Jet calibration in ATLAS @ LHC
隅田 土詞 (CERN → 京都)
7th Oct 2011
HEP 研究室セミナー

(Self-) Introduction• CERN での所属
- 職名 : CERN(-Japan) fellow
CERN‣ 内部での区別なし ( オススメ )- 所属: PH-ADE-CA (物理-ATLAS検出器-カロリメータ)
- ボス
PH
IT
BE
TE
...
‣ Ana Henrique- TileCal (ハドロンカロリメータ) グループリーダー
ATLAS
CMS
Theory...
‣ Tancredi Carli- Jet/EtMiss グループコンビナー• やった仕事CERN ATLAS TEAM (CAT)- 10.2008-3.2010 : TileCal
Detector‣ TileCal EMスケールキャリブレーション
Opearation
Inner Detector- Csキャリブレーションシステム
Point1 Operation- 宇宙線を使った TileCalキャリブレーションのCalorimter
パフォーマンステスト
ATALS Management
Muon Spectrometer- ノイズ study- 4.2010-現在 : Jet/EtMiss performance,
Trigger and DAQ
Computing
SM QCD physics
Computing
Data Aquisition‣ Jetクリーニング (non-collision event, bad cal. region, etc.)‣ JetEtMissグループのData Processing
Trigger
performance study 用データの準備‣ Jetキャリブレーション- パフォーマンステスト- Jetキャリブレーションの systematic uncertainty 見積り‣ Pile-up の Jet への影響の study‣ Jetの生成断面積測定
Kyoto HEP seminar , 7 Oct 2011
Jet calibration in ATLAS@LHC
Toshi SUMIDA
2

Outline• Introduction- ATLAS @ LHC- ATLAS の最新結果 (ちょっとだけ)• Calorimetry in ATLAS- 電磁カロリメータ : Liquid Argon (LAr)- ハドロンカロリメータ : Tile Calorimeter (TileCal)• Jet calibration in ATLAS- ジェット(jet)って？
‣ 物理から測定まで- Jet のキャリブレーション‣ 基本メソッド‣ “in-situ” validation/calibration‣ ジェットキャリブレーションにおける systematic uncertainty- 最近の話題/問題‣ 主に pile-up、Jet topology/physics dependence, そして TeV jet へ…
• まとめと今後の展望
Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

3

ATLAS @ LHC

LHC• Large Hadron Collider- CERNにある世界最大の陽子陽子衝突型加速器‣ スイスのジュネーブとフランスの国境‣ 全周: 27 km‣ 最大衝突エネルギー- 7+7 TeV (陽子-陽子)• 4+2 個の実験
- ATLAS, CMS‣ 汎用検出器- LHC-B‣ Bの物理- ALICE‣ 重イオン衝突実験- LHCf, TOTEM‣ 超前方散乱、全断面積測定

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

5

Total Integrated Luminosity [pb-1]

LHC status• 2010/2011 の年ラン- √s : 3.5+3.5 = 7TeV
• peak luminosity- 2.1x1032 / 3.3x1033 cm-2 s-1• integrated luminosity- 45 / ~4000 pb-1
-1

多分今年中に 5fb ！

Parameter

2010

2011

NominalBeam energy

3.5 TeV

3.5TeV

7 TeV

Beam squeeze

3.5 m

1.0m

0.55 mTransverse emittance

2-3 µm rad

2.5 µm rad

3.75 μm rad

Protons per bunch

up to 1.2x1011

1.6x1011

1.15x1011

Bunch separation

150 ns

50 ns

25 ns

Number of bunches
max peak luminosity (cm-2s-1)

Kyoto HEP seminar , 7 Oct 2011

368

1380

2808

2.1x1032

3.3x1033>1034

Jet calibration in ATLAS@LHC

Total Integrated Luminosity [fb -1]✓

60
ATLAS Online Luminositys = 7 TeV

LHC Delivered

50

ATLAS Recorded

40

Total Delivered: 48.1 pb-1
Total Recorded: 45.0 pb-1

30
20
10

2010

0
24/03

19/05

14/07

ATLAS Online Luminosity

5

08/09
03/11
Day in 2010
s = 7 TeV

LHC Delivered
ATLAS Recorded

4

Total Delivered: 4.39 fb-1
Total Recorded: 4.13 fb-1

3
2
1
0
24/02

2011
21/04

16/06

11/08
06/10
Day in 2011

Toshi SUMIDA

6

ATLAS実験• A Toroidal LHC ApparatuS- 100GeV~TeVスケールでの様々な物理に対応した汎用検出器• コラボレーション- ~ 3000人の研究者‣ 1000人以上のPhD students- 174 institutions- 38 countries• ATLAS検出器- weight: ~ 7000 tons
- height: 25m- length: 45m- ~108 channels‣ (90% は tracker のもの)

