W Cross Section measurement at CDF RunII University Of Athens and INFN-Sezione di Pisa University Of Athens and INFN-Sezione di Pisa HEP2006 Ioannina 13-16 April HEP2006 Ioannina 13-16 April Athanasios Staveris-Polykalas Athanasios Staveris-Polykalas e + 1
Outline Why the W cross section Why the W cross section W cross section at CDF W cross section at CDF W boson in Forward region W boson in Forward region Strategy of analysis Strategy of analysis Results Results Conclusions Conclusions 2 Athanasios Staveris-Polykalas
Why W cross section � Precise electroweak measurements -> Constrain Standard Model (or) Suggest Physics Beyond Standard Model � W signal is well established -> Base of detector performance studies � Cross section measurement e -> Ensure good understanding of -> Common cross check for other analyses NEW DATA AVAILABLE!! NEW DATA AVAILABLE!! -> ~300 pb -1 -1 of additional data collected of additional data collected -> ~300 pb 2003-2004 2003-2004 3 Athanasios Staveris-Polykalas
W cross section at CDF Tevatron -> W hadronic decay is overwhelmed by QCD -> W boson is identified by the leptonic decay (in our case electron neutrino) = # of observed events N Data = # of expected background N Background N Data - N Background �� Br � W � e �� = = Geometric and kinematic A A � � � � L dt Acceptance (from MC) � = efficiency (trigger, reconstruction, ID) � L dt = integrated Luminosity 4 Athanasios Staveris-Polykalas
W boson in Forward region of CDF detector Extended electron ID to forward region Extended electron ID to forward region of detector-> 1.2 � | � | � 2.8 of detector-> Use of combined information from Use of combined information from forward EM calorimeters and forward EM calorimeters and extended tracking system (ISL) extended tracking system (ISL) Central drift chamber Central drift chamber Central drift chamber Central drift chamber Plug Detector Plug Detector Increases statistics for other physics Increases statistics for other physics analyses for the given luminosity analyses for the given luminosity i.e. top physics, W F/B charge i.e. top physics, W F/B charge asymmetry asymmetry Silicon Detector Silicon Detector 5 Athanasios Staveris-Polykalas
Strategy of analysis Acceptance from MC Acceptance from MC Event selection: Event selection: Efficiencies from Z->ee data Efficiencies from Z->ee data Trigger (Missing Et + Trigger (Missing Et + � and MC and MC Plug EM object) Plug EM object) Calorimetric Calorimetric 1.2 � | � | � 2.8 � Cuts Cuts Background from data and Background from data and E T � 20 GeV � MC MC Electron ID Electron ID � (Had/Em<0.05 && IsoRel<0.1) (Had/Em<0.05 && IsoRel<0.1) ME T � 25 GeV � Largest systematic contribution Largest systematic contribution � from Acceptance ~2% (PDFs) from Acceptance ~2% (PDFs) | �� X � | , | �� Y � | � 3 cm � Total background contamination Total background contamination � Track Cuts Track Cuts Track matching ~4.5% ~4.5% � E/p< 2 Acceptance x Efficiency of signal Acceptance x Efficiency of signal � selection ~7 % selection ~7 % We end up with 48144 48144 candidate events 6 Athanasios Staveris-Polykalas
7 Athanasios Staveris-Polykalas
8 Athanasios Staveris-Polykalas
