e e  DD @ 4.009GeV
 
南京师范大学
钟彬
苏州 2017.04.08
1
Outline
Introduction
 Neutral channel and Charged channel
Summary
2
Introduction
3
X(3872)
Decay mode
B K X ppJ/y
B0 K0 X ppJ/y
D*0D0
ppp0J/y
wJ/y
J/y
y’
4
Z family
5
Ground state of charmed mesons?
D meson J  0
P
e e  DD
 




DD J  0 ,1 ,2
'
'
c0 c2
P
Even something more interesting!
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Branching fraction of D
 K-p+ (3.93 ± 0.04)%
 K-p+p+p- (8.06 ± 0.23 )%
Neutral D meson
 K-p+p+ (9.46 ± 0.24)%
 K-p+p+p0 (6.14 ± 0.16)%
Charged D meson
 Ksp+p+p- (3.05 ± 0.09)%
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Final states
 KKpp
D0K-p+ D0Kp
 KK4p
DKpp
D0 K-p+
pp
D0Kppp
 KK6p
D0Kppp
 DKpp
DKppp0
 DKpp
DKsppp
DKpp
D0Kp
D0 K+p-
D0Kppp
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Event Selection
• Charged track
Vr< 1cm, |Vz|<10cm
|cosq|<0.93
• Event Level
require two K mesons
PID: ProbK > 0.001 && ProbK > Probp
Ncharge = 4, 6, 8
2<40
• Neutral track
|McandidateMD| < 0.015MeV
TDC [0,14] (50ns)
Ang>20o
E>25MeV(Barrel); E>50MeV(End-cap)
N  1
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MC sample
y(4040)X(3772) X(3772)D0D0K-p+K+p-
e  24.74%
X(3927)D0D0K-p+K+p-
e  17.29%
y(4040)X(3927)
y(4040)X(3772) X(3772)D+D-K-p+p+K+p-p-
e  12.53%
y(4040)X(3772) X(3772)D0D0K-p+K+p-p+p-
e  11.85%
y(4040)X(3772) X(3772)D0D0K-p+p+p-K+p-
e  11.84%
y(4040)X(3927) X(3927)D+D-K-p+p+K+p-p-
e  8.14%
y(4040)X(3927) X(3927)D0D0K-p+K+p-p+p-
e  7.90%
y(4040)X(3927) X(3927)D0D0K-p+p+p-K+p-
e  8.20%
y(4040)X(3772) X(3772)D0D0K-p+p+p-K+p-p+p-
e  5.11%
y(4040)X(3927) X(3927)D0D0K-p+p+p-K+p-p+p-
e  3.34%
KKpp
KK4p
KK6p
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Some distribution in inclusive MC sample
XYZ sample
Final state KpKp
11
Some distribution in inclusive MC sample
XYZ sample
Final state KppKpp
12
Some distribution in inclusive MC sample
XYZ sample
Final state KpKppp
13
Some distribution in inclusive MC sample
XYZ sample
Final state KpppKp
14
Some distribution in inclusive MC sample
XYZ sample
Final state KK4p
Clear peaks of X(3772) and X(3930) is observed.
It validates the method is available, if the backgrounds are estimated
well, it is expected to observe some structures in real data.
15
Some distribution in inclusive MC sample
XYZ sample
Final state KpppKppp
16
Some distribution in data sample
 DKpp
DKppp0
 DKpp
DKsppp
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Some distribution in data sample
Final state KpKp
18
Some distribution in data sample
Final state KppKpp
19
Some distribution in data sample
Final state KpKppp
20
Some distribution in data sample
Final state KpppKp
21
Some distribution in data sample
Final state KK4p
It is seems that there is something around 3.772GeV.
If it is a real signal which decays to KK4p, it can not be observed
in inclusive MC sample except XYZ sample.
22
Some distribution data sample
Final state KpppKppp
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Some distribution data sample
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Some distribution data sample
Signal: 13
backgrounds: 19
from open charm and ISR processes
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Summary
Increase the efficiency in the channels with many tracks.
It does not seem easily to find some structure with
ground state of charmed mesons at this energy point.
Through the very preliminary results, the most important
issue is to estimate the backgrounds from ISR process.
At least, the upper limit can be gotten.
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