catania lepton tag andrea boccivitaliano ciulliriccardo ranieri infn and università di firenze...

Catania Lepton TagCatania Lepton Tag

Andrea Bocci Vitaliano Ciulli Riccardo Ranieri

INFN INFN andand Università di Firenze Università di Firenze Alessia Tricomi

INFN INFN andand Università di Catania Università di Catania

CMS CPT Week - b MeetingCMS CPT Week - b Meeting33rdrd November 2004 November 2004

b Meeting CPT Week3rd November 2004

Catania Lepton Tag II Riccardo Ranieri 2

Soft Lepton TagSoft Lepton Tag

– Based on identification of the soft leptons from semileptonic B-meson decays we studied only leptons=muonsleptons=muons case

– Efficiency of soft lepton tagging limited by the fraction of B-meson decays containing leptons (20%)

– Provide a valuable complement with respect to the impact parameter tagging

– Some very very preliminary very very preliminary results with ORCA reconstruction already presented at bτ meeting during July Tracker Week

» http://agenda.cern.ch/askArchive.php?http://agenda.cern.ch/askArchive.php?base=agenda&categ=a042955&id=a042955s1t7%2Fmorbase=agenda&categ=a042955&id=a042955s1t7%2Fmoreinfo%2FCataniaLeptonTag.ppteinfo%2FCataniaLeptonTag.ppt

http://www.unict.it/



The test samplesThe test samples– QCD jets from Christian’s test samples

2500 “b”, 4750 “c”, 5000 “udsg” 80<pT[GeV/c]<120

no pileup

– some problems related to the samples:1. Not well defined separation between signal and

background– “udsg” means no requests: this sample contains also c or

b jets depending on c/b quark production probability– “c”(“b”) means at least one c(b) quark in the final state:

this sample is pure QCD enriched in c(b) quark content

2. Variable number of jets– we have not under control the number and flavour of jets

we expect to see» problems in debugging algorithms

– if jets are separated in ET bins too few jets per bin

^




Monte Carlo TruthMonte Carlo Truth

• Muons– information on the origin of the muon

(i.e. “mother” particle of the generated muon)

– information on the origin of the decay chain (i.e. the particle which originates the

decay chain) to separate b→μ and c→μ from b→c→μ

• Jets– we used Christian’s BReco/BTagMCToolsBReco/BTagMCTools

package– associates to the reconstructed jet the main

parton within ΔR(η,φ)<0.3 and assigns jet flavour some modifications inside JetIdentifierJetIdentifier and MCPartonMCParton/LundCodeLundCode classes




Modified BTagMCToolsModified BTagMCTools

– JetIdentifier.hJetIdentifier.h added methods to return not only the HepLorentzVectorHepLorentzVector

(Energy-Momentum) of the three partons, but also the partons themselves to access all the MCPartonMCParton’s methods too

MCPartonMCParton mainParton mainParton (){(){returnreturn m_MainParton;} m_MainParton;}

MCPartonMCParton heaviestParton heaviestParton (){(){return return m_HeaviestParton;}m_HeaviestParton;}

MCPartonMCParton closestParton closestParton (){(){returnreturn m_ClosestParton;} m_ClosestParton;}




Modified BTagMCToolsModified BTagMCTools– JetIdentifier.cc

inside the loop to assign the most suitable MCPartonMCParton to the jet, partons with PYTHIA status = 3 are excluded

– example: Gluon Fusion gg→bb event:

-

E X C L U D E DE X C L U D E DE X C L U D E DE X C L U D E D




Modified BTagMCToolsModified BTagMCTools– MCPartonMCParton

mother and grandmother HEP-PID and top quark decay

intint getMotherLundCodegetMotherLundCode() () constconst {{returnreturn motherLundCode;} motherLundCode;}

intint getGrandMotherLundCodegetGrandMotherLundCode()() constconst {{returnreturn grandmotherLundCode;}grandmotherLundCode;}

boolbool getIsFromTgetIsFromT()() constconst {{returnreturn isFromT;} isFromT;}

Gluon Splitting Finder– loop on PYTHIA lines to find qq pairs from gluon common

mother» at least a gluon in PYTHIA event (lines 3 or 4 or 5 or 6 or 7 or 8)» search for parton-antiparton with PYTHIA status≠3 “daughters” of

the previous gluon » both q and q are labelled as coming “fromGluonSplitting”

– too much PYTHIA-dependent– already passed to Pisa people… waiting for feedback…

-

-




ReconstructionReconstruction– Studies done with ORCA_8_2_0– Reconstruction of RecMuonRecMuon objects

L3 Muon Reconstructor– RecQuery query (RecQuery query ("L3MuonReconstructor""L3MuonReconstructor"););– no further thresholds applied

– Reconstruction of JetWithTracksJetWithTracks objects L2 KtKt jet algorithm

– RecQuery RecQuery jetFinderjetFinder ("PersistentJetFinder"); ("PersistentJetFinder");– jetFinder.setParameter (jetFinder.setParameter ("JetAlgorithm""JetAlgorithm", , 44); // Kt=4); // Kt=4

