Nov. 6-8, 2006 TeV Physics and LHC Workshop , CCAST 1 Physics Goals Of Chinese Group @ CMS Yajun...
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![Page 1: Nov. 6-8, 2006 TeV Physics and LHC Workshop , CCAST 1 Physics Goals Of Chinese Group @ CMS Yajun Mao (Peking University) for CMS-Chinese Group Nov. 6,](https://reader035.fdocuments.us/reader035/viewer/2022070415/5697c02b1a28abf838cd8a05/html5/thumbnails/1.jpg)
1TeV Physics and LHC Workshop, CCASTNov. 6-8, 2006
Physics Goals Of Chinese Group @ CMS
Yajun Mao (Peking University)
for CMS-Chinese Group
Nov. 6, 2006
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 2
Outline
Overview of Our Physics Goals
Current Status of Physics Analysis
Summary
Introduction of CMS Chinese Group
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 3
CMS Chinese Group
PKU: RPC, physics analysis Yajun Mao, Yong Ban, Sijin Qian , Siguang Wang + post-doc + students
USTC: physics analysis ?? + post-doc + students
IHEP: CSC, physics analysis Hesheng Chen, Guoming Chen, Cunhua Jiang Ming Yang + post-doc + students
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 4
CMS Compact Muon Solenoid
IHEP: 1/3 Muon Detector ( CSC )
IHEP: Support for magnet, floor
PKU: 1/3 mID detector (RPC)
Chinese Contribution: 5M CHF 25M (Chinese Contribution: 5M CHF 25M (3.673.67++21.3321.33M) RMBM) RMB
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 5
RPC From PKU (part)
Mass production, installation-2006.2.13.
264 panels , 2000m2, 3.72M RMB
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 6
Well done in hardware contribution ticket for further physics analysis Chance + Challenge
Chance: Substantial physics output from China New appearance in HEP community?
Challenge: huge data sample + high BG + complex of detector + great competition ( ~2000 scientists from ~200 institutions )
collaboration of chinese experimentalists and theorists!!
Physics Analysis @ CMS?
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 7
(Possible) Resource for Analysis
Support for data analysis (include M&O)???
Two Tier-2 for CMS & ATLAS funded by MOST???
NFSC Support: Key project for LHC physics simulation
1.35M RMB in total for CMS & ATLAS
CMS-IHEP 0.30M RMB Bc, HVV
CMS-PKU 0.35M RMB high pT J/Ψ
ATLAS-IHEP 0.30M RMB Htt
ATLAS-SDU 0.30M RMB tt
Common 0.10M RMB public use
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 8
Selection of Physics Topics @CMS
Better combined to our hardware contribution
Better collaboration with chinese theorists
muon as probe
suggestions from them
Earlier physics output to earn credit
topics at low lum.
Hot topics to compete in the community
topics at high lum.
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 9
List of Our Physics Goals
1) High pT Heavy Quarknium Production
2 ) Bc via Bc ( J/l , J/), J/ll
3) New resonance search via double l decay
4) Higgs, HZZ ( Z+, e+e; Z, qq ) 5) Invisible Higgs, via
6) HVV abnormal coupling
7) Search for majorana neutrino
8) Top physics
9) Search for chaged super heavy particle with long life time
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 10
切入点 选取 2l+X sample
头三年 , 亮度≈ 1033, 轻子触发横动量 :
single electron >29GeV double electron >17GeV single muon >19GeV double muon >7GeV 合计 事例率 : 60Hz 每年 : RECO 75TB, AOD 25TB, 共 100TB 所需计算能力与一个 Tier-2 相当
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 11
优先研究 μμ+x 事例, 如经费和人力可,同时研究 e e +x 事例
1 重建效率 μ 子高 2 触发的横动量阈值 μ 子低 3 μ/π 分辨优于 e/π 分辨 4 我们熟悉 μ 子探测器
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 12
刻度
选取 +-+x ( e+e-+x )事例 , 利用 J/ , Υ , Z0 这三个明显的峰来刻度探测器
• 理解探测器 / ( e/) 分辨能力随入射粒子动量的变化 ;
• 理解能、动量测量的线性 和精度 ;
• 考察探测器不同部位的一致性 .
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 13
大横动量 J/ l+l- , l+l- 的研究
在 J/ , 的峰位同时正确,宽度合理,本底清楚以后:
• 测量 J/ , 的横动量分布 .• 测量 J/ , 的极化随横动量的变化 .
