Transcript Experimental results in charmonium decays from BES Rong-Gang Ping (presented by F. Harris) for BES collaboration Charm 2007 Aug.

Experimental results in charmonium
decays from BES
Rong-Gang Ping
(presented by F. Harris)
for BES collaboration
Charm 2007
Aug. 6, 2007
(2s) data samples
outline
’ decays
30
26M
25
Leptonic decays
Radiative decays
Hadronic decays
20
14M
15
cJ decays
VV
10
PPP
4M
5
3M
0
MKI
MKII
MKIII
CBAL
BESI
BESII
CLEO CLEOc
Also 6.42 pb-1 of data at Ecm=3.65 GeV
for background study.
Expected? Sequential lepton hypothesis:
BESII: remeasure with larger sample
Measured in     ee
Characterized by
•2 charged tracks; 1  and 1 e
•missing energy and momentum
•no extra hits in BSC
 = 17.8%
BESII   
Result:
B(  ) =
(3.100.210.38) x 10-3
Lepton universality
is tested in
charmonium decays.
PRD 74: 112003 (2006)
Bee (10-3)
7.35  0.38
B (10-3)
B/0.3885 (10-3)
7.3  0.8
8.0  1.1
 2S radiative decays
 Only limit edmodes measuredby BESI
-  ' [P RD58,097101(1998)]
-  2S     PRD67,032004(2003)
 Measure moremodes
 Br(  2S     X)
- 2 - prong:         pp,
- 4 - prong: 2(   )            pp,2(K  K  ), K S K    c.c.
- 6 - prong: 3(   )2(   )   
’ radiative decays
PRL 99, 011802 (2007)
Background including
1. QED processes
2. multi- photo processes,
 2S    hadrons,   hadrons
Bg
3. other bg.
2
2
 obs
 w s sig
  w bg  2bg
data
bg
 2S     
signal
n  bg.
QED Bg.
others
Background
Observation of ’ radiative decays
• Expect ~1% BR, but only 0.05% previously observed.
• Potential channels for hadron spectroscopy study, including search for non-qqbar
states, if enough statistics.
• ~ 0.1% more observed in this analysis.
Mode
BR (10-5)
[m<2.9 GeV/c2]
 pp-bar
2.9 ± 0.4 ± 0.4
 ’
12.6 ± 2.9 ± 1.5
 2(+-)
39.6 ± 2.8 ± 5.0
 KSK+-+c.c.
25.6 ± 3.6 ± 3.6
 +-K+K-
19.1 ± 2.7 ± 4.3
 +-ppbar
2.8 ± 1.2 ± 0.7
 2(K+K-)
< 4.0
 3(+-)
< 17
 2(+-)K+K-
< 22
PRL99, 011802 (2007)
PRD74, 072001 (2006).
PRD74, 072001 (2006).
MARK-II
K*K
ρπ
 First measurement by BESI, remeasureBR with a
larger  2S  data sample.SU(3) symmetryobserved.
 "12%rule" tested.

 
0
2
m p (GeV / c )
0
2
m p   (GeV / c )

 

m p   (GeV / c 2 )
x 10-4
Angular distribution:
2
x 10-4
Baryonic decays
Rich structure (N*s),
statistics (~850 evts
in each mode). Still
low for a partial wave
analysis.
PRD74, 012004 (2006)
Test I-spin symmetry
(prediction: 1:2:2)
J /  pn    c.c.
100,000eventsobtained
PRL97,062001,2006
B( '  pp 0 ) : B( '  pn   ) : B( '  pn  )  1 : 1.86  0.27 : 1.91  0.27
PRL 99,011802 (2007)
PLB642, 197 (2006)
c0
c1
cJ→2(K+K)
Pair production of vectors
c2
Improved precision over PDG (BESI) results
on cJKKKK and .
First measurement of cJKK.
cJ decays into PPP
c1→KSK+-+c.c.
K*
PRD74, 072001 (2006)
cJ→KK and 
c1
c2
PRD 74, 072001 (2006)
c0→PPP is suppressed
by spin-parity selection;
Nsig=418± 60

c1→ +Nsig=222±28 (8.8s)
 sideband
Nsig=58± 14 (4.5s)
a sideband
BES: cJ→KK and 
PRD 74, 072001 (2006)
CLEO-c, PRD75, 032002
’(J/)
+0/
arXiv: 0707.1127 [hep-ex]
Submitted to PRD
• Is it really B(0)>B()?
background from
J/  ΣΛπ
signal
First measurement!
Summary
 ’ leptonic decays, hadronic decays, radiative decays
are studied to search for new phenomena and to test
QCD predictions.
 c decays are studied using ’ data sample.
 CLEOc will take the leading role in ’ and c decays;
we are now preparing for the BESIII data taking and
the physics analysis.
Thanks a lot !