Analysis status for heavy charged Higgs with H +

Higgs WG meeting, 23 October 2007R. Kinnunen, S. Lehti

Analysis status for heavycharged Higgs with H+

R.Kinnunen, S. LehtiHelsinki Institute of Physic, Helsinki

Higgs WG MeetingCERN, 23 October, 2007


Contents:

- Workplan and status for fully hadronic gg->tbH+, H+

- Background analysis for 100 fb-1 with W-> in tt and W+jet events

- Background analysis for 100 fb-1 with QCD events

- ”Hard reconstruction” in the signal events


Off-line event selection

• Veto on isolated electrons and muons, pT >~ 10-20 GeV/c

• MET > 100 GeV

• jet reconstruction, ET > 100 GeV

• isolation: no track with pT > 1 GeV/c in the isolation cone of 0.04 < R < 0.4 around the leading track

• Electron rejection: At least one HCAL cell with ET > 2 GeV in the jet

• One-prong selection:

– One reconstructed track in the signal cone

– ptrack / E jet > 0.8

• Three-prong selection:

– Three reconstructed tracks in the signal cone

– Matching between ET(CALO cluster) and pTtrack to select ->

– ptrack / E jet > 0.8 or ptrack / E jet < 0.4

• Tagging of one b jet and top mass reconstruction

• Transverse mass reconstruction from jet and MET


Backgrounds for gg->tbH+, H+

Main background processes: tt, W+3jets, QCD multi-jet eventsIn ideal case, - signal at large mT( jet,MET), with an endpoit at mT( jet,MET) ~ mH+

- backgrounds from W-> (tt, W+jets) distributed to mT( jet,MET) < mW


Sources background in the signal area

Background in the signal area (mT( jet,MET) > 100 GeV) can be devidedinto 3 gategories:

• Diffusion of background events to the signal area due to MET measurement - This background in tt and W+jets events can be measured with muons from W-> decays in tt and W+jets events - Background due to QCD multi-jet events can be measured in QCD events measuring fake probability in other processes

• Fake jets due to difficulty of the identification Could be measured from data exploiting + jet events as proposed in CMS NOTE-2006/028

• Fake leading tracks (pT > 80 GeV) Can be reduced with strong quality cuts, studies going on (PFlow group), L. Wendland for ’s in gg->tbH+, H+


• Isolated electron veto to suppress W->e in tt events• One muon with pT

> 100 GeV• Muon isolation• ET

miss > 100 GeV• 3 jets, ET > 20 GeV• W+3jet selection: no b jets, suppression of tt • tt selection: 2 b jets, suppression of W+3jets• mT(,MET) reconstruction

Background analysis for 100 pb-1 in muon events

Event selection:1. Single muon trigger2. Off-line selection cuts:


Background in the signal area can be estimates through:

Ntt-sel = (Ntt

-sel – NW3jcont) * (/) * (

-sel/ sel )* top rec.

-sel / b-tag

Nw3j-sel = (Nw3j

-sel – Nttcont) * (/) * (

-sel/-sel)* top rec.

-sel * b-tag / (b-antitag)

NW3jconand NW3j

conarethe W+3jet and tt contamination to tt and W+3jet selections

: to be estimated from MC not enough events from Z-> -> jet in this energy scale

MET( sel.): MET efficiency in signal (jet) selectionMET( sel.): MET efficiency in background (jet) selection

b-tag : to be measured in b enriched tt events

b-antitag : can be measured from +jet events, if fraction of +b events is below 1%

- top reconstruction: to be checked if affects the shape of the mT( jet, ET

miss) distribution


Event selection:• Events from tau + MET trigger• At least one jet with pT

jet > 100 GeV• One of the jets with pT

jet > 100 GeV taken randomly as candidate• ET

miss > 100 GeV• 3 jets, ET > 20 GeV • one ”b” jet• top mass reconstruction• mT( candidate,MET) reconstruction

Background analysis for 100 pb-1 in QCD events

Events in the signal area:

NQCD(-sel) NQCD(QCD-sel) * miss-id)

miss-id) can be measured in +jet events


Software version and data samples

- CMSSW version CMSSW_1_6_7 used

- Data samples used:

tt: tt0j_mT_70-alpgen, = 840 pbW+3 jets: W3jet_0ptw100-alpgen, 0 < pT

W < 100 GeV, = 588 pb W+4 jets: W4jet_0ptw100-alpgen, 0 < pT

W < 100 GeV, = 124 pb QCD: QCD_Pt_120_170, 120 < pT

jet < 170 GeV Signal: RelVal160pre8ChargedHiggsTausM200 mH+ = 200 GeV, 5000 events


Muons from reco::MuonCollection - tracker isolation in a cone of R=0.3 and pT

cut = 1 GeV used

Muon off-line selection


MET reconstruction

reco::CaloMET used including muons from reco::MuonCollectionNo MET corrections yet


B tagging

JetTagCollection: trackCountingHighPurJetTags

2 tagged b jets, ET(jet) > 20 GeV, discriminator > 1.5 (not optimized yet)


Expected behaviour from MC variables in tt events

Transverse mass mT(,MET) distributions


Transverse mass mT(,MET) distributionsPreliminary results for tt, t1->b,t2->hadrons

Unnormalized distributions

Events in the signal area were wound to originate mainly from real neutrinosfrom W-> originating from the secod top-need to implement -jet veto in the muon selection and second veto in the signal selection

W2-> and W2->eremoved with MC info

tail due to MET resolution

Some events from W->

MET should originatefrom W->


Transverse mass mT(,MET) distributionsPreliminary results for W+3jet, W->

All remaining events at large mT are signal-like with well measured MET

Originate from the BW tail of the W need to genetate the W mass in bins to study the effect


- Select jets passing the the IsolatedTauTagInfoCollection with ET > 100 GeV Parameters for the IsolatedTauTagAlgo: pT

leading track > 20 GeV, R(match) =0.1, R(signal)=0.07, R(isol) = 0.45, pT(min) = 1 GeV

- Require matching with the MC jet from gg->tbH+, H+

- Definition of energy resolution: ETjet / ET

visible MC -1

- Event sample used: RelVal160pre9ChargedHiggsTausM200 - small statistics, 5000 events !