Figure 1.1: Cut-away view of the ATLAS detector. The dimensions of the detector are 25 m

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

7

最近の結果 from ATLAS∼0) = 0 GeV
Squark-gluino-neutralino model, m(χ1
ATLAS
0 lepton 2011 combined

CLs observed 95% C.L. limit

1750

CLs median expected limit
Expected limit ±1 σ

1500

m1/2 [GeV]2000• SUSY 0-lepton analysis- 1fb-1 (arXiv:1109.6572)- q̃ < 1TeV は絶望的 (DM大変)‣ 細かく topology を分けた解析（simplified model）へ
MSUGRA/CMSSM: tanβ = 10, A 0= 0, µ>0

ATLAS∫ L dt = 1.04 fb , s=7 TeV

Tevatron, Run IσSUSY = 0.01 pb~
g (1200)

400

D0, Run II

CDF, Run II

2010 data PCL 95% C.L. limit~g (1000)~q (10σSUSY = 0.1 pb

00)

750

Theoretically excluded

Reference point

0)

1000

Expected limit ±1 σ

500

-1

∫ L dt = 1.04 fb , s=7 TeV(internal)

CLs median expected limit

LEP2 ∼
χ1~~
D0 g, q, tan β=3, µ <0, 2.1 fb-1
CDF ~
g,~
q, tan β=5, µ <0, 2 fb-1±

600

2010 data PCL 95% C.L. limit

1250

0 lepton 2011 combined
CLs observed 95% C.L. limit-1~q (140squark mass [GeV]• Higgs to WW- 2fb-1 の最新 plot
‣ 未 approved

300~
g (800)σSUSY = 1 pb

500~
g (600)

)

0

200

00

250

~q (6

σSUSY = 10 pb

LEP2 ~
q

0

250

500

750

1000 1250

1500 1750

2000

gluino mass [GeV]

500

1000

1500

2000

2500

3000

3500

m0 [GeV]0
Kyoto HEP seminarOct 2011
Jetmodelscalibration
Toshi
Figure,2:7Combined
exclusion limits for simplified SUSY
with m(χ̃1in) = ATLAS@LHC
0 (left) and MSUGRA/CMSSM models with tan β = 10,
A0 = 0SUMIDA
and µ > 0 (right).

8

Calorimetry in ATLAS

コライダーでの座標表示• pseudo-rapidity- η = -ln(tan(Θ/2))‣ Θ: 天頂角- 0 : 検出器中心から垂直の面‣ coverage in ATLAS : |η| < ~ 4.9• ビーム軸周りの方位角- -π < Φ < π (rad)• 検出器中心から延びる方向- “longitudinal” (あんまり気にしない)

90.-180./3.141592*2*atan(exp(-x))
90

zenith angle(deg)Figure 5.26: Schematic of the transition region between the barrel and end-cap cryo
80
additional scintillator
elements are installed to provide corrections for energy lost in i
terial (not shown),such as the liquid-argon cryostats and the inner-detector services
70
tile calorimeter is fully integrated into the extended barrel tile calorimeter. The gap a
60
scintillators are read out together with the other tile-calorimeter channels (see text).
50

40 scintillators had to be removed on each side for the routing of the signthese cryostat
minimum-bias
30 scintillators. They will be reinserted for operations at full luminosity.
There are several locations around the circumference of the calorimeter, in which
20
gap instrumentation is not possible, for example the region opposite the support feet fo
10 In these locations, the plug calorimeter is reduced further in its len
cryostat [112].
location of theline, no plug calorimeter can be accommoda
00 exit of the1 barrel cryogenic
2
3
4
5
6
replaced entirely by scintillators. Finally, the inner support of the end-cap cryostat sit
in Layer
3 the tile-calorimeter modules themselv
calorimeter at its inner radius. Cells
In these
regions,
Δϕ×Δη = 0.0245×0.05
provide the support surface on which the cryostat support jacks sit. The gap scintillat
Triggemissing in this region.
r Tow

η

e
Δη = 0 r.1

2X0

5.6 Calorimeter readout electronics, calibration and services
m

0m

16X0

47

5.6.1.1 Overview

m

m

Trig

g
This section describes the on-detector (front-end) and off-detector (back-end)
electr
Tow erΔϕ = 0er.098toATLAS calorimetry. The major tasks required of the readout electronics are
2 provi
4.3X
0level (L1) trigger system with the energy deposited in trigger towers of size Dh ⇥ Df
and to measure, for L1-triggered beam crossings, the energy deposit in each calorimete

00

1.7X0
Δϕ=0.0245x36.8m 4mx
=147.3 4mm

15• 物理オブジェクト同士の”距離”- ΔR = √(Δη2 + ΔΦ2)
‣ ちょっと乱暴だけど、便利だし実際の大きさも中心領域では似たようものなので、まぁいいか?

