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TauID Algorithm に関する研究

TauID Algorithm に関する研究. Motivation Tau identification To do for improvement conclusion. 中村浩二. Motivation (TauID の改良 ). Invariant mass distribution of VBF H tautau (M H =120GeV) with fast simulation. 40 GeV. 20 GeV. VBF H tau tau is promising channel for Higgs discovery.

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TauID Algorithm に関する研究

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  1. TauID Algorithm に関する研究 Motivation Tau identification To do for improvement conclusion 中村浩二

  2. Motivation (TauIDの改良) Invariant mass distribution of VBF Htautau (MH=120GeV) with fast simulation 40 GeV 20 GeV VBF Htau tau is promising channel for Higgs discovery But as we can see the statistics of the signal is limited. BG Signal Pt distribution of tau jet (MH=125GeV) Our Pt threshold of tau jet is 40GeV But many signals are in the lower Pt region. Low Pt Tau jet identification and reconstruction are very important to increase statistics.  We have developed tau identification optimized low Pt region

  3. Tau identification • Tau candidates are selected based on track (finding Isolate 1 track or 3 tracks) • We also use cells information . Tau 1prong Tau 3prong QCD Jet We also required isolation there is no more Pt>2GeV track in DR<0.4. Find Pt >5 GeV tracks only 1 track 3tracks in DR<0.1 (Find two more Pt>2GeV tracks) Find a seed cell associated with this track, and make Cluster (The seed is defined as a cell with larger than 6s of Noise near the track) reconstruction identification “Narrowness” cut is applied for identification ( I will talk in later slides)

  4. Energy deposit on EM calorimeter PreSampler EM1 EM2 EM3 0.4 0.4 ATLASのEM calorimeter は、presampler と、3つのsampling 層からなる。 Sampling 2が、main component で、DhxDf=0.025x0.025と、segment が細かい。 phi eta We use cell based narrowness definition not DR.

  5. Cell-based narrowness 0.025 f 0.1 0.025 h 0.1 Tile Sampling 0 LArHEC Sampling 0 LArEM Sampling 2 If Seed Cell is not on LArEM Seed Cell

  6. 1prong 3prong Signal QCD(17-35GeV) QCD(35-70GeV) Narrowness Narrowness Narrowness distribution after 1prong/3prong selection We can enhance the signal against the BG by setting narrowness threshold. For example 0.7/0.6(1prong/3prong)

  7. Total gluon jet quark jet • Efficiency & Rejection We plotted efficiency/rejection as the function of visible Tau Pt. For di-jet sample (20GeV-140GeV) 1pr…0.7 3pr…0.6 1prong 3prong 0.7 0.6 Tagging Efficiency 1/R 10 50 Visible tau Pt [GeV] Jet Pt [GeV] 50%のefficiency が得られる。Rejectionに関しては、改善の可能性がある。

  8. Signal Di-Jet To do… • Track invariant mass for 3prong Mp±=139.6 [MeV] を仮定して、3本のtrack の invariant mass を求める。 Track invariant mass for 3prong [GeV]

  9. Electron veto Inclusive Tau Gen Matching Tau purely tau Inclusive Tau Signal MC all tau candidate (tau, electoron,muon,VBFjets) Electron peak ! Gen Matching Tau 1.0 EMEt/TrkPt EMEt/TrkPt ~ 1 && HDET/TrkPt ~ 0 を veto Pt(Pi+-)<Pt(Pi0) Cut のoptimize をする。 1.0 EMEt/TrkPt

  10. muon veto Gen Matching Tau Muonは、tau jet Et cut でveto される Inclusive Tau HDEt/TrkPt muon EMEt~HDEt~0 Electron HDEt=0 EMEt~1 EMEt/TrkPt

  11. QCD Event Topology のcheck phi phi Di-Jet event Pt>2GeV tracks Pt>2GeV track event display eta eta ▼ # of Tracks distribution Rec Track (iPad) phi phi ~10% becomes 1pr/3pr candidate eta eta phi phi Mean :6.3 eta # of Tracks in 1 Jet eta

  12. Conclusion • VBF process で生成し、tau レプトン対に崩壊するHiggs 粒子探索で、統計を増やすため、low Ptのtauにoptimizeした、track base のtauIDのアルゴリズムを開発中である。 • Efficiency に関しては、50%程度出ているが、Rejectionに関しては、十分な性能が出ていない。 • QCD background をsuppress するため、Rejection factor を、現在の3-5倍よくする必要がある。-> Wjjj, jjjj BG から。 To do (Plan) • 3prong のtrack invariant mass cut • Lepton veto • QCD event topology の再チェック • p0 p+- invariant mass • すべての cut valuable のoptimization 　　　　　　　　　などなど

  13. Back Up

  14. Signal selection • electron Pt>25GeV,muon Pt>20GeV • Tau jet with Pt>40GeV DR >0.7(from lepton) • Forward Jet : At least 2 Jet , Pt>20GeV(Leading 40GeV) • Forward Jet : h1*h2<0,|h1-h2|>4.4 • h1+0.7< hl,t <h2-0.7 • |cosflh| < 0.9 for missing Et • Transverse mass between lepton and missing energy less than 30GeV • Missing Et > 30GeV • Invariant mass of the tagged forward jets larger than 700GeV • Central Jet Veto : There is no Pt>20GeV jet in h1+0.7< h <h2-0.7

  15. Background 0.42fb Signal… • Major QCD background • W+3jets : Wjjj -> ltaujj -> depend onmainly TauID • bbjj : bbjj -> ltau jj • bbjj -> l j tau j • jjjj : jjjj -> ltau jj • WWjj : WWjj -> tau taujj -> cross section is small • ttbar : WWbb ->tau taujj 0.27fb last talk of this session ?? fb 0.00fb 0.04fb Fake of W->lepton(tau) is also suppress with W transverse Mass cut • Z->tt background 0.19fb • Z+njets : Zjj -> tau(l)tau(h)jj Final state is the same as the signal So we can only use “central jet veto” for suppress the BG

  16. Introduction(2) … ATLAS LAr HEC Tile HD • ATLAS検出器 LAr FCal • 飛跡検出器 • Pixelシリコンピクセル検出器 • SCT シリコンマイクロストリップ検出器 • TRT 遷移輻射ストローチューブチェンバー LAr EM Muon System • カロリーメータ • LAr EM 液体アルゴンカロリーメータ (Pb) • Tile HD シンチレータタイルカロリメータ • LAr HECハドロンエンドキャップ(Cu) • LAr FCal 超前方カロリーメータ (Pb) • Muon 検出器 • MDTドリフトチューブチェンバー • TGC,RPC ,CSCトリガー用チェンバー

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