experimental research on
DESCRIPTION
at the CMS. Experimental Research on. Bo ZHU. School of Physics, Peking University. Motivation Results of MC Conclusion. as a Test of NRQCD. Heavy quarkonium for QCD testing NRQCD and pQCD for CDF quarkonium puzzle Polarization sources Direct - PowerPoint PPT PresentationTRANSCRIPT
Experimental Research on
/cj J
School of Physics, Peking University
at the CMS
Bo ZHU
MotivationResults of MC Conclusion
2
Heavy quarkonium for QCD testing
NRQCD and pQCD for CDF quarkonium puzzle Polarization
sources
Direct
Prompt ( ) (40%)
B-Decay
0, 1, 2c c c
/J /J
/J
/J
as a Test of NRQCD/J
3
Traditional decay length method to distinguish prompt
Detector resolution limitation
High background
from B-decay , maybe difficult since:
Current Status of
Integral Luminosity 10pb-1
High pt get worse
No constrain
5-7 0.07(0.02) 0.02(0.02)
7-10 0.09(0.01) 0.02(0.01)
10-15 0.15(0.01) 0.04(0.01)
>15 0.23(0.02) 0.06(0.02)
0.01c cm ( / )Tp GeV c
c
/J /J
/J
/
( / )
( / )B
J B
Br B J X
Br B J X
4
Advantage of The channel is cleaner
With an additional photon
Small b hadrons decay branch ratio
CMS experiment (CDF )
ECAL , MUON system (CDF )
/cj J
ECAL
MUONs
3 2.4 0.6
14s TeV 1.96s TeV
5
NRQCD: Non-Relativistic QCD
Quarkonium production: Generate Quark Pair Quark Pair involves into quarkonium
Non-Relativistic: Heavy quark moves slowly in heavy quarkonium rest frame . With CSM and COM:
Long Distance Matrix ElementProbability of the quark pair binding to the quarkonium.
Short Distance Coefficient:quark-antiquark pair created.independent of final product.Can be computed by pQCD
( ) ( [ ] ) [ ]H
n
d H X d QQ n X n
6
Polarization
Bernd A. Kniehl etc. PHYSICAL REVIEW D, VOLUME 62, 114027
cj
polarization: From fragmenting gluon 100% transversally polari
zed from ,
cj
/J cj 0.2
7
Data sample CSM &COM, 800K Prompt , 3.7pb-1
370K , 12.8pb-1
Prompt branch ratio
Decay Branch ratio Events from
1.3% 10.4K
36% 224K
20% 120K
800K 340K
Data Samples
/ , ( ) 2.5 / , 2.5TJ p GeV c
/J / ( )b hadron J X
cj
~40% prompt events are from decay
c0c1c2
/J cj/J
cj
cj
8
Expecting Yield
trigger rates at a Luminosity = 1032cm-2s-1
Event Sample Rate(Hz)
Prompt ( ) 1.4(0.5)
ppX (include b hadrons decay ) 1.1
~10M events pass trigger in the first year.
S.QIAN CMS B-physics meeting CERN 28/8/2007
/cj J
/cj J
cj/J /J
cj
9
38K events normalized to 10pb-1
Only photon are reconstructed,(28%) ECAL acceptance: Angle can be used to decrease background
in Generator Level
cj
cj
cjcross section
cj / ( ) , ( ) 2.5 / , ( ) 2.5TJ p GeV c
2.9 1 /Tp GeV c
10
Sources of Background
• Sources of Background1. b hadrons’ decay2. General QCD, W+jets, Z+jets
• Sources of Background1. b hadrons’ decay2. General QCD, W+jets, Z+jets
/J
cj
b-hadrons
B0 7.1±1 <1 94.3±10.6
B+ 8.9±1.4 <0.4 61.8±8.6
B0s - - 50±8.9
BC - - 20±4.1
b-baryon - - 4.7±2.8
Journal of Physics G: Review of Particle Physics, Vol 33 (2006), page 779
1c 4(10 ) 4(10 ) 4(10 )2c /J
• b hadrons’ decay branch ratio
11
•Use constrain
• mass range 2.9-3.3GeV/c2
•
(GeV/c)
Signal eventsNo
constrain
No constrain
5-7 0.07(0.01) 0.02(0.01) 108949 93862
7-10 0.10(0.01) 0.03(0.01) 176900 161105
10-15 0.15(0.01) 0.04(0.01) 129576 123384
>15 0.22(0.01) 0.07(0.01) 53432 52151
>25 0.27(0.01) 0.09(0.01) 6970 6908
>5 0.13(0.01) 0.04(0.01) 468857 430503
/
( / )
( / )B
J B
Br B J X
Br B J X
c
•b hadrons to fraction
( / )Tp J
Signal/Background for
0.01c cm
0.01c cm 0.01c cm c
/J
/J
/J
12
( )
( )cj
B cj
B cj
Br B X
Br B X
•Use constrain• mass range 2.9-3.3GeV/c2
• Number of photons <3
• mass range 3.3-3.7GeV/c2
•
cj
(GeV/c)
Signal eventsNo
constrain
No constrain
5-7 0.07(0.02) 0.02(0.02) 2545 2135
7-10 0.09(0.01) 0.02(0.01) 6027 5489
10-15 0.15(0.01) 0.04(0.01) 4881 4602
>15 0.23(0.02) 0.06(0.02) 1675 1638
>5 0.14 (0.01)
0.04(0.01) 15167 13864
c
•b hadrons to fractioncj
( / )Tp J
Signal/Background for
cj0.01c cm
0.01c cm 0.01c cm c
/J
13
cj
No
constrain
0.23(0.02) 0.06(0.02)
0.22(0.01) 0.07(0.01)
c
•b hadrons fraction
in High RangeTp >15GeV/c
No constrainc
Tp vs. /J
( )cjM
( / )M J
/
( / )
( / )B
J B
Br B J X
Br B J X
Tp >15GeV/cNo constrainc
0.01c cm
cj/J
( / )M J
( )cjM
0.01c cm
0.01c cm
Tp >15GeV/c
Tp >15GeV/c
14
Summary can be used on CMS to test NRQCD
There will be about 10M event pass CMS trigger in the first year
With the constrain of number of photon and , the signal of prompt is about 15 times of the number of B-decay background in high pT range (pT>15GeV/c).
Future work Polarization study
/cj J
cj
ccj
15
16
backup
17Fraction 0.21
18
Number of photon
In prompt chi_cj event
Mean=
Number of photon
In B to J/Psi eventNumber of photon
In prompt J/Psi event