First 13 TeV results from CMS

Transcription

1 First 3 TeV results from Ferenc Siklér Wigner RCP, Budapest for the Collaboration ISMD 5, Wildbad Kreuth 9 Oct 5

2 Introduction pp at s = 3 TeV First physics basics, QCD d/dη of charged hadrons 55 k and 7 k events two-particle angular correlations, ridge 7 nb Top physics very first look t t and single top production 4 pb dilepton or lepton+jet inclusive and/or differential ew physics? very first look search for narrow resonances using dijets 4 pb All new! Ferenc Siklér: First 3 TeV results from

3 First physics basics, QCD Ferenc Siklér: First 3 TeV results from 3

4 Charged hadrons d/dη Why? most basic physical observables in high-energy particle collisions essential first step in exploring the physics of a new energy regime combination of perturbative and nonperturbative QCD: saturation of parton densities, multiparton interactions, parton hadronization, and soft diffractive scattering How to measure? special circumstances: no magnetic field (cryo problem at ) trigger on incoming proton bunches from LHC (inelastic) use 3D hits in the silicon tracker look for hit pairs at different radii (tracklets) look for hits on straight lines (tracking) Unusual conditions technically challenging measurement Ferenc Siklér: First 3 TeV results from 4

5 Charged hadrons the silicon tracker Layers with 3D hits double-sided strip modules very preliminary May: quiet beams, pixel detector off, low pile-up pixel modules final result 7 June: ±3σ beam separation, very low pile-up Ferenc Siklér: First 3 TeV results from 5

6 Charged hadrons strip hits hit pairs Tracklets they are used to reconstruct the position of the primary vertex combinatorial background estimated from the sideband region ( < φ < ) efficiency down to 5 MeV/c in p T charged particle multiplicity from the height of the ( η, φ) correlation peak DP-5/ Ferenc Siklér: First 3 TeV results from 6

7 Charged hadrons strip hits straight lines Event 3 probability y [cm] Pythia8 CUETP8M - z [cm] reco d simu at µ reco d data mean of Poissonian µ =.3 ±.9 3 number of reconstructed vertices x [cm] Tracking transform (x, y, z) coordinates to (η, φ) agglomerative clustering with fp search fit them to a straight-line model vertexing: cluster tracks using fitted (z, σ z ) estimate pile-up from data, with help of simulated response DP-5/ Ferenc Siklér: First 3 TeV results from 7

8 Charged hadrons strip hits very preliminary / ev d/dη very preliminary pp s = 3 TeV inelastic tracking tracklets Pythia8 CUETP8M -3-3 η d/dη η very preliminary ISR UA5 PHOBOS ALICE parabolic extrapolation in ln(s) 3 4 s [GeV] pp inelastic The raw d/dη is corrected using a Pythia8 tune, bin-by-bin The typical size of the correction at midrapidity is -3% Averaged inelastic d/dη from tracklet and tracking Estimated 7% systematic uncertainty DP-5/ Ferenc Siklér: First 3 TeV results from 8

9 Charged hadrons pixel hits hit pairs fraction of tracklets η pp s = 3 TeV data PYTHIA8 CUETP8M fraction of tracklets φ pp s = 3 TeV data PYTHIA8 CUETP8M Pixel hits on three barrel layers: much better position resolution, close Sharp correlation peak at ( η, φ) =, nice match with simulation Combinatorial background estimated from the sideband region ( < φ < ) arxiv:57.595, PLB accepted Ferenc Siklér: First 3 TeV results from 9

10 Charged hadrons pixel hits tracking r [cm] Tracking only barrel layers are used search for hit pairs from layers and, with φ <. search for another hit from layer 3, with φ 3 <. select triplets on a straight line, with θ,3 <. clean them z [cm] Ferenc Siklér: First 3 TeV results from

11 Charged hadrons pixel hits tracking Pixel hits Event 3 5 y [cm] z [cm] x [cm] fraction.6 Pythia8 CUETP8M.5 γ z =.3 cm pixel-only z rec - z sim [cm] Straight lines excellent track-pointing very good vertex position resolution we are able to resolve multiple pp collisions within a bunch crossing Ferenc Siklér: First 3 TeV results from