η = 5.6.1
0 Readout electronics– 137 –Δϕ = 0ϕ

Square cells in
Layer 2.0245

Δη = 0.025
m/8 =4.69 mm
Δη = 0.0031
Strip cells in Layer 1

37.5m

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHCηToshi SUMIDA

10

The ATLAS Calorimeter• 電磁カロリメータ- Liquid Argon : “LAr”- 鉛アコーディオン型radiator + LAr (ionization)- Segment: 0.025 x 0.025 η-Φ, longitudinal に3段 (“cell”)- Resolution: σE/E = 10%/√E ⊕ 0.7%
• ハドロンカロリメータ- “TileCal”- 鉄 absorbers+ タイル型plasticシンチレータ- Coverage‣ Long Barrel: |η| < 1.0‣ Extended Barrel:
0.8< |η| < 1.7- η-Φ Segment: 0.1 x 0.1, longitudinal に3段- Resolution: σ /E (jet) = ~50%/√E⊕3%
E- goal :Jet energy scale uncertainly: 1-2%
• その他
- Hadron Endcap Calorimeter‣ “HEC”, |η|<3.2- Forward Calorimeter‣ “FCAL”, 3.1<|η|<4.9✓ いずれも技術は LAr
Kyoto HEP seminar , 7 Oct 2011

Figure 1.3: Cut-away view of the ATLAS calorimeter system.
Jet calibration in ATLAS@LHC

Toshi SUMIDA

11

Jet について

陽子-陽子衝突で起こること• 高エネルギーでのハドロン衝突 = パートン + パートン衝突- 2→2 プロセス‣ gg 反応(一番多い)
g

g g

g g

q̄

g

q

, etc.
g‣ qg 反応

g g

q

g g

q

g

q̄

g

, etc.
gq

LHC で起こるほとんどの事象は QCD で作られる。
放出された高エネルギーパートン(クォーク、グルーオン) がジェットになる。

‣ qq 反応
q

q

q̄

q̄

, etc
q

Kyoto HEP seminar , 7 Oct 2011

q

q

q

Jet calibration in ATLAS@LHC

Toshi SUMIDA

13

もう少し…

The structure of an event
ハドロン衝突で起こっていること(W + jet 生成の場合)

Warning: schematic only, everything simplified, nothing to scale, . . .

pp/p

Incoming beams: parton densities

K. Hanagaki

W+
u
d

g

p
p/p

Hard interaction

Hard subprocess:by
described
by matrix
elements
described
matrixelement

c

s
W+

u
d

g

p
p/p

Resonant decay

Resonance decays: correlated with hard subprocess

c

s
W+

u
d

g

p
p/p

Initial state radiation

Initial-state radiation: spacelike parton showers

c

s
W+

u
d

g

p
p/p

Final state radiation; parton shower
Final-state radiation: timelike parton showers

c

s
W+

u
d

g

p
p/p

Multipleinteraction
Multiple parton–parton interactions . . .

c

s
W+

u
d

g

p
p/p

Initial and ﬁnal state radiationfor each interaction. . . with its initial- and final-state radiation

Beam remnants

Beam remnants and other outgoing partonsColor connection

Everything is connected by colour confinement strings
Recall! Not to scale: strings are of hadronic widths

Hadronization

The strings fragment to produce primary hadronsmany hadrons unstable and decay
Many hadrons are unstable and decay further

c

s
W+

u
d

g

p
p/p

Underlying Event と Multiple Interactions
Many hadrons are unstable and decay further
Resonance decays: correlated with hard subprocess

何故ジェットを測るのか• もちろん、コライダーでは何でも測る- e/γ‣ EM calo, track 有/無- µ‣ tracker, chamber- τ(ちょっと難しい)- q (u, d, s, c, (b)) , g→qq̄
‣ 全部jetになる✓

ジェットも測る• 物理解析/測定- Jet 生成 (di-jet, multi-jet)- W/Z→qq̄(’) , W→lν, Z→ll
- t →bW- H→bb, γγ, ττ, WW, ZZ- g̃→qq̃→qqχ̃- 重要な物理には全部何かしらジェットが出てくる。
- 上の項目は下の項目のバックグラウンドになる。
✓