色单 / 色八 的贡献, NRQCD 我们唯一在研究, 出束后 2—3 年发表文章
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 14
通过 J/+ l, J/+ 道 研究 Bc
利用 Bc J/ l, J/ , J/ l+l- 来测量 Bc 的质量,寿命和相对分支比
• Bc 是唯一由两个不同重夸克组成的介子,对于理解NRQCD(non-relativistic QCD) 有重要意义。
• 我国理论所张肇西教授在 Bc 的理论研究上领先。• 目前我们在这个题目的研究处于领先,争取在头三年
作出结果,发表文章,在 CMS 取得信誉。
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 15
新的双轻子共振峰寻找
• 在 J/ , Υ 和 Z0 这三个峰的基础上看在其它位置有否共振峰 .
• 同时寻找标准模型不允许的 e+-, +e- 等共振态 .
• 历史上的很多发现都是理论上没有预言的 , 而LHC 处于高能量的前沿 .
• 从实验开始到结束,这一寻找要一直进行下去 .• 有竞争
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 16
通过 Z(l+l-)+X 道寻找 SM Higgs
1. H→ZZ→4μ 2. H→ZZ Z →μ+ μ- Z →υυ
3. H→ZZ Z → μ+ μ- Z →qq
4. H→Zγ Z → μ+ μ-
产生道 : gg fusion, VBF
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 17
H→ZZ→4
• 大热门• HZZ 4道 : 与美国 Florida 大学合
作
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 18
H→ZZ, Z → + -, Z →υυ
• 相对较冷• 可以利用横动量丢失建立横质量 • 其分支比高于轻子 10 倍 • 横质量分布较宽,显著性降低
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 19
H→ZZ, Z → +-, Z →qq
• 相对较冷• 其分支比高于轻子 20 倍 • 本底大 • jet 重建误差大 , 显著性降低
做好能量流分析 , 提高 jet 能量分辨 , 有可能是发现道 .
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 20
H→Zγ, Z →μ+μ-
• 冷门• 本底小 , 没有能量丢失• 分支比小
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 21
物理背景
通过 Z+ 大 pT 丢失寻找 Invisible Higgs
信号:轻子对 + 大 pT丢失朱守华的模拟( HEP-PH/0512055)给出 LHC上在 10fb-1积分亮度,该道在理论上具有超出 5的灵敏度。
Z→μ+μ- , H →DM
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 22
同号轻子末态 +MET : HVV 反常耦合
•通过测量 HVV ( ZZ , WW ) 的反常耦合来确定 Higgs 属于 哪个理论 • 我国理论家邝宇平院士在这方 面的研究领先 • W+W+W+W+ l+ υ l+ υ最 灵敏 •现在还未见有人分析
qql+l+ υ υ
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 23
同号轻子末态无MET : Majorana中微子的寻找
• 日本超级神冈实验发现了中微子振荡,说明中微子具有质量
• 中微子究竟是属于Dirac还是 majorana ?
• 现在还未见有人分析• 我国有好几个理论工
作者正在计算截面 Majorana 中微子
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 24
长寿命、大质量、带电粒子的寻找
• 迹象 : 云南站事例, kolar金矿事例 , AMS01 例。L3+C: 未发现
• 可能是暗物质的候选者 • 它在 CMS 探测器中很象子,但比子重• CMS 可以利用子探测器的 DT(drift tube) 和来测
测量飞行时间,用电磁量能器来测量 dE/dX 可以识别 .
• GMSB(Gauge-mediated SUSY Breaking) : Stau 是次轻粒子 , 寿命高达 10 7 s
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 25
top 夸克对产生中的宇称破坏测量• 北大李重生教授建议,可以通过 t tbar 产生中 tbW+
(W+l+n) 中 l+ 的角分布来获得 top 夸克极化信息(反top 夸克的极化被积分掉),从而测量 top 夸克对产生中的宇称破坏。
• 在 LHC, 当积分亮度达到 10fb-1 时可产生约 107t tbar事例,理论上估计对宇称破坏的测量精度可达 1%.而根据标准模型估计宇称破坏应当小于 1% ,因此如果实验测量观察到超过 1% 的宇称破坏,则意味着超出标准模型的新物理。
• 而 10fb-1 的积分亮度估计在 LHC运行后三年即能达到,估计在第四年即可发表文章。这是中国理论家独特的思想,在 CMS 目前尚无人在做。
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 26
Physics Motivation CSM
Conventional Mechanism of Heavy Quarkonia
CSM LO Feynman Diagram CSM Fragmentation Feynman Diagram
parton interaction produces quark pair(c c )
quark pair bind into quarkonia(J/psi, psi’...)
color and spin is conserved during binding. The quarkonia is color-singlet, so the quark pair must be color-singlet too.
Color Singlet Model (CSM)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 27
High pT heavy quarkonium production
HVV anomalous gauge coupling
Status of Our Physics Analysis?
