Post on 26-Jan-2021
Double-Tag Analysis ofe+e−→ π+(DD∗)−
Andreas PitkaBESIII Physics & Software Workshop September 16
1 / 44PhysSoft Sept16
N
Overview
1 Basic Event Reconstruction
2 Overview of analysed Data Samples
3 Background
4 Fit Results√s = 4.23 GeV
5 Fit Results√s = 4.26 GeV
6 Fit Results√s = 4.36 GeV
7 Fit Results√s = 4.42 GeV
8 Fit Results√s = 4.6 GeV
2 / 44PhysSoft Sept16
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Motivation
)2) (GeV/cJ/±π(maxM3.7 3.8 3.9 4.0
2Ev
ents
/ 0.
01 G
eV/c
0
20
40
60
80
100
)2) (GeV/cψ±(max
2Ev
ents
/ 0.
01 G
eV/c
)2±(max
2Ev
ents
/ 0.
01 G
eV/c
Data
Total fitBackground fit
PHSP MC
Sideband
)2) (GeV/c−*D0M(D3.9 3.95 4 4.05 4.1
)2Ev
ents/
(4.0
MeV
/c
0
20
40
60
)2) (GeV/c*0D−M(D3.9 3.95 4 4.05 4.1
)2Ev
ents/
(4.0
MeV
/c
0
20
40
60
)2) (GeV/c−*D0M(D3.9 3.95 4 4.05 4.1
)2Ev
ents/
(4.0
MeV
/c
0
10
20
30
)2) (GeV/c*0D−M(D3.9 3.95 4 4.05 4.1
)2Ev
ents/
(4.0
MeV
/c
0
10
20
30
40
Nature of Zc(3885)± still unknown.DD∗ molecule.Hadro charmonium.Tetraquark.DD∗ threshold effect.. . .
JP = 1+ is favored but needs confirmation.Perform full PWA at XYZ datasets to better understand nature of Zc and confirm quantumnumbers.
3 / 44PhysSoft Sept16
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Basic Event Reconstruction
Basic Event Reconstruction
Event Topology
Simulation and Analysis withBOSS 6.6.5.p01
Use (D0, D̄0)− and (D0, D−)− Tags
red:Measurement via missing fourmomentum.
D0 Decay ChannelsD0 → K−π+ (Br = 3.88 %)
D0 → K−π+π0 (Br = 13.9 %)
D0 → K−2π+π− (Br = 8.08 %)
D0 → K−2π+π−π0 (Br = 4.2 %)∑Br i = 30.06 %
D+ Decay ChannelsD+ → K−2π+ (Br = 9.13 %)
D+ → K−2π+π0 (Br = 5.99 %)
D+ → KSπ+ (Br = 1.47 %)
D+ → KSπ+π0 (Br = 6.99 %)
D+ → KS2π+π− (Br = 3.12 %)
D+ → K−K+π+ (Br = 0.954 %)∑Br i = 27.65 %
4 / 44PhysSoft Sept16
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Basic Event Reconstruction
Basic Event Selection
Good TracksCut on interaction region: Rxy < 1 cm, Rz < 10 cm.
Cut on direction: | cosϑ| < 0.93.
π± from KS DecaysCut on interaction region: Rxy < 2 cm, Rz < 20 cm.
Cut on direction: | cosϑ| < 0.93.
Good Photons0 < t < 14 · 50 ns.Endcap: Eγ > 50 MeV.
Barrel: Eγ > 25 MeV.
min. angle to next charged track: 20◦.Kinematic fitSelection of topology by best χ2.
χ2 < 50.
Cut on π0 mass112 MeV < mγγc
2 < 145 MeV.
Cut on KS mass487.8 MeV < mπ+π−c
2 < 507.7 MeV.
Cut to suppress D∗+D∗− Backgroundpπ± > 150 MeV/c.
PID Pions (dE/dx, ToF1 and ToF2)L(π) > L(K).
PID Kaons (dE/dx, ToF1 and ToF2)L(K) > L(π).