つまり一番最初の反応 (2→2)から、統計が増えて様々な解析を行う全ての段階で、ジェットの E, pTを正確に測る事は非常に重要。

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

26

つまりジェットとは何か
Whatare
Jets ? are Jets?
What• カロリメータジェット (calo/reco jet)1. 高エネルギーパートン•CollimatedCollimatedbunchesof stable
bunchesof hadrons
stable hadrons,- originatingfrom(quarks(quarks& gluons) &が放出され、
originating
frompartonspartons
after 2.
fragmentation/hadronization
ハドロン化し、
gluons)after
fragmentation andhadronization
3. 崩壊により準安定化±, measurement
K, p, n, etc.)し、• Difficulty in(γ,theπjet- needto understandevery stage
Jet
Finding
is the approximate
4.カロリメータと反応して‣ Prediction
by theory
attempt
toreverse-engineer
the
シャワーを作った、- parton
distribution processes ofquantummechanical
5.そのひとかたまりのこと✓ quark/gluon

4.
カロリメータでの反応:
電磁/ハドロンシャワー

π, K, ...

fragmentationand hadronization- hadronization! not
a Findingunique procedure ->‣ Jet• several
particlejet/ track
jetto reverse- approximate
attempts
different
approaches

2.

q, g

ハドロン化

1.

✓ そもそも、「何を測っているか」を簡単に見失えてしまうので、Toshi SUMIDA
TLAS-Japan 物理研究会,
11.Dec.2010

とてもよく考える事が重要。
Philipp Schieferdecker (KIT)

Kyoto HEP seminar , 7 Oct 2011

ハドロンの崩壊(準)安定粒子化

ココから見える• 3. engineerまでの段階で
the quantum mechanicalprocesses of hadronization
ジェットを組んだもの
Jets arethe observable objects to‣ Calorimeter
response‣ (MC truth)
particle jet はrelate -experimental
in the EM scale observations totheory- predictions
formulated in
tocalibrationに使う
hadrons‣ track
jetandは neutralterms ofquarksgluonsparticle なし

Vivian’s Meeting
April 17th 20093.

Jet calibration in ATLAS@LHC

2/14

パートン放出4

物理
Toshi SUMIDA

27

Jet reconstruction@(A8#',#0,!"#,B"3C

J./%!/*2+-12*.,;")("$21)*.'&,&*"*&E-.*&#"+).#&"#-00*&##.)+• ジェットを組む、とはClustering:- エネルギークラスター構築
DEFEG"#$%&'&"()*"$)+#,*-$,.+/"!
‣ EM/Hadron shower でできた calorimeter
cell を一纏めにする,)0)1)/.$21"$1-#,&*"2+3"#-00*&##.+/"&1&$,*.$"+).#&4‣ threshold は pedestal の “σ “ の整数倍が基準!!"##$#!
56 7&11#"8.,%"H*HIDJ(0&'""#&&3",%&"- noise を抑える事が重要$1-#,&*
96 7&11#"8.,%"H*HIFJ(0&'"".,&*2,.:&1;"- typical なσの値 : 40MeV
233&3‣ “4-2-0 method“<6 =&./%>)*"$&11#"8.,%"H*HIG"()*'"#-*(2$&")(",%&"$1-#,&*- E>4σ の cell を seed にして!%&'()&*+$',"-'.!)"/&01*$2$0,!0$3410$!5"#0&'1)!
! =).#;"$&11#"?@A65BC"2*&"'2#D&3"2+3"+),"
その周りの E>2σ の cell、-#&36
さらにその周りの全て cell energy=)+!$)'0&+#2,.+/"$21)*.'&,&*"
を加える!
Jets are reconstructed using the anti-k- 3D (R, η, Φ) Topological Cluster(TopoCluster)*&E-.*&#"%23*)+.$"$)**&$,.)+#"()*"F&,"algorithm with size parameter R set at 0.4(0.6)- M. Cacciari and G. P. Salam, Phys. Lett. B 641, 57 (2006)
2+3"GHI6✓ electric noise に強い
4- この Topoクラスターを
Jet
Requirements
jet reconstruction algorithm への
input
とする
Jet Requiremen• !Collinear- and Infrared-Safe‣ 昔: SIS-cone, ATLAS-cone, kt !
• !Collinear- and Infrared-Safe!
‣ default: “Anti-kt” アルゴリズム, w/ R=0.4/0.6- 2008年くらいに採用- Infrared-safe, collinear safe
✓ 素性が良いCollinear-Safety
Infrared-Safety Collinear-Safety
InfrareT

collinear splitting shouldn’t change jets
soft emissions shouldn’t change jets

Kyoto HEP seminar , 7 Oct 2011

proceduer on parton- and hadron-level• !Identical
To compare theory calculations to experimental measurements

