9/29/2006 FJPPL Meeting@KEK 1

PFA Study with Jupiter

Contents :1. Introduction2. GLD-PFA3. Z->qqbar Study4. Zh Study5. Summary

FJPPL Meeting @ KEKSeptember 29th, 2006

Tamaki Yoshioka ICEPP, Univ. of Tokyo

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Introduction- Most of the important physics processes to be studied in the ILC experiment have multi-jets in the final state. → Jet energy resolution is the key in the ILC physics.

- The best energy resolution is obtained by reconstructing momenta of individual particles avoiding double counting among Trackers and Calorimeters.

- Charged particles (~60%) measured by Tracker.- Photons (~30%) by electromagnetic CAL (ECAL).- Neutral hadrons (~10%) by ECAL + hadron CAL (HCAL).

→ Particle Flow Algorithm (PFA)

- In this talk, general scheme and performance of the GLD-PFA, using the GEANT4-based full simulator (Jupiter), will be presented.

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Geometry in Jupiter

Muon Detector

Solenoid

Hadron Calorimeter (HCAL)

Electromagnetic Calorimeter (ECAL)

TPC

VTX, IT

Dodecagonal ShapeAs of August 06

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229.8cm

349.4cm

299.8cm419.4cm

Readout Line =10cm

270cm

Endcap.InnerRadius=40cm

BarrelHD

BarrelEM

EndcapEM

EndcapHD

Barrel.InnerRadius=210cm

Barrel.HalfZ=280cm

210cm

280cm

Calorimeter Geometry in Jupiter

IP

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Calorimeter Structure

ECALW/Scinti./Gap

3/2/1 (mm) x 33 layers

HCALFe/Scinti./Gap

20/5/1 (mm) x 46 layers

Absorber

Active Layer

Current cell size :2x2cm

Can be changed.

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GLD-PFA

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Particle Flow Algorithm for GLD

Flow of GLD-PFA

1.Photon Finding 2.Charged Hadron Finding3.Neutral Hadron Finding4.Satellite Hits Finding *Satellite hits = calorimeter hit cell which does not belong

to a cluster core

Note : Monte-Carlo truth information is used for muonand neutrino.

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Photon Likelihood (Input)

trkdis velocity meanlay

Edep/nhits chi2

Photon

Other

- Five variables are selected to form the photon likelihood function.

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Photon Likelihood (Output)

- Cut position is set to be 0.7.

linear

log

PhotonOther

Photon

Other

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Charged Hadron Finding- Basic Concept : Extrapolate the charged track and calculate a distance between a calorimeter hit cell and the extrapolated track. Connect the cell that in a certain tube radius (clustering).

Charged TrackCalorimeter input position

Hit Cellsdistance

ECAL

HCAL

- Tube radius for ECAL and HCAL can be changed separately.

- Calculate the distance for any track/calorimeter cell combination.

Extrapolated Track

Tube Radius

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Neutral Hadron Likelihood (Input)- Four variables are selected to form the NHD likelihood function.

Neutral Hadron

Satellite Hits

velocity Edensity

Edep/nhits meanlayer

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Neutral Hadron Likelihood (Output)

- Cut position is set to be 0.73.

linear

log

NeutralHadron

SatelliteHits

Neutral Hadron

Satellite Hits

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Z -> qqbar

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Z-pole Event Display

End View Side View

- 2cm x 2cm tile (GLD backup solution) is used in this study.

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e+

e-

Event Display

Yellow : Photon

Red, Green : Charged Hadron

Black, Blue : Neutral Hadron Z → qqbar @ 91.2GeV

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Yellow : Photon

Red, Green : Charged Hadron

Black, Blue : Neutral Hadron

Event Display

Gamma Finding

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Yellow : Photon

Red, Green : Charged Hadron

Black, Blue : Neutral Hadron

Event Display

Charged Hadron Finding

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Yellow : Photon

Red, Green : Charged Hadron

Black, Blue : Neutral Hadron

Event Display

Satellite Hits Finding

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Yellow : Photon

Red, Green : Charged Hadron

Black, Blue : Neutral Hadron

Event Display

Remaining : Neutral Hadron

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cluster type e photon e chd e nhd Pphoton Pchd PnhdPhoton 93.6 1.88 18.5 87.21 3.57 7.53

CHD 2.44 85.8 12.8 1.31 93.8 3NHD 1.07 3.6 52.8 3.28 22.7 70.7

Satellite 2.86 8.74 15.8 10.20 63.9 24.8

Definition

Efficiency : exxx (total xx E in collected hits)/(true xxx total E in CAL)

Purity : Pxxx (total xxx E in a cluster)/(total E in a cluster)

xxx = Photon, CHD, NHD, Satellite

both e and P values are energy-weighted

Performance

- Energy-weighted Efficiency and Purity

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- In barrel region, ILC goal of 30% has been achieved.- Performance in 0.7<|cosθ|<0.8 is too bad. → Already fixed.

All angle

- Z → uds @ 91.2GeV, new calorimeter geometry, 2cm x 2cm tile

Jet Energy Resolution

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Energy Dependence- Energy dependence of jet energy resolution.

- Bad performance for higher energy.- Not so bad performance for < 100 GeV Jet.

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Linearity

- Good linearity. Jet energy can be corrected.

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Zh → h

First look at the Zh events with Jupiter and realistic PFA.

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Typical Event Display

- Two jets from Higgs can be seen.

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Zh → h @ 350GeV

- Jet energy is corrected by an empirical formula obtained by Z → qqbar studies.- Selection Criteria

- 90 < Evis < 200 GeV - pt >20 GeV/c

Higgs Mass Visible Energy

Missing Mass

- Fast MC• w/o correction• w/ correction

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Kinematical Fit- 6 Measured Variables

Jet1 : Ej1, j1, j1

Jet2 : Ej2, j2, j2 (Note : Ej1 > Ej2)- 3 Unmeasured Variables

Z0 : Ez, z, z

- 4 Constraintspj1cosj1sinj1pj2cosj2sinj2pZcosZsinZpj1sinj1sinj1pj2sinj2sinj2pZsinZsinZpj1cosj1pj2cosj2pZcosZEj1 + Ej2 + Ez – Ecm = 0

(Note: jet mass is fixed : pfit = √{Efit2

– (Emeas2 – pmeas

2)} )

→ 1C-fit can be performed.

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Fitted Results

Prob > 0.02

- Higgs mass resolution is significantly improved. … But,- Peak at prob=1 indicates the fitting didn’t work well.

Very Preliminary

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Stretch Functions

2,

2,

,,

ifitimeas

ifitimeas XX

• The stretch function should form a normal Gaussian if the X and are proper.

Too Narrow= Overestimated

Strange

Need tounderstand.

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Summary

• Realistic PFA has been developed using the GEANT-4 based full simulator of the GLD detector.

• Jet energy resolution is studied by using Z->qq events. ILC goal of 30% has been achieved for Z-pole events.

• ZH study based on current PFA performance is now ongoing.