R des 2 jets et HT des evenements

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1 R des 2 jets et HT des evenements
R: separation spatiale dans le plan x des 2 jets de plus grande impulsion transverse. On observe un bon accord entre les donnees et la simulation. Comparaison realisee avec la simulation Alpgen Loose Tight HT: somme des impulsions transverses des jets contenus dans l’evenement. On observe une discrimination entre les evenements Top et Wbb.

2 CDF: production W(en/mn)H(bb)
Selection des evenements : e/ central isole, pT > 20 GeV MET > 20 GeV Deux jets: ET > 15 GeV, || < 2 Veto Di-lepton, extra jet  Observe 2072 evenement dans Lint=162 pb-1 Demande au moins un jet etiquete  Observe 62 evenements de donnees  Attendu 61 ± 5 events Principal bruit de fond attendu : Attend 0.3 evts du Higgs Efficacite du signal ~ 1.8% pour MH = 110 – 130 GeV Mis-id Wc(c) Wbb QCD top 14 13 12 10 9

3 CDF: production W(en/mn)H(bb)
Determination de limite a 95% C.L. sur la section efficace du Higgs multiplie par le rapport d’embranchement : ×B < 5 pb Etudes systematiques Source Erreur(%) ISR / FSR 19 Vertex secondaire 8.6 Identification lepton 5 Calib. energie jets 3 PDF 1 Declenchement 0.7 Total 22 Depasse les resultats de CDF au Run I [PRL 79, 3819(1997)] ×B < 14 – 19 pb pour MH = 70 – 120 GeV

4 Les performances du tracking
reconstruction des : combinaison du tracking central et des chambres à  SMT: dE/dx possibilité d'identification des particules résolution du paramètre d'impact résolution: M(J /)=60 MeV/c2 (DCA)  16 PT = 10 GeV (DCA)  54 PT = 1 GeV bonne comparaison data/MC

5 L'échelle d'énergie des jets
erreur systématique principale pour de nombreuses analyses actuellement erreur conservatrice de 6-7% - objective: 2% (2.5% au RunI) Correction de l'énergie mesurée par: Offset: bruit électronique, bruit d'uranium, événement sous jacent événements zéro-biais et biais minimum (données) "out of cone showering": densité d'énergie autour du cône du jet (données) Réponse: Emeas/Edeposit  1 comparaison de l'énergie dans des événements  +jet (données)

6 La résolution des jets Jet pT Resolution N = 0.0  2.2,
Résolution des jets en pT: en utilisant l'asymétrie en pT dans des événements di-jet Jet pT Resolution la résolution est paramétrée par: N = 0.0  2.2, S =  0.045, C =  0.008 amélioration en cour par calibration en fonction de la fraction em!

7 Conclusion on Coarse Hadronic…
For zero and minimum bias events : at 1.5 the CH energy represents 29% of total scalar ET at 2.5 the CH energy represents 22% of total scalar ET For QCD events : at 1.5 the CH energy represents 21% of total scalar ET at 2.5 the CH energy represents 15% of total scalar ET Just adding more noise:    +4 GeV Coarse Hadronic With Coarse Hadronic Without Coarse Hadronic MET SET

8 DØ: W(en)bb production (1)
Motivation: Background to WH production Event selection Central isolated e, pT > 20 GeV Missing ET > 25 GeV ≥ two jets: ET > 20 GeV, |η| < 2.5 2587 evts. in Lint=174 pb-1 of data Simulations with Alpgen plus Pythia through detailed detector response Cross sections normalized to MCFM NLO calculations Good understanding of data

9 b-jet tagging Essential for Hbb searches
Can make use of the track impact parameter (IP) measurements or secondary vertex reconstruction CDF: performance of sec. vtx. algorithm (after kinematics cuts) ~50% b-tag efficiency for ~0.6% light quark mis-tag rate in |η| < 1 DØ in Run II is able to b-tag up to |η| < 2.5 Performance being improved b-tagging efficiency vs light quark mis-tag rate DØ RunII Preliminary Both experiments are demonstrating good b-tagging capabilities