Jet calibration in ATLAS@LHC

collinear splitting shouldn’t change jets
soft emissions shouldn’t change jets

proceduer on parton- and hadron-level• !Identical
To compare theory calculations to experimental measu
Toshi SUMIDA
28

(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

ET

-

ET

-

-

kt

Anti-kt
Sequential
C
Based on the following distan•
Sequential ClusteringA!
⇥

distance dij between two particle

Clustering Algorithms

on the following distance measures:
2p
2p• !Based
d
=
min
k
,
k
ij
Ti Tj
distance d between two particles i and j:
ij

2p
2p
dij = min kTi, kTj

CTEQ-MCnet school 2008
Gavin Salam Lectures on Jets

Kt

Paolo Francavilla

ij

D

!

D

distance
between2 any particle2 i2ij = (yiyj ) + ( i

j)

2p
d
=
k
iB
! distance between any particle i and the beam (B)TidpiB=: +1: Kt

2p
diB = kTi
(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

ET

⇥

ij

AntiKtCompute all distancesp = -1 : AntiKt
d and

•

ij

(Cacciari/Salam/Soyez)! if smallest
is a dij, combine (sudistances,
proceed findin
ETall distances dij and diB, update
φ or Compute
η
φthe
or
η
find
smallest
1. η-Φ平面で全ての
input
について
d
ij, diB を計算! four
if smallest
is athediB,
removepar! if smallest is a dij, combine (summomenta)twoparticlesia•

最小のものを選ぶ
Jet update
Algorithms
distances,2.proceed
findint next smallest 5•
2-b. もし diB が最小なら、i はジェット
are•clustered
intoD:
jetScales the dij w
Parameter• Repeat until all particles
3. 1-2 を繰り返す
jets a and b are at least separ• Parameter D: Scales the dij w.r.t. the diB2 such2 that any pair ojets a and b are at least separated
by ab =
p:Dgoverns the rela
• Parameterscales to distinguish the three• Parameter p: governs the relative power of of energy vs geom!

2-a. もしparticle
dij Repeatが最小なら、iとj
if smallest is a diB, remove
i, call until
it a jetallをくっつける
particles are cscales to distinguish the three algorithms:
2=kT, 0=C/A,-2=
Vivian’s Meeting
Philipp Sc
April 17th 2009

Vivian’s Meeting
April 17th 2009

φ or η

Philipp Schieferdecker (KIT)φ or η

(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

ET

ET

kt

Anti-kt

Clustering Algorithms
CTEQ-MCnet school 2008
Gavin Salam Lectures on Jets

AntiKtKt(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)ET
Paolo Francavilla

φ or η

ETφ or η

Jet Algorithms

φ or η

7

φ or η

(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

ET

ET

kt

Anti-kt

Clustering Algorithms
CTEQ-MCnet school 2008
Gavin Salam Lectures on Jets

AntiKtKt(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)ET
Paolo Francavilla

φ or η

ETφ or η

Jet Algorithms

φ or η

9φ or η

(Cacciari/Salam/Soyez)(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

ET

ET

kt

Anti-kt

Clustering Algorithms
Clustering
Algorithms
CTEQ-MCnet school
2008
Gavin Salam Lectures on Jets
CTEQ-MCnet school 2008
Kt on Jets
Gavin Salam Lectures

AntiKt(Cacciari/Salam/Soyez)
AntiKt(Catani/Dokshitzer/Seymour/Webber - S.Ellis/Soper)

Kt

ET(Catani/Dokshitzer/Seymour/Webberφ- orηS.Ellis/Soper)ETE

PaoloT Francavillaφ )or η(Cacciari/Salam/Soyez

ET

Jet Algorithms

11

Different result=
φ or η

φ or η

ジェット
ジェット
Jet reco. algorithms の比較
人工的に再構築••••人工的に再構築
人工的に再構築
人工的に再構築• Anti-Kt は優秀！

23 23 in ATLAS@LHC
Jet calibration

Toshi SUMIDAJHEP04(200JHEP04(2008
JHEP04(2008
JHEP04(200Kyoto HEP seminar , 7 Oct 201133

Jetのキャリブレーション

Jet のキャリブレーション
Features of Hadronic Signals

P.
P. LochLoch
UofArizona
U of Arizona
June
June 23,
23, 2009
2009

Features of Hadronic Signals• ジェットは組んだが、その組んだジェットのエネルギーはどうなっている？
- 基本的に、カロリメータで測るのは “EM scale“ energy:
Each signal component fraction depends on energy‣ LAr: ビームテストでの electron を使った calibration
が fraction
base
Visible non-EMe1decreases
withE‣ Tile: 137Cs を使った独自システムでの calibrationが base
m 1

