Z ττ Observation Status

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1 Obervation Statu Standard Model Plenary Meeting, CERN Ryan Reece Univerity of Pennylvania Novemeber 12, 21 On behalf of the ubgroup Ryan Reece Penn Obervation Statu 1 / 32

2 Outline l h Analyi Introduction to and hadronic tau. Summary of our election Background etimation Sytematic / Outlook ll Analyi e/µ channel e/e, µ/µ channel Summary Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 2 / 32

3 Introduction au are important ignature for many Higg/BSM phyic earche. Hadronic tau decay are difficult to identify becaue the ignificant jet fake rake 1% and the huge jet cro ection at the LHC. h l, where one trigger on the lepton, i the bet SM proce for geing a pure control ample of tau for evaluating the tau trigger, recontruction, and ID efficiencie. he viible ma ditribution of h and l i enitive to the tau energy cale. he invariant ma of the h, l, and E, uing the collinear approximation i enitive to the E cale. We are currently preparing to claim obervation of with 8.5 pb 1. Further meaurement and efficiency tudie will continue with 1 1 pb 1. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 3 / 32

4 Phenomenology of tau decay 17.8% 9.% e ν e ν µ ν µ ν 17.4% π π ν 25.5% π ν 1.9% π 2π ν 9.3% K (Nπ )(NK )ν 1.5% π 3π ν 1.% π π π + ν π π π + π ν 4.6% } leptonic 35.2% 1 prong 49.5% } 3 prong 15.2% Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 4 / 32

5 rigger e-channel: EF e15 medium µ-channel: EF mu1 MG Event / (2.5 GeV) dt L = 8.53 pb = 7 ev p [GeV] ha very oft lepton, p 1 3 GeV. hi analyi i under threat of being precaled without uing iolated lepton trigger at 1 33 cm 2 1. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 5 / 32

6 Object Selection Muon preelection Electron preelection taco author 1 or 3 p > 1 GeV p > 1 GeV η < 2.4 η < 2.47 combined muon exclude η = exclude bad OX medium Muon election Electron election p > 15 GeV p > 15 GeV.15 < pms pid <.2 robut tight p ID z < 1 mm χ 2 < 15 Muon iolation Electron iolation etcone4/p <.1 etcone3/p <.1 ptcone4/p <.6 ptcone4/p <.6 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 6 / 32

7 Object Selection Preelected lepton are ued for overlap removal with tau candidate and counted for the dilepton veto. au are elected by: Augut 21 verion of afe tight ID electron veto tight muon veto he elected lepton i paired with the elected tau. Event Selection dilepton veto co φ <.15 m (l,e ) < 5 GeV m vi = GeV N track ( h ) = 1 or 3 charge( h ) = 1 Oppoite ign h and l Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 7 / 32

8 W lν +jet Suppreion Event / (.5) co(φ(lep) - φ(e )) + co(φ( )) h ) - φ(e co φ <.15 dt L = 8.53 pb = 7 ev Event / (5 GeV) m (lep, E ) [GeV] m < 5 GeV dt L = 8.53 pb = 7 ev Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 8 / 32

9 Background Etimation EW background are etimated from Monte Carlo provided that they are mall and W Monte Carlo i normalized in a W rich control region. Agreement i een in other EW rich region (high E, high lepton p,...) Rate of real and fake lepton in dijet are not expected to be modeled well in Monte Carlo. background etimation mut be driven. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 9 / 32

10 W Control Region W Monte Carlo agree well prior to requiring tau ID, but the MC overetimate when requiring tau ID. he tau fake rate i overetimated in Monte Carlo. Scale the W Monte Carlo to match the in a W rich control region (WCR) defined by inverting the W uppreion cut. Before tau ID After tau ID Event / (2.5 GeV) 2 dt L = 8.53 pb 18 = 7 ev p [GeV] Event / (2.5 GeV) p [GeV] dt L = 8.53 pb Correct the for contamination from other EW procee uing Monte Carlo. N WCR W k W N WCR W = N WCR N WCR other EW k W = 6 7% Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 1 / 32 = 7 ev