Study of Bc Meson
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 28
Test NRQCD via High pT Heavy Quarkonium Production
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 29
CDF Result vs CSM
1-2 order of magnitude discrepancy between CSM prediction and CDF Result
Prompt charmonium production Bottomonium production
black dot: CDF experimentdashed line: color-singlet solid line : NRQCD fit
J/ : PRL, 79 (1997) 572
: PRL, 88(2001)161802
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 30
New Mechanism: COM
New Mechanism of Heavy Quarkonia parton interaction produces quark pair(c c ), quark pair can be color-octet
quark pair can change color and spin through emitting gluon and then
bind into quarkonia(J/psi, psi’...) Color Octet Mechanism (COM)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 31
NRQCD Interpretation For CDF
NRQCD: Non-Relativistic QCD
Non-Relativistic: heavy quark moves slowly.
Consider both CSM and COM.
Production of Quarkonia can be factored into 2 steps– Creation of the quark pair (q qbar)
– quark pair bind into quarkonia
Long Distance Matrix Element(LDME):How likely the quark pair will bind to the quarkonia.
Short Distance Coefficient:Creation of quark-antiquark pair.This step is independent of final product.Can computed pertubatively
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 32
End of The Story? No!!
Problem: Polarization of Heavy Quarkonia
=+1: transversely polarized
=1: longitudinally polarizedPRL, 85 (2000) 2886
CDF RUN 1 results
J/ direction in lab frame
direction in J/ rest frame
PRL, 87 (2001) 022002 kT facterization approach
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 33
Bigger Discrepancy To CDF Run2
Problem: Polarization of Heavy Quarkonia
PRL, 85 (2000) 2886
CDF RUN 1 results CDF RUN 2 results
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 34
Test NRQCD @ CMS?
Higher luminosity: better statistics in general especially important for which is expected to be described better by NRQCD
Higher Collision Energy: larger cross-section higher PT region reached
Better Muon Measurement preferable for J/ ,
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 35
Simulation of Heavy Quarkonia
PYTHIA 6.3.24 in CMKIN_6_0_0 include both CSM and COM
Reproduce CDF Result to confirm our understanding to set the NRQCD parameters
Quarkonia simulation LHC collision energy Same set of parameters fitted from CDF FAMOS for CMS simulation
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 36
Reproduce CDF Result
1800GeVs |y|<0.4 for 100k MC events
J/
||<0.6 for J/ CTEQ5L PDFLDME from hep-ph/0106120
(J/) & PRD-63-094006 ()
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 37
J/ @ CMS
1M MC events
NRQCD parametersfrom CDF fitting( hep-ph/0106120 )
Through FAMOS
Normalized to 1fb
J/ PT > 8GeV/c|| < 2.4
~5000events/(GeV/c) @ 50GeV/c
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 38
@ CMS
1M MC events
NRQCD parametersfrom CDF( PRD-63-094006 )
Through FAMOS
Normalized to 1fb
cut || < 2.4
~500events/(GeV/c) @ 50GeV/c
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 39
Polarization can be determined from muon angular distribution
Polarization Extraction
2
21
21
3(cos ) (1 cos )
2( 3)
31: (1 cos )
83
1: (1 cos )4
I
I
I
1
3
: fully trans 。 polarization
: fully longi 。 polarization
1 1(cos ) (1 )I I I
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 40
The Procedure Of Extraction
1 1(cos ) (1 )I I I
CMS efficiency
= -1 = +1
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 41
The Loop Fitting
Solid Line is alpha input Data point is alpha fit value
Normalize to the MC templates
Weighted efficiency
23
11Signal Pt distribution
efficiency
Weighted efficiency
……
2
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 42
Avoid Dependence
•
• Same cross-section equivalent
to Same Bin content
• So we can use this bin to normalize signal and template
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 43
Neural Network Fit
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 44
Neural Network Fit
Neural network well fits input value.The result is not dependent on a
and PTThe distribution of deviation
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 45
Summary for High pT J/,
The NRQCD prediction of quarkoniapolarization contradicts CDF result
CMS is a suitable place to answer the question due to high lumi. and collision energy as well as better muon measurement The polarization could be well extracted with our studyBackground and trigger influence study is undergoing
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 46
Feasibility to Study the Bc Meson at CMS
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 47
Outline
• Introduction
• Process & results
– Production of Signal & Backgrounds
– Event selection, by studying Bc signal &
backgrounds
– Results
• Summary
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 48
Bc Meson Introduction• The Bc meson is the lowest-mass bound state of a charm quark and
a bottom anti-quark. It is the latest such meson predicted by the Standard Model.
• Because Bc meson carry flavor, it provides a new window for studying heavy-quark dynamics for the two different heavy quarks, which is very different from the window provided by quarkonium.