12 Charged hadrons pixel hits tracking EPOS LHC EPOS LHC.8.8 tracking efficiency.6.4 tracking efficiency.6.4. pixel-only. pixel-only -3-3 η.5.5 p T [GeV/c] Very few duplicate tracks (-%), small number of fakes (3-6%) Checked both with Pythia8 and EPOS LHC How to estimate the number of inelastic collisions? Measured pile-up using detector response and a Poissonian model Ferenc Siklér: First 3 TeV results from

13 Charged hadrons pixel hits pile-up reco d simu at µ reco d data reco d simu at µ reco d data µ =.55 ±.3 µ =.545 ±. probability - -3 Pythia8 CUETP8M probability - -3 EPOS LHC number of reconstructed vertices pixel-only number of reconstructed vertices pixel-only Input Reconstructed 3 4 reco d Pythia8, one coll.35% 86.9%.7%.%.% reco d Pythia8, two colls.57% 3.8% 66.36%.3%.4% reco d Pythia8, three colls.7% 8.59% 37.35% 5.4%.65% reco d EPOS LHC, one coll 5.6% 83.54%.8%.%.% reco d EPOS LHC, two colls.3% 38.8% 58.%.44%.5% reco d EPOS LHC, three colls.39%.6% 4.% 4.73%.87% reco d data 95.5% 4.37%.%.%.% Ferenc Siklér: First 3 TeV results from 3

14 Charged hadrons pixel hits fraction pp s = 3 TeV data PYTHIA8 CUETP8M EPOS LHC number of reconstructed tracks d ch /dη pp s = 3 TeV inelastic tracklets tracks PYTHIA8 CUETP8M EPOS LHC η arxiv:57.595, PLB accepted Detailed studies on systematics: MC-dependence, mostly on the fraction of unseen events (diffraction) Multiplicity distribution closer to EPOS LHC Tracklet and tracking methods are compatible, they are averaged Ferenc Siklér: First 3 TeV results from 4

15 Charged hadrons d/dη result d ch /dη pp s = 3 TeV inelastic data PYTHIA8 CUETP8S EPOS LHC -3-3 η d ch /dη η < ALICE PHOBOS UA5 ISR PYTHIA8 CUETP8S EPOS LHC parabolic fit in ln(s) 3 4 s [GeV] pp inelastic Inelastic pp: d/dη η <.5 = 5.49 ±.(stat) ±.7(syst) It is consistent with Pythia8 (with tunes CUETP8S and CUETP8M), while for the full η range EPOS LHC gives a better description arxiv:57.595, PLB accepted Ferenc Siklér: First 3 TeV results from 5

16 Charged hadrons d/dη comparisons 8 7 unpublished pp s = 3 TeV inelastic /dη ch d 9 8 ALICE (IEL>) ALICE (IEL) (IEL) EPOS LHC PYTHIA 8 (Monash-3) PYTHIA 6 (Perugia-) d ch /dη 4 3 tracklets tracks hits PYTHIA8 CUETP8M EPOS LHC -3-3 η 6 5 pp, s = 3 TeV η with hit counting ALICE arxiv: Consistent with other alternative method (hit counting) Also compatible with measurement from others Ferenc Siklér: First 3 TeV results from 6

17 Charged hadrons angular correlations low multi high multi Preliminary pp offline trk < p T < 35 < 3 GeV/c s = 3 TeV (a) Preliminary pp offline trk < p T 5 < 3 GeV/c s = 3 TeV (b) pair d d η d φ trig φ (radians) η 3 4 pair d d η d φ trig φ (radians) Why and how? Various structures: jet peak, backward jet, and... the ridge η 3 4 PAS FSQ5- Long range η > ear side φ Ferenc Siklér: First 3 TeV results from 7