11 Control Region looe not tight tau C D tight tau A B iolated lepton non-iolated lepton All region include the dilepton veto and W uppreion cut. B, C, and D are rich, while A i a mix of Signal, EW background, and background. Key aumption: the iolation ratio for i the ame in AB a in CD. N A N B = NC N D Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 11 / 32

12 hen the number of event in A can be predicted: ( ) N C N A = NB N D = N B R where R i the iolation ratio meaured in CD region. Since region B, C, and D aren t completely pure, we correct for the expected EW contamination from MC. both e/µ channel have N i = Ni Ni EW, for i = B,C,D R =.58±.2, he hape of the ditribution are taken from the in region B. All the gray hitogram in thi talk are thi driven model. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 12 / 32

13 Region A, before W cut Muon Channel Event / (2.5 GeV) dt L = 8.53 pb = 7 ev Event / (5 GeV) dt L = 8.53 pb = 7 ev Event / (.5) dt L = 8.53 pb = 7 ev p [GeV] m (lep, E ) [GeV] φ(e )) co(φ(lep) - φ(e )) + co(φ( ) - h Event / (5 GeV) dt L = 8.53 pb = 7 ev Event dt L = 8.53 pb = 7 ev Event / (5 GeV) dt L = 8.53 pb = 7 ev E [GeV] m vi (lep, h ) [GeV] Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 13 / 32

14 Region A, after W cut Muon Channel Event / (2.5 GeV) dt L = 8.53 pb = 7 ev Event / (5 GeV) dt L = 8.53 pb = 7 ev Event / (.5) dt L = 8.53 pb = 7 ev p [GeV] m (lep, E ) [GeV] φ(e )) co(φ(lep) - φ(e )) + co(φ( ) - h Event / (5 GeV) dt L = 8.53 pb = 7 ev Event dt L = 8.53 pb = 7 ev Event / (5 GeV) dt L = 8.53 pb = 7 ev E [GeV] m vi (lep, h ) [GeV] Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 14 / 32

15 Final ignal election, muon channel After including m vi = GeV N track ( h ) = 1 or 3 charge( h ) = 1 Oppoite ign h and l Event / (5 GeV) m vi (lep, h ) [GeV] event tat. MC tat bkg EW bkg W lν W ν Z ll t t dt L = 8.53 pb Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 15 / 32 = 7 ev

16 Region A, before W cut Electron Channel Event / (2.5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event / (.5) dt L = 8.32 pb = 7 ev W e ν Z e e p [GeV] m (lep, E ) [GeV] φ(e )) co(φ(lep) - φ(e )) + co(φ( ) - h Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event dt L = 8.32 pb = 7 ev W e ν Z e e Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e E [GeV] N track ( h ) m vi (lep, h ) [GeV] Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 16 / 32

17 Region A, after W cut Electron Channel Event / (2.5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event / (.5) dt L = 8.32 pb = 7 ev W e ν Z e e p [GeV] m (lep, E ) [GeV] φ(e )) co(φ(lep) - φ(e )) + co(φ( ) - h Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e Event dt L = 8.32 pb = 7 ev W e ν Z e e Event / (5 GeV) dt L = 8.32 pb = 7 ev W e ν Z e e E [GeV] N track ( h ) m vi (lep, h ) [GeV] Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 17 / 32

18 Final ignal election, electron channel After including m vi = GeV N track ( h ) = 1 or 3 charge( h ) = 1 Oppoite ign h and l Event / (5 GeV) m vi (lep, h ) [GeV] event tat. MC tat bkg EW bkg W lν W ν Z ll t t dt L = 8.32 pb Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 18 / 32 = 7 ev W e ν Z e e

19 OS/SS Background Etimation Method A complementary method for background etimation. non-iolated C D lepton iolated A B lepton OS SS Depend le on the ytematic of meauring the iolation ratio. Ue ame-ign lepton-tau ample to etimate the background. Doe imilar correction for EW contamination and W normalization. Currently tatitically limited by ame-ign ample. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 19 / 32

