Recent Results of J/ and (2S) at BESII

Zhiyong Wang Zhiyong Wang

IHEP, BeijingIHEP, Beijing

for the BES Collaboration

Rencontres de Moriond 2007QCD and High Energy Hadronic Interactions

La Thuile, Italy, 10 – 24, March

Moriond QCD ,2007 2

Outline• J/ results

– Wide resonance X(1580).– Threshold enhancement in J/ – , invisible

(2S) results– Hadronic decay– Radiative decay (2S)+

cJ decay

Moriond QCD ,2007 3

0

5

10

15

20

25

30

MKI MKII MKIII CBAL BESI BESII CLEOc

Data samples

28M

14M

6.42 pb-1 continuum data at Ecm=3.65 GeV for background study.

4M

J/ (2S)

Moriond QCD ,2007 4

J/ results

Moriond QCD ,2007 5

New Observations at BESII

In past three years, a number of new structures were observed at BESII

• A possible bound state: mass threshold enhancement in and new observation of X(1835) in .

• mass threshold enhancement in

• mass threshold enhancement in

In this talk, I will report two new structures

pp

ppJ /

pKJ /K

p pKJ /

pp

'/ J

Moriond QCD ,2007 6

)1580(X0

)890(*K

)1580(X

)1410(*K

Observation of X(1580) in J/ K+K- 0

Background

PRL97,142002(2006)

47.26.3

0

264 22133 23

98 4991 55

10)6.05.8()()/(

1

MeV/c )818(2

)1576(2

KKXBrXJBr

J

iiM

PC

Moriond QCD ,2007 7

How to understand broad X(1580)?

• Search of a similar structure in J/ KS

K will help to determine its isospin.

• X(1580) could have different nature from conventional mesons:

– Width is much broader than other mesons.

– Broad width is expected for a multiquark state.

Moriond QCD ,2007 8

recoiling against

Observation of mass threshold enhancement in J/

• We studied DOZI process:J/ + + +-0 K+ K-

Moriond QCD ,2007 9

M2()

M2 (

) backgroundX(1810)

Observation of mass threshold enhancement in J/

M()

Phys. Rev. Lett., 96 (2006) 1620024-

2

21926

100.65)0.27(2.61

MeV/c 2820105

MeV/c 181812

M

Spin-parity favors 0++

Possible interpretations: Multiquark, Hybrid, Glueball

Moriond QCD ,2007 10

Searching for /’ Invisible Decays Via J//’

• Reconstructing K+K ,

looking at missing momentum of decays

• Fast (1.2 GeV) will help us define the decay

direction of invisible decay of / (958) .

Tag direction

Missing direction

58 M J/

..%90@1069.6)'(

)'(

..%90@1065.1)(

)(

2

3

LCBR

invisibleBR

LCBR

invisibleBR

No any hit information are required outside of the core of decays.

Signal MC

missing momentum distribution

PRL97,202002(2006)

Moriond QCD ,2007 11

(2S) results

Moriond QCD ,2007 12

(2S) hadronic decay

12%B

B

B

BQ

eeJ/ ψ

eeψ'

XJ/ ψ

Xψ'h

M. Appelquist and H. D. Politzer, PRL34, 43 (1975)

KKbodyMulti

npnpppppbody0

0

:

,,,:3

Moriond QCD ,2007 13

’ 3-body

921±40914±42

256±18 44.8±8.7

PRD71,072006(2005); PRD74, 12004 (2006)

Moriond QCD ,2007 14

’ 3-body BESII: PRD71, 072006 (2005)

BESII: PRD74, 12004 (2006)

Moriond QCD ,2007 15

Multi-body ’ decays BESII, PRD73, 052004 (2006)

Moriond QCD ,2007 16

Multi-body ’ decays

Many intermediate states are observed for the first time.

Moriond QCD ,2007 17

(2S) radiative decayMany channels for (2S)+hadrons with the invariant

mass of hadrons below 2.9GeV have been studied.

Hep-ex/0612016

Moriond QCD ,2007 18

Search for the strong mass threshold enhancement X(1860) in

• A strong mass threshold enhancement was observed in

• No obvious strong mass threshold enhancement was observed in

acceptance

X(1860)

Fit

CL

ppXSB

%90@104.5

))1860()2((6

pp

pp pp

ppS )2(

ppS )2(ppJ /

M(pp)-2mp (GeV)

0 0.1 0.2 0.3

M=1859 MeV/c2

< 30 MeV/c2 (90% CL)

+3 +510 25

5107~

))1860(/(

ppXJB

acceptance

Moriond QCD ,2007 19

KKS ,)2(

PRD74, 072001(2006)

(2S) radiative decay

Moriond QCD ,2007 20

BBS )2(

Channel CLEOc BES-II2.870.120.15 3.310.090.23

3.280.230.25 3.390.200.32

2.630.350.21 2.350.360.32

2.380.300.21 3.000.420.31

00

pp

Accepted by PLB

2cos1cos

d

dN

B(BBbar)

According to the hadron helicity conservation, the angular distribution of J/ ， (2S)B8B8 satisfy:

)2( S

Theo. Exp.

0.58 Claudson et al 0.670.150.04

E835

0.80 Carimalo 0.850.240.04

BES

))2(( ppS

Moriond QCD ,2007 21PRD74, 112003(2006)

(2S)+

Bree Br Br/0.3885

7.350.18 7.3 0.8 7.93 0.54 0.97

Moriond QCD ,2007 22

cJ decay

)1270(,)890(,

..

,

,,

20

0

00

fa

ccKK

ppKK

KKKKKK

cJ

ScJ

SScJ

cJ

PLB642,197(2006)

PRD73,052006(2006)

PRD74,072001(2006)

PRD74,072001(2006)

Most channels are measured for the first time

Moriond QCD ,2007 23

cJK+ K K+ K

cJ++ ppbar

cJ+K,+

Moriond QCD ,2007 24

Summary• A wide 1-- resonance X(1580) is observed in J/

K+K0 .• The mass threshold enhancement is observed in J

/. • The invisible decay mode is studied for and

via J//.• A lot of (2S) radiative and hadronic decay chan

nels are measured and the 12% rule are tested.• Many cJ decay modes are observed and most are

measured for the first time.

Thanks a lot !