electroweak fit? How much data do we really need to tightly constrain the Higgs trilinear coupling? S. Zenz - Higgs Seminar 4

Higgs Trilinear Coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions What if we combine these constraints with di-higgs searches,

43 Higgs Trilinear Coupling Non-SM trilinear coupling also changes single Higgs cross sections, including changing differential distributions What if we combine these constraints with di-higgs searches, or even do a broader electroweak fit? How much data do we really need to tightly constrain the Higgs trilinear coupling? Should we be thinking bigger and measuring a range of Effective Field Theory (EFT) parameters? Electroweak LHC Higgs Run 1+ arxiv: S. Zenz - Higgs Seminar 43

44 Outline The Higgs, the Standard Model, and the Large Hadron Collider Compact Muon Solenoid detector (as an example) Higgs Properties Analysis Strategy Production and decay modes Overview of H ɣɣ (as an example) Where we are: what sort of Higgs Boson is it? Production and decay Differential measurements Where we re going: the High Luminosity LHC (05 and beyond) Analysis projections and measurements Higgs trilinear couplings How to get there, and what can we learn along the way? Measurements for Run (0158) and Run 3 (01-3) Stepping stones toward the HL-LHC S. Zenz - Higgs Seminar 44

New Properties to Measure in Run and 3 Run SM Higgs analyses must be adapted for improved properties measurements Example idea being implemented: Simplified Higgs Template Cross Sections Extract

45 New Properties to Measure in Run and 3 Run SM Higgs analyses must be adapted for improved properties measurements Example idea being implemented: Simplified Higgs Template Cross Sections Extract μ-like cross section scalings in defined phase space(s) Reduce theory uncertainties More precisely targeted as more data become available Other frameworks: expanded κ s, Effective Field Theory parameters What s the best approach for experiment to communicate with theory? Handbook of LHC Higgs Cross Sections: 4. Deciphering the Nature of the Higgs Sector, arxiv: S. Zenz - Higgs Seminar 45

46 STXS Stage 1 STXS Regions bbh thw thq tth V gg Hll ( 1-jet, p T 150 GeV) V gg Hll (0-jet, p T 150 GeV) V gg Hll (p T < 150 GeV) V qq Hll (p T 50 GeV) V qq Hll ( 1-jet, 150 p T < 50 GeV) V qq Hll (0-jet, 150 p T < 50 GeV) V qq Hll (p T < 150 GeV) V qq Hlν (p T 50 GeV) V qq Hlν ( 1-jet, 150 p T < 50 GeV) V qq Hlν (0-jet, 150 p T < 50 GeV) V qq Hlν (p T < 150 GeV) j qq Hqq (p T 00 GeV) qq Hqq (rest) qq Hqq (VH) qq Hqq (VBF-like, 3-jet) qq Hqq (VBF-like, 3-jet veto) ggh (VBF-like, 3-jet) ggh (VBF-like, 3-jet veto) H ggh ( -jet, p T 00 GeV) H ggh ( -jet, 10 p T < 00 GeV) H ggh ( -jet, 60 p T < 10 GeV) H ggh ( -jet, p T < 60 GeV) H ggh (1-jet, p T 00 GeV) H ggh (1-jet, 10 p T < 00 GeV) H ggh (1-jet, 60 p T < 10 GeV) H ggh (1-jet, p T < 60 GeV) ggh (0-jet) ATLAS Simulation H γ γ, m = GeV ggh 0J CEN ggh 0J FWD ggh 1J LOW ggh 1J MED ggh 1J HIGH ggh 1J BSM ggh J LOW ggh J MED ggh J HIGH ggh J BSM VBF loose, low p Hjj T VBF tight, low p Hjj T VBF loose, high p Hjj T VBF tight, high p Hjj T VH had loose VH had tight jet BSM VH MET LOW VH MET HIGH VH lep LOW VH lep HIGH VH dilep th had 4jb th had 4j1b tth had BDT4 tth had BDT3 tth had BDT tth had BDT1 tth lep th lep 1fwd th lep 0fwd H Category Region Purity / Category arxiv: S. Zenz - Higgs Seminar 46