• Its mass is predicted to be
And its lifetime is predicted to be between 0.4 and 0.7 ps
V.V.Kiselev, PACS number:13.20.Gd,13.25.Gv, 11.55.HxV.V.Kiselev, PACS number:13.20.Gd,13.25.Gv, 11.55.Hx
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 49
TEVATRON: CDF (1998)
20 J/ψ lυ events, mass :6.40±0.39±0.13
GeV
life time :
03.046.0 18.016.0
ps
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 50
Recent results of Bc Meson
Experimental observation (CDF & D0 , Tevatron)
1998
2004
2005
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 51
Production of Bc at LHC
pp pp
LHC LHC (14TeV)(14TeV)
g-g fusion
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 52
Adavantages of study Bc at CMS1. Higher Collide Energy LHC: PP collider
2. Larger detector region than CDF The CMS detector has the similar structure as CDF ,but it has larger detector region than CDF. CMS: eta~(-2.5,2.5) CDF: eta~(-1.0,1.0) (RUN I) eta~(-1.5,1.5) (RUN II) (Muon system)
3. A better identification ability to muons The CMS detector has a better identification ability to muons ,this is more
useful for the channels which include muon/muons in the final state.
TeVs 14 TEVTRONLHC
cc BB 20~
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 53
• The goal: to measure the mass and life time of Bc with a larger statistics.
• The first channel to look:
Bc → J/ψ π (J/ψ → µµ)
• First publication at about 1 fb-1
Goal & status
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 54
Process & results
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 55
Generator of Bc signal• BCVEGPY IPT, Beijing, by Chang et al.• Russian package IHEP, Protvino, by Berezhnoy et al.• PYTHIA
BCVEGPY is used: faster agrees well with PYTHIA
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 56
Particle Decay channels σ (pb) Generated (*104)
Bc Bc→J/ψπ
(J/ψ→µµ )
1.781 5.2082
kine cut : Bc Pt≥10GeV |eta|≤2.0
Mu Pt≥4GeV |eta|≤2.2 Pion Pt≥2GeV |eta|≤2.4
About 30 1/fb Bc events were produced for efficiency study with both OSCAR/ORCA and FAMOS
Another independent 1/fb Bc were produced as data OSCAR_3_7_0 ORCA_8_7_3 FAMOS_1_3_2
Bc signal
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 57
Backgrounds
1. Other B hadrons’ decay include J/ψ
2. Prompt J/ψ
3. ccbar→μμx
4. bbbar →μμx
5. General QCD, W+jets, Z+jets
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 58
Backgrounds (1,2,3)generated by CMKIN & produced by FAMOS
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 59
Backgrounds (4,5)CMS official production with OSCAR/ORCA
Dataset σ(mb) Nevents
bb→mumu+ X 4.8*10-3 100,000
QCD 57.6 950,000
W+jets 1.56*10-4 880,000
Z+jets 3.82*10-5 710,000
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 60
J/Ψ candidates: 2 muons Pt ≥ 4.0 GeV , |η|<=2.2 2 muons share the same vertex 2 muons have different charge 2 muons’ invariant mass around the J/Ψ [3.0,3.2]GeV
Data Selection
Selection I
Bc → J/ψ π (J/ψ → µµ)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 61
Pion candidate: Not identified as a lepton Pt ≥ 2 GeV |η|<=2.4 Share the same vertex with 2 muons (J/Ψ vertex)
Selection II
Bc → J/ψ π (J/ψ → µµ)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 62
Selection III
Signal selection cuts:• cos(thetasp)>0.8 thetasp: is the angle between the direction from the primary vertex to the second vertex and the direction of the reconstructed Bc momentum • PDLxy >60 μm (Proper decay length)• PDLxy /σxy >2.5
P. V. S. V.
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1fb-1
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 64
Selection IV
Bc mass window (6.25, 6.55) GeV
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 65
Summary of the Number of EventsBc 120±11
B+ 0.7±0.2
Bs 0.1
B0 0.9±0.3
Prompt J/ψ 0.1
QCD 0.7±0.1
Λb 0.1
ccbar 0.01
bbbar 0.01
Total Bkgs: 2.6±0.4
Normalize to 1fb-1
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 66
Bc number uncertainty
source:1. LO only
2. color singlet only (no color-octet available)
3. Values of inputs
mass of b quark, c quark ;
parton distribution function (pdf).
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 67
Kinematic fitting
Bc→J/ψπ, J/ψ→μμ
Totally 3 tracks:
2 muon tracks: J/ψ mass constraint
all the 3 tracks: share the same vertex
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 68
M(Bc):6402.0±22.0 MeVInput:6400MeV
cτ(Bc): 148.8±13.1 μm Input 150 μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 69
Systematic errorsource: • Misalignment
1. muon momentum scale uncertainty
2. muon momentum resolution deterioration
3. vertex resolution deterioration• Efficiency uncertainty• Theoretical uncertainty• Cuts sensitivity
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 70
Summary of systematic error
Bc mass (MeV) Bc cτ (μm)
P scale 11 0.2
P smear 10 0.8
Vertex smear / 2.4
Cuts 0.1 0.2
Efficiency / 0.1
Theoretical / 1.5
Total 14.9 3.0
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 71
SummaryWith MC data, the feasibility for CMS to measure the mass and
the lifetime of Bc meson was studied.
