Top Quark Mass Measurements at the Tevatron. Gianluca Petrillo (for the CDF and DØ collaborations) University of Rochester

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1 Top Quark Mass Measuremens a he Tevaron Gianluca Perillo (for he CDF and DØ collaboraions) Universiy of Rocheser March 13 h, 013, Renconres de Moriond: QCD and High Energy Ineracions CDF G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

2 Ouline 1 Top quark and is mass Mehods of measuremen 3 Measuremens l+jes final sae /E T +jes final sae 4 Tevaron combinaion 5 Summary G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, 013 / 4

3 The op quark and is mass op quark is he heavies among he observed paricles i can be measured direcly: i decays before hadronizing is mass, m, is a free parameer of Sandard Model: presen in loop correcions of W mass wih, W and H masses, he SM predicions are severely esed a precise measuremen helps undersanding our models [GeV] M W M W M H =50 GeV 68% and 95% CL fi conours w/o M W and m measuremens 68% and 95% CL fi conours w/o M W, m and M H measuremens world average ± M H =15.7 1σ M H =300 GeV M H =600 GeV Tevaron average m [GeV] Global fi of measuremens in he SM [1] W b kin m W ± 1σ G fier SM Sep 1 G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

4 Experimenal signaures Top quarks are produced by srong ineracion in pairs. Each decays ino a quark and a W boson: final sae deermined by W decays: di-lepon exremely pure, low rae, no fully reconsruced l+jes compromise: good puriy, one fully reconsruced all-je large background, wo fully reconsruced he quark is almos always a b quark: jes from b conain long-lived B hadrons heir feaures can ofen be idenified in he je we call such jes b-agged q q elecron+jes muon+jes au+jes eτ µτ ττ eµ µµ µτ ee eµ eτ dilepons b q q ν l l b all-hadronic au+jes muon+jes elecron+jes G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

5 Measuremen mehod The measuremens of op mass goes hrough some common seps: 1 assign a likelihood for each even, funcion of he op mass: L i (m ;...) maximize a global likelihood L (m ;...) = i evens L i (m ;...), including all he evens, o exrac he m esimaor 3 calibrae o remove any bias of he mehod ) Residual (GeV/c 0 Residuals: MET+Jes Evens par0: ± par1: 0.07 ± M op (GeV/c ) Calibraion curve of m from CDF measuremen from 8.7 fb 1 in /E T +jes our analyses are calibraed on Mone Carlo simulaion we measure m wih he definiion implemened in MC! he precision of he experimenal measuremens helps he inerpreaion of his parameer (cfr. PRD 80, (009)) G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

6 Mehods: Marix Elemen Marix Elemen mehod explois he full opology of he even: P (x, m ) = 1 f (q 1 ) f (q ) σ (y, m ) W (x, y) dq 1 dq dy σ (m ) flavours scaering marix elemen (in σ) for a final-sae paron configuraion y (including 4-momena of all he 6 final sae paricles) probabiliy f ( q 1/ ) of having a specific iniial sae (Paron Disribuion Funcions) p p jes, lepon, /E T probabiliy W of reconsrucing he scaering final sae y as our measured jes/lepon objecs x (Transfer Funcions) G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

7 Mehods: emplaes ) Templaes mehod inerpres he disribuion of one or more observables sensiive o m as probabiliy densiies: disribuions are exraced from full deecor simulaion correlaions beween observables can be included up o hree observables used Fracion of Evens/(.5 GeV/c rec m emplaes, ags evens ( JES = 0.0) M op M op M op rec P s(m = = 17.5 = M, JES) op rec m [GeV/c ] m emplae (CDF measuremen from 5.8 fb 1 in all-hadronic final sae) m vs. m jj emplae (m =171.5 GeV/c ) from CDF measuremen from 8.7 fb 1 in l+jes G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