5 / 44PhysSoft Sept16
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Overview of Analysed Data Samples
Overview of analysed Data Samples
Event yield and rough estimate of signal cross sections√s (MeV) 4230 4260 4360 4420 4600∫Ldt (pb−1) 1047.34± 0.03 825.67± 0.13 539.84± 0.10 1073.56± 0.14 566.93± 0.11
(1 + δr) · (1 + δv) 0.838 0.957 0.828 0.866 0.971
e+e− → π+D0D∗−
Nrec [data] 1114 447 1285 3545 1298ε (%) [sig. MC] 5.38± 0.04 5.62± 0.04 6.38± 0.04 6.50± 0.04 7.04± 0.04Nbg [inc. MC] 27± 5 30± 4 79± 6 188± 8 98± 12σBorn (pb) 265.7± 2.3 108.4± 1.4 488.1± 3.9 640.9± 4.4 357.3± 4.9
σold anaBorn (pb) 264± 5± 15 154± 5± 9 495± 10± 30 707± 9± 42 460± 13± 28
e+e− → π+D−D∗0
Nrec [data] 868 394 974 2985 1192ε (%) [sig. MC] 4.73± 0.04 5.04± 0.04 5.84± 0.04 6.05± 0.04 6.55± 0.04Nbg [inc. MC] 56± 6 35± 4 80± 6 200± 9 113± 12σBorn (pb) 181.5± 2.6 95.7± 1.5 313.9± 3.6 474.6± 4.1 321.8± 5.2
Estimate of Born cross section
σ =Nrec −NBg
Br · (1 + δr) · (1 + δv) ·∫Ldt · ε
Selected events for PWAMinimum:312 (
√s = 4.26 GeV, D∗+ → D0π+)
Maximum:2533 (
√s = 4.42 GeV, D∗+ → D0π+)
6 / 44PhysSoft Sept16
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Overview of analysed Data Samples
Event yield and rough estimate of signal cross sections
0
200
400
600
800
1000
4200 4250 4300 4350 4400 4450 4500 4550 4600 4650
σ(p
b)
√s (MeV)
e+e− → π+D0D∗− + ccBESIII Measurement e+e− → π+D0D∗− + cc
e+e− → π+D−D∗0 + cc
Good aggreement with old BESIII analysis.Cross section for channel with D∗0 shows similar shape as channel with D∗+.
7 / 44PhysSoft Sept16
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Overview of analysed Data Samples
Dalitz plots for different√s (all D∗ channels)
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4230 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4260 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4360 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4420 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4600 MeV
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
Available Phasespace grows with center of mass energy.8 / 44
PhysSoft Sept16N
Overview of analysed Data Samples
Dalitz plots for different√s (all D∗ channels)
4.6
4.8
5
5.2
5.4
5.6
3.9 4.2 4.5 4.8 5.1
√s = 4230 MeV
4.64.8
55.25.45.65.8
4 4.4 4.8 5.2
√s = 4260 MeV
4.5
4.8
5.1
5.4
5.7
6
6.3
4 4.5 5 5.5
√s = 4360 MeV
4.54.85.15.45.7
66.36.6
4 4.5 5 5.5 6
√s = 4420 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4600 MeV
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)9 / 44
PhysSoft Sept16N
Background from Open Charm Reactions
Background
Contributing Background Channels (inc. MC)√s (MeV) 4230 4260 4360 4420 4600
σ (nb) 6.5 4.4 10.6 10.6 7.8∫Ldt (pb−1) 43 + 1011 515 + 291 523 42 + 993 506
N (inc. MC) 1.1 · 107 1.1 · 107 1.7 · 107 3.4 · 107 3 · 106Scaling Factor 1.6 3.1 3.1 3.1 0.78
Signalπ+D0D∗− 1452 2148 8396 20638 2373π+D−D∗0 1258 1871 6984 18192 1988
Backgroundπ+D∗0D∗− 5 29 122 311 28π0D0D̄∗0 19 31 85 253 32π0D∗+D− 4 14 47 180 32π0D∗0D∗0 0 0 2 6 1π0D∗+D∗− 0 1 5 24 6D0D̄∗0 36 51 54 122 16D∗+D− 17 17 24 55 8D∗0D̄∗0 20 12 51 102 12D∗+D∗− 6 13 31 62 6D0D̄0 0 1 1 4 0D+D− 1 0 2 6 0D+s D
−s 0 0 2 0 0
D∗+s D−s 13 5 18 41 1
D∗+s D∗−s 0 2 1 2 0
S/B 22± 2 22± 2 34± 2 33± 1 31± 3S/√S +B 50.9± 0.5 62.1± 0.5 122.3± 0.5 194.2± 0.5 65.0± 0.5
B/S (%) 4.5± 0.4 4.4± 0.3 2.9± 0.2 3.0± 0.1 3.3± 0.3
Studied backround contamination with the available inc. MC samples.For most reactions the cross section is not known.Big systematic uncertainty by assumed σ in EvtGen model (EvtOpenCharm).