The study focus on the decay channel Bc→J/ψπ.
120 events can be selected with the first 1 fb-1 data
Mass resolution is estimated to be
cτ resolution is
corresponding to the lifetime error to be
Uncertainty: effects of misalignment, theoretical uncertainty on the Bc Pt
distribution, and limited Monte Carlo statistics.
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 72
This study had been reported for 6 times at CERN.
This study had been written into 2 notes: CMS Notes & Analysis Notes
And Physics TDR.
The results can be available from the following website
http://cmsdoc.cern.ch/doc/notes/docs/NOTE2006_118
Continue…
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 73
Testing Anomalous Gauge Couplings ofthe Higgs Boson via Weak-Boson Scatterings
at CMS
Outline
1. Motivation
2. Extraction of anomalous coupling
constants via Neural Network
3. Study of signal and backgrounds
4. Summary & to do list
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 74
1. whether there exists a sub-TeV Higgs Boson.
2. Discriminate the EWSB sector of the new physics model from that of the SM.
Motivation
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 75
---------
p
p u
u
d
d
W
W
W
W
+
+
+
+H
l+
v
l
v
+
Zhang Bin and Kuang Yuping et. al. (Tsinghua Univ.)
proposed a sensitive way of testing AHVVC via VV (V =
W+ , Z0 ) scatterings, especially the WW scatterings at LHC and provided the matrix element level generator .
It is
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 76
among them, fw and fww are the most sensitive ones.
Hence, only fw and fww are considered.
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 77
To suppress backgrounds, the cuts suggested by theorists
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 78
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 79
Distribution of the number of events with fw
Normalized to 300 fb-1
mH=115 GeV
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 80
For the small number of events, large fluctuation occurred.
For the number of events fluctuated according Poisson distribution, the neural network can make the resolution of parameter fw better after taking the distribution of two leptons’ invariant mass as one of the inputs.
1.5
2.5
1.5 / 33 0.26
2.5 / 60 0.32
fw
fw
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 81
Extract anomalous coupling constant fw via Neural Network
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 82
Neural Networkinputs:
(1) number of events
(2) distribution of the invariant mass of 2 leptons.
outputs: anomalous coupling constants fwtraining: fw =0 ,1,2,3,4
evaluate: fw =1.5 ,2.5
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 83
Distribution of two leptons’ invariant mass
Normalized to 300 fb-1
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 84
2200 ~
4000960 ~
2200480 ~
9600 ~
480
two leptons’ invariant mass (GeV)
4 3 2 1bin
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 85
Evaluated f w = 1.5
26.018.0 5.1 wfsigma
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 86
Evaluated f w = 2.5
32.017.0 5.2 wfsigma
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 87
Study of signal and backgrounds
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 88
Reconstruction results of the Signal
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 89
channels Sigma Events/300 fb-1
Obtained via Grid job or reconstructed by myself
WZ 3l 4.4E-10 (mb)
132000 40000
ZZ 4l 1.6E-11 (mb)
4800 40000
Z0 t t 4l + X 1.7 (fb) 510 1000
W+ t t 3l + X 3.0 (fb) 900 1000
t t 4l + X 1.25E-9 (mb)
375000 121000
Zbb_4l+(njets) 2E-11 (mb)
6000 129000
Zbb_cc_4l+(njets) 8E-12 (mb)
2400 3000
ZWjets_leptonic 2.6E-9 (mb)
780000 50000
ZZjets_leptonic 1.5E-10 (mb)
45000 100000
Backgrounds
_
_
_
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 90
Comparison of the Signal & Backgroundsafter the basic Cuts
—2 lepton’s invariant mass and tagging jet’s pt
(Taking WZ→3 l as example)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 91
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 92
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 93
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 94
No background of the channels listed in the table can exits, after adding all cuts suggested by theorists to the backgrounds with the limited statistics. so we suggest to relax the cuts in order to get more signal events, which is what we will to do.
channels Sigma background events
Obtained via Grid job
WZ 3l 4.4E-10 (mb)
0 40000
ZZ 4l 1.6E-11 (mb)
0 40000
Z t t 4l+X 1.7 (fb) 0 1000
Wt t 3l+X 3 (fb) 0 1000
t t 4l + X 1.25E-9 (mb)
0 121000
Zbb_4l+(njets) 2E-11 (mb) 0 129000
Zbb_cc 4l+(njets) 8E-12 (mb) 0 3000
ZWjets_leptonic 2.6E-9 (mb) 0 50000
ZZjets_leptonic 1.5E-10 (mb)
0 100000
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 95
Summary• Extracting anomalous coupling constant fw via Neural
Network, we can get more sensitivity results using the number of events & invariant mass of 2 leptons than that using the number of events only on the theory.