8 in siu Je Energy Scale Calibraion ) in some final saes, W boson can be fully reconsruced consrain a m W esimaor wih he known W mass nuisance parameer JES is measured, describing an addiional global scale of je energy diagram wih W q q Fracion of Evens/(.5 GeV/c rec m W emplaes, ags evens (M op = 17.5) JES =.0 JES = 0.0 JES =.0 rec P s(m W M op, JES) rec m W [GeV/c ] m jj emplae (CDF measuremen from 5.8 fb 1 in all-hadronic final sae, m =17.5 GeV/c ) G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

9 Exising measuremens Four experimens measure m ; mos precise resuls o dae: CDF CDF (Tevaron) l+jes, Marix Elemen on 5.6 fb 1 : ± 0.9 (sa.+jes) ± 0.9 (sys.) (rel: 0.7%) [] (updae in his alk!) DØ (Tevaron) l+jes, Marix Elemen on 3.6 fb 1 : ± 1.1 (sa.+jes) ± 1.0 (sys.) (rel: 0.85%) [3] Tevaron: CDF and DØ combinaion (July 01) From many channels, up o 5.8 fb 1 (updae in his alk!): m = ± 0.56 (sa.) ± 0.75 (sys) GeV/c (rel: 0.54%) [4] LHC combinaion (ATLAS and CMS) m =173.3 ± 0.5 (sa.) ± 1.3 (sys) GeV/c (rel: 0.8%) [5] G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

10 CDF measuremen: l+jes [PRL 109, (01)] The even selecion: l + one isolaed elecron or muon W + ν four or more jes sample spli according o he number of idenified b-jes up o 4 je-o-quark assignmen combinaions q q g W b b q' q Improvemens on he exising 5.6 fb 1 measuremen: full CDF daase: 8.7 fb 1 Je Energy Scale improved by an addiional calibraion based on mulivariae analysis addiion of he daa sample wih no idenified b-jes G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

11 CDF measuremen: l+jes resul [PRL 109, (01)] Templaes are buil wih hree observables (including correlaions): wo op mass esimaors, m reco and m reco(), from he wo mos -like combinaions 100 m jj, mass of he wo non-b-agged 50 jes which is closes o M W 0 (GeV/c ) CDF 8.7 fb 1 op mass from l+jes: 17.85±0.71 (sa.+jes)±0.85 (sys.)gev/c = ± 1.11 GeV/c (rel. 0.63%) ) Evens/(5 GeV/c CDF II Preliminary -1 Daa (8.7 fb ) Signal+Bkgd Bkgd only All reco m Leading uncerainies [ GeV/c ]: signal model 0.56 background shape 0.0 CDF II Preliminary 8.7 fb -0.4 M residual JES 0.5 b-jes 0.18 op (GeV/c ) (σ c) JES log(l) = log(l) =.0 log(l) = 4.5 G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

12 CDF measuremen: /E T +jes [CDF noe 10810] The final sae: four o six jes large ransverse momenum imbalance ( /E T ) Main differences w.r.. l+jes analyses: emplaes mehod adaped for missing W a leas one b-agged je is required a mulivariae discriminan enhances he puriy of he sample (o S:B = :1) CDF 8.7 fb 1 op mass from /E T +jes: ± 1.6 (sa.+jes) ± 0.9 (sys.) GeV/c = ± 1.9 GeV/c (rel. 1.1%) Evens/(16 GeV/c ) q q b (W ) b q q reco (GeV/c ) m -1 CDF II Preliminary (8.7 fb ) MET+ag jes: 4 jes Daa Background G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

13 Combinaion of mass measuremens A join CDF and DØ working group performs he combinaion of op quark measuremens: mass, producion cross secion and properies. using Bes Linear Unbiased Esimaor requires he knowledge of he correlaion of uncerainies beween measuremens a lo of care mus be aken in defining he sysemaic uncerainies sysemaic disribuions are assumed (symmeric) gaussian In selecing he measuremens among he 50 ha he collaboraions published, he focus is on precision and independence. G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