1

1

h
e
E
E
Hadronic
signals
more




- ジェットの reconstruction も今のところ EM energy で行われている0“electromagnetic” at high energy
MC-derived
of
0.80  m calibration
0.85
Measured by the electron/pion• “本当の”ジェットと比べると？
ratio measured at the same
 1 GeV  
Goal: E
Calibratethe “uncorrected” jet e- Truth jet : ハドロンレベルの情報を使ってdeposited energy
0 
2.6 GeV p
Hadron response not linear withObtain calibrated energy c consistent w
Anti-kt アルゴリズムでジェットを再構成したもの • Numerical Inversion using the jet energy
E in ATLAS, e/h > 1 for each subor,-detector
find calibration f T.A.
(u)Gabriel,such D.E.
thatGroom,c=- Reco jet: カロリメータから出発したジェット
Nucl. Instr. Meth. A338 (1994) 336“e” is the intrinsic response to visible EM
Separate calibration functions derived d- ハドロンは e/γよりも落とすエネルギーが小さい“(h”e/h~ 1.3) response to visible
is theintrinsic
non-EM‣ invisible energy (原子核の励起, slow neutron, invisibleetc.) energy is the main source of e/h > 1- Dead material によるエネルギー損失
Large fluctuations of each component fraction
29
29

MC-derived calibr

Non-compensation amplifies fluctuations

Hadronic calibration attempts to:• ので、再構成されたジェットのエネルギーに対して、… provide some degree of software compensation
補正 factor をかける必要がある… account for the invisible and escaped energy- MC を使って、Truth jet を作る- E(reco)/E(true): をある E, η の bin でplot すると、右の図の様になるので基本的にこの中心値の”逆数”をtrue energy に戻すための補正 factor として使う‣ “Numerical Inversion” と呼ぶ
Jet energy response for (Etrue , )-bin be

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Note: Same eventsin both plots, but
xToshi SUMIDA
35

Jet のキャリブレーション (続き)Jet Energy Response (1/JES)• さらに、各 E, η bin での inversion factorに対して、
log(E) の polynominal で fit する- この結果を parameter として database に持つ‣ この constants を“Jet Energy Scale” または “JES” という‣ EM scale に JES をかけて得られたエネルギーを“EM+JES” と呼ぶ

Final energy calibration curve
0.9-0.1 < det< -0.0

0.85
0.8
0.75
0.7
0.65
0.6
0.55

 2 /Ndof = 4.40

0.5

[i]*log(x)

4

true
T

EtaJESJet p response: pT reco /pT

1.2
1.15

i

i=0

3

102

10

• 重要な物理量であるジェットの pT (横方向運動量)はTopoCluster を massless と見做して、4-vector を組む

Anti k R=0.6 (topo cluster)T
EM scale

10Ereco [GeV] at

Jet p calibration curveT-0.1 < det< -0.0Anti k R=0.6 (topo cluster)T

EtaJES+EM scale

1.1
1.05
1
 2 /N0.95

dof= 1.074

[i]*log(x)ii=0Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

0.9

2
10Toshi
SUMIDA 10

336

Pythia QCD jets (nominal)
Alpgen + Herwig + Jimmy
Perugia2010 Tunejet

<E /Ett

1.08

JES uncertainty

1.06
1.04
1.02
1
0.98
0.96
0.94

ATLAS Preliminary• どれだけ正確にジェットをキャリブレーションできているか- “正確に” とは ”精度良く“ (resolution) ということではない。1.1
(a)
1.08
1.1
ある E, pT binで、中心値をどう間違い得るか、の指標。
1.06
1.08
• JES uncertainty の source
1.04
1.06
- 全部MCに頼ってのcalibrationなので、
1.02
1.04
1.021
jet energy response は 物理モデル
0.981(パートン放出、ハドロン化、シャワー生成)に依る
0.96
0.98
ATLAS Preliminary
‣ ~3%
0.94
0.96
ATLAS
10
2×10
10
2×10
30 40 Preliminary- Dear material の MC での記述が間違っていたら…
0.94
p [GeV]
10
2×10
10
2×10
30 40
p [GeV]‣ 2-3%(a)higher than the noise thresholds. Higher topocluster thresholds contribute to the JES uncertainty at the- ノイズの大きさと(b)1.1
2% (1%)
level in the centralの関係(endcap) regions.
threshold1.08
jet‣ 1-2%
1.1
Figure 6: Simulated energy response (a) and pT response (b) and as a functio
30 40

