Nov. 6-8, 2006 TeV Physics and LHC Workshop ， CCAST 1 Physics Goals Of Chinese Group @ CMS Yajun...

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

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


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


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


RPC From PKU (part)

Mass production, installation-2006.2.13.

264 panels ， 2000m2, 3.72M RMB


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?


(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


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.


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


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


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


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 .


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


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。


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


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


H→ZZ→4

• 大热门• HZZ ４道 : 与美国 Florida 大学合

作


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


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 .


H→Zγ, Z →μ+μ-

• 冷门• 本底小 , 没有能量丢失• 分支比小


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


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


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


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


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。


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)


High pT heavy quarkonium production

HVV anomalous gauge coupling

Status of Our Physics Analysis?

Study of Bc Meson


Test NRQCD via High pT Heavy Quarkonium Production


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


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)


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


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


Bigger Discrepancy To CDF Run2

Problem: Polarization of Heavy Quarkonia

PRL, 85 (2000) 2886

CDF RUN 1 results CDF RUN 2 results


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/ ,


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


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 ()


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


@ CMS

1M MC events

NRQCD parametersfrom CDF（ PRD-63-094006 ）

Through FAMOS

Normalized to 1fb

cut || < 2.4

~500events/(GeV/c) @ 50GeV/c


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


The Procedure Of Extraction

1 1(cos ) (1 )I I I

CMS efficiency

= -1 = +1


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


Avoid Dependence

•

• Same cross-section equivalent

to Same Bin content

• So we can use this bin to normalize signal and template


Neural Network Fit


Neural Network Fit

Neural network well fits input value.The result is not dependent on a

and PTThe distribution of deviation


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


Feasibility to Study the Bc Meson at CMS


Outline

• Introduction

• Process & results

– Production of Signal & Backgrounds

– Event selection, by studying Bc signal &

backgrounds

– Results

• Summary


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


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


Recent results of Bc Meson

Experimental observation (CDF & D0 , Tevatron)

1998

2004

2005


Production of Bc at LHC

pp pp

LHC LHC (14TeV)(14TeV)

g-g fusion


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~


• 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


Process & results


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


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


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


Backgrounds (1,2,3)generated by CMKIN & produced by FAMOS


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


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



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



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.

1fb-1


Selection IV

Bc mass window (6.25, 6.55) GeV


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


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).


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


M(Bc):6402.0±22.0 MeVInput:6400MeV

cτ(Bc): 148.8±13.1 μm Input 150 μm


Systematic errorsource: • Misalignment

1. muon momentum scale uncertainty

2. muon momentum resolution deterioration

3. vertex resolution deterioration• Efficiency uncertainty• Theoretical uncertainty• Cuts sensitivity


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


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.


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…


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


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


---------

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


among them, fw and fww are the most sensitive ones.

Hence, only fw and fww are considered.


To suppress backgrounds, the cuts suggested by theorists



Distribution of the number of events with fw

Normalized to 300 fb-1

mH=115 GeV


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


Extract anomalous coupling constant fw via Neural Network


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


Distribution of two leptons’ invariant mass

Normalized to 300 fb-1


2200 ~

4000960 ~

2200480 ~

9600 ~

480

two leptons’ invariant mass (GeV)

4 3 2 1bin


Evaluated f w = 1.5

26.018.0 5.1 wfsigma


Evaluated f w = 2.5

32.017.0 5.2 wfsigma


Study of signal and backgrounds


Reconstruction results of the Signal


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

_

_

_


Comparison of the Signal & Backgroundsafter the basic Cuts

—2 lepton’s invariant mass and tagging jet’s pt

(Taking WZ→3 l as example)





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


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.


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.


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


THANK YOU！


Backup slides


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%


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)

http://cmsdoc.cern.ch/~shulga/SIMUB/SIMUB.html

http://cmsdoc.cern.ch/~shulga/SIMUB/SIMUB.html


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


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+



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


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



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


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



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


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



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


)(/ _01 Jc

)(/ _0 Jc

_/ J

)(/ _02 Jc

)()( gg(1)

PYTHIA


_/ Jgccqgqg _

)()((2)

PYTHIA


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


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)


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

http://cmsdoc.cern.ch/cms/production/www/cgi/SQL/dataset-discovery.php?ProducedOn=&scriptstep=1&DSPattern=jm03b_qcd_0_15&OwPattern=jm_DST8713_2x1033PU_g133_OSC












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


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


Prompt J/ψ


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



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


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


Muon momentum resolution

I. Belotelov et al

CMS note

2006/017

Muon momentumwere smearedaccording to This result

Mass: 11 MeVCtau: 0.8μm


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


Cuts sensitivity

• Momentum cuts changed by one σ

• Other cuts changed by 10%

mass: 0.1 MeV

cτ : 0.2 μm


Efficiency uncertainty

To estimate theefficiency uncertaintysqrt(N) events subtracted , efficiencyrecalculated

cτ: 0.1 μm


Theoretical uncertainty

Bc events were reweighted according the their Bc pT, sothat the Bc pT distribution agrees with Gouz’s distributioncτ: 2.4μm


Muon momentum resolution

CMS 1/fb:Mass: 22.0(fit) ±14.9(syst) MeV lifetime: 0.044(fit) ±0.010(syst) ps


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


• 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


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

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