Upload
tobit
View
38
Download
0
Tags:
Embed Size (px)
DESCRIPTION
Recent BESII Results Representing BESII Collaboration Weiguo Li Institute of High Energy Physics, Beijing 100049, P.R. China [email protected] Sino-German Workshop Frontiers in QCD DESY, Hamburg, Sep. 20, 2006. Outline Introduction Hadron Spectroscopy from J/ Decays - PowerPoint PPT Presentation
Citation preview
Recent BESII ResultsRepresenting BESII Collaboration
Weiguo Li
Institute of High Energy Physics,
Beijing 100049, P.R. China
Sino-German Workshop
Frontiers in QCD
DESY, Hamburg, Sep. 20, 2006
Outline
Introduction
Hadron Spectroscopy from J/ Decays
(2S) and CJ Physics
(3770) non DD Decays
Future Plan
Summary
BESII DetectorBESII Detector
VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 250 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.4 % = 7.9 mr B field: 0.4 T p/p=1.8(1+p2) z = 2.3 cm Dead time/event: 〈 10 ms
Data from BESI and BESIIEcm (GeV)
Physics BES Data Other Lab.
3.10 J/ 7.8106 8.6106
3.69 (2S) 3.9106 1.8106
4.03 1.0105 LEP
4.03 DS, D 22.3 pb-1 CLEO
3.55 m scan m 5 pb-1
2-5 R scan
2. 2.2,2.6,3.0
R value,
QED, (g-2)
QCD
6+85 points 2, MarkI Crystal Ball Pluto……
3.1 3.69 3.78
J/ (2S) (3770)
5.8107
1.46107
~27 pb-1
BESII finished data taking April 2006
• Scalars: , clearly observed
• Possible pp bound state in J/ pp
• X(1835) in J/ ’
• The threshold enhancement in J/
• New observation of a broad 1- - resonance in
J/ K+K- 0
• other topics
Light Hadron Spectroscopy from J/ Decays
The pole in at BESII
/J
M()
M(+-0)
M(+-
)
0
Averaged pole position: (541 39) (252 42)i MeV
Phys. Lett. B 598 (2004) 149
κ
24877
8173 MeV/c )45309()30841(
i
Phys. Lett. B 633 (2006) 681
Observation of an anomalous enhancement near the threshold of mass spectrum at BES II
M=1859 MeV/c2
< 30 MeV/c2 (90% CL)
J/pp
M(pp)-2mp (GeV)0 0.1 0.2 0.3
3-body phase space acceptance
2/dof=56/56
acceptance weighted BW +3 +5
10 25
pp
BES II
Phys. Rev. Lett. 91, 022001 (2003)
• This indicates X(1860) has a production property similar to ’ meson.
• This also indicates X(1860) may have strong coupling to gluons as ’ meson.
This narrow threshold enhancement is NOT observed in J/ pp at BESII
No narrow strong enhancement near threshold
Preliminary
C.L. %95@%5.0)/(/)/( XJBrXJBr
04.0)'/(/)'/( JBrJBr
2GeV/c 2 ppp MM
J/ pp
Not seen in pp experiment
• In pp experiments, its expected cross-section is much smaller than continuum process
• In pp elastic scattering, I=1 S-wave dominant, while in J/ radiative decays I=0 S-wave dominant. Pure FSI disfavored
not seen in: B+ K+ pp (BELLE) Y(1S) pp ( CLEO)
Observation of X(1835) in J/+-
'
' X(1835)6.0
X(1835)5.1
'
'/J
'
'/J
Statistical Significance 7.7
JCombine two channels
X(1835)
7.7
2
2
MeV/c 7.73.207.67
MeV/c 7.21.67.1833
54264
M
Nobs
410)4.04.02.2()()( XBXJB
Phys. Rev. Lett., 95 (2005) 262001
59.18.0 10)4.00.7()()(:..
ppXBXJBfc
Re-fit to J/pp including FSI
Include FSI curve from A.Sirbirtsev et al. ( Phys.Rev.D71:054010, 2005 ) in the fit (I=0)
M = 1830.6 6.7 MeV
= < 153 MeV @90%C.L.
ppp mM 2
In good agreement with X(1835)
X(1860) and X(1835) might be the same state
• masses and widths are consistent.