102

2×102

3

10

3

2×10
p jet [GeV]

jet truth
<p /p
>
<E
/E
>
T
T

T

Anti-kt R =0.6, EM+JES, 0.3 ≤ |η | < 0.8

jet

truth

Pythia QCD jets (nominal)
Anti-k
R =0.6, Dead
EM+JES,0.3 ≤ |η | < 0.8tAdditional
Material
PythiaQCD
jets(nominal)
Additional Dead Material (ID only)
Alpgen + Herwig + Jimmy
Perugia2010 Tune

2

2

3

3

2

2

jet
3 T

3

jet

1.04

AntiK T , R=0.6, JES Calibration, 0.3<|η|<0.8
Additional Dead Material
Shifted Beam Spot
10% Higher Topo-cluster Thresholds
10% Lower Topo-cluster Thresholds

1
0.98
0.96
0.94

T

Anti-kt R =0.6, EM+JES, 0.3 ≤ |η | < 0.8

T>

MC truth jet

jet

1.06

T

<p /p

T

1.08

1.06

Pythia QCD jets (nominal)
Additional Dead Material
Additional Dead Material (ID only)

region (0.3< |η | ≤0.8) for Alpgen+Herwig+Jimmy (open squares) and Pythia
1.04
tune (full triangles). The responseof the nominal Monte Carlo sample is show
circles).
1.02
1

1.02

Kyoto HEP seminar , 7 Oct 2011

<p /p

truth

>

jet
T

measured relative to those of0.98
the central jets following a technique called “the min [19, 65]. Measurements of this relative jet response are performed using the
0.96
corresponding to an intergrated luminosityof ≈ 35 pb−1 , as well as using sever
ATLAS Preliminary
is found that the MC
predictions for the3 relative3 jesamplesdetailed
ATLAS Preliminary
Monte Carlo
QCD jets in [65]. It0.94
10
2×10
102
2×102
30 40
jet
3 while the data lie between the predictions.
2 low-p
2 T forward jets,
p
[GeV]
10
2×10
10
20 30 40
T
jet
These effects
pT [GeV]are accounted for in the uncertainty by including the intercal
with |η | > 0.8 in the total JES uncertainty as in the(b)following:(a)

Jet calibration in ATLAS@LHC

Toshi SUMIDA

37

Fractional JES systematic uncertainty

JES uncertainty (続き)
0.12

0.03
0.3≤ |η| <0.8
2.1≤ |η| <2.8

0.02

3.6≤ |η| <4.5

0.015
0.01

ATLAS Preliminary

0.005
0

30 40

102

2×102

Anti-k t R =0.6, EM+JES, 0.3 ≤ | η | < 0.8, Data 2010 + Monte Carlo QCD jets

ALPGEN + Herwig + Jimmy

Noise Thresholds
PYTHIA Perugia2010
Additional dead material

JES calibration non-closure
Single particle (calorimeter)
Total JES uncertainty

ATLAS Preliminary

102

30 40

2×102

3

10

3

2×10
jet
p [GeV]
T

0.25

jet

Figure 9: Fractional jet energy
scale systematic uncertainty as a function of pT jets
for jets in the pseudAnti-k t R =0.6, EM+JES, 3.6 ≤ | η | < 4.5, Data 2010 + Monte Carlo QCD
rapidity region 0.3 ≤ |η | < 0.8 in the calorimeter barrel. The total uncertainty is shown as the sol
ALPGEN + Herwig + Jimmy
Noise Thresholds
light blue area. The
individual sources are also shown, with uncertainties
from the fitting procedure
0.2
PYTHIA Perugia2010
JES calibration non-closure
applicable.
Single particle (calorimeter)
Additional dead material

Anti-kt R=0.6, EM+JES, NPV = 2

0.025

Fractional JES systematic uncertainty
ractional JES systematic uncertainty

Relative pile-up uncertainty• 2010 data での結果
0.1
- 4% @ pT=30GeV, 0.3<|η|<0.8
The uncertainty on the jet energy scale is conservatively estimated by adding all uncertainties0.08
inforwardquadrature, including
the one では
from the ~10%
non-closure of the correction. Since the track-jet method canbe used only
to |η | < 1.9 due to the limited coverage of the tracking detector, the di-jet balance
0.06
- up
右の絵に
pile-upmethod that is used for the η intercalibration uncertainty and detailed in Section 6.6 have been used toestimate the uncertainty
for |η | > 1.9 by comparing the relative jet response in events with only 0.04
one
(同時に複数のcollisionが起こる場合)
reconstructed vertex with the response measured in events with several reconstructed vertices. The dijet
balance method
yields uncertainties similar to those intrinsic to the method also in the case of |η | < 1.9.の不定性は入っていない
0.02
The offset correction and its uncertainty are derived as a function of the number of reconstructed‣ ~the1%in 2010
vertices. This allows
correction
and its uncertainty to be valid also for data periods where the number0of reconstructed‣primaryvertices is higher than the periodin
wherethe correction
is derived.
酷い事になっている
2011
(次回)