• After studying the signal and backgrounds, using the cuts we can cut off all the backgrounds considered with limited number of events available.
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 96
To do list
• Further study of signal and backgrounds, then find out the best proper cuts.
• Try other ways to fix the anomalous coupling constants.
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 97
Summary
Physics topics @ CMS has been proposedwith great help from theoretical colleagues
Part of them has been studied with MC simulation, results are reasonable
3 notes have been accepted by CMS and many more could be expected
If support fund becomes true, we areconfident to reach our final goals in list
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 98
THANK YOU!
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 99
Backup slides
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 100
Cross section comparison
• Bc vs other B
σ(other B) =1000 σ( Bc) • LHC vs TEVATRON 20 times larger
H.C. Chang X.G. Wu
Pt cut (GeV) 0 5 50 100
TEVATRON/LHC
6.3% 5.2% 1.0% 0.3%
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 101
1. Bc→J/Ψlν(J/Ψ→l+l-)
Bc→J/ψµν(J/ψ→µµ)Bc→J/ψeν(J/ψ→µµ)Bc→J/ψµν(J/ψ→ee)Bc→J/ψeν(J/ψ→ee)
2. Bc→J/Ψπ(J/Ψ→l+ l-)
Bc→J/ψπ(J/ψ→µµ)Bc→J/ψπ(J/ψ→ee)
Bc decay and interface with OSCAR:
Force Bc to decay with the final states we needand interface with OSCAR (Implemented within SIMUB ) SIMUB is one of CMS Supported generator packages ,which is dedicated for simulation of B-meson production and decays. http://cmsdoc.cern.ch/~shulga/SIMUB/SIMUB.html
G.M. Chen S.H. Zhang IHEP BeijingA.A. Belkov S. Shulga JINR Dubna (Russia)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 102
Number decay channels Branch Ratio Nev σ(pb)after
Kine cut
5110 B0 → JPsi + K0 0.08% 170000 16.040
5111 B0 → JPsi + K0* 0.14% 290000 28.288
5112 B0 → chi_c1 + K0 0.19% 120000 11.192
5113 B0 → chi_c1+ K0 * 0.25% 150000 14.808
Background of Bc→J/ψπ (J/ψ→µµ) from B0
channels Branch Ratio
JPsi → mu+ mu- 5.88%
chi_c1 → JPsi + γ 31.6%
K0* → Random
K- Pi+
K0 Pi0
K0 γ
66.5%33.3%
0.2%
Kinematic cuts at generator llevel
Mu: pt ≥ 4.0GeV |eta| ≤ 2.4
K : pt ≥ 2.0GeV |eta| ≤ 2.7
More than 10 fb-1 bkg from B0 were produced
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 103
Number decay channels Branch Ratio Nev σ(pb) after kine cut
5210 B+ → JPsi + K+ 0.08% 170000 16.056
5211 B+ → JPsi + K+* 0.14% 290000 28.611
5212 B+ → chi_c1 + K+ 0.19% 120000 11.150
5213 B+ → chi_c1+ K+* 0.25% 150000 14.921
Background of Bc→J/ψπ (J/ψ→µµ) from B+
channels Branch Ratio
JPsi → mu+ mu- 5.88%
chi_c1 → JPsi + γ 31.6%
K+* → Random
K0 Pi+
K+ Pi0
K+ γ
66.6%33.3%
0.1%
Kine cut:
Mu: pt ≥ 4.0GeV |eta| ≤ 2.4
K : pt ≥ 2.0GeV |eta| ≤ 2.7
More than 10 fb-1 bkg from B+ were produced
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 104
Number decay channels Branch Ratio Nev σ(pb) after kine cut
5310 Bs → JPsi + phi 0.14% 30000 2.215
5311 Bs → JPsi + eta 0.04% 40000 3.198
5312 Bs → JPsi + eta’ 0.04% 30000 2.968
5313 Bs → chi_c1+ eta 0.1% 30000 2.064
5314 Bs → chi_c1+ eta’ 0.09% 20000 1.738
5315 Bs → chi_c1+ phi 0.25% 30000 2.583
Background of Bc→J/ψπ (J/ψ→µµ) from Bs
channels Branch Ratio
JPsi → mu+ mu- 5.88%
phi → K+ K- 48.9%
chi_c1 → JPsi + γ 31.6%
eta → Random 1
eta’ → Random 1
Kine cut
Mu: pt ≥ 4.0GeV |eta| ≤ 2.4
K : pt ≥ 2.0GeV |eta| ≤ 2.7
More than 10 fb-1 bkg from Bs were produced
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 105
Background of Bc→J/ψπ (J/ψ→µµ) from Λ0b
