Transcript J/ - Istituto Nazionale di Fisica Nucleare

(2S) radiative and
hadronic transitions at BES
Zhiyong Wang
IHEP, Beijing ,China
for the BES Collaboration
International Workshop on Heavy
Quarkonium
October 12-15, 2004 , IHEP Beijing
BESII Detector
VC: xy = 100 m
TOF:
MDC: xy = 220 m
BSC:
dE/dx= 8.5 %
p/p=1.7%(1+p2)
T = 180 ps
E/E= 22 %
 = 7.9 mr
z = 3.1 cm
 counter: r= 3 cm
z = 5.5 cm
B field: 0.4 T
World J/ and (2S) Samples (×106)
(2S)
J/
14 M
58 M
60
14
50
12
40
10
8
30
6
20
4
10
0
2
MarkIII
DM2
BESI
BESII
0
MKI
MKII
MKIII
CBAL
BESI
BESII CLEO
outline
(2S)0J/,0
J/
(2S)J/,
(BES-II data)
(2S)c1 , c1 J/

J/e+e，
+
(2S)c2 , c2 J/
(2S)J/
X+J/
(2S)J/
(BES-I data)
(2S)c1 , c1 J/
(2S)c2 , c2 J/

J/+
Charmonium System
'   J/
Measure:
'  oJ/, J/
'  cJ    J/
• Old measurements disagree.
• B(’  oJ/) very crude:
(J=1,2)
(23 evts at CBAL, 7 evts at MRK2).
• Theoretical predictions for charmonium hadronic
transition amplitudes can be tested by high
statistics measurements.
(  ( 2 S )   0 J /  )
R
 0.0162
((2S )  J / )
( '   )
R 
 0.0025
((2S )  J / )
'
( ''   )
R 
 0.0013
((2S )  J / )
''
'   J/
Previous experiment results((2S)…)
PDG2002
Channel
0 J/
J/
C1
C2
(9.72.1)10-4
(3.130.21)%
(8.40.7)%
(6.80.6)%
Branching
Ratio
Experiment
Data
Sample(M)
Events
(15.66)10-4
MARK-II(1980)
1.0
7
(921)10-4
CBCL(1980)
1.8
13
(4.30.8)%
MARK-I(1980)
1.0
44
(2.550.29)%
CBAL(1980)
0.78
386
(4.20.6)%
CNTR(1978)
0.63
164
(4.51.2)%
DASP(1979)
(9.00.50.7)%
CBCL(1986)
1.8
(7.11.9)%
CNTR(1977)
0.63
(8.00.50.7)%
CBAL(1986)
1.8
(7.02.0)%
CNTR(1977)
0.63
17
'   J/
J/
 cJ    J/
Take +
final state as
an example
MC
0J/
J/e+e or +, 5C (J/
mass) kinematic fit is applied!
BKG from 00J/
'   J/
(2S) → 0J/
 (2S) → cJ →   J/
  e+e
  e+e
  +
(2S) → J/
 (2S) → cJ →   J/
  +
  e+e
  +
'   J/
PDG04
2.67 ± 0.15
1.30 ± 0.08
'   J/
BES most
 c1
accurate
J/
 c2
oJ/
BES
BES measures the BRs
with high precision!
Phys.Rev.D70:012006,2004
’   J/
Discussions
2
( ( 2 S )   J /  ) 27  p  2
R

r  0.00162


 (  ( 2 S )  J /  )
16  p 
0
PCAC [G. A. Miller,
Phys. Rep. 194,1(1990)]:
Casalbuoni et al: give an
improved expression
R 
[PLB 309,163(1993)], but
A and B are unknown
27
16
 p

 p


ˆf


2B

1

2

2
2

3
A
m

m


2
0
 r 

ˆf


B


1


2
A m   m2


BES result: R=0.048±0.007
B/A=-1.420.12
QCD Multipole Expansion & BTG potential model
[Y. P. Kuang, PRD24, 2874(1981), ibid. 37, 1210(1988)
m 
 (     )
R 
  c 
( (2S )  J /  )  mb 
3
 f ( ) 
  0.0025
 
f
(

(
2
S
))


3
 f ( ) 
  0.0013
 
f
(

(
2
S
))


2
 p ( ) 


 p ( (2S )) 
 

2
 p ( ) 


 p ( (2S )) 
 

m 
(    )
R 
  c 
( (2S )  J /  )  mb 







2
2
B/A=-3.11  0.15
BES (+PDG for ):
R<0.0098
R<0.0065
2
'  X J/
M. Suzuki, PRD63,
054021, (2001).
B((2S)  hadrons)/B(J/  hadrons) =
B((2S)  ggg + gg)/B(J/  ggg + gg)
Y. F. Gu and X. H. Li,
= 0.23 ± 0.07
PRD63, 114019 (2001).
Disagrees with “12 % Rule”
Important to measure ’  X J/ and
components.
Method – identify J/+
Select muons.
1 C fit to mJ/
determine mX
pX
p μ+
pJ/
p μ-
'  X J/
Inclusive measurement – use events
that satisfy 1 C fit.
J/ peak
Fit distribution:
•
background (mμμ < 3.4)
1307 events
•
signal 44498 events
Background
e+ e-   μ+ μ- and
e+ e-  ’   μ+ μ-
'  X J/
Exclusive measurements
To separate ’  00 J/ and + J/, plot mX for
no extra charged tracks and for extra charged tracks.
Fit two simultaneously with component shapes.
no extra
extra
0 0
+
η
backgrd
c2 c1
η
2 < 7
'  X J/
Determine ratio of branching ratios to
B(’  + - J/ ) to cancel systematic errors.
Constrain C2/c1 since shapes similar.
Results
Phys.Rev.D70:012003,2004
measured
BESI – 4 million (2S) events.
Summary
• The precision of B((2S)0J/, 00J/
J/,c1,2) are improved, especially for
B((2S)0J/)
• Some theoretical models are tested by our
new measurement results
Thank you !
谢谢!