20 OS SS Background Etimation Reult hi i for period E3-G EF e15 medium 8318 nb 1 Etimation for the ignal region, OS Low Mt, Low Iol: N DAA = 29 N EWK MC = 4.437±.8475 From we meaure the component to be: N Data = 1.813±1.998 hi give a ignal count from of : N ZauauData = 22.75±2.17 Purity : 78 % From MC we expect a ignal count of : N ZauauMC = 23.1±1.344 N.B. Statitical error only hi i for period A-G EF mu1 MG nb 1 Etimation for the ignal region, OS Low Mt, Low Iol: N DAA = 46 N EWK MC = 3.411±.4288 From we meaure the component to be: N Data = 2.258±2.315 hi give a ignal count from of : N ZauauData = 4.33±2.354 Purity : 88 % From MC we expect a ignal count of : N ZauauMC = 35.42±1.668 N.B. Statitical error only

21 Sytematic We are till cro checking our method for error propagation and etimating our ytematic error. Ryan Reece Penn Obervation Statu 21 / 32 jet tau fake rate 5% all bkg MC except W mc9 overetimate the fake ource error effect comment luminoity 11% all MC theor. xec 5% all MC electron eff 5% all MC except W muon efficiency 3% all MC except W tau ID eff 8% ignal MC tau energy cale 2% m vi tudy by varying cluter E k W 3% W tat. in WCR lepton trigger eff all MC Z ll tag+probe e tau fake rate 3% all bkg MC except W from W ν mu tau fake rate 8% all bkg MC except W from W ν contant R 7% R

22 Sytematic Io/NonIo RANS_MASS SUM_COS_DPHI SELECED_AU OS VIS_MASS_2 AU_CHARGE_1 AU_NUMRACK_1_OR_3 cut he aumption that the iolation i invariant among our event election i valid. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 22 / 32

23 Invariant Ma Candidate For a ubet of the candidate, the invariant ma of the Z boon can be recontructed, under the aumption that the neutrino from the tau decay are collinear with the decay product. Event / (5 GeV) dt L = 8.53 pb = 7 ev m inv (let, h ) [GeV] 4 candidate in the muon channel through period G. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 23 / 32

24 Summary Updated l h analyi through period G (8.5pb 1 ). 46 µ-channel candidate with expected S/B e-channel candidate with expected S/B 3. We have two independent background etimate which are converging. Sytematic evaluation i ongoing. Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 24 / 32

25 Zll Zll: elect two lepton, p > 1 GeV Lower ignal yield (BR(l) ~35%), but two clean lepton in final tate Conider elec-muon, elec-elec and muon-muon channel Aim: meaure cro ection ue a probe for medium p lepton (reco + trigger efficiency) tudy invariant ma recontruction 2 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 25 / 32

26 Baeline Selection Muon Preel: p > 1 GeV, < 2.4 SACO icombined d < 1 mm -.15< p (MS) p (ID) /p (ID) <.2 Match ChiSq < 15 Charge =+/- 1 Elec Preel: p > 1 GeV < 2.47,!(1.35 < < 1.52), IEM Robut Medium, Author == 1 OR 3 OX Map cut Charge = +/- 1 Jet Preel: AntiKt4opo p > 1 GeV, < 4.8 Good Event Cut EF_mu1_MG (µµ, eµ), EF_e1_medium (ee) N(Lepton p > 1 GeV) = 2, Oppoite ign Good Event Cut WZ Common GRL >= 1 vertex with 3 track, z < 15 mm Jet Quality Cut Iolation: Elec: PtCone4/p <.6, EtCone3/p <.1 Muon: PtCone4/p <.6, Etcone 4/p <.6 Sum Co( lep-me) > -.15 Sum E (Lep, Jet) + ME < 15 GeV 25 < m(lep Lep) < 6 GeV 3 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 26 / 32

to keep p threhold a low a poible EF_2mu1 emu 35.2 pb emu 32.