18 Charged hadrons angular correlations pair - C d d φ..5. < p <. GeV/c T Preliminary offline trk < 35 C =.75. < p <. GeV/c T. pp s = 3 TeV C =. pp s = 7 TeV pair - C d d φ.5. < p < 3. GeV/c T. C =.4 pair - C d d φ.5 3. < p < 4. GeV/c T C =.3 trig trig trig - C.5 offline 35 < 8 (35 trk offline trk < 9) C =.8.5 C =.43 - C.5 C =.8 3 C =.4 3 φ (radians) - C.5 φ (radians) d pair d φ d pair d φ d trig pair d φ trig trig pair - C d d φ pair - C d trig d φ trig.5.5 offline 8 < 5 (9 ( offline trk offline trk trk offline trk 5 ) < ) C = 3.8 pair - C d d φ.5 trig C = 4.77 pair - C d d φ trig 3 φ (radians).5 C =.93 pair - C d d φ.5 trig 3 C =.7 φ (radians) pair - C d d φ trig 3 φ (radians).5 C =.9 3 φ (radians) pair - C d d φ trig.5 3 C =.8 φ (radians) pair - C d d φ.5 trig 3 φ (radians) C =.6 3 φ (radians) 3 C =.9 φ (radians) 3 φ (radians) Correlation function vs φ, for several p T and offline trk settings Extract ridge yield with zero-yield-at-minimum procedure PAS FSQ5- Ferenc Siklér: First 3 TeV results from 8

19 Charged hadrons angular correlations Associated yield / (GeV/c).4. Preliminary pp pp s = 3 TeV, s = 7 TeV, Glasma+BFKL, Glasma+BFKL, 4 p T offline trk offline trk offline trk offline trk (GeV/c) 5, 3 TeV, 7 TeV (a). < p T Glasma+BFKL, 3 TeV Glasma+BFKL, 7 YeV <. GeV/c. < η < Associated yield shows maximum in the range < p T < GeV/c Approximately linear increase with multiplicity for offline trk 4 Gluon saturation models: these arise from initial collimated gluon emissions offline trk (b) PAS FSQ5- Ferenc Siklér: First 3 TeV results from 9

20 Charged hadrons angular correlations Associated yield / (GeV/c).. Preliminary PbPb ppb pp pp s s s s =.76 TeV = 5. TeV = 3 TeV = 7 TeV 3 offline trk. < η < 4.. < p T <. GeV/c Correlation strength is similar to that found in lower energy pp data, but is measured up to much higher multiplicity values Strong collision system size dependence (pp vs ppb vs PbPb) PAS FSQ5- Ferenc Siklér: First 3 TeV results from

21 Top production t t Why? great discovery potential for physics beyond the SM test of the production mechanism, dominated by gg fusion check the validity of QCD important source of background in searches for beyond the SM How to measure? t can decay leptonically: t W b (l ν) (b-jet) hadronically: t hadrons (two jets) both leptonic: one electron and one muon of opposite charge, and at least two jets in the final state leptonic+hadronic: one electron or one muon, and at least four jets in the final state Ferenc Siklér: First 3 TeV results from

22 Top production t t both leptonic umber of Events 4 pb (3 TeV) 8 e ± µ Data 6 4 Preliminary tt on W/Z VV tw ± Z/γ* e µ ± ± umber of Events 4 pb (3 TeV) 5 e ± µ Data Preliminary tt on W/Z 4 VV tw ± 3 Z/γ* e µ.7 ± ± Data/MC Data/MC umber of jets (GeV) H T umber of Events Data/MC 4 pb (3 TeV) 9 e ± µ + jets Data Preliminary tt 8 on W/Z 7 VV 6 tw 5 ± Z/γ* e µ ± Muon p (GeV) T ± umber of Events Data/MC 4 pb (3 TeV) 45 e ± µ + jets Data Preliminary tt 4 on W/Z 35 VV 3 tw ± Z/γ* e µ 5 5 ice significance 5.7 ± ± Muon η PAS TOP5-3 Ferenc Siklér: First 3 TeV results from

