Tau Trigger Study at L1

Takashi Mitani, Kohei YoritaWaseda University

Soshi TsunoKEK

06/April/2013

KEK-WASEDA Meeting 2

Introduction

06/Apr/2013

Channel Trigger Trigger Threshold Offline ThredholdLepton-Lepton e-μ trigger 12(e)/8(μ) GeV 15/10GeV

Lepton-Hadron Single-lepton 24GeV 26/20GeV

Hadron-Hadron di-tau 29/20GeV 40/25GeV

• di-tau Trigger– Require two hadronic taus at trigger level.– Trigger rate is very large due to the fake from multi-jet events.

　　→ Compared to other decay channel, trigger pT thresholds are high.

→di-tau Trigger is important for this channel.

• For LHC Run2, it is important to design new tau trigger which reject the multi-jets events and control trigger rate with keeping higgs signal sensitivity.

• In this talk, we present the first results of optimization of L1 tau trigger.

Too High!

• H→ττ→hadron-hadron analysis have the 2nd largest sensitivity in the H→ττ. σ/σSM<1.24 ( ∫Ldt = 4.6+20.3fb-1, 95% C.L@mH=125GeV)

KEK-WASEDA Meeting 3

Tau Trigger System

06/Apr/2013

Threshold Lead tau Sublead tau

L1 15GeV 11GeV

L2 20.7GeV 15.2GeV

EF 29.0GeV 20.0GeV

Current di-tau Trigger Threshold

EM Calorimeter

Hadron Calorimter

Core Region

Isolation Region

• Level1(L1): Hardware Based– Calorimeter Tower: Δη×Δφ 0.1×0.1– Core : 2×2, Isolation : 4×4-2×2– Use Cluster ET and Isolation information

Focus on Level 1 trigger in this talk.• Level2(L2): Software Based

– Use information at RoI region– Energy information: 2 variables Track information: 4 variables– Cut based trigger

• EventFilter(EF): – Multivariate analysis trigger(BDT)

KEK-WASEDA Meeting 4

Data Set

06/Apr/2013

• Samples are 8TeV MC and data. Signal: ggH, VBFH, WH, ZH (125GeV)– mc12_8TeV.161577.PowHegPythia8_AU2CT10_ggH125_tautauhh.merge.NTUP_TAU.e1217_s1469_s1470_r3542_r3549_p1344.no_trigger.v1/– mc12_8TeV.161617.PowHegPythia8_AU2CT10_VBFH125_tautauhh.merge.NTUP_TAU.e1217_s1469_s1470_r3542_r3549_p1344.no_trigger.v1/– mc12_8TeV.161657.Pythia8_AU2CTEQ6L1_WH125_tautauhh.merge.NTUP_TAU.e1217_s1469_s1470_r3542_r3549_p1344.no_trigger.v1/– mc12_8TeV.161697.Pythia8_AU2CTEQ6L1_ZH125_tautauhh.merge.NTUP_TAU.e1217_s1469_s1470_r3542_r3549_p1344.no_trigger.v1/

… common D3PD data used by had-had analysis group. QCD Background: Enhanced Bias data– data12_8TeV.00202798.physics_EnhancedBias.merge.NTUP_TAU.r3870_r3871_p1153_p1130/

– Fire unprescaled L1 triggers, i.e., EM3, MU4, TAU5, J18, FJ18, XE25, TE250.

Tau Objects• L1 trigger objects are dR(<0.2) matched with offline tau objects,

which are selected by next slide offline tau object selection.• For QCD background, we don’t require the matching with offline tau.

KEK-WASEDA Meeting 5

Event & Objects Selection for Signal, Optimization Point @ L1

• At least 1 primary vertex with num_Tracks >=4• Event Cleaning (i.e. core Flag, LAr, Tile, jet cleaning)• Muon veto• Electron veto• Require exactly 2 taus

06/Apr/2013

Tau object (Sub)Leading pt > 30 (20) GeV |eta|<2.5 Two taus pass BDTMediumID Tau author == 1 or 3 numTrack == 1 or 3 EleVetoLoose MuonVeto Veto, if leading tau track is in crack

region , 1.37<|eta|<1.52 2 taus have opposite charge Same Primary Vertex

Event Selection Based Trigger EF_tau29Ti_medium1_tau20Ti_medium1

Optimization Point @ L1 Δη threshold EM Isolation threshold ET threshold Require additional 1jet

KEK-WASEDA Meeting 6

Estimation of trigger rate at LHC Run2

06/Apr/2013

• We refer to the following talk.– https://indico.cern.ch/getFile.py/access?contribId=3&resId=0&materialId=slides&confId=172055

• Plan of LHC– √s = 14(13) TeV and 25(50)ns bunch spacing– Peak luminosity turn up step by step (2015: 1.0×1034, 2019:2-3×1034cm-2s-1)

→In this talk, estimate L1 rate assuming √s=14TeV, L=1.0×1034cm-2s-1.• Most L1 rates are driven by multi-jet production.

– Can extrapolate by ratio of parton luminosities between √s=8TeV and 14TeV 　 – Not consider pile-up effect in this talk. (e.g. 1 minbias event per crossing.)

• ex ） Di-tau Trigger @ L=1.0×1034cm-2s-1

L1 Menu Offline pT 8TeV Rate 14TeV Rate 14/8 TeV Ratio

2TAU11I_TAU15 40/25 20.7kHz 43.2kHz 2.1

→The goal is reducing L1 rate from 43.2kH to ~15kHz using L1 trigger objects.

KEK-WASEDA Meeting 7

Cluster ET distribution @ L1

06/Apr/2013

• If we raise Cluster tau ET threshold, we can reduce QCD jets events. But higgs events are also reduced.

– If we raised “only” lead L1 tau ET threshold, it is possible to reduce QCD jets events keeping signal acceptance.

Lead L1 Tau Objects Sublead L1 Tau Objects

KEK-WASEDA Meeting 8

Requirements at L1

06/Apr/2013

Menu L1 RateET cut, IsolationEM 4 GeV (current)≦ 43.2 kHzET cut, Δη<2.0,IsolationEM 3≦ GeV 24.7 kHzET cut, Δη<2.0,IsolationEM 3≦ GeV+1jet(ET>10GeV) 7.49 kHzET cut, Δη<2.0,IsolationEM 3≦ GeV+1jet(ET>20GeV) 1.85 kHz

3 GeV

Δη<2.0

Δη(τ1,τ2)

EM Isolation

• EM Isolation Hadronic tau objects are narrow. → Require tighter isolation from 4 to 3GeV• Δη(τ1,τ2) In proton-proton collision, higgs is boosted to the beam axis. → 2 taus are in the same hemisphere with respect to η.

• Require additional jet at L1

Candidates of L1 trigger objects

Accept!

Accept!

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