14 Measuremens included in he combinaion 1 resuls from he wo experimens are combined: ll+jes l+jes 0.1 fb fb 1, marix elemen CDF CDF 8.7 fb 1, emplaes 3.6 fb 1, marix elemen 1.9 fb 1, decay lengh CDF 0.1 fb fb 1, emplaes 5.6 fb 1, emplaes 5.3 fb 1, emplaes all jes 0.1 fb 1 CDF 5.8 fb 1, emplaes CDF 8.7 fb 1, wih /E T G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

15 Measuremens included in he combinaion 1 resuls from he wo experimens are combined: 15 Mass of he Top Quark March 013 (* preliminary) CDF-I dilepon ± (±10.30 ± 4.90) DØ-I dilepon ± 1.8 (±1.30 ± 3.60) CDF-II dilepon ± 3.79 (±.19 ± 3.09) DØ-II dilepon ±.76 (±.36 ± 1.44) CDF-I lepon+jes ± 7.36 (±5.10 ± 5.30) DØ-I lepon+jes ± 5.31 (±3.90 ± 3.60) CDF-II lepon+jes ± 1.11 (±0.5 ± 0.98) DØ-II lepon+jes ± 1.49 (±0.83 ± 1.4) CDF-I alljes ± (±10.00 ± 5.70) CDF-II alljes ±.07 (±1.43 ± 1.49) CDF-II rack ± 9.46 (±9.00 ±.90) CDF-II MET+Jes * ± 1.85 (±1.35 ± 1.6) G. Perillo (for CDF and DØ) Tevaron combinaion Top mass* measuremens a Tevaron ± 0.87 (±0.51 Moriond ± 0.71) QCD, March 13, / 4

16 March 013 combinaion [TeVcomb] uncerainies are spli in 14 caegories: je energy scale (7) signal modelling background modelling () modelling of reconsruced objecs () modelling of addiional p p ineracions calibraion mehod heir definiions are chosen in such a way ha hey are eiher uncorrelaed or fully correlaed beween measuremens Mass measuremens from Tevaron: March 013 combinaion m =173.0 ± 0.51 (sa.) ± 0.71 (sys.) GeV/c = ± 0.87 GeV/c (rel. 0.50%) Dominan uncerainies: Je Energy Scale and Signal Modelling G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

17 Summary and oulook 15 Mass of he Top Quark March 013 (* preliminary) CDF-I dilepon ± ) (±10.30 ± precision measuremen of he mass of op quark is sill imporan oday i is measured wih a precision of 0.50%! firs CDF measuremens wih he complee daase curren challenge: reducing sysemaic uncerainies measuremens are all consisen DØ-I dilepon ± ) (±1.30 ± CDF-II dilepon ± ) (±.19 ± DØ-II dilepon ± ) (±.36 ± CDF-I lepon+jes ± ) (±5.10 ± DØ-I lepon+jes ± ) (±3.90 ± CDF-II lepon+jes ± ) (±0.5 ± DØ-II lepon+jes ± ) (±0.83 ± CDF-I alljes ± ) (±10.00 ± CDF-II alljes ± ) (±1.43 ± CDF-II rack ± ) (±9.00 ± CDF-II MET+Jes * ± ) (±1.35 ± Tevaron combinaion * ± 0.87 (±0.51 ± 0.71) (± sa ± sys) CDF March' χ /dof ±.66 = 8.5/11 (±1.50 (67%) ±.0) m op (GeV/c ) G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

18 References o he measuremens described in his alk [CDFl+jes] The CDF Collaboraion, Precision Top-quark Mass Measuremen a CDF, PRL 109, (01), [arxiv: [hep-ex]] [CDF /E T +jes] The CDF Collaboraion, A Measuremen of Top Quark Mass Using MET + Jes Evens Wih Full CDF Daa Se 8.7 fb 1, CDF noe 10810, 05/16/01 [TeVcomb] The CDF Collaboraion, Combinaion of CDF and DØ resuls on he mass of he op quark using up o 8.7 fb 1 of p p collisions, CDF noe 10976, DØ noe 6381, March 013 G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