• both connected with ’ meson.
Its spin-parity should be 0-+: this would be an important test.
Excited ’ ? Glueball? pp bound state?
A mixture of glueball and pp bound state?
M(+-0)
M(K
+K-
)
M(K+K-)
MeVMMKK
15||
MeVMMMeVKK
35||20
M(+-0)
Dalitz plot
Observation of thresholdenhancement in J/
M2()
M2 (
)
A clear threshold enhancement is
observed
Eff. curve
Phase Space
Side-bands
Side-bands do not have mass threshold enhancement!
• The decay of J/ is observed and an enhancement in is found near the threshold.
• PWA shows: the enhancement favors 0+
+
2
21926
MeV/c 2820105
MeV/c 181812
M
410)65.027.061.2()()/( XBrXJBr
Phys. Rev. Lett., 96 (2006) 162002
• Is it the same 0++ observed in KK or , or is it a
glueball, or a hybrid …..?
• Further study in , K*K*, …. desirable !
0
background 0 sideband
?
K*(892)
K*(1410)
hep-ex/0606047, accepted by PRL
)1580(X
New observation of a broad 1- - resonance in J/ K+K- 0
What is the threshold bump?
• JPC should be 1--, 3--, … (Parity conservation)
• PWA results
– Following components are neededK*(892), K*(1410), (1700), X
– 1– is much better than 3—
– Pole position of X is
– Br
– Big destructive interference among X, (1700)
and PS
MeV )409()1576( 32116712
98499155
i
47.26.3
-0 10)6.05.8( )KKX ,Xπ(J/ψ
More Checks
• Replace X by (770), (1900), (2150) with interference among each other, S = 85
not from the interference of known particles
• Replace X by (1450) S = 36 ( 8.2)& Br((1450) K+K-) < 1.6 10-3 (95% C.L.)
not (1450)
Further look in to determine its isospin Search for its K*K, KK decay modes
πKKJ/ψ S
Property of X(1580)
• The width is much broder than other mesons, such as (1450), (1700)
Could have different nature from conventional mesons.
• The large width is the expectation for a multiquark state (Tetraquark interpretation: M. Karliner, H.J. Lipkin, hep-ph/0607093)
Observation of an enhancement near mass threshold in process
p pKJ /
Phys. Rev. Lett. 93 (2004) 112002
M = (2075 12 5) MeV
Γ = (90 35 9) MeV 7 stat. sig.
BR = (5.9 1.4 2.0) 10-5
Near threshold enhancement in..ccK
../ ccpKJ
)(GeV/c2 MMM KKΛ
(PS, eff. corrected)Nx
Nx
Mass 1500~1650MeVWidth 70~110MeVJP favors 1/2-
4102~)()/( KNBRpNJBR XX
suggesting a strong coupling to K
In the internal referee process
M(+-0)(GeV/c2) M(+-0)(GeV/c2) M(+-0)(GeV/c2)
M(
+-0
)(G
eV/c
2 )
sideband
BES II Preliminary
signal after best candidate selection (best masses)
signal with multiple entries
0 ,/ J
Eff. curve
Phase Space Side-bandM() M()
(1760) f0(1710)f0(1790)f0(1810)
PWA analysis
M()
Total
f2(1910) f2(160) BGUsing observed mass and width for f0(1810)in J/
f0(1710)
f2(1910) 5.8
f2(1640) 5.5
BG
(1760) > 10
f0 6.5
M() (GeV/c2)
dominated by (1760) a 0++ is possible needed (6.5 )
Accepted by PRD, hep-ex/0604045
3-
22421
2
100.32)0.08(1.98
))1760(())1760(/(
MeV/c 25244
MeV/c 15101744
BrJBr
M
Study of the excited baryons
The evidence of 2 new N* states in
N*(1440)?
