Top properties and ttv LHC

Transcription

1 Top properties and ttv LHC Emmanuel MONNIER CPPM/IN2P3 Aix-Marseille Université (Marseille, FRANCE) On behalf of the ATLAS and CMS collaborations 15 March 2016 Moriond EW@La Thuile

2 a Many top results obtained so far!! Now LHC-Run1 data analyzed: 2011~5fb Outstanding 2012~20fb LHC! 8/10/13 2

3 a Now LHC-Run2 data analyzed: 2015~4fb Outstanding LHC! 3.8 T = 2.8 fb -1 CMS Preliminary Good for all: 2.2 fb -1 Good for many*: 2.6 fb -1 Good for muons: 2.7 fb -1 Preliminary luminosity uncertainty: 50 ns 25ns * h < 3.0 for jets and MET 8/10/13 Recorded = 3.9 fb -1 All good = 3.2 fb -1 3

4 Top properties 6M tt 8TeV & 25 fb -1 Heaviest elementary particle Coupling to Higgs ~1 Decay before hadronization (probe bare quark) and before spin decorrelation (predicted by pqcd) τ t (10-25 )<τ QCD (10-24 )<τ Spin (10-21 ) Access to true properties through decay products Properties sensitive to new physics. Look at Spin, Charge, FCNC 4

5 ATLAS, arxiv: CMS, arxiv: v1 Spin 8TeV Gluon helicities top spin correlation decay product. Max in low M tt regime Lepton final state ~100% transmission (for quark, depends on flavor) Di-lepton angular distribution: best probe in lab frame Δϕ (indirect) or in top rest frame vs a direction basis (helicity, ), cos θ l, cos θ l cos θ l (direct). f SM = 1.20 ± 0.05 (Stat) ± 0.13 (Syst) f SM = 1.14 ± 0.06 (Stat) ± (Syst) 0.11 (theo) 5

6 Spin Correlation: direct measurement ATLAS, arxiv: Inclusive distrib. parton level 2OS l, 2high p T jet, 1b, large E T miss Theory: Bernreuther et al. arxiv: arxiv: v2 arxiv: v1 Depend on production & Basis C helicity = ± (Stat) ± (Syst) = -9<c 1 c 2 >= -4A h ; C SM NLOW = ± converted to f SM = 1.02 ± 0.20 (Stat) ± 0.16 (Syst) 6

7 Spin Correlation: direct measurement CMS, arxiv: Inclusive distrib. parton level 2OS l, 2high p T jet, 1b, large E T miss Theory: Bernreuther et al. arxiv: arxiv: v2 arxiv: v1 Unfolding all angular distributions and get asymmetries: A Δϕ, A h, A cosφ, A P C h =-9<c 1 c 2 >= -4A h Polarisation=2A p C SM NLO QCD+EWW = 0.318(5) A h = ± (Stat) ± (Syst) f SM = 0.87 ± 0.17 (Stat) ± 0.21 (Syst) ±0.04 (theo) A P = ± (Stat) ± (Syst) P CPC = ( 2.2 ± 5.8 )% P CPV = ( 0.0 ± 1.6 )% 7

8 Correlated (SM) Spin correlation 1l+j 8TeV : ME method CMS, arxiv: µ +jets, use matrix element method to get more from distribution, full reco. λ event = P uncor, fit -2ln λ P event distribution cor f SM = 0.72 ± 0.08(Stat.) (Syst. ) 8

9 Spin correlation: Summary most precise f SM Δϕ 2l : 1.20 ± 0.14 (8TeV) ; 1.19 ± 0.20 (7TeV) ME 2l : 0.87 ± 0.18 (7TeV) Δϕ l+j: 1.12 ± 0.25 (7TeV) Δϕ 2l : 1.16 ± 0.15 (8TeV) D 2l : 0.90 ± 0.16 (8TeV) ME l+j: (8TeV) Consistent with SM, systematic limited already for some of the measurement. 9

10 top quarks pair production at NLO give non zero charge asymmetry from interferences between diagrams, gg interaction symmetric Valence quarks interact with sea anti-quarks & Top quark connected to the incoming parton t quark more forward than anti t Charge Asymmetry tree-level and box diagram: + asymmetry ISR and FSR: asymmetry 10

11 Charge Asymmetry: di-lepton Inclusive distrib. parton level 2OS l, 2high p T jets + b /large E T miss ATLAS, arxiv: CMS, arxiv: A ll c = ± stat. ± syst. A ll c = ± stat. ± syst. ll = ± scale A SM NLO QCD+EW A tt c = ± stat. ± syst. A tt c = ± stat. ± syst. tt A SM NLO QCD+EW = ± scale 11

12 Charge Asymmetry: 8TeV Inclusive and differential measurements parton level 1high p T tight l, 4high p T jets, 0b + large E T miss + m T W Full event reco with kinematic fit ATLAS, arxiv: A c = ± stat. +syst. 12