27 Cut Flow EF_e15_medium ee 29.7 pb mumu 34.7 pb Electron (muon) trigger threhold raied to p =15 (13) GeV in period G Ue dilepton trigger to keep p threhold a low a poible EF_2mu1 emu 35.2 pb emu 32.5 pb EF_mu1_MG / EF_e1_looe_mu6 N Data (after MLepLep cut) EE MuMu EMu N (Data) Signal Purity (%) Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 27 / 32

After SumE + ME cut e mu Channel Clear Z auau ignal above mall background But: no a MC tat too low etimate after dilepton cut ABCD Etimate in ignal region: N(A) = N(B) * N(C)/N(D) Same Sign Oppoite

28 After SumE + ME cut e mu Channel Clear Z auau ignal above mall background But: no a MC tat too low etimate after dilepton cut ABCD Etimate in ignal region: N(A) = N(B) * N(C)/N(D) Same Sign Oppoite Sign N Data (32.5 pb ) Data after dilepton election B = 18 D = 635 A = 159 C = 1189 Iolated Anti-Iolated Define anti-iolation region by inverting iolation cut Dominant background in Io Same Sign: Zµµ (.86 evt), Wµ (1.33 evt) purity in AntiIo: 99.8% 7 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 28 / 32

29 Etimate (e mu) Cut Et Cone Rel / N(Data) N (Zauau) N(Other EW MC) N( 35.2 pb etimate) N(MC + Et) / / / /- 8.9 MLepLep 61. +/ / / / / pb Only tatitical error N(MC + Et) conitent with after Iolation cut Etimate Sum Co( lep-me), Sum E (Lep, Jet) + ME, m(lep Lep) cut efficiencie from anti-iolated region N(MC + Et) overhoot after MLepLep Cut Still need etimate of ytematic on etimation hp://epace.cern.ch/atla-perf-tau/ztautau/lit/general%2dicuion/flat.apx?rootfolder=%2fatla %2dperf%2dtau%2fZtautau%2fLit%2fGeneral%2Dicuion%2fLepLep%2EMu%2analyi%2%2b %2%2etimation%2for%235%2e2%2pb %2d1&FolderCID=x1224DB2572C4EA934191F3FA2D4EB8634&opicView=hp%3A%2F %2Fepace%2Ecern%2Ech%2Fatla%2Dperf%2Dtau%2FZtautau%2Fdefault%2Eapx 8 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 29 / 32

2 2 dimenional cut: ME p Lep 4617SumEME 46 GeV Signal purity increae from 5.2% to 24.

30 ee and mumu Channel ee Channel Like flavour channel dominated by Drell Yan background wo new cut to reduce Drell Yan: (p Lep1 - p Lep1 )/(p Lep1 + p Lep1 ) >.2 2 dimenional cut: ME p Lep 4617SumEME 46 GeV Signal purity increae from 5.2% to 24.9% (ee channel) hp://indico.cern.ch/getfile.py/acce? contribid=3&reid=&materialid=lide&confid= Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 3 / 32

31 ee and mumu Channel Sum Co( lep-me) < -.15 Sum Co( lep-me) > -.15 Still need to etimate Z + Drell Yan BG Split into ABCD region uing M(LepLep) and Sum Co( lep-me) Ue control region to check ratio (A/B) in and MC (factor F = /MC ratio) Etimate contribution in D uing ratio (C/D) from MC: DData(DY Zll) = F C DataDMC(DY Zll) /CMC Data baed etimate agree with MC, but within large error 15.6 pb N (DY+Z) N (Zauau) N (Ztauau) MC ee / mumu / hp://indico.cern.ch/getfile.py/acce?contribid=3&reid=&materialid=lide&confid= Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 31 / 32

32 Summary and Plan Zll for 35.2 pb : EE MuMu EMu N (Data) Signal Purity(%) Background etimate for principle background in emu, ee and mumu channel Drell Yan background reduced Route to obervation note: Include ytematic for analyi and background etimate dicuion with performance group to determine bet ytematic for medium p lepton Full lumi for ee and mumu channel 9 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 32 / 32

33 Backup Slide Ryan Reece Penn Obervation Statu 33 / 32

34 Fiher like cut for ee, mumu 1 Ryan Reece Penn ryan.reece@cern.ch Obervation Statu 34 / 32

35 Drell Yan Backgroud Etimation 11 Ryan Reece Penn Obervation Statu 35 / 32

Introduction The CLEO detector and Y(5S) data sample Analysis techniques: Exclusive approach Inclusive approach Summary

Introduction The CLEO detector and Y(5S) data ample Analyi technique: Excluive approach Incluive approach Summary Victor Pavlunin Purdue Univerity CLEO collaboration Preented at Firt Meeting of the APS