ICHEP’04 Beijing, China

ee++ee-- double (cc) at Belle double (cc) at Belle

ee++ee-- J/ J/ (cc) (cc)resres

Full eFull e++ e e- - J/J/ cc reconstruction reconstruction

Angular analysisAngular analysis

ee++ee-- (2S) (cc)(2S) (cc)resres

Recent search: strong evidence for a Recent search: strong evidence for a

new charmonium state X(3940) in new charmonium state X(3940) in

ee++ee-- J/ J/ X(3940) X(3940)

P.Pakhlov (ITEP, Moscow)(for Belle collaboration)

P.Pakhlov (ITEP, Moscow) 2

Double cc productionDouble cc production

(e+e-→ J/c) 10 theory calculated for single virtual photon diagram Double virtual photon annihilation (Bodwin, Lee, Braaten):

(e+e-→J/J/ ) (e+e-→J/c) in this case!

Peaks at Mrecoil are glueballs? (Brodsky, Goldhaber, Lee + Dulat, Hagiwara, Lin) This analysis is described in hep/ex-0407009 (accepted for PRD-RC)

Belle observed e+ e-J/cc, where additional cc pair fragments into either charmonium or charmed mesons PRL 89, p.142001 (2002)

P.Pakhlov (ITEP, Moscow) 3

ee++ee-- →→ J/ J/(cc)(cc)res res with L=155 fbwith L=155 fb-1-1

Yields for J/, c1, c2, (2S) ~ 0 set UL

c, c0, c’ confirmed J/, c1, c2, (2S) not seen

N M [ GeV/c] c

J/c0

c1

+c2

c’

(2S)

235 26-14 2089 2410 27

164 30-26 29

2.9720.007fixed

3.407 0.011

fixed3.630 0.008

fixed

10.7--

3.8--

6.0--

Study recoil mass against J/:

Mrecoil ((Ecms –EJ/)2 –PJ/2)½

Include all known charmonium states:

c, J/, c0, c1, c2, c’, (2S)

P.Pakhlov (ITEP, Moscow) 4

Verify MVerify Mrecoilrecoil scale scale

Check Mrecoil using the dataUse radiative return

e+ e- (2S) for calibration.

very clean sample (>99% purity)Fit to M2

recoil ((2S)) with free peak positionNo shift in the data:

M2recoil((2S)) < 0.025 GeV2

Mrecoil(J/) < 3 MeV

M2recoil ((2S)) Gev2/c4

Recoil mass is subtle: momentum scale bias may result into large M2

recoil bias misinterpretation of recoil system nature…

P.Pakhlov (ITEP, Moscow) 5

ee++ee-- →→ J/ J/ cc full full reconstructionreconstruction

cKsK, KKKK

Require: EJ/+E c ~ Ecms

3 events are found in the data (>4)2.6 events are expected from MC based on Mrecoil fit yield

MC No ISR ISR >10MeV

Data

P.Pakhlov (ITEP, Moscow) 6

Angular analysisAngular analysis

Fit Mrecoil(J/) in bins of J/ production and helicity angles

P.Pakhlov (ITEP, Moscow) 7

Angular analysisAngular analysis

Correct on efficiencyFit with ~(1+cos2)

production and helicity angles separatelysimulteneously: prod=hel

prod hel prod=he

l

L=0/1

NRQCD

glueball

c

c0

c’

+1.4+1.1-0.8

-1.70.5+1.9+2.0

-1.2

+0.5+07-0.5

-0.5+0.7-0.5

+0.3+1.0-0.7

+0.93+0.87-0.47

-1.01+0.38-0.33

+0.87+0.86-0.63

+1.0-1.0+1.0

+1.0+0.25+1.0

-1.0-1.0-1.0

P.Pakhlov (ITEP, Moscow) 8

ee++ee-- →→ (2(2SS)(cc))(cc)resres

Similar analysis for reconstructed (2S)J/

Fit to Mrecoil ((2S)) spectrum:N

c

J/c0

c1 +c2

c’

(2S)

36.7 10.46.9 8.9

35.4 10.76.6 8.0

36.0 11.4-8.3 8.5

4.2--

3.5--

3.4--

Similar tendency: c, c0, c’ seen… J/, c1, c2, (2S) not seen

5.3 observation of sum of c, c0, c’

P.Pakhlov (ITEP, Moscow) 9

X-sectionsX-sections

c J/ c0 c1+

c2

c(2S) (2S)

J/(2S)

25.62.83.4 16.34.63.9

<9.1 <16.9

6.41.71.0 12.53.83.

1

<5.3<8.6

16.51.70.4 16.34.63.9

<9.1 <16.9

For efficiency assume: prod=hel=+1 for prod=hel=-1 for

Calculate Born cross-sections:Find the fraction of events with EISR<Ecutoff =10 MeV from MCNo correction for the cut on charged multiplicity: the result is

EISR<Ecutoff =10 MeV

EISR>Ecutoff =10 MeV

* BR (recoil charmonium >2charged) fb

P.Pakhlov (ITEP, Moscow) 10

Recent updateRecent update

L=101 fb-

1

L=155 fb-

1

Whole Belle data set collected by July 2004 L=287 fb-1

2003

2002

P.Pakhlov (ITEP, Moscow) 11

Evidence for new charmoniumEvidence for new charmonium

The reconstruction and selection procedure is not changed since the first Belle paper

Extend the studied region

No signal of X(3872)Significant peak at M=3.9400.011 GeV/c2

N=14833 (4.5)The width is surprisingly narrow <~ resolution (= 32 MeV)

X(3872)

P.Pakhlov (ITEP, Moscow) 12

Search for X(3940) Search for X(3940) DD(*) DD(*)Idea: Reconstruct J/ and one D; Look for the second D(*) in the event at recoil mass against reconstructed (J/ D)Use only the cleanest D0K-+ and D+K-++

e+e-J/D(*)D(*)+nothing clearly seenLook at Mrecoil (J/) when

Mrecoil (J/ D) ~ M(D*) N=9.93.3 (4.5)

Mrecoil (J/ D) ~ M(D)N=4.12.2 (2.1)

P.Pakhlov (ITEP, Moscow) 13

SummarySummary

e+e- J/ (cc)res is studied in details:

(cc)res = c, c0, c’ are confirmed; angular analysis is done

(cc)res = J/, c1, c2, (2S) not seen

e+e- (2S) (cc)res is observed for the first time

Strong evidence for a new charmonium state at M~3.94 GeV:

produced in the process e+e- J/ X(3940)

small width

hint on the decay X(3940) into DD*