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