N*(1520)
N*(1535) N*(1650)
N*(1675)
N*(1680)
?
npJ /
MeV 4012165
MeV 32068M 1540
PRL97, 062001 (2006)
(2S) Decays
• Transitions (~82%)– Hadronic transitions (~54%)– Radiative transitions (~28%)
• Leptonic decays (~ 2%)• Hadronic decays (~15%)
– Strong decays (~13%)– EM decays (~ 2%)
• Radiative decays (~ 1%)• Rare decays and beyond SM (<<1%)
(2S) leptonic decays: B(’+
-)• First observation by DASP: ZPC1, 233(1979), no BR
• First measurement by BESI: PRD65, 052004 (2002)– B=(0.271±0.043±0.055)%
• Improvements:– Continuum contribution measured in data– Efficiency and background estimation – Interference subtraction more reasonable
• Results: – 1015 events at resonance– 146 at continuum– B=(0.320±0.022±0.040)%– Lepton universality checked
BES: preliminary
Continuum contribution and phase in (2S) decays
Phase
Branching ratios
Continuum contribution should be subtracted …
Interference needs to be considered.
The interference are neglected in many of the current analyses.
(2S) and CJ Physics
In analyzing (2S) decays, the continuum contribution should be subtracted and the phases between three glue and one photon process can be measured.
With BESII 14 M (2S) events and 6.4 pb-1 (s=3.65 GeV) and CLEOc 3 M events and 21 pb-1(s=3.67 GeV)
12% rule are tested and the phases between three glue and one photon process for different processes are measured.
The universal -90°phase?
J/ψ Decays: 1. AP: 90° M. Suzuki, PRD63, 054021 (2001)
2. VP: (106 ±10)° J. Jousset et al., PRD41, 1389 (1990)
D. Coffman et al., PRD38, 2695 (1988)
N. N. Achasov, talk at Hadron2001
3. PP: (90 ±10)° M. Suzuki, PRD60, 051501 (1999)
(103±7)° BES, PRD69, 012003 (2004)
4. VV: (138 ±37)° L. Köpke and N. Wermes, Phys. Rep. 174, 67 (1989)
5. NN: (89 ±15)° R. Baldini et al., PLB444, 111 (1998)
ψ(2S) Decays: 1. VP: φ=180° (± 90 ° ruled out!) M. Suzuki, PRD63, 054021 (2001)
φ=180° or φ=-90° P. Wang et al., PRD69, 057502 (2004)
2. PP: (-82±29)° or (121±27)° BES, PRL92, 052001 (2004) & Yuan, Wang, Mo, PLB567, 73 (2003)
|φ|
The “12% rule”
M. Appelquist and H. D. Politzer, PRL34, 43 (1975)
12%B
B
B
BQ
eeJ/ ψ
eeψ'
XJ/ ψ
Xψ'h
This is the famous (or notorious)
“12% rule”.
Violation found by Mark-II , confirmed
by BESI at higher sensitivity. Extensively studied by BESII/CLEOc
VP mode: , K*+K-+c.c., K*0K0+c.c., 0,…PP mode: KSKL, K+K-, +-
BB mode: pp, , …VT mode: K*K*2, f2’, a2, f2
3-body: pp0, pp, +-0, …Multi-body: KSKShh, +-0 K+K- , 3(+-), …
“12% rule” and “ puzzle”
K*K
ρπ
MARK-II
’ PP BES, PRL 92, 052001 (2004)
CLEO, PRD74, 011105(R)(2006)
Interference between ’ and continuum amplitudes in K+K- was not considered.
156 evts
53 evts139 evts4 evts
Two possible phases: -80° or +121°.
J/, ’ PP: 12% rule BES, PRL 92, 052001 (2004)
CLEO, PRD74, 011105(R)(2006)
KK mode enhanced relative to the 12% rule.Pure EM mode not enhanced, may be suppressed.J/ and ’ are related by ee of charmonia and form factors.
’ (10-5) J/ (10-4) Qh (%)
+- 0.8±0.8±0.2 (CLEO)
(<2.1 @ 90% C.L.)
1.47 ± 0.23
(PDG04)
5.4 ± 5.6
(<15@ 90% C.L.)
K+K- 6.3±0.6±0.3 (CLEO) 2.37 ± 0.31
(PDG04)
26.6 ± 4.6
KSKL 5.8±0.8±0.4 (CLEO)
5.24±0.47±0.48 (BE
S)
5.44 ± 0.54 (average)
1.82 ± 0.13
(BES04)
31.9 ± 5.4
28.8 ± 4.2
29.9 ± 3.7
BESII CLEOc
229 0s 196 0s
BES and CLEOc in good agreement!