9 / 44PhysSoft Sept16
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Background
Contributing Background Channels (inc. MC)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
4.26 4.36 4.42 4.6
NB
g/N
S(1
0−
2)
√s (GeV)
π+D∗0D∗−
π0D0D̄∗0
π0D∗+D−
π0D∗0D∗0
π0D∗+D∗−
D0D̄∗0
D∗+D−
D∗0D̄∗0
D∗+D∗−
D0D̄0
D+D−
D+s D−s
D∗+s D−s
D∗+s D∗−s
No large variation of NBg/NS by√s.
The variation is dominated by the variation of the assumed σ in the EvtGen model.
10 / 44PhysSoft Sept16
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Background
Distribution of Background in Dalitz plot (inc. MC)
4.6
4.8
5
5.2
5.4
5.6
3.9 4.2 4.5 4.8 5.1
√s = 4230 MeV
4.64.8
55.25.45.65.8
4 4.4 4.8 5.2
√s = 4260 MeV
4.5
4.8
5.1
5.4
5.7
6
6.3
4 4.5 5 5.5
√s = 4360 MeV
4.54.85.15.45.7
66.36.6
4 4.5 5 5.5 6
√s = 4420 MeV
4.85.25.6
66.46.87.27.6
4 4.8 5.6 6.4
√s = 4600 MeV
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
Events not scaled to data.Distributions relatively flat.
11 / 44PhysSoft Sept16
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Background
Why Extraction of Background Distribution frommD Side-bands does not work
0
100
200
300
400
500
1.75 1.8 1.85 1.9 1.95 2 1.75 1.8 1.85 1.9 1.95 2
events
mD0 (GeV/c2)
Signal MCπ+D∗0D∗−
π0D0D̄∗0
π0D∗+D−
D0D̄∗0
D∗0D̄∗0
D∗+D∗−
D∗+D−
mD+ (GeV/c2)
Distributions for 106 events per channel.Background is peaking under signal region.Sidebands are not representative for open charm background distribution.Tried also sidebands in mD∗ , Emiss, pmiss, mmiss, ED − Ebeam and mbc.Plot for
√s = 4.42 GeV.
12 / 44PhysSoft Sept16
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√s = 4.23GeV
Fit Results√s = 4.23 GeV
Dalitz Distribution at√s = 4.23GeV
4.6
4.8
5
5.2
5.4
5.6
4.6
4.8
5
5.2
5.4
5.6
0 20 40 60 80
0
10
20
30
40
50
60
70
4 4.4 4.8 15 15.5 16 16.50
10
20
30
40
50
60
70
m2(πD∗)(G
eV2/c4
)
m2(πD∗)(G
eV2/c4
)
eventsdatainc. MC Bg
events
m2(πD) (GeV2/c4)
events
m2(DD∗) (GeV2/c4)
Channel: D∗+ → D0π+811 events
13 / 44PhysSoft Sept16
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Fit Results√s = 4.23 GeV
Resonances at√s = 4.23GeV
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4 4.5 5 4 4.5 5 4 4.5 5 4 4.5 5
m2(πD∗)(G
eV2/c4
)
Production: aLSDecay: bLS
a01
b00
a21
b00D∗0(2400)
a10
b11D(2550)
a01
b01
a01
b21
a21
b01
a21
b21D1(2420)
a01
b20
a21
b20
a22
b20
a23
b20
a43
b20
D2(2460)
→ πDa22
b21
D2(2460)
→ πD∗
m2(πD) (GeV2/c4)
a01
b01
a01
b21
a21
b01
a21
b21Zc
Partial waves for possible resonances.Added a small phasespace term to show suppression (resonance out of phasespace, angularmomentum barrier).