Number decay channels Branch Ratio Nsel σ(pb) after kine cut
51220 Lambda_b0 →
JPsi + Lambda0
0.22% 130000 12.797
51221 Lambda_b0 → chi_c1+ Lambda0
0.44% 70000 6.642
channels Branch Ratio
JPsi → mu+ mu- 5.88%
chi_c1 → JPsi + γ 31.6%
Lambda0 → Random
Kine cut
Mu: pt ≥ 4.0GeV |eta| ≤ 2.4
More than 10 fb-1 bkg from Λb were produced
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 106
Number decay channels Branch Ratio N(sel) σ(pb) after kine cut
4430 g (γ) + g (γ) →
JPsi
Chi_c0
Chi_c1
Chi_c2
5.88%
0.7% * 5.88%
31.6% * 5.88%
13.5% * 5.88%
10000
10000
40000
180000
0.440
0.794
3.902
17.553
4431 g (q) + g (q) →
c cbar + g (q)
5.88% 260000 217.57
Background of Bc→J/ψπ (J/ψ→µµ) from prompt J/ψ
Kine cut:
Mu: pt ≥ 4.0GeV |eta| ≤ 2.4
channels Branch Ratio
JPsi → mu+ mu- 5.88%
chi_c0 → JPsi + γ 0.7%
chi_c1 → JPsi + γ 31.6%
chi_c2 → JPsi + γ 13.5%
More than 10 fb-1 bkg from 4430 were produced. Only 1 fb-1 events fromChannel 4431
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 107
)(/ _01 Jc
)(/ _0 Jc
_/ J
)(/ _02 Jc
)()( gg(1)
PYTHIA
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 108
_/ Jgccqgqg _
)()((2)
PYTHIA
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 109
Backgound estimation
None of the QCD, W+jets, Z+jets,ccbar and bbbar passed the selection.As the number of events produced is lessthan one 1/fb, the number of backgroundevents from these samples will be estimatedstep by step
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 110
QCD background estimation
selection efficiency
1. two muons
pT>4GeV, |η|<2.2 ε(2μ)
2. J/ψreconctruction
same vertex,
mass(μμ) : (3.0,3.2) ε(rec)
3. Final cuts
Lxy/σ>2.5, PDL>60μm
cos(thesp)>0.8
mass(J/ψ,π): (6.25, 6.55) ε(prompt)
The total efficiency is ε(2μ)*ε(rec)* ε(prompt)
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 111
Dataset σ(mb) No. of events getted using Grid
No. of
Single Mu
(>= 1 Mu)
No. of
Double Mu
(>= 2Mu)
jm03b_qcd_0_15 55.22 23999 10 0
jm03b_qcd_15_20 1.50006 44999 122 1
jm03b_qcd_20_30 0.641733 89999 461 4
jm03b_qcd_30_50 0.155929 92997 933 12
jm03b_qcd_50_80 0.02093883 198993 4382 126
jm03b_qcd_80_120 0.002949713 90000 3408 147
jm03b_qcd_120_170 0.000499656 70000 3872 248
jm03b_qcd_170_230 0.000100995 40000 3130 247
jm03b_qcd_230_300 2.3855*10-5 50000 4963 453
jm03b_qcd_300_380 6.39108*10-6 243983 31873 3769
jm03b_qcd_380_470 1.88967*10-6 5000 744 111
Kine cut: Mu: pt ≥ 4.0GeV |eta| ≤ 2.2
ε(2μ) can be estimated from QCD samples
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 112
ε(rec) estimation
• Using ccbar→μμx sample
total: 210,000
The number of events pass 2 muon selection: 147778, reconstructed J/ψ: 192
ε(rec)= (1.3±0.1) × 10-3
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 113
ε(prompt) estimation
• Using prompt J/ψ sample• The number of events pass the above selection is 434,566• Enlarge the mass window from (6.25,6.55) to (5.0,8.0), 27 events obtained assuming random distribution of the 27 eventsε(prompt)=(6.55-6.25)/(8-5)*27/434566= (6.2±1.2) ×10-6
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 114
Prompt J/ψ
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 115
Dataset σ(mb) ε(2 mu) Total ε N1fb-1
jm03b_qcd_0_15 55.22 (1.736256
±0.17363)e-7
(1.40157
±0.19937)e-15
0.077
±0.011
jm03b_qcd_15_20 1.50006 (7.35045
±0.06025)e-6
(5.93353
±0.29930)e-14
0.089
±0.004
jm03b_qcd_20_30 0.641733 (4.444494
±2.222247)e-5
(3.58775
±1.04850)e-13
0.230
±0.067
jm03b_qcd_30_50 0.155929 (1.290364
±0.372496)e-4
(1.04161
±0.13080)e-12
0.162
±0.020
jm03b_qcd_50_80 0.02093883 (6.331881