23 Top production t t both leptonic umber of Events 4 pb (3 TeV) 5 4 Preliminary e ± µ + jets Data tt on W/Z VV tw 3 ± Z/γ* e µ ± ± Data/MC M e ± µ ± (GeV) e ± µ probes the existence of a new heavy object decaying into a top quark pair PAS TOP5-3 Ferenc Siklér: First 3 TeV results from 3

24 Top production t t both leptonic cross section [pb] Inclusive tt 3 * Preliminary ) Tevatron combined*.96 TeV (L=8.8 fb dilepton 7 TeV (L=.3 fb ) l+jets 7 TeV (L=.3 fb ) dilepton 8 TeV (L=5.3 fb ) l+jets* 8 TeV (L=.8 fb ) LHC combined eµ* 8 TeV (L= fb eµ* 3 TeV (L=4 pb ) ) LO+LL (pp) Preliminary LO+LL (pp) Czakon, Fiedler, Mitov, PRL (3) 54 = 7.5 GeV, PDF α uncertainties according to PDF4LHC m top s [TeV] σ tt = 77 ± 6(stat) ± 6(syst) ± 93(lumi) pb In agreement with the expectations from the standard model = 83 ± 46 pb σ LO+LL tt S PAS TOP5-3 Ferenc Siklér: First 3 TeV results from 4

25 Top production t t leptonic+hadronic Events / GeV Preliminary 4 pb (3 TeV) l+jets data tt signal tt background Single top V+Jets QCD Events / 8 GeV 4 pb (3 TeV) 4 l+jets Preliminary data 35 tt signal 3 tt background Single top 5 V+Jets QCD Data/Sim p (tt) [GeV] T Data/Sim M(tt) [GeV] Events / GeV Data/Sim Preliminary 4 pb (3 TeV) l+jets data tt signal tt background Single top V+Jets QCD p (tt) (tt) [GeV] [GeV] T Events / 8 GeV Data/Sim 4 pb (3 TeV) 4 l+jets Preliminary data 35 tt signal 3 tt background Single top 5 V+Jets QCD M(tt) M(tt) [GeV] [GeV] σ tt = 836 ± 7(stat) ± 84(syst) ± (lumi) pb In good agreement with the theoretical expectation PAS TOP5-5 Ferenc Siklér: First 3 TeV results from 5

26 Top production t t cross section [pb] Inclusive tt 3 Tevatron combined*.96 TeV (L=8.8 fb eµ* 7 TeV (L=5 fb ) l+jets 7 TeV (L=.3 fb ) eµ* 8 TeV (L=9.7 fb ) l+jets* 8 TeV (L=.8 fb ) LHC combined eµ* 8 TeV (L= fb eµ* 3 TeV (L=4 pb ) l+jets* 3 TeV (L=4 pb ) * Preliminary ) ) 8 6 Preliminary LO+LL (pp) LO+LL (pp) Czakon, Fiedler, Mitov, PRL (3) 54 3 s [TeV] = 7.5 GeV, PDF α uncertainties according to PDF4LHC m top s [TeV] S Plotting both dilepton and lepton+jets channels Ferenc Siklér: First 3 TeV results from 6

27 Top production differential ] [GeV ) h (t dσ dp σ T theory data dσ d n-jet σ theory data 3 4 pb (3 TeV) 9 l+jets 8 Preliminary data sys stat 7 stat 6 Powheg Pythia8 Powheg Herwig++ 5 amc@lo Madgraph p (t ) [GeV] T h Preliminary 4 pb (3 TeV) l+jets data sys stat stat Powheg Pythia8 Powheg Herwig++ amc@lo Madgraph >=3 additional jets PAS TOP5-5 dσ σ GeV tt dp Theory Data T Preliminary 4 pb (3 TeV) Dilepton Data Powheg+Pythia8 Powheg+Herwig++ amc@lo+pythia8 MadGraph+Pythia8 Stat Stat. Syst. tt p GeV T tt p T Plots in several variables, agreement with theory GeV PAS TOP5 Ferenc Siklér: First 3 TeV results from 7

