Recent BESII ResultsRepresenting BESII Collaboration

Weiguo Li

Institute of High Energy Physics,

Beijing 100049, P.R. China

liwg@ihep.ac.cn

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+

+-

qq

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