±0.56409)e-4
(5.11131
±0.25650)e-12
0.107
±0.005
jm03b_qcd_80_120 0.002949713 (1.633333
±0.134715)e-3
(1.31848
±0.06467)e-11
0.039
±0.002
ε(JPsi →Bkg) = (6.2±1.2 ) ×10-6
ε(2mu→JPsi) = (1.3±0.1) × 10-3
QCD background contribution
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 116
Dataset σ(mb) ε(2 mu) Total ε N1fb-1
jm03b_Wjets_0_20 1.110015*10-4 (5.13333
±0.5850)e-4
(4.14380
±0.22887)e-12
(4.5997
±0.2541)e-4
jm03b_Wjets_20_50 2.729528*10-5 (1.4350
±0.08471)e-3
(1.15838
±0.05297)e-11
(3.1618
±0.1446)e-4
jm03b_Wjets_50_85 1.006911*10-5 (2.880
±0.120)e-3
(2.32483
±0.10225)e-11
(2.34090
±0.1030)e-4
jm03b_Wjets_85_150 6.30697*10-6 (4.4650
±0.149416)e-3
(3.60430
±0.15630)e-11
(2.2732
±0.0986)e-4
jm03b_Wjets_150_250 1.20248*10-6 (7.740
±0.27821)e-3
(6.24799
±0.27202)e-11
(7.5131
±0.3271)e-5
jm03b_Wjets_250_400 2.632455*10-7 (1.123333
±0.061192)e-2
(9.0679
±0.40713)e-11
(2.3871
±0.1072)e-5
ε(JPsi →Bkg) = (6.213095±1.19571 ) ×10-6
ε(2mu→JPsi) = (1.299246±0.093765) × 10-3
W+Jets has none
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 117
Muon momentum scale uncertainty
Δ(1/pT)=0.0005/GeV (Albert De Roeck)
Bc mass changes by 11 MeV
cτ changes by 0.2 μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 118
Muon momentum resolution
I. Belotelov et al
CMS note
2006/017
Muon momentumwere smearedaccording to This result
Mass: 11 MeVCtau: 0.8μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 119
Vertex resolution
P. Vanlaer et al, CMS note 2006/029Primary Vertex : x, y: smear 5.7μm, z:3.7μmSecond Vertex: x, y: smear 12.4 μ m , z: 11.4μmcτ: 2.4 μ m
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 120
Cuts sensitivity
• Momentum cuts changed by one σ
• Other cuts changed by 10%
mass: 0.1 MeV
cτ : 0.2 μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 121
Efficiency uncertainty
To estimate theefficiency uncertaintysqrt(N) events subtracted , efficiencyrecalculated
cτ: 0.1 μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 122
Theoretical uncertainty
Bc events were reweighted according the their Bc pT, sothat the Bc pT distribution agrees with Gouz’s distributioncτ: 2.4μm
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 123
Muon momentum resolution
CMS 1/fb:Mass: 22.0(fit) ±14.9(syst) MeV lifetime: 0.044(fit) ±0.010(syst) ps
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 124
Outlook (Real data 2008)
• J/ψ+ 1track will be selected as a control sample
• B+ → J/ψ+K+ will be used to estimate the Bc efficiency
• J/ψ peak side band will be used for the Bc background estimation
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 125
• Color Singlet Matrix Element :– Determine from Potential Model. valid for S-wave and P-wave state
– or Determine from leptonic decay. only apply for S-wave state
Determine the LDME
• Color-Octet Matrix Element– can be fitted from experiment data.
Measured from Experiment FittedCalculated
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Nov. 6-8, 2006 TeV Physics and LHC Workshop, CCAST 127
Upsilon on CDF
• Use Pythia 6.324 which include color octet mechanism• need to manually set 5 NRQCD parameter
NRQCD Paramter Choice (in Pythia 6324) (PRD-63-094006)C Parameter of NRQCD(Inclusive Parameter) C PARP(146) : (D=1.) <O(Upsilon)[3S1(1)]>C PARP(147) : (D=1.) <O(Upsilon)[3S1(8)]>C PARP(148) : (D=1.) <O(Upsilon)[1S0(8)]>C PARP(149) : (D=1.) <O(Upsilon)[3P0(8)]>/m_b^2C PARP(150) : (D=1.) <O(chi_b0)[3P0(1)]>/m_b^2 PARP 146=12.8 PARP 147=11.6E-2 PARP 148=10.9E-2 PARP 149=0 PARP 150=0