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e + e - J/ (cc) res Full e + e - J/ c reconstruction Angular analysis e + e - (2S) (cc) res Recent search: strong evidence for a new charmonium state X(3940) in e + e - J/ X(3940). P.Pakhlov (ITEP, Moscow) (for Belle collaboration). Double cc production. - PowerPoint PPT Presentation
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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*