Tracks in cone ∆R<0.3∆R<0.3 around jet axis– RecQuery query (RecQuery query ("BTagJetWithTracksAlgo""BTagJetWithTracksAlgo"););– query.setComponent ("JetFinder", jetFinder);query.setComponent ("JetFinder", jetFinder);– query.setComponent ("TrackFinder", query.setComponent ("TrackFinder", RecQuery(RecQuery(“CombinatorialTrackFinder”“CombinatorialTrackFinder”));));

– query.setParameter (query.setParameter ("deltaRCut""deltaRCut", , 0.30.3););




Reconstructed MuonsReconstructed Muons

Association between RecMuon’s and TkSimTrack’s– 93% of the times we are able to say what is the simulated

particle reconstructed as a muon

Sim Sim TrackTrack

Rec Rec MuonMuon

μμ±± 639639

ππ±± 123123

ΚΚ±± 8080

otherother 1414

not-assnot-ass 6868

TotalTotal 924924

Entr

ies/

bin




Reconstructed MuonsReconstructed Muons

We can study the “life” of the RecMuon associated to a SimTrack

– PYHTIA list navigation, decay chains…– for the moment we are not able to reconstruct the story of

PYTHIA “stable particles” (GEANT decays)

Entr

ies/

bin

here there are both b→c→μ and c→μ




L2 Jets corrected EL2 Jets corrected ETT

Reconstructed L2 Jets with ET>40 GeV– jet flavour from MC association– more than 80%80% of bb//cc jets are selected– jet η and φ recalculated with tracks

» improved resolution from 0.05 to 0.03

Entr

ies/

bin

Jet Jet FlavourFlavour

L2 JetsL2 Jets[no E[no ETT cut] cut]

L2 JetsL2 Jets[E[ETT>40 >40 GeV]GeV]

bb 30603060 25092509

cc 37093709 29712971

udsuds 3624736247 68076807

gg 1839418394 1205912059

TotalTotal 6141061410 2434624346




Gluon SplittingGluon Splitting

Fraction of jets coming from Gluon Splitting (GS)

– sample: selected L2 jets ET>40 GeV

– 50% of bb//cc jets come from GS

Jet Jet FlavourFlavour

L2 JetsL2 Jets

from GSfrom GSL2 Jets L2 Jets

not from not from GSGS

L2 JetsL2 Jets

TotalTotal

bb 12101210 12991299 25092509

cc 16371637 13341334 29712971

udsuds 24062406 44014401 68076807

gg 00 1205912059 1205912059

TotalTotal 52535253 1909319093 2434624346




Number of L2 JetsNumber of L2 Jets

4 bins in jet ET

light-flavoured jets have lower ET than b/c

0

5000

10000

15000

20000

25000

30000

0-40 40-80 80-120 120-8

L2 Jet ET range [GeV]

Nu

mb

er o

f L

2 Je

ts

bJet

cJet

udsJet

gJet




0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18

0-40 40-80 80-120 120-8


Fra

ctio

n o

f L

2 Je

ts w

ith

L3

Mu

on

s

bJet

cJet

udsJet

gJet

L3 Muons inside L2 JetsL3 Muons inside L2 Jets

A L3 Muon is associated to the L3 jet if ΔR(η,φ)<0.5

– 691/924=75%75% of L3 Muons are inside L2 Jets

– Fraction of 40<ET[GeV]<120 jets with muons:» b b 12.9%12.9% cc 6.2%6.2%» udsuds 0.88%0.88% gg 1.2%1.2%

L2 Jet L2 Jet Flavour Flavour [E[ETT>40 >40 GeV]GeV]

L3 MuonsL3 Muons

ΔΔR(R(ηη,,φφ)<0.)<0.55[no HLT cut][no HLT cut]

bb 313313

cc 178178

udsuds 5858

gg 142142

TotalTotal 691691

Statistical Error: Statistical Error: ±±0.010.01




Where are generated b Where are generated b muons?muons?

494494 MC generated b Muons are inside L2 Jets [ET>40 GeV]

– Fraction of 40<ET[GeV]<120 jets with generated muons (pT>0.5 GeV/c, |η|<2.5) coming from b mesons/baryons decay:

» b b 18.6%18.6% cc <0.1%<0.1%» udsuds 0.26%0.26% gg 0.2%0.2%

L2 Jet L2 Jet Flavour Flavour [E[ETT>40 >40 GeV]GeV]

MC b MC b MuonsMuons

ΔΔR(R(ηη,,φφ)<0.)<0.55[|[|ηη|<2.5, |<2.5, ppTT>0.5 >0.5 GeV/c]GeV/c]

bb 452452

cc 00

udsuds 1717

gg 2525

TotalTotal 494494

0

0.05

0.1

0.15

0.2

0.25

0.3

0-40 40-80 80-120 120-8


Fra

ctio

n o

f L

2 Je

ts w

ith

MC

Mu

on

s fr

om

b

bJet

cJet

udsJet

gJet

Statistical Error: Statistical Error: ±±0.010.01




ConclusionsConclusions

• We have a lotlot of work to do and problems to solve

• A simplersimpler di-jet event sample (DAQ-TDR like) would help to debug our code


catania lepton tag andrea boccivitaliano ciulliriccardo ranieri infn and università di firenze...

Documents

b meeting cpt week

bc jets

fraction of jets

number of l2 jets

b c jets brecobtagmctools

fraction of b

e t reconstructed l2

selected l2 jets e t