14 / 44PhysSoft Sept16
N
Fit Results√s = 4.23 GeV
Fit with Zc and phasespace term: Dalitz
4 4.2 4.4 4.6 4.8 5
4.6
4.8
5
5.2
5.4
5.6
4 4.2 4.4 4.6 4.8 5
Data
4 4.2 4.4 4.6 4.8 5
Fit
−3−2.5−2−1.5−1−0.500.511.52
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 2 4 6 8 10
Fit Result at√s = 4.23 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
Z−c 48.6± 5.5 3895.0± 1.7 70.0± 6.9constant phasespace 51.4± 5.5 − −
Sum: 100.0± 7.4
Fit does not describe the structure at the border (bottom right) of the Dalitz plot.
15 / 44PhysSoft Sept16
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Fit Results√s = 4.23 GeV
Fit with Zc and phasespace term: m2ij
10
20
30
40
50
60
70
80
01020304050607080
−3−2−1
0123
02468
101214
4.2 4.5 4.8 4.8 5.1 5.4 15 15.5 16 16.5
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Enhancement in m2(πD) can not fully described by a kinematic reflection of Zc.
16 / 44PhysSoft Sept16
N
Fit Results√s = 4.23 GeV
Fit with Zc and phasespace term: Helicity Angles
10
20
30
40
50
60
70
80
−3−2−1
0123
1
02468
101214
-1 -0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Symmetric distribution in cos(θπRπD) could indicate dynamics in the πD system.To get a non flat distribution in cos(θπRπD): JRes ≥ 1.For a decay Res→ πD and J = 1 → Parity P = −1.No D∗∗ with JP = 1− in the mass region of interest!
17 / 44PhysSoft Sept16
N
Fit Results√s = 4.23 GeV
Fit with D1(1−)+ and phasespace term: Dalitz
4 4.2 4.4 4.6 4.8 5
4.6
4.8
5
5.2
5.4
5.6
4 4.2 4.4 4.6 4.8 5
Data
4 4.2 4.4 4.6 4.8 5
Fit
−5−4−3−2−10
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 5 10 15 20 25
Fit Result at√s = 4.23 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
D1(1−)+ 27.8± 4.3 2223.4± 2.7 19.3± 5.4
constant phasespace 72.2± 5.4 − −
Sum: 100.0± 6.4
Fit with a (hypothetic) resonance D1(1−)→ π+D0.Let mass and width float: Startvalues m = 2430 MeV/c2, Γ = 25 MeV.
18 / 44PhysSoft Sept16
N
Fit Results√s = 4.23 GeV
Fit with D1(1−)+ and phasespace term: m2ij
10
20
30
40
50
60
70
80
01020304050607080
−3−2−1
0123
02468
101214
4.2 4.5 4.8 4.8 5.1 5.4 15 15.5 16 16.5
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Good description of m2(πD) and m2(πD∗).Better description of m2(DD∗) might be gained by including D1(2420).
19 / 44PhysSoft Sept16
N
Fit Results√s = 4.23 GeV
Fit with D1(1−)+ and phasespace term: Helicity Angles
10
20
30
40
50
60
−3−2−1
0123
1
02468
101214
-1 -0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Good description of angular distribution.
20 / 44PhysSoft Sept16
N
√s = 4.26GeV
Fit Results√s = 4.26 GeV
Dalitz Distribution at√s = 4.26GeV
4.64.85
5.25.45.65.8
4.64.855.25.45.65.8
0 10 20 30
0
5
10
15
20
25
30
35
3.9 4.2 4.5 4.8 5.1 15 15.5 16 16.5 17051015202530354045
m2(πD∗)(G
eV2/c4
)
m2(πD∗)(G
eV2/c4
)
eventsdatainc. MC Bg
events
m2(πD) (GeV2/c4)
events
m2(DD∗) (GeV2/c4)
Channel: D∗+ → D0π+312 events
21 / 44PhysSoft Sept16
N
Fit Results√s = 4.26 GeV
Resonances at√s = 4.26GeV
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4.85.25.6
4 4.5 5 4 4.5 5 4 4.5 5 4 4.5 5
m2(πD∗)(G
eV2/c4
)
Production: aLSDecay: bLS
a01
b00
a21
b00D∗0(2400)
a10
b11D(2550)
a01
b01
a01
b21
a21
b01
a21
b21D1(2420)
a01
b20
a21
b20
a22
b20
a23
b20
a43
b20
D2(2460)
→ πDa22
b21
D2(2460)
→ πD∗
m2(πD) (GeV2/c4)
a01
b01
a01
b21
a21
b01
a21
b21Zc
Partial waves for possible resonances.Added a small phasespace term to show suppression (resonance out of phasespace, angularmomentum barrier).