3

10

3

2×10
jet
p [GeV]
T

0.15
0.12

Total JES uncertainty

Intercalibration

Anti-k t R=0.6, EM+JES, 2.1 ≤ | η | < 2.8, Data 2010 + Monte Carlo QCD jets

0.1
0.1

ATLAS Preliminary

ALPGEN + Herwig + Jimmy
JES calibration non-closure
Single particle (calorimeter)

0.08
0.05
0.06
0
0.04

Intercalibration

30

40

50 60 70

Noise Thresholds
PYTHIA Perugia2010
Additional dead material
Total JES uncertainty

ATLAS Preliminary
102
2×102
p jet [GeV]

Figure 8: Relative pile-up uncertainty for anti-kt jets with R=0.6 in the case of two measured primaryT
vertices, NPV = 2, for central (0.3< |η | ≤0.8, full circles), endcap (2.1< |η | ≤2.8, open squares) 0.02
andjet
Figure11:
Fractional
jet energy scale systematic uncertainty as Toshi
a functionof pT for jets in the pseudorη | ≤4.5, fulljets as a function of jet pT . Jet calibration in ATLAS@LHC
forward
Kyoto(3.6<
HEP |seminar, 7triangles)
Oct 2011
SUMIDA38

pidity region 3.6 < |η | < 4.5. The JES uncertainty for the forward region is extrapolated from the bar

“In-situ” JES validation

Data / MC• MC に頼り切りでは、どこで間違えるかわからないので、データを使った jet calibration の確認をして、JES の不定性を評価したい- di-jet inter-calibration‣ barrel と forward を比べて、η での一様性を保障する- multi-jet method
1.14
Multi-jet‣ high-pT ジェットと low-pT recoil jet system を比べる 1.12
ATLAS Preliminary
1.1
Track-jet
1.08- 一番高い pT までいける
γ -jet direct balance
γ -jet MPF
1.06- gamma-jet balance method
1.04
1.02
‣ robust な EM scale の energy 測定と比較する
1
0.98- track-jet/calo-jet
0.96‣ track だけで jet を組んで、それと比較
0.94
0.92
anti-k R =0.6, EM+JES
JES uncertainty- neutral particle がないので resolution は落ちるが
0.9
10
10
- response 自体は良くわかっているp [GeV]✓ pile-up が大きいと、track-jet の方が得？
jet
Figure12:
Jetenergyscale
uncertaintyasafunctionofp
T in 0 ≤ |η | < 1.2. Thi- Z-jet balance
to Monte Carlo simulation ratios for several in-situ techniques that test the jet en
photon jetができる
balance (direct balance or using the missing transverse momentum proje‣ Zのmassが大きいので、low Pt jet のvalidation
t

2

3

jet
T

balance of a leading jet with a recoil system of two or more jets at lower transversjets) or using the momentum measurement of tracks in jets.

Kyoto HEP seminar , 7 Oct 2011

improvements are due to new measurements of the single hadron response, to a mof the uncertainties associated to neutral hadrons and to the recalibration of the elec
calorimeterwith Z → ee events measured in-situ. Toshi SUMIDA
Jet calibration in
ATLAS@LHC
39

まとめと今後

まとめ• ジェットとは- 高エネルギーパートンを元とするハドロンの束• ジェットのキャリブレーション- カロリメータの EM-scale でのレスポンス- エネルギークラスターの構築- ジェットの再構築‣ を行なって、MCで求めた “JES” をかける
• キャリブレーションがどれくらい合っているか- “JES uncertainty”‣ 複数の物理モデルや、検出器の物質を変更したMCで系統誤差を評価- “In-situ” validation‣ データを使って JESを検証

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

41

今後
• 次回
- 本当は、最近は single particle measurement(E/p analysis ) を使って、JES uncertainty を評価しているが、ややこしいので省略した。
- In-situ measurements の現状 in 2011- 現在、高い pile-up rate での JES の求め方、

pile-up で足された energy の補正、それを考慮した JES uncertainty の評価について
study が進行中。
‣ 以上、次があれば報告します。

Kyoto HEP seminar , 7 Oct 2011

Jet calibration in ATLAS@LHC

Toshi SUMIDA

42