jet analysis

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jet analysis

Dec.22/2008 ~

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JET PROPERTIESvisible , without smear, |eta|<1, [0.1,0.1] cells, pp5500GeV

1. divide η-φ space in [0.1, 0.1] cells

2. calculate transverse energy (eTcell) in each cell

3. select candidates of jet-seed by eTcell > ”eTseed”

4. calculate sum of eTcell in the cone which center positioned at jet-seed (eTsum=ΣeTcell)

5. requirement : eTsum>”Min-eT”

6. define the survivors as found jets

Parameters to input are“eTseed”, “coneRadius”, “Min-eT”

Celljet (the Jet-Finding Method)

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Distance btw primary parton and celljet center• assumption:

– dr<1にprimary partonからの jetが入っている– dr<1に他の jet がない

• dr<1 の中で celljet.eT が最大の jetを primary parton 起源の jetとした• celljet.coneradius = 1.• distance b/w primary parton & celljet center

proton proton

parton

dr

found jet

photongluonquark

80%

integral(0~r)

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• assumption:– dr<1にprimary parton からの jet が入っている– dr<1に他の jetがない

• dr<1の中で celljet.eT が最大の jetを primary parton 起源の jet とした• celljet.coneradius = 1.• distance b/w celljet center & each tracks (eT weighted)

Distance btw celljet center and each tracks

photongluonquark

80%

integral(0~r)

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dr = 0.4, coneRadius=0.25dr={0.45(quark),0.55(gluon),0.3(photon)}, coneradius=1.0

jet energy balance• dr(distance btw parton & celljet)

• coneradius• qq/gg/γγ : jet2 energy/jet1 energy(jet2 energy<jet1 energy)

• qγ/gγ : q/g jet energy/photon jet energy

qq gg γγ qγ gγ

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SINGLE JET ANALYSIS

visible/charged/neutral , with smear, |eta|<3, [0.1,0.1] cells, pp5500GeV, quark jet, dr<{0.45/0.55/0.30}, coneRadius=1.0,

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charged/neutral• MineTcharged = MineTvisible*2/3 の確認• energy fraction of each particle seed against with energy sum of generated

particles

MinBias pTHatMin=200GeV

だいたい OK?

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• assumption:– ALICE-EMC,TPC resolution

• setting : – dr<0.45(quark) の中で celljet.eT が最大の jet– dr<0.55(gluon) の中で celljet.eT が最大の jet– dr<0.30(photon) の中で celljet.eT が最大の jet– coneRadius=1.0

influence by smear

charged : TPC, Neutral : EMCparticle energy(momentum) is smeared

assume pion mass

TPC+ITS

€

σP

P= 0.068 ⋅P + 0.608[%]

€

σE

E= 2.42 + 8.4

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E[%]

EMC

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energy resolution1. 見つけた celljet-eT と jet-eT(parton-eT) の相関を作る2. 直線 Fit から補正係数を決定3. 見つけた celljet-eT を補正したもの (E’) と jet-eT(parton-eT)(E) から (E’-E)/E を計算4. resolution = (E’-E)/E 分布の RMS

eT-eT correlation (E’-E)/E Profile resolution

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jet energy resolution• setting:

– visible : MineT = 20 GeV– charged : MineT = 20*2/3 GeV– neutral : MineT = 20*1/3 GeV– eTseed = 0.3 * MineT

quark gluon photon

gluon jet resolution が quark に比べよい？=>low-pT 粒子で smearing の桁落ち？

visible resolution があまりによい=> 計算違い？

なんだか怪しいが、計算ミスは見当たらない…

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parton energy resolution• setting:

– visible : MineT = 20 GeV– charged : MineT = 20*2/3 GeV– neutral : MineT = 20*1/3 GeV– eTseed = 0.3 * MineT

quark gluon photon

visible で 10~20% 程度ほとんど kinematics で決まっている

前 page と同じ計算なので少し自信がない…

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JET FINDING METHOD

visible , |eta|<2, [0.1,0.1] cells,embedded jet : jet center eta < 1. coneradius = 1.0 quark jet(pp5500GeV からの B-to-B jet)+(HYDJET HD+J event),