BESII: PLB619, 247 (2005)CLEOc: PRL94, 012005 (2005)’ + - 0
56.15.1
0
50
10)8.28.18()'(:
10)9.18.11.18()'(:
BCLEOc
BBESII
Dalitz plots after applying 0 mass cut!
Very different from J/ 3!
Similar Dalitz plots, different data handling techniques:
PWA vs counting!
J/
’ + - 0
CLEOcBESII
58.07.0
5
10)2.04.2()'(:
10)1.17.01.5()'(:
BCLEOc
BBESII
’ is observed, it is not completely missing, BR is at 10-5
level!
BESII : PLB614, 37 (2005); PRD73, 052007 (2006)CLEOc : PRL94, 012005 (2005)J/, ’ VP
mode
BESII:
B(’)(×10-5)
CLEOc:
B(’)(×10-5)
PDG04/BESII/…
B(J/)(×10-4)
B(’)/B(J/)
(%)
5.1±0.7±1.1 2.4+0.8-0.7±0.2 234±26 0.13±03
(2150) 19.4±2.5+11.5-3.4 N/A N/A N/A
+-0 18.1±1.8±1.9 18.8+1.6-1.5±2.8 200±9 0.92±11
K*0K0+c.c. 13.3±2.7±1.7 9.2+2.7-2.2±0.9 42±4 2.6±0.6
K*+K-+c.c. 2.9±1.7±0.4 1.3+1.0-0.7±0.3 50±4 0.34±0.20
1.87+0.68-0.62±0.28 2.5+1.2
-1.0±0.2 5.38±0.66 3.7±1.2 1.78+0.67
-0.62±0.17 3.0+1.1-0.9±0.2 1.93±0.23 10.9±3.4
’ 1.87+1.64-1.11±0.33 N/A 1.05±0.18 18±16
<0.40 N/A <0.064 N/A
3.3±1.1±0.5 2.0+1.5-1.1±0.4 8.98±0.92 3.0±1.2
’ 3.1±1.4±0.7 N/A 5.46±0.64 5.7±3.0 <3.1 <1.1 23.5±2.7 <0.53’ 3.2+2.4
-2.0±0.7 N/A 2.26±0.43 14±11
Multi-body ’ decays BES: PRD71, 72006 (2005); PRD74, 12004 (2006)
Some modes are suppressed, some are enhanced, while some others obey the 12% rule!
CLEOc:PRD72, 051108(2005)
BESII, PRD73, 052004 (2006)
CLEOc: PRL95, 062001 (2005)
’ radiative decays
• Total BR measured ~ 0.12% (total radiative decays ~1%)
Mode Nsignal Efficiency (%)
BR [m<3.0 GeV/c2] (10-5)
pp-bar 114±23 35.7 2.27 ± 0.45 ± 0.51
’ 23±5 7.58 12.6 ± 2.9 ± 1.5
2(+-) 664±53 10.7 44.4 ± 3.5 ± 5.6
KSK+-+c.c. 160±18 5.35 32.2 ± 3.6 ± 4.5
+-K+K- 183±22 5.37 24.3 ± 2.9 ± 6.3
2(K+K-) 22±6 4.61 3.21 ± 0.86 ± 0.67
+-ppbar <20 7.36 <1.77
3(+-) 44±16 0.56 < 92
2(+-)K+K- 19±10 0.73 18.3 ± 6.4 ± 5.0
BES: preliminary
Mesonic decays
Mode B(’X )(10 – 4) B (J/X )(10 – 4) Qh ( % )
+- 0 K+K- 11.7±1.0±1.5 120±28 (PDG) 9.8±2.8
K+K- 2.38±0.37±0.29 16.8±2.1 (BESII) 14.2±3.4
f0(1710)K+K- 0.59±0.20±0.09 6.6±1.3 (BESII) 8.9±3.8
K*(892)0K-+0+c.c. 8.6±1.3±1.8 - -
K*(892)+K-+-+c.c. 9.6±2.2±1.7 - -
K*(892)+K-0+c.c. 7.3±2.2±1.4 - -
K*(892)0K-++c.c. 6.1±1.3±1.2 - -
3(+-) 5.45±0.42±0.87 40±20 (PDG) 14±8
2(+- ) 4.5±1.0 (PDG) 35.3±1.2±2.9 13±3
+- KSKS 2.20±0.25±0.37 - -
In agreement with 12% rule expectation
BES: PRD73, 052004 (2006) PRD72, 012002 (2005) PLB630, 21 (2005)
Baryonic decays