47 Stepping Stones: STXS Bin Merging Process Measurement region Particle-level stage region ggh + gg! Z(! qq)h 0-jet 0-jet 1-jet, p H T < 60 GeV 1-jet, p H T < 60 GeV 1-jet, 60 apple p H T < 10 GeV 1-jet, 60 apple p H T < 10 GeV 1-jet, 10 apple p H T < 00 GeV 1-jet, 10 apple p H T < 00 GeV 1-jet, p H T > 00 GeV 1-jet, p H T > 00 GeV -jet, p H T > 00 GeV -jet, p H T < 00 GeV or VBF-like -jet, p H T < 60 GeV -jet, 60 apple p H T < 10 GeV -jet, 10 apple p H T < 00 GeV VBF-like, p Hjj T < 5 GeV VBF-like, p Hjj T 5 GeV qq 0! Hqq 0 (VBF + VH) p j T < 00 GeV pj T < 00 GeV, VBF-like, phjj T < 5 GeV p j T < 00 GeV, VBF-like, phjj T 5 GeV p j T < 00 GeV, VH-like p j T < 00 GeV, Rest p j T > 00 GeV pj T > 00 GeV VH (leptonic decays) VH leptonic q q! ZH, p Z T < 150 GeV q q! ZH,150<p Z T < 50 GeV, 0-jet q q! ZH,150<p Z T < 50 GeV, 1-jet q q! ZH, p Z T > 50 GeV q q! WH, p W T < 150 GeV q q! WH,150<p W T < 50 GeV, 0-jet q q! WH,150<p W T < 50 GeV, 1-jet q q! WH, p W T > 50 GeV gg! ZH, p Z T < 150 GeV gg! ZH, p Z T > 150 GeV, 0-jet gg! ZH, p Z T > 150 GeV, 1-jet Top-associated production top t th W -associated th (thw ) t-channel th (thq) b bh merged w/ ggh b bh STXS bins as initially defined are tough to measure! Limited statistics Sometimes hard to separate even in principle arxiv: S. Zenz - Higgs Seminar 47

48 Stepping Stones: Double-differential Distributions / dp T fid ATLAS H, s = 13 TeV, 36.1 fb Data, tot. unc. Syst. unc. gg H default MC + XH XH = VBF+VH +tth+bbh d 1 1 With HL-LHC data, we can provide decent measurements of double-differential distributions First examples arriving Future binning not mapped out (yet) what will the impact really be? Goal at each step is to give the finest binning that has a meaningfully small statistical and expert arxiv: / dp XH Ratio to default MC + T fid d XH Ratio to default MC p T [GeV] N = 0 N = 1 N = 3 jets jets ATLAS H, s = 13 TeV, 36.1 fb Data, tot. unc. Syst. unc. 1 0 p T [GeV] gg jets H default MC + XH XH = VBF+VH +tth+bbh N jets cos( *) < cos( *) < 1.0 S. Zenz - Higgs Seminar 48

49 Conclusions Many ways to use make precision measurements of SMlike Higgs properties and potential deviations Cross sections (differential, STXS, ) Fits to parameters that modify the SM (κ s, EFT s) Related approaches would take several more seminars Direct searches for BSM Higgs bosons SM Higgs bosons in BSM events Fits for parameters in specific BSM models (e.g. HDM) More fundamental work: detector upgrades, reconstruction, and reducing systematics Which ideas will bear fruit, and when? All we can do is try, and find out! My prediction: whatever precision we need, the right combination of state-of-the-art techniques will get us there before our current projections suggest Higgs looks like the Standard Model, but stay tuned... κv S. Zenz - Higgs Seminar 49 κ F CMS Preliminary H bb H ZZ H WW H ττ H γγ Combined Best fit 35.9 fb (13 TeV) SM expected 1 σ region σ region

The Compact Muon Solenoid Experiment. Conference Report. Mailing address: CMS CERN, CH-1211 GENEVA 23, Switzerland

The Compact Muon Solenoid Experiment. Conference Report. Mailing address: CMS CERN, CH-1211 GENEVA 23, Switzerland Available on CMS information server CMS CR -08/036 he Compact Muon Solenoid Experiment Conference Report Mailing address: CMS CERN, CH GENEVA 3, Switzerland 30 April 08 (v4, 08 May 08) Measurement of the