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parameter selection(threshold/coneRadius)

• BKG subtraction1. eTcell(sum of eT in cell) < threshold を集めてくる2. それらの cell を使い mean-eT を求める (mean-eT)3. mean-eT を中心に、 v2 に応じた BKG を計算 (mean-eT’)4. 全ての eTcell から mean-eT’ を引く5. pythia-celljet と同じ作業

• threshold/coneRadius はどの程度に設定すべきか？• (Ejet’-Ejet)/Ejetの幅が最小となる値を見つけたい

threshold[GeV](0~22)cone

Radi

us(0

.05~

0.5)

jet energy resolution(0.1~0.75)

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50GeV

100GeV

150GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

threshold : 15GeVconeRadius : centrality の関数

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parameter selection(Min-eT/eTseed)

• S/(S+B), efficiency の値から Min-eT, eTseed の最適化• {S/(S+B)}*{efficiency}

• S/(S+B) ≡ Nreal/Nfound

• efficiency ≡ Nreal/Nembed

Nreal : 見つかった pythia からの B-to-B jet の数Nfound : celljet で見つけた B-to-B jet の数Nembed : 埋め込んだ B-to-B jet の数

Min-eT/pTHat(0.2~1.0)eTse

ed/M

in-e

T(0.

1~0.

9)

S/(S+B)(0~1)efficiency(0~1){S/(S+B)}*{efficiency}(0~0.9)

B-to-B jet の決め方 / 答え合わせ方法|dφ-π|<0.284

dr(pythia-jet/found jet) < 0.111.-|Efound jet/Epythia jet| < 0.45

隣の cell まで許容energy resolutionpythia B-to-B jet : dphi-PI

1.5sigma

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S/(S+B)efficiency{S/(S+B)}*eff50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

single quark jet

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100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

BtoB quark jet

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plan• gluon jet, photon jet でも同様に coneRadius 等の最適化• gamma-jet の S/(S+B),efficiency の計算• gamma-jet の energy balance の計算• (method dependence)• jet quenching した上で、 parton energy loss の計算 ( 再現性能 )

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JET FINDING METHOD

visible , |eta|<2, [0.1,0.1] cells,embedded jet : jet center eta < 1. coneradius = 1.0 gluon jet(pp5500GeV からの B-to-B jet)+(HYDJET HD+J event),

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50GeV

100GeV

150GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

threshold : 15GeVconeRadius : centrality の関数

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ed/M

in-e

T(0.

1~0.

9)




隣の cell まで許容pythia B-to-B jet : dphi-PI1.5sigma

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100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

single gluon jet

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100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

BtoB gluon jet

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jet(parton) energy resolution• coneRadius : function of centrality• threshold : 15GeV• Min-eT : pTHat * 0.5• eTseed : 0.3 * Min-eT

central peripheral

上 : (pythia jet eT) vs (celljet eT(corrected))下 : (pythia parton eT) vs (celljet eT(corrected))

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jet(parton) energy resolutionjet energy resolution parton energy resolution

100GeV jet energy resolution = 25% 程度 (central)100GeV parton energy resolution = 25% 程度 (central)

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S/(S+B), efficiency, eff*S/(S+B)

• Min-eT : pTHat * 0.5• eTseed : 0.3 * Min-eT




S/(S+B) efficiency {S/(S+B)}*eff

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JET FINDING METHOD

visible , |eta|<2, [0.1,0.1] cells,embedded jet : jet center eta < 1. coneradius = 1.0 photon(pp5500GeV からの B-to-B jet)+(HYDJET HD+J event),

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50GeV

100GeV

150GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

threshold : 15GeVconeRadius : 0.1

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ed/M

in-e

T(0.

1~0.

