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VBF H-> tt -> hadron+lepton 用の tauID の研究 ＆ 活動報告 ～ 2004 年のまとめ～

VBF H-> tt -> hadron+lepton 用の tauID の研究 ＆ 活動報告 ～ 2004 年のまとめ～. Junichi Tanaka ICEPP, University of Tokyo. 内容. VBF H-> tt ->hadron+lepton 用の tauID の研究 活動報告 Higgs WG SUSY WG 今後の予定. VBF H-> tt ->hadron+lepton 用の tauID の研究 （野本君の仕事の継続）. Contents. Motivation Strategy of tauID さまざまな分布

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VBF H-> tt -> hadron+lepton 用の tauID の研究 ＆ 活動報告 ～ 2004 年のまとめ～

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  1. VBF H->tt->hadron+lepton用のtauIDの研究＆活動報告～2004年のまとめ～ Junichi Tanaka ICEPP, University of Tokyo ATLAS日本総会@河口湖

  2. 内容 • VBF H->tt->hadron+lepton用のtauIDの研究 • 活動報告 • Higgs WG • SUSY WG • 今後の予定 ATLAS日本総会@河口湖

  3. VBF H->tt->hadron+lepton用のtauIDの研究 （野本君の仕事の継続） ATLAS日本総会@河口湖

  4. Contents • Motivation • Strategy of tauID • さまざまな分布 • p0の取り扱い • How to identify tau-jet? • Improvement of taujet’s momentum • Pileup & Noise effect ATLAS日本総会@河口湖

  5. Motivation • VBF H->tt->hvtlvtvl is very important to discover Higgs at the low mass region. • ATL-PHYS-2003-004/005, ATL-COM-PHYS-2003-007 • Identification of hadronic tau is one of important things for this analysis. • Many variables are used to identify tau-jets. However most of them represent one characteristics of tau-jets. -> Narrow jets T.Takemoto (Univ. of Tokyo) ATLAS日本総会@河口湖

  6. Strategy of tauID • Use tau-jets with low Pt > 20GeV or 15GeV… • Properties of tau-jets. • Hadronic decay of tau-> Number of charged tracks and jet charge. • Narrow jets-> Fraction of energy in DR<0.1 • Shower shape related with decay products (p0,p+-) of t-> Distributions of fraction of energy at each layer. -> Can make a likelihood function from them. • Lifetime (ct~87mm) … not studied yet … ATLAS日本総会@河口湖

  7. Jet Charge • Number of charged tracks should be 1,2 and 3. -> Jet charge should be –2,–1, 0, +1 and +2. 30<Pt<40GeV 50<Pt<70GeV Tau QCD ATLAS日本総会@河口湖

  8. Fraction of energy in DR<0.1 • As Pt larger, a tau-jet becomes narrower.-> Fraction of energy in DR<0.1 (FDR<0.1) becomes larger! 20 < Pt < 30 40 < Pt < 50 70 < Pt < 130 Tau-jets QCD-jets Cut on FDR<0.1 is used to tune “effand R”. ATLAS日本総会@河口湖

  9. Distributions of fraction of energy at each layer • After applying the 3 criteria (Ntrk, Qjet, FDR<0.1),the following distributions are obtained. Due to no p0 jet PreEM Tau Layer1EM QCD 40<Pt<50GeV, |h|<1.8 ATLAS日本総会@河口湖

  10. 40<Pt<50GeV, |h|<1.8 Layer2EM Layer3EM Tau QCD Layer1Had LayerOthersHad • Distributions of remaining QCD-jets are similar with those of tau-jets. -> Not need to use them for tauID. ATLAS日本総会@河口湖

  11. p0 in jet • By using generator information, we check ratios of jets including p0. • Tau-jets20<Pt<30 GeV 40<Pt<50 70<Pt<130p0 = 0, p+- > 0 : 24% 22% 20%p0 > 0, p+- > 0 : 76% 78% 80% • QCD-jets 20<Pt<30 GeV 40<Pt<50 70<Pt<130p0 = 0, p+- > 0 : 11% 5% 2%p0 > 0, p+- > 0 : 88% 95% 98% • p0 information will be used for tauID. • For no p0, use looser cut ATLAS日本総会@河口湖

  12. How to identify p0 in jet? • By using DPtp0, we can determine if a jet has p0. DPtp0 = Pt of jet – S Pt of charged tracks Np0=0, Np+-=1 Np0=1, Np+-=3 DPtp0 (GeV) DPtp0 (GeV) ATLAS日本総会@河口湖

  13. How to identify tau-jet? Jet Check Ntrk + Qjet no Non-tauJet yes Cuts on FDR<0.1 aretuned for each category. Check DPtp0 < 10GeV p0 >0, p+- = 1~3 p0 = 0, p+- = 1 p0 = 0, p+- = 3 Check FDR<0.1 Check FDR<0.1 Check FDR<0.1 Tau-jet Non-tauJet ATLAS日本総会@河口湖

  14. Improvement of tau-jet’s momentum using charged trks • For no p0 tau-jet, we can use “S P of charged tracks” as a momentum of tau-jet. • Can improve resolution of mass of Higgs candidates.-> could improve tail of Z ->tt backgrounds. Np0=0, Np+-=1 Pt(Jet) - Pt(Gen) Pt(Charged Trk) - Pt(Gen) ATLAS日本総会@河口湖

  15. Np0=0, Np+-=3 • There is a possibility to use sum of charged tracks’ momentum as tau-jet’s momentum. Pt(Jet) - Pt(Gen) Pt(Charged Trks) - Pt(Gen) ATLAS日本総会@河口湖

  16. Number of Charged Tracks 50<Pt<70GeV 20<Pt<30GeV VBF No large dependence. Ntrk becomes smallin pileup events. QCD Ntrk ATLAS日本総会@河口湖