19 Oher references [1] from he GFier collaboraion, Sandard Model plos on Sepember 01 (hp://gfier.desy.de/sandard_model) [] The CDF Collaboraion, Top Quark Mass Measuremen in he lepon+jes Channel Using a Marix Elemen Mehod and in siu Je Energy Calibraion, PRL 105, 5001 (010) [arxiv: [hep-ex]] [3] The DØ Collaboraion, Precise measuremen of he op-quark mass from lepon+jes evens a D0, PRD 84, (011) [arxiv: [hep-ex]] [4] The CDF and DØ Collaboraions, Combinaion of he op-quark mass measuremens from he Tevaron collider, PRD 86, (01) [arxiv: (v4) [hep-ex]] [5] The ATLAS and CMS Collaboraions, Combinaion of ATLAS and CMS resuls on he mass of he op quark using up o 4.9 fb 1 of daa, ATLAS-CONF , CMS-PAS-TOP-1-001, July 01 G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

20 CDF l+jes measuremen: combinaions and χ The four jes can be combined in he W and in differen ways; for each of hem, he quaniy: χ (m reco ) = jes ( p i,fi T ) p i,meas T σ i + (M jj M W ) Γ W + (M bjj m reco ) Γ + k=x,y + (M lν M W ) Γ W ( U fi k + (M blν m reco ) Γ ) Umeas k σk is minimized, where σ s and Γ s are experimenal resoluions and heoreical widhs, and M W = 80.4 GeV/c. je momenum and /E T are allowed o floa wihin heir resoluion he je energies are consrained by he known W mass he op mass esimaor m reco is aken from he minimizaion G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

21 CDF /E T +jes measuremen: combinaions and χ The four jes can be combined in he W and in differen ways; for each of hem, he quaniy: χ (m reco ) = jes ( p i,fi T ) p i,meas T σ i + (M jj M W ) Γ W + (M bjj m reco ) Γ + + k=x,y ( U fi k ( ) Mb,missing m reco Γ ) Umeas k σk is minimized, where σ s and Γ s are experimenal resoluions and heoreical widhs, and M W = 80.4 GeV/c. je momena are allowed o floa wihin heir resoluion he je energies are consrained by he known W mass he op mass esimaor m reco is aken from he minimizaion G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

22 Comparison of Tevaron and LHC combinaions Uncerainy Tevaron LHC [ GeV/c ] July 01 March 013 June 01 Measured m Saisical Sysemaic Toal G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

23 Sysemaic uncerainies of combinaion Uncerainy name Tevaron LHC CDF [ GeV/c ] July 01 March 013 June 01 l+jes In siu ligh-je calibraion Response o b/q/g jes n/a 0.09 Model for b-jes Ou-of-cone correcion n/a 0.1 Ligh-je response () Ligh-je response (1) Lepon modelling Signal modelling Je modelling Offse n/a Background from heory Background based on daa Calibraion mehod Muliple ineracions model G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, 013 / 4

24 Sysemaic uncerainies of combinaion (II) Differences beween LHC and Tevaron caegories: Response o b/q/g jes in LHC is shared by he b-je model and he ligh-je response () Ou-of-cone correcion in LHC is included in he ligh-je response () Ligh-je response () from uncerainies on he calibraion samples Ligh-je response (1) remaining JES uncerainies (excep ) Offse for Tevaron, his is RunI DØ uncerainy only; in LHC is from he modelling of he pile-up evens G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4

25 Sysemaic uncerainies of CDF l+jes measuremen l+jes /E T +jes Measured value Residual je energy scale Signal modelling Higher-order correcions 0.09 b-je energy scale b-agging efficiency 0.03 Iniial and final sae radiaion Paron disribuion funcions Gluon fusion fracion Lepon energy scale 0.03 Background shape Muliple hadron ineracion Colour reconnecion MC saisics 0.05 Trigger simulaion 0.1 Calibraion 0. Toal sysemaic Toal saisical G. Perillo (for CDF and DØ) Top mass measuremens a Tevaron Moriond QCD, March 13, / 4