9)




隣の cell まで許容pythia B-to-B jet : dphi-PI1.5sigma

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100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

single photon

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100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

BtoB photon

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jet(parton) energy resolution• coneRadius : function of centrality• threshold : 15GeV• Min-eT : pTHat * 0.5• eTseed : 0.3 * Min-eT

central peripheral

上 : (pythia jet eT) vs (celljet eT(corrected))下 : (pythia parton eT) vs (celljet eT(corrected))

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jet(parton) energy resolutionjet energy resolution parton energy resolution

100GeV jet energy resolution = 25% 程度 (central)100GeV parton energy resolution = 25% 程度 (central)

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S/(S+B), efficiency, eff*S/(S+B)

• Min-eT : pTHat * 0.5• eTseed : 0.3 * Min-eT




S/(S+B) efficiency {S/(S+B)}*eff

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BACK UP SLIDES

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PYTHIA jet resolutioncorrelation of jet eT

correlation of parton/jet eT

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jet-Not smearedvisible

charged

neutral

quark gluon photon

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jet-smearedvisible

charged

neutral

quark gluon photon

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parton-Not smearedvisible

charged

neutral

quark gluon photon

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parton- smearedvisible

charged

neutral

quark gluon photon

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|dφ-π|<0.38dr(pythia-jet/found jet) < 0.11

1.-|Efound jet/Epythia jet| < 0.45

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

S/(S+B)

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

efficiency

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

{S/(S+B)}*eff

Min-eT = 0.5*pTHateTseed = 0.3*Min-eT実際にはひとつの値しか使えない

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|dφ-π|<0.3dr(pythia-jet/found jet) < 0.11

1.-|Efound jet/Epythia jet| < 0.2

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

S/(S+B)

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

efficiency

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50~100GeV

100~150GeV

150~200GeV

0-10% 10-20% 20-30% 30-40% 40-50% 50-60% 60-75%

{S/(S+B)}*eff

PYTHIA-jet の作り直し• parameters

– R=0.7 : 充分広く– MineT =20GeV : efficiency ,eTseed=6GeV : MineT*0.3– dr=0.3 : (prparton-celljet) の dphi,deta の RMS~0.2– energy fraction 0.1 : (2~3)*RMS– BtoB variable 0.2 : (2~3)*RMS

gluonquark

その前に．．．• quark/gluon jet separation は難しそう

– quark(gluon) enrich sample• dijet, gamma-jet

dijet はなんとか識別 method を作った方がよいgamma-jet は quark-rich

0.73-1.01e-3x0.27+1.02e-3x

50GeV 100GeV 150GeV

gluon 0.68 0.63 0.58

quark 0.32 0.37 0.42

BKG の選択• mean-eT = <eTcell>|(eTcell<threshold) を求める• mean-eT を中心とした、 dphi 分布 (eT-

weighted) の幅を持たせてた分布から BKGを設定

jet energy resolution• celljet energy によって R を変えるのは変なバイアスがかかりそうで気持ち悪い• quark/gluon jet は同じ coneRadius を選ぶ

Min-eT, eTseed• single/di-jet の S/(S+B) * efficiency の最大値• 本物の決め方 (1jet)

– PYTHIA-jet と celljet の距離 <0.15^2– |eTjet-eTcelljet|/eTjet<0.45

• BtoB の決め方– |dphi-PI|<0.3– エネルギーの高い jet から選んでいき、一度使ったものは使わない

• 本物の決め方 (dijet)– (1jet)+(1jet)

• 実際には一種類しか使えない– 50GeV conf.(Min-eT=25GeV, eTseed=7.5GeV) で一度 jet を見つけ、その jet-

eT に対し seed-cell-eT > 0.3*jet-eT を要請

yield

• 前頁の dijet のグラフよりそれぞれのcentrality での jet-yield を計算– Ncoll で重み付け

• 前に求めた efficiency をかけることでreconstruct 可能な jet 数が求まる

• acceptance の効果を加えることで annual (reconstucted) yield が求まる

jet analysis

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