10 Run / LBN Selection Final Luminosity: 174.3 pb-1 Selection:
 Bad Runs from the CAL, SMT, CFT are rejected. Events with bad luminosity blocks are rejected : Jet/Met lumi-blocks Ring of fire A few contiguous lumi-blocks in which there is high proportion of unphysical Scalar ET Before all this luminosity = 187 pb-1 (+7pb-1 summer 2002) Final Luminosity: pb-1

11 Zee for Calibration M(ee) 1 and 2 Tights Data compared to detailed simulation in which a gaussian smearing of 3.5% and a rescaling of +0.75% is applied to the electron energy. 130pb-1 di-em skim M(ee) 1 and 2 Tights

12 Tevatron: current and projected performance
36×36 bunches 396 ns bunch crossing design: challenging base: conservative FY’04 Integrated Luminosity 11/23/ /18/ /14/04 Measured luminosity 12 pb-1 / week is also above the design projection Start of Fiscal Year Integrated Luminosity (fb-1)

13 CDF: W(en/mn)H(bb) production (2)
Enrich the b-content of events Require at least one b-tagged jet  Observe 62 events in data  Expect 61 ± 5 events Main contributions to the bkgd: Expect 0.3 evts from Higgs Signal acceptance of ~ 1.8% for MH = 110 – 130 GeV Mistags Wc(c) Wbb QCD top 14 13 12 10 9 good agreement between data and MC

14 Résolution en masse du Higgs
Significativité en fonction de la résolution à Mhiggs=120 GeV Masse invariante bb : Résolution 15 % 10% Signal événements/fb-1 4 Wbb 59 32 WZ 11 6 tt 34 24 Top (électrofaible) 14 10 Pour 10 fb-1 Actuellement 12% de résolution pour un Higgs de 115 GeV.

15 Feynman  g

16 b-Tagging with JLIP, CSIP, SVX
Taggability is now common to the 3 algorithms: % in MC, % in data. What about tagging ? Medium or Tight criteria ? Jlip tight Csip t. Svx m. March

17 Correlations tight JLIP/tight CSIP
JLIP : 100 vs CSIP: 124 vs 110.0 70 Data vs 62.5 Bck di-jets events single tagged by JLIP and CSIP simultaneously. Better than at LP Warning: Here MC has slightly changed after 03/03 (but before EB review) jet reco efficiency, data/mc-tagging efficiency

18 b-Tagging with Tight JLIP
What happens in ALPGEN Wjj ? Tight JLIP allows to keeps good correlation, also true for CSIP. The simulation is corrected by the differences of efficiencies with data ( %) Tagging algorithms also applied on the simulation. 1 tag 0 tag 2 tags Initial flavor compos. b from gluon splitting/PS c from cc/g.s.

19 Final Plots… Jet Multiplicities

20 Data Selection Isolation < 0.10 Em HM7 < 30 Em HM8 < 75
EmFraction isolation EmFraction isolation

21 xy-shift in Missing ET, xy-rms
TMB fix +T42 After run selection one entry per file (about 10 lumiblocks) The missing ET - x is convoluted with a gaussian of mean 0.0 GeV and RMS 1.2 GeV Missing ET-y with a gaussian of mean –0.4 GeV and a RMS of 1 GeV. GeV GeV

22 W+  2 jets If we applied a cut on WT>25 GeV, no more bump. Moriond
Loose Tight Tight Loose Tight If we applied a cut on WT>25 GeV, no more bump.

23 identified as electron
What’s happening? JET 45 Gev (JES) You have a Di-Jet event of 20 GeV, one is identified as an electron, the other is fluctuating at 30 GeV. You applied JES to the 30 GeV jet  45 GeV.  You then have a missing ET of 25 GeV. JET 30 Gev (Fluctuation) MET 25 GeV JET 20 Gev Your event is passing the criteria, the W mass will be low, the PT of the W will be 20+25=45 GeV. JET identified as electron 20 Gev el - MET - 