28 Top production t-channel single top Why and how? testing QCD and electroweak processes, specifically the twb vertex, and the CKM matrix element V tb select events with one muon in the final state (from t W µ or via t W τ µ decays) get signal from a fit to the η distribution of the (light) recoil jet Ferenc Siklér: First 3 TeV results from 8

29 Top production t-channel single top Events /.5 Data / MC jet -tag (SR) Preliminary Data 4 pb (3 TeV) t -channel tt, tw W/Z+jets QCD η j' Events /.5 Data / MC jet -tag Preliminary Data 4 pb (3 TeV) t -channel tt, tw W/Z+jets η j' PAS TOP5-4 Maximum likelihood fits Templates from simulation, normalized by data 3.5 σ observed significance, while.7 σ is expected Ferenc Siklér: First 3 TeV results from 9

30 Top production t-channel single top t -channel total cross section [pb] Preliminary LO+LL QCD ± (scale PDF) Kidonakis, Phys. Rev. D 83 () 953 Tevatron.96 TeV (L 9.7 fb ) arxiv: TeV (L =.7/.56 fb ) JHEP () 35 8 TeV (L = 9.7 fb ) JHEP 6 (4) 9 3 TeV (L = 4 pb ) -TOP5-4, preliminary s [TeV] σ t ch = 74 ± 98(stat) ± 5(syst) ± 33(lumi) pb V tb =. ±.4(exp) ±.(theo) In agreement with SM PAS TOP5-4 Ferenc Siklér: First 3 TeV results from 3

31 ew physics? very first look Ferenc Siklér: First 3 TeV results from 3

32 Exotica search for narrow resonances using dijets Event with a dijet mass of 5.4 TeV PAS EXO5 Ferenc Siklér: First 3 TeV results from 3

33 Exotica search for narrow resonances using dijets ormalized Yield / GeV (3 TeV) Simulation Preliminary WideJets η <.5 & η <.3 jj Quark-Quark Quark-Gluon Gluon-Gluon Dijet Mass [GeV] Expected mass spectra for qq, qg, and gg resonances (simulation) For resonance masses greater than 5 TeV this search is more sensitive than those done at s = 8 TeV PAS EXO5 Ferenc Siklér: First 3 TeV results from 33

34 Exotica search for narrow resonances using dijets 4 pb (3 TeV) [pb / GeV] dσ/ dm jj - Preliminary data background fit to data QCD MC q* (4.5 TeV) (Data-Fit)/σ η <.5, Δη <.3 M jj >. TeV Wide Jets Dijet Mass (GeV) Dijet Mass [GeV] Spectrum is well described by a smooth parameterization o evidence for new particle production PAS EXO5 Ferenc Siklér: First 3 TeV results from 34

35 Exotica search for narrow resonances using dijets A [pb] B σ Preliminary 4 pb (3 TeV) String Excited quark Axigluon/coloron Scalar diquark S8 W SSM Z SSM RS graviton (k/m=.) 95% CL upper limits gluon-gluon quark-gluon quark-quark Resonance mass [GeV] A [pb] B σ Preliminary 4 pb (3 TeV) Axigluon/coloron Scalar diquark W SSM Z SSM 95% CL upper limits Observed Expected ± σ ± σ qq resonance mass [GeV] Lower limits are set on the mass of string resonances, excited quarks, axigluons, colorons, scalar diquarks and color octet scalars PAS EXO5 Ferenc Siklér: First 3 TeV results from 35

36 final and preliminary results 3 TeV The full list pseudorapidity distribution two-particle angular correlations t t production, to e+µ+jets, incl t t production, to lepton+jets, incl+diff t t production, to dilepton+jets, diff t-channel single top-quark, incl narrow resonances using dijets arxiv:57.595, PLB PAS FSQ5- PAS TOP5-3 PAS TOP5-5 PAS TOP5 PAS TOP5-4 PAS EXO5 More to come: spectra, correlations, search for new physics (already > fb ) Thank you for your attention! Ferenc Siklér: First 3 TeV results from 36