Mode B(’X )(10 – 4) B (J/X )(10 – 4) Qh ( % )
0 p pbar 1.32±0.10±0.15 10.9±0.9 (PDG) 12.1±1.9
p pbar 0.58±0.11±0.07 20.9±1.8 (PDG) 2.8±0.7
p nbar - 2.45±0.11±0.21 23.6±2.1 (BESII) 10.4±1.4
pbar n + 2.52±0.12±0.22 24.7±2.4 (BESII) 10.2±1.5
p nbar - 0 3.18±0.50±0.50 - -
p pbar 3.35±0.09±0.23 21.7±0.8 (PDG) 15.4±1.3
bar 3.39±0.20±0.32 15.4±1.9 (PDG) 22.0±3.7
0 0bar 2.35±0.36±0.32 13.1±1.0 (PDG) 17.9±3.9
- bar+ 3.00±0.42±0.31 18±4 (PDG) 16.7±4.7
0 bar <?? <1.2 -
bar <?? 3.14±0.85±0.50 -
Most modes in agreement with 12% rule expectation, also exceptions!
BES: PRD71, 072006 (2005)BES: preliminary
Summary of “12%” rule,
’ VP suppressed’ PP enhanced’ VT suppressed’ BB obey/enhMulti-body obey/sup
Similarly ’’ decays have a rule of 0.02%, more data and more sophisticated analysis are needed to extract the branching fractions from the observed cross sections. Here because the time limitation, I will omit the results in this talk.Model to explain J/, ’ and ’’ decays naturally and simultaneously?
•S-D mixing in ’ and ’’ [J. L. Rosner, PRD64, 094002 (2001)]•DD-bar reannihilation in ’’ (J. L. Rosner, hep-ph/0405196)•Four-quark component in ’’ [M. Voloshin, PRD71, 114003 (2005)]•Survival cc-bar in ’ (P. Artoisenet et al., PLB628, 211 (2005))•Other model(s)?
Seems no obvious rule to categorize the suppressed, the enhanced, and the normal decay modes of J/ and ’.
The models developed for interpreting specific mode may hard to find solution for other (all) modes.
ψ(2S) Decay is a cJ factory
ψ(2S)→cJ, J=0,1,2–BJ~9%, “cJ factory”–observed in inclusive analysis–B(cJ→hadrons ) are not well known
BES: cJ→2(K+K)hep-ex/0607025
Improved precision over PDG (BESI) results on cJKKKK and .
First measurement of cJKK.
c2
c0 c1
Pair production of vectorscJ
Pair production of vectors
BES: PLB630, 7 (2005)
First observation:
B(c0) =
(2.290.580.41)10-3
B(c2) =
(1.770.470.36)10-3
28c2
38c0
cJ
c2
c1
cJh0h+h− BES: hep-ex/0607023
BES: PRD74, 012004 (2006)
B (cJ→ h0h+h− )
2
BES preliminary
CLEO preliminary
hep-ex/0607072CLEO preliminary (%)
BES preliminary Notice: different units
BES and CLEO in good agreement!
1/2
BES: PRD74, 012004 (2006)
BES: PRD73, 052006 (2006)
c0
cJ
Evidences for c0 and c0,2.
Agree with COM and QCM predictions.
BES: hep-ex/0605031cJpn()
JB()<1.2×10-4
BES: hep/ex-0607023 cJ→KK and
c0→PPP is forbidden by spin-parity; +- mode is first observation.
