Atlas TTbar to Tau Analysis

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Atlas TTbar to Tau Analysis. William P. Edson , Teeba Rashid Adviser: Mohammad Sajjad Alam State University of New York at Albany Anirvan Sircar Adviser: Dick Greenwood Loisianna Tech April 14, 2013. ttbar to tau Interaction Overview. q. W +. t. q ’. b. bbar. tbar. W -. - PowerPoint PPT Presentation

Transcript of Atlas TTbar to Tau Analysis

Atlas TTbar to Tau Analysis

Atlas TTbar to Tau AnalysisWilliam P. Edson, Teeba RashidAdviser: Mohammad Sajjad AlamState University of New York at AlbanyAnirvan SircarAdviser: Dick GreenwoodLoisianna TechApril 14, 20131ttbar to tau Interaction OverviewtW+btbarW-bbar -qq2

Top Pair Branching Fractions for ttbar decays[5]CutflowC0: GRLC1: TriggerC2: Primary vertex with ntracks > 4 C3: Electron/muon overlap, larVeto C4: Jet cleaningC5: Lepton Veto C6: njets >= 4 with eta < 2.3 and |jvf| > 0.75C7: MET > 60GeVC8: ptmiss significance > 8C9: MT < 70GeVC10: Sum ET < 500GeVC11: >= 1 bjet (MV1 > 0.601713)C12: Tau n 1, BDTScore > 0.7C13: Trigger matched tau n 1 and pT >= 40GeVC14: MC tau object matchBackgroundsQCD multi-jetestimated contribution determined via data driven techniquesW + jetsZ + jetsDibosonttbar decay (muons and electrons)4QCD multi-jet not modeled well in MC following selection criteria4ABCD RegionsSignal Region (A):BDTScore > 0.7 and Closest Top Mass < 230GeVBackground Regions (B, C and D):B: BDTScore < 0.7 and Closest Top Mass < 230GeVC: BDTScore > 0.7 and Closest Top Mass >230GeVD: BDTScore < 0.7 and Closest Top Mass > 230GeVBDTScore per RegionClosest Top Mass per RegionTop Mass with Highest pT b-jet per RegionTop Mass with Second Highest pT b-jet per RegionMjj per RegionMC Subtraction HistogramsBDTScore per RegionClosest Top Mass per RegionTop Mass with Highest pT b-jet per RegionTop Mass with Second Highest pT b-jet per RegionMjj per RegionCutflow -> Teeba Rashids AnalysisNo cutC0:Event Cleaning: GRL && larError!=2C1:TriggerC2: Primary vertex, ntr >4C3 :LAr FEBC4: Event Cleaning: JetsC5: Jets: > = 4 jetsC6: ==1 TauC7: lepton vetoC8: MET > 60C9: sumPt > 0C10: Pt miss significance > 13C11: >=1 bC12: mt 120 - 240

17Sources of Uncertainty % Uncertainty Jet Energy Resolution +/-1.33 Jet Energy Scale +-/11 Jet Reconstruction Efficiency +/-0.39 B-JES +0.23 -0.30 Pdf In Progress QCD In Progress MC generator +/- 4.91 ISR/FSR Obtained Numbers/ some doubts to obtain the final Value Pile up In Progress JVF In Progress MET In Progress Parton Shower Obtained Numbers /some doubts to obtain final value Tau ID efficiency In Progress Tau Energy Scale In Progress Etmiss uncertainty In Progress

18Cross-Section Measurementtt = 147.06 13 (stat) pb

SM Prediction tt = 166.8 +17.3 18.4 pb (Eur. Phys. J.C63:189-285, 2009)

Nikhef ( + jets) tt = 194 18 (stat) pb (arXiv:1211.7205v1)

+ tt = 186 13 (stat) 20 (syst) pb (Phys. Lett. B 717 (2012) 89-108) 19Conclusions20ThanksDr. Sajjad AlamDr. Pat SkupicDr. Dick GreenwoodCatrin Berniusttbar to tau group21References[1] Marion Lambacher, Study of fully hadronic ttbar decays and their separation from QCD multijet background events in the first year of the ATLAS experiment. July 2007.[2]CTEQ.[3] V. Chekelian, Standard model physics at HERA. 2001. hep-ex/0107053.[4][5]Neil Collins, TopCross Section (Current Status and Early LHC Prospects). 10 March 2010.[6]Zofia Czyczula, Search for New Physics in Tau-pair Events in ATLAS at the LHC. June 2009.[7]Noel Dawe, Tau Identification with Boosted Decision Trees. 18 March 2010.[8]Bjorn Gosdzik, Tau Reconstruction at the ATLAS experiment. 22 January 2009.[9][10][11][12][13][14] The ATLAS Liquid Argon Calorimeter at the LHC: Overview and Performance Mathieu Aurousseau,[15][16] ATLAS Tile calorimeter commissioning status and performance Ana Henriques,[17] Muon Spectrometer Technical Design Report,[18][19] The ATLAS Experiment at the CERN Large Hadron Collider. 2008. [20] CERN faq LHC the guide. [21] Jane T. Bromley.,Investigation of the Operation of Resistive Plate Chambers. September 1994.[22] Joel Feltesse, Introduction to Parton Distribution Functions. Scholarpedia. 6 November 2010.[24] CMS collaboration, First Measurement of the top quark pair production in the dilepton channel with tau leptons in the final state in pp collisions at s = 7 TeV. CMS-PAS-TOP-11-06[25], Particle Physics Glossary. 2009.[26] David Griffiths, Introduction to Elementary Particles. 2004. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim[27] Noel Dawe, Dugan ONeil, Tau Identification with Boosted Decision Trees. 15 July 2010.[28] Michael Wright, Exclusive Jet Study with Kt, AntiKt and Cambridge Aachen Jet Finders. 10 June 2010.[29] Mark R. Leach, The INTERNET Database of Periodic Tables. 1999-2001.[30] Arghir, S; Behar, S; Cavaliere, V; Coadou,Y ; Czodrowski, P; Flechl, M; Kopp, A; McCarn, A; zur Nedden, M ;Neubauer, M; Randle-Conde, A; Rozen, Y; Sekula, S; Takahashi, Y; Tomoto, M; Vickey, T; Xella, S, Data-driven estimation of the background to H+ searches with hadronic-tau final states. 31 March 2011.