  17. Sum of Charge 50<Pt<70GeV 20<Pt<30GeV No large dependence. Qjet Pileup and noise don’t givea large effect oncharged track reconstruction. (track pt > 2GeV) ATLAS日本総会@河口湖

  18. Fraction of energy in DR<0.1 50<Pt<70GeV 20<Pt<30GeV • Jets become wider as increasing the effect of pileup. • Effect of noise seems to be small. • A fraction is slightly large at low F01. ATLAS日本総会@河口湖

  19. Performance of tauID (1) Rejection factor as a function ofefficiency. lumi00 • Much worse as expected. -> look them at each pt region. See next. lumi02 70<Pt<130 50<Pt<70 40<Pt<50 30<Pt<40 20<Pt<30 ATLAS日本総会@河口湖

  20. Performance of tauID (2) • Pileup gives a large effect onthe tauID performance. • Results of noise effect is similaras those of lumi01 not lumi00. ATLAS日本総会@河口湖

  21. Performance of tauID (3) • We can see clear decreases of tauID performance depending on the size of the pileup and noise. ATLAS日本総会@河口湖

  22. Mass（tautau） • Kyle（Wisconsin）のトラペより@2004年12月15日 • Et missingの理解不足->まだまだ研究が必要。 • Pileup等の影響も。 Central jet vetoなし ATLAS日本総会@河口湖

  23. 活動報告 ATLAS日本総会@河口湖

  24. Higgs WGのまとめ • Higgs WG meeting • 2004年（年度じゃなく） 8回 • 2日間の予定だったが、初回を除いてすべて1日のみの開催。 • 回数を増やした分、その間の進展が少なくなるのは当たり前 • 年間を通してWinconsinグループが半分程度のトークを維持。 • 活動 • VBF H->tt->hadron+lepton用のtauIDの研究 • 成果発表3回 • ATLAS-COM-PHYS-2004-069 • 10人程度でTau meetingをスタート（12月に初回）。 • Continuous Production for ROME@Higgs WG （予定） • 手は挙げた…が…。 ATLAS日本総会@河口湖

  25. SUSY WGのまとめ • SUSY WG meeting • 2004年 6回（phone meeting除く） • 活動 • お仕事（奉仕） • Btaggingの評価（not 開発） • DC2 Production Data for SUSY • 2回ほどSUSY WG meetingで報告した。 • Inclusive studyの開始（目的：兆候から発見へ） • 佐々木君が中心となって研究。 -> 今日のトーク • 12月のSUSY WG meetingで経過報告（by 浅井さん） ATLAS日本総会@河口湖

  26. 今後の予定 • ATLAS Physics WS@ローマ • 2005年6月7日-11日 • 物理本 : Readiness for Physics at ATLAS • 2006年 • Higgs • VBF H->tt->hadron+leptonの研究を維持 • tauID+tau jet calibration • 中村君（kojin、筑波）が参戦。 • Et missing（非常に重要） • VBF H->bb + W, WでBGを落とす。Yb測定にとって重要。 • VBF H->WW->lnjj • SUSY • Inclusive studyを継続。 • データベースを作る。（佐々木君） • 特定のポイントにおける詳細な研究 ATLAS日本総会@河口湖

  27. バックアップ ATLAS日本総会@河口湖

  28. Dataset • Pythia 6.2 (without Tauola) • All the samples were simulated by the DC1 scheme at the TOKYO PC farm. • No pileup • Reconstruction • ATHENA : ver 7.0.3 • Cone jet algorithm (R=0.4) • No noise VBF H->tt (mH=125) : ~100k QCD jets : ~20k ATLAS日本総会@河口湖

  29. Dataset • Pythia 6.2 (without Tauola) • All the samples were simulated by the DC1 scheme. • No pileup (lumi00) • Pileup : 1 x 10^33 (lumi01) • Pileup : 2 x 10^33 (lumi02) • Reconstruction • ATHENA : ver 7.0.3 • Cone jet algorithm (R=0.4), xKalman for charged tracks • Without noise for lumi00, lumi01, lumi02 • With noise for lumi00 (lumi00N) (mH=125GeV) lumi00 lumi01 lumi02 lumi00N ATLAS日本総会@河口湖

  30. 野本君の昨年のトラペ tau-lepton ・ mass 1.777GeV/c2 ・ life time 290.61×10-15 s ( cτ = 87.11μm ) Main tau decay mode Branching fraction τ- -> μ-νμντ 17.4 % e-νeντ 17.4 % (1prong) π-ντ 11.1 % π-π0ντ 25.4 % π-π0π0ντ 9.4 % (3prong) π-π+π-ντ 9.5 % π-π+π-π0ντ 4.4 % ATLAS日本総会@河口湖

  31. 野本君の昨年のトラペ VBF->tautau ・ VBFはgluon-fusionに比べて1桁くらい断面積が小さい。 ATLAS日本総会@河口湖

  32. 野本君の昨年のトラペ VBF->tautau ・ けれど、 - central jet veto 中央のrapidity gapにQjetがいるeventを捨てる。 - forward jet tagging Forward領域でhigh Pt jetが観測される。 　　という強力なevent-selectionによってきれいにイベントを取り出せる。 ATLAS日本総会@河口湖

  33. 野本君の昨年のトラペ VBF->tautau • tautauの特徴 - tauの崩壊でneutrinoが出てくるのに、Higgs massのreconstructが可能 ATLAS日本総会@河口湖

  34. EM σ/E=10%/SQRT(E) Fine: 0.025*0.025 第一段目のη：π/γ 角度分解能 50mrad/SqrtE ATLAS日本総会@河口湖

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