c1 c2
cJ decays into PPP
c1→KSK+-+c.c. c1→ +-
K*
a0(980)
f2(1270)
B(c1→KSK+-+c.c.) (4.1±0.3±0.7)×10-3
B(c2→KSK+-+c.c.) (0.8±0.3±0.2)×10-3
B(c1→+-) (6.1±0.8±1.0)×10-3
B(c1→a0+ -
+-)(2.0±0.5±0.5)×10-3
B(c1→f2(1270)) (2.1±0.5±0.4)×10-3
(3770) non-DD decays
(3770) decays most copiously into DD. (3770) is a mixture of the 13D1 and 23S1, other (2S)-like decays for (3770) are expected. (mixing angle 122o). Many theoretical calculations estimate the partial width for (3770) +- J/. (Lipkin, Yan, Lane, Kuang, Rosner) Recently, Kuang obtained a partial width for (3770) +- J/ in the range of 25 -113 keV. (Y.P. Kuang, PRD 65 (2002) 094024)
BES first reported (3770) non-DD decay
(3770) +- J/
8.48.11)/)3770(( JN
Open histogram is for e+e-, histogram in yellow is for +-
ISR todue production '
mainly
The histogram is ’ error bars are ’+’’
/Jψ ''
/' Jψ
data MC
20 times large than the data
keV )233380()/)3770((
)%09.014.034.0()/)3770((
J
JBrhep-ex/0307028PLB 605 (2005) 63
27.7 pb-1
Measurements of R values
BornhadR
trighad
hadobshad L
N
)1(
obshadBorn
hadR -
e+
e-
+
h a d ro n s-e
e+
q-
q
f la v o rc o lo r
= Qf2
lowestorder
pQCD calculates the R ratio in continuum region
Experimentally, one measures
: # of hadronic hadN
: Luminosity L: Effs.hadhad ,
events
: radiative correction factor
)1(
22 (GeV)
nb 8544.86
cmee E
had)1( Have to be determined precisely !
When scan over 3.770 GeV
Just before the scan experiment
Mass [MeV]
PDG04
BEPC
BEPC
BEPC
011.0916.3096
05.030.3095
034.0093.3686
01.090.3684
02.050.3684
BEPC energy calibration
'
'
'J/
J/
3095.33684.8
MM3095.3)(EME
PDGJ/ψ
PDG
ψBEPCPDG02J/ψ
true'
EBEPC is the energy of BEPC set in the experiment,
Etrue is the true energy
01.070.3684
8.36842
9.36847.3684
During the cross section experiment, we performed 4 fast cross section scans over J/ and ’ resonances to calibrate the BEPC energy.
Events Recorded by BESII
N0
e+e-e+e-
+
+-
e+
e-e- -
e+ + +
e- e-
e+ e+
e+
e-
Nhad
e- e-
e+ e+
+-
N0
e+e-e+e-
+
+
-e
e +
q-
q
Cosmic-ray and beam associated background
The distributions of the averaged Z of events
could be estimated based on cross sections, luminosity and acceptancebN
bN
bN
hadn
)1( hadNhad
n
Radiative correction could remove the effects of high order processes from the observed cross section, and gives
The
eve
nts
obse
rved
in th
e ex
peri
men
t
)hadrons( eeB
ECM [GeV] σobshad R
3.650
3.665
3.773
udstot R and R
22.098.18
27.030.18
27.068.27
16.062.14
21.015.14
22.014.23
02.025.2
03.020.2
04.075.3
)hadrons(0 ee
GeV 3.773 @ 20.004.075.3 R
09.002.023.2 udsR
11.005.026.2 udsR
Obtained by fitting the (3770) and (3686) cross sections
see before
Obtaining by fitting to the R values measured by BES in the range from 2.0 to 3.0 GeV
14.026.2| GeV 3.0 to 2.0 udsR
stat. & p-to-p systematic error
R values measured at three energy points
Comparison of R measurements from different experiments
Born)3770((3770) & R σ
udsEcm RERRcm
GeV 3.773)3770( |)(
Taking the R for light hadron production to be a constant, then
13.004.052.1)3770( RWe obtain
nb 80025.028.9Born)3770( .
nb 74.108.11))3770(()1(
122
)3770(VP
Born)3770(
eeBF
M
)024.0047.1()1( VP obtained based on PDG04 (3770) resonance parametersPLB 603(2004)130
My
calc
ula
tio
n It is consistent with
)non)3770(( DDBF determined with DDσR &
Preliminary
Including (3770)
)()(
)(12)( 2222 sMMs
ss
tot
feeB
2/41
0|))1((1|))1(( ),( )(
2
xsxssxfdxssM Bobs
DD
D
Assuming that decay exclusively into (3770) DD
Radiative correction
PR D62 (2000)012002-1024.0047.1)1(|))1((1| 2
vpxs
Radiative correction factor B
obs
g
Born
obsDD
Born
BornDDDD
σgN
NDDBF
)3770(IIBES)3770(prd
(3770)
prd
))3770((
Obtained from analysis of R
Determination of branching fractions withobs
DD Born
)3770(and
014.0764.0IIBES g
Some systematic uncertainties can be canceled out
Radiative correction factor obtained based on new (3770) resonance parameters measured by BES-II.