RESULTS P P u u b b l l i i s s h h N Data - N Background e e d d C C �� Br � W � e �� = D D F F A � � � � L dt N N u u m m b b e e r r s s Denominator Numerator Denominator Numerator N Data = 48144 � 0.0048 � syst � Acc = 0.2555 � 0.0002 � stat � -0.0039 N Bck � QCD � = 877 � 59 � stat � � 438 � syst � � 0.0021 � syst � � Total = 0.0732 � 0.0011 � stat � - 0.0019 N Bck � Z � ee � = 233 � 3 � stat � � Ldt = 223 � 13 � syst � N Bck � W ���� = 1073 � 12 � stat � Forward CDF W cross section measurement with 223 pb -1 -1 Forward CDF W cross section measurement with 223 pb � 94 � syst � � 169 � lum � pb �� Br � W � e �� = 2815 � 13 � stat � -89 Central CDF W cross section measurement with 72 pb -1 -1 Central CDF W cross section measurement with 72 pb �� Br � W � e �� = 2780 � 14 � stat � � 60 � syst � � 167 � lum � pb �� Br � W � e �� Th = 2687 � 54 pb Theoretical Prediction: Theoretical Prediction: NNLO (Stirling, van NNLO (Stirling, van 9 Neerven) Neerven) Athanasios Staveris-Polykalas
Our contribution to physics Our contribution to physics σ × Br (nb) σ× Br(W → l ν ) 1 NNLO theory curves: Martin, Roberts, Stirling, Thorne σ× Br(Z → l + l - ) CDF II (e,1.2 < | η | < 2.8),223 pb -1 D0 II (e) -1 10 CDF II (e+ µ ),72pb -1 CDF (630) D0 II ( µ ) CDF II Z( µ ), 337pb -1 UA1 ( µ ) CDF I (e) CDF II Z( τ ), 349pb -1 UA2 (e) DO I (e) 0.5 0.75 1 1.25 1.5 1.75 2 2.25 2.5 E cm (TeV) 10 http://www-cdf.fnal.gov/physics/ewk/2006/plugw/ http://www-cdf.fnal.gov/physics/ewk/2006/plugw/ Athanasios Staveris-Polykalas
Conclusions � Our measurement consistent with central results and theory Our measurement consistent with central results and theory Better understanding of plug region of CDF detector Better understanding of plug region of CDF detector � More data can be used for other analyses: More data can be used for other analyses: � (Top physics and W Forward-Backward charge (Top physics and W Forward-Backward charge asymmetry) asymmetry) 11 Athanasios Staveris-Polykalas
From now on Backup 12 Athanasios Staveris-Polykalas
13 Athanasios Staveris-Polykalas
14 Athanasios Staveris-Polykalas
Zee control sample Central tight electron + Control sample Z->ee (CP) Plug leg : � MC zewk6d for Z->ee (~1.9M) � Loose plug electron � data zewk0d for Z->ee (223pb-1) (denom for eff study) 1.2<|eta|<2.8 Et >20GeV Had/Em<0.125 Control sample used for: � ID selection � Efficiency evaluation Had/Em<0.05 � L2,L3_PEM20 trigger study IsoRel <0.1 � Evaluating Scale&Smear � Track matching parameters -> tuning parameter 3D Track Matched (pt>1GeV, ∆ X,Y < 3cm) applied on energy � E/P<2 In efficiency and trigger study we apply invariant mass window 80-100 GeV 15 Athanasios Staveris-Polykalas
Trigger summary Efficiency: +0.0009(syst) � L1_EM8 =99.9988 ± 0.0007(stat) % -0.0061(syst) � L1&L3_MET15 = 99.42 ± 0.1 +0.87(syst) � L2_PEM20 = 95.99 ± 0.37(stat) % -1.05(syst) +0.31(syst) � L3_PEM20 = 99.61 ± 0.1(stat) % -1.12(syst) Eff TOT = Eff L1_MET15 & L3_MET15 x Eff L2_PEM20 x Eff L3_PEM20|L2_PEM20 +0.009(syst) Eff TOT = 95.06 ± 0.009 (stat) % -0.015(syst) 16 Athanasios Staveris-Polykalas
# events per cut Requirement N. Of events East West MET_PEM trigger 724062 - - fired 1.2 � | � | � 2.8 706735 373104 393640 E T � 20 GeV 689504 338205 360090 IsoRel � 0.1, 251692 125681 126154 Had / Em � 0.05 ME T � 25 GeV 79800 40677 39139 Matching track 74091 37826 36267 | TrkZ 0 | � 60 cm 71861 36797 35066 E/p <2 48144 24591 23553 17 Athanasios Staveris-Polykalas
Systematics Source Syst. Uncertainty(%) Syst. Uncertainty(%) e scale plug E T +/-0.232 +/-0.232 e resolution E T +/-0.043 +/-0.043 P T +/-0.031 +/-0.031 � U +/-0.35 +/-0.35 Material +/-0.713 +/-0.713 PDF' s +2,55-1,7 (CTEQ) +1.70-1.29(CTEQ+PRD) PVZ study +/-0.049 +/-0.049 Total +2,68-1,89 (CTEQ) +1.89-1.54 (CTEQ+PRD) 18 Athanasios Staveris-Polykalas
Eff vs track algo 0.8 0.7 0.6 0.5 Track. Eff. 0.4 Combined Inside Out Outside In 0.3 SiSa 0.2 0.1 0 -2 -1 0 1 2 η DET 19 Athanasios Staveris-Polykalas
Recommend
More recommend