First tentative for a ”hard algorithm”


Visible hadronic

mH+ = 200 GeV

ET(MC jet)

MC jet)


Possible algorithm of reconstructing large ET one-prong ’s R. Kinnunen and A. Nikitenko

for good geometrical ECAL-HCAL-track matching do following: 1. If |ET

HCAL+ECAL - pTtrack| < 2 CALO: use ~ track p, corresponds to ±

2. If ETHCAL+ECAL – pT

track > 2 CALO 2.1 if |ET

HCAL - pTtrack| < 2 HCALuse ~ track p + ECAL cluster,

corresponds to ±n with charged pion not interacting in ECAL 2.2 if pT

track - ETHCAL > 2 HCAL ±interaction in ECAL, take the calo jet

2.3 if ETHCAL - pT

track > 2 HCAL hadronic jet, reject

- Optimization of the cones forenergy collection in ECAL and HCAL needed

2.1) 2.2)

±±

HCAL

ECAL


Definition: ETcalo cluster / pT

track – 1 Calo cluster reconstruction from CaloRecHits withR(ECAL impact point, cell) < 0.1 in ECALR(ECAL impact point, cell) < 0.2 in HCAL

One prong decay mode without neutrals,-> h

Test CALO cluster/track matching for one-prong ’s

Almost all events withinETcalo cluster / pT

track – 1| < 0.5

Matching variable


Calo cluster/track matching forn

Test here the HCAL cluster/track matching

pjet ~ ptrackBad track ?reject

Matching variables

III


Loss of energy observed, try to minimize the effect with an asymmetric cut:

- 0.5 < ETcalo cluster / pT

track – 1 < 0.2

candidates with Calo Cluster/track matchingregion II

Energy resolution forn

Energy resolution forwith Calo Cluster/track matching

Resolutions


HCAL cluster/track matching:add the ECAL cluster to include 0’s

±interaction in ECAL, take the calo jet

Hadronic jet: reject

HCAL cluster/track matching fornRegion III

Select large window |ET

HCAL cluster / pTtrack – 1 |< 0.8

due to energy loss in this area

Matching variables


Comparison with reco::Jet

Resolutions


All one-prong ’s selected with MC info


Conclusions and plans

1) Background analysis with W-> in tt and W+3jet events and in QCD events in progress Large mass tail observed in mT(,MET): - mainly due to W-> in tt events - due to natural W width in W+3jet events

2) First results from a ”hard -tau” algorithm for one-prong ’s in gg->tbH+,

H+ with ET-jet > 100 GeV were presented

- Improvement of jet resolution possible with a simple algorithm

• New group members: Katri Lassila, fake probability from +jet events Matti Kortelainen, top mass reconstruction, Benedict Hegner should join

later Richard Cavanaugh, with PFlow, MET


Backup slides


const CaloJet* caloJet = dynamic_cast<const CaloJet*>(&(iTau->jet()));

vector<CaloTowerRef> towers = caloJet->getConstituents();

for(vector<CaloTowerRef>::const_iterator iTower = towers.begin(); iTower != towers.end(); iTower++){

// access CaloRecHits for(size_t j = 0; j < numRecHits; j++) { DetId recHitDetID = (**iTower).constituent(j);

DetId::Detector detNum=recHitDetID.det();

if( recHitDetID.det() == DetId::Ecal ){ if( recHitDetID.subdetId() == 1 ){ // Ecal Barrel

EBDetId ecalID = recHitDetID; EBRecHitCollection::const_iterator theRecHit = EBRecHits->find(ecalID);

if(theRecHit != EBRecHits->end()){ DetId id = theRecHit->detid();

const CaloCellGeometry* this_cell = EB->getGeometry(id); if(this_cell){

GlobalPoint hitPos = this_cell->getPosition(); double eta = hitPos.eta(); double phi = hitPos.phi();

double theta = hitPos.theta(); if(theta > 3.14159) theta = 2*3.14159 - theta;

// ecalCells.push_back(hitPos); double energy = theRecHit->energy();

double et = energy * sin(theta); Double_t px = energy * sin(theta)*cos(phi); Double_t py = energy * sin(theta)*sin(phi); Double_t pz = energy * cos(theta);

4. EBRecHit4. EBRecHit


5. ECAL impact point

- using TransientTrack

const TransientTrack transientTk = (transientTrackBuilder->build(&(leadTk)));

- ecalHitPosition is taken as maxTowerEt position

TrajectoryStateClosestToPoint TSCP = transientTk.trajectoryStateClosestToPoint(ecalHitPosition);

GlobalPoint trackEcalHitPoint = TSCP.position();

Documents

Analysis status for heavy charged Higgs with H +