Assuming that there are no other new structures and effects except (3770) and continuum hadron production in the energy region from 3.70 to 3.87 GeV, we have
)%5.31.11.36())3770(( DDBF )%9.33.15.50())3770(( 00 DDBF
)%9.57.16.86())3770(( DDBF
)%9.57.14.13())3770(( DDnonBF
Results of branching fractions
With BES previously measured cross sections for DD production.
PLB603(2004) 130
hep-ex/0605107 accepted by PRL
These result in the non-DD branching fraction
nb 0.63)0.19(7.09obs)3770(
nb 0.80)0.25(9.28Born)3770(
)1( Is calculated with the (2S) resonance parameters measured by scanning the (2S) peak.
)%6.32.19.37())3770(( DDBF )%1.43.10.53())3770(( 00 DDBF
)%2.68.18.90())3770(( DDBF )%2.68.12.9())3770(( DDnonBF
Results of branching fractions
09.002.027.2 udsR nb 0.79)0.25(8.85Born)3770(
Considering the possible interference between the two amplitudes …
If we consider the possible interference …
nb 0.62)0.19(6.76obs)3770(
hep-ex/0605107 accepted by PRL
)1( Is calculated with the (2S) resonance parameters measured by scanning the (2S) peak.
trgcmhadcm
hadcm
obshad EEL
nE
)( )()(
1
0
exp ))1(( ),( )( xssxFdxs Becthad
)()(
)(12)( 2222 sMMs
ss
tot
feeB
(Kuraev and Fadin)
functionsampling issxF ),(
Observed cross section
For (3770), we use energy-
dependent total width )(tot s
)hadrons( ee
The distribution of event vertex in Z
Fitting the distribution of the event vertex gives the number of hadronic events nhad.
Resonance parameters of (3770) , (3686) and branching fractions
)mode(2
)()(
tag single
tag single
D
D
DBL
ENE
cm
cmobs
DD
KD0
KD
Distributions of invariant masses of
mKn
Energy dependent cross sections
KD0
DD-bar production
combinations at different c.m. energies
Mar. 2003 data set
00DD
DD
DD
Inclusive hadrons
Inclusive hadrons
Ob
serv
ed c
ross
sec
tio
n f
or
had
ron
pro
du
ctio
n [
nb
]
Observed cross sections
(3686) resonance region
(3770) resonance region
Mar. 2003 data set
Mainly due to vacuum polarization corrections
(3770)
(3686)
(3686)
To measure the resonance parameters of (3770) or (3686), one had better to simultaneously fit (3686) and (3770) resonances, since there are strong correlations between the fitted parameters of the two resonances.
If one do not consider the effects of vacuum polarization corrections on the observed cross sections in the data reduction, the total width of (3686) would decrease by about 40 keV!
hep-ex/0605107,. Accepted by PLB
After subtraction of (3686) , (3770) and J/ from the observed cross sections, one obtains the expected cross sections of the continuum hadron production.
Mar. 2003 data set
experiment
E760
BES-II
PDG04
This work
(MeV) M ' (keV) tot' (keV) '
ee
AN / 27264 21.044.2
03.009.3686 17281 12.012.2
3.00.05.3685 258331 11.004.033.2
1636306 3.01.00.3686
Comparison of (3686) Resonance Parameters
)%033.0122.0704.0(])3686([ eeB
510)03.006.093.0()])3770([( eeB
hep-ex/0605107, accepted by PLB
510)17.012.1()])3770([( eeB
)%031.0755.0(])3686([ eeB
PDG04
Obtained based on cross section scan
Mar. 2003 data set
00DD
DD
Inclusive hadrons
Branching fractions
)%8.27.39.36())3770(( DDBF
)%3.27.47.46())3770(( 00 DDBF
)%2.43.76.83())3770(( DDBF
)%2.43.74.16())3770(( DDnonBF
Obtained from fitting to the inclusive hadron and the DD-bar production cross sections simultaneously.