13 Charge Asymmetry: 8TeV CMS, arxiv: CMS, arxiv: Inclusive and differential measurements parton level Alternative template method using shape of Δ η distribution A c = 0.33 ± 0.26 stat. ± 0.33 (syst. ) 13

14 T. Schwarz Charge Asymmetry: Boosted 8TeV ATLAS, arxiv: Inclusive and differential parton level 1high p T tight l, m tt > 0.75 TeV, -2 < Δ y < 2, Large-R jet R=1.0 Hadronic top reconstructed with large R jet A c = ± (stat. +syst. ) A c SM = ±

15 Charge Asymmetry: Summary G μ : A new color-octet neutral vector boson exchanged in the s channel W : A charged color-singlet vector boson Z exchanged in the t channel in dd tt φ : A color-singlet scalar doublet with hypercharge 1/2 exchanged in t channel Ω 4 : A charge 4/3 scalar color sextet exchanged in the u channel ω 4 : A charge 4/3 scalar color triplet exchanged in the u channel 0.042± 0.020± arxiv:

16 FCNC Highly suppressed in SM but not in BSM 16

17 FCNC: t 8TeV ATLAS, arxiv: Not possible in tt because of multijet bckgnd t-channel single top selection: 1 lepton,1 b-tagged jet and missing ET Neural network to separate signal from SM bkgnd. σqg t B t Wb < exp B t ug < B t cg <

18 FCNC: t 8TeV ATLAS, arxiv: l, 2jets, 1b + ETmiss B t Zq < %CL E. Monnier - Moriond EW /03/

19 FCNC: t 8TeV ATLAS, arxiv: (bb) ATLAS, arxiv: (γγ) CMS, PAS-TOP ,020 (γγ) CMS, PAS-TOP (ml) t bw (W l/hν) t Hq, H bb/γγ (depending analysis) ATLAS B t uh < 0.61% B t ch < 0.56% CMS B t uh < 0.42% B t ch < 0.47% 19

20 FCNC: Summary 20

21 t tw, t tz@8tev Expected small SM cross sections (~200 8TeV) but probe for BSM Direct coupling infos to bosons Background for tth and BSM searches Dominant production modes: ATLAS, arxiv: At least 1l p T > 20 GeV p T > 15 or 7GeV for additional leptons Bin of leptons: 2l OS, 2l SS, 3l, 4l Jet multiplicity, b jets, E T miss, Z mass constraint 15 SR + 5 CR, NN for 2l OS Fake leptons and Charge Misid Bkgnd from data CR+SR combined in profile LH σ(ttz) and σ(ttw) as free parameters 21

22 t tw, t tz@8tev ATLAS, arxiv: Cross Sections: σ t tw = stat. ± 44 syst. fb σ t tz = stat. ± 24 syst. fb 5.0σ (3.2σ) for t tw (1 st obs) 4.2σ (4.5σ) for t tz 22

23 t tw, t tz@8tev CMS PAS-TOP l p T > 20 GeV p T > 10 for others 5SR Full reco, Matching + Kyne. BDT fit 23

24 t tw, t tz@8tev CMS PAS-TOP l p T > 20 GeV p T > 10 for others 5SR Full reco Matching + Kyne. BDT fit t tz t tw σ t tw = stat + syst. fb σ t tz = stat + syst. fb 4.8σ (3.5σ) for t tw 6.4σ (5.7σ) for t tz (1 st obs) 24

25 t tw, t tz@13tev ATLAS-CONF WZ CR ZZ CR 25

26 t tw, t tz@13tev ATLAS-CONF SR & 2CR fitted together for t tz 2 SR & 2CR fitted together for t tw Profile LH fit σ t tw = 1.38 ± 0.70 stat. ± 0.33 syst. pb σ t tw (SM) = 0.57 ± 0.06 pb (NLO) σ t tz = 0.92 ± 0.30 stat. ± 0.11 syst. pb σ t tz (SM) = 0.76 ± 0.08 pb 26

27 t tw, t tz@13tev CMS PAS-TOP SR & 2CR fitted together for t tz Profile LH fit σ t tz = stat (syst. ) pb 27

28 t ATLAS, arxiv: l+jets channel with at least 1 b-tagged jet, E T (γ) > 20 GeV profile LH fit to the photon track-isolation distribution background template from multijet events with inverted photon shower shape measurement within the fiducial phase space σ fid t tγ BR = 63 ± 8 stat syst. ) ± 1(lumi. fb SM: 48 ± 10 fb first observation of t 5.3σ 28

29 Conclusion Top studies at full swing with Run1 and now Run2 data Lots of property measurements performed and about to be systematics limited. Need for improvement to reduce instrumental systematics as wells as theoretical ones. Will allow to be more sensitive to new physics through direct and indirect searches In 2016 we will have a full run2 13 TeV and higher luminosity, so higher Tops statistics, 20M tt and 5M t, 20k ttz to study and search for new phenomena. 13 TeV top analysis are just starting to arrive. A bright future is ahead of us!!