where the first error is statistical and second systematic, which arises from the un-canceled systematic uncertainties in hadron cross sections (~4.4 %), neutral DD-bar cross sections (~4.5 %) and charged DD-bar cross sections (~7.4 %).
hep-ex/0605107, accepted by PLB
Mar. 2003 data set
Observed Cross Sections Preliminary !
No obvious cross section discrepancy at the two energy points is observed. However, to extract the non-DD-bar branching fractions of (3770) decays, we need to consider the interference between the two amplitudes of the continuum and the resonances, and to consider the difference of ISR & vacuum polarization corrections at two energy points.
Search for decays of (3770) DDnon
CLEO (3770) non-DDbar decay
s
+ c0
’’XJ/:
missing event energy (GeV) after finding +, -, J/(ll)
e+e-’ (J/+-)’’
J/+-
’’c
J:
cJJ
/:
cJh
adro
ns:
((3770)hadrons)(6.5 0.1 +0.4
-0.3 ) nb
((3770)DD)(6.39 0.10 +0.17
-0.08 )nb
( (3770)non-DD)(-0.01 0.12 +0.40
-0.33 )nbtranslates into BR UL
B((3770)non-DD) < 10%
Exclusive channels:Mode BR (%)
+J/ 0.1890.0200.020
00J/ 0.0800.0250.016
J/ 0.0870.0330.022
c0 0.730.070.06
c1 0.390.140.06
(3.10.60.3)10-2
other ~2
Summary
J/ decays -- excellent lab to study light hadron
spectroscopy, and search for new hadronic states.
12% rule has been tested extensively, more data, but no satisfactory explanation yet. CJ can be studied by
(2S) decays.
(3770) non DDbar decay are studied, now the results are not conclusive, more data will help.
BESIII will answer a lot of questions in the above three areas, data are expected in 2008.
Thanks
谢谢
PWA of 0/ ppJ
π0
η
Comparison of data with fit results
+ : datahist.: fit
N(1440), N(1520), N(1535), N(1650), N(1675), N(1680), N(1720) are needed.
Nx(2065) exists in this channel (stat. sig. >>5σ) The spin-parity favors 3/2+ MeV 565230 MeV, 252040 3
4 M
N* M(MeV/c2) (MeV/c2) JP fraction(%)
1/2+ 9.74~25.932.38~10.926.83~15.58 6.89~27.94
4.17~30.1023.0~41.8
3/2-1/2-1/2-
N(1710) 1/2+ 0.54~3.863/2+
N(1440) 1.33~3.54
N(1535) 0.92~2.10N(1650) 0.91~3.71
N(1520) 0.34~1.54
N(2065) 0.91~3.11
Br (×10-4)
481455 27
141513 34
121537 26
271650 36
391715 22
56230 88
75316 56
38127 78
39135 88
30145 510
252040 34
4595 21
BES: PRD72, 092002 (2005) c0→+K+K
Different way for scalar study:1. Start from JPC=0++, 1++,
2++
2. Start from gluon+gluon3. Pair production of
scalars, very different information than in J/ decays
1371 evtsc0
c1
c2
Can study different kinds of resonances:
• ( )( K K )• (K )(K )• (K ) K
Pair production of scalars
( )( K K )
f0(1710) f0(2200) f0(980)
f0(1370)
(770)
BES: PRD72, 092002 (2005)
Q. Zhao, PRD72, 074001 (2005), try to understand these data and the scalars …
(K )(K )
K*0/2(1430)
K*0(1950)
K*(892)0With Kappa-kappa
Without Kappa-kappaS=39.
BES: PRD72, 092002 (2005)
1371 events
M(K ) [896±60] MeV
M( ) [700,850] MeV
K1(1270)
K1(1270)
K1(1400)
K1(1270)
BES, c0→+K+K
The mixing angle between K1A and K1B >57 degrees, while in ’ decays to K1K, the
angle is <29 degrees. Why?
(K )K