22 / 44PhysSoft Sept16
N
Fit Results√s = 4.26 GeV
Fit with Zc and phasespace term: Dalitz
4 4.2 4.4 4.6 4.8 5 5.2
4.6
4.8
5
5.2
5.4
5.6
5.8
4 4.2 4.4 4.6 4.8 5 5.2
Data
4 4.2 4.4 4.6 4.8 5 5.2
Fit
−4
−3
−2
−1
0
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 2 4 6 8 10 12 14
Fit Result at√s = 4.26 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
Z−c 45.6± 6.0 3888.9± 1.5 27.4± 10.4constant phasespace 54.4± 6.4 − −
Sum: 100.0± 7.9
Fit does not describe the structure at the border (bottom right) of the Dalitz plot.
23 / 44PhysSoft Sept16
N
Fit Results√s = 4.26 GeV
Fit with Zc and phasespace term: m2ij
10
20
30
40
0
10
20
30
40
−3−2−1
0123
02468
101214
4.2 4.5 4.8 5.1 4.8 5.1 5.4 5.7 15 15.5 16 16.5 17
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Fitted width ΓZc = (27± 11) MeV.Much broader at
√s = 4.23 GeV: ΓZc = (70± 7) MeV.
Double-tag BESIII publication ΓZc = (31.5± 3.3) MeV.24 / 44
PhysSoft Sept16N
Fit Results√s = 4.26 GeV
Fit with Zc and phasespace term: Helicity Angles
5
10
15
20
25
−3−2−1
0123
1
02468
101214
-0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Note: With only Zc the cos(θDRDD∗ ) distribution would be symmetric.
Compared to√s = 4.23 GeV: Less pronounced (cos2 +1) distribution in cos(θπRπD).
25 / 44PhysSoft Sept16
N
Fit Results√s = 4.26 GeV
Fit with D1(1−)+ and phasespace term: Dalitz
3.9 4.2 4.5 4.8 5.1
4.6
4.8
5
5.2
5.4
5.6
5.8
3.9 4.2 4.5 4.8 5.1
Data
3.9 4.2 4.5 4.8 5.1
Fit
−6−5−4−3−2−10
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 2 4 6 8 10
Fit Result at√s = 4.26 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
D1(1−)+ 37.0 2241.3± 1.4 23.7± 6.2
constant phasespace 63.0 − −
Sum: 100
At√s = 4.26 GeV has moved into the available phasespace.
Does not describe data.26 / 44
PhysSoft Sept16N
Fit Results√s = 4.26 GeV
Fit with D1(1−)+ and phasespace term: m2ij
10
20
30
40
0
10
20
30
40
−3−2−1
0123
02468
101214
4.2 4.5 4.8 5.1 4.8 5.1 5.4 5.7 15 15.5 16 16.5 17
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Very bad description in region of Zc.
27 / 44PhysSoft Sept16
N
Fit Results√s = 4.26 GeV
Fit with D1(1−)+ and phasespace term: Helicity Angles
5
10
15
20
25
−3−2−1
0123
1
02468
101214
-0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Again: Good description of angular distribution.
28 / 44PhysSoft Sept16
N
√s = 4.36GeV
Fit Results√s = 4.36 GeV
Dalitz Distribution at√s = 4.36GeV
4.5
5
5.5
6
4.5
5
5.5
6
0 20 40 60 80 100
0
10
20
30
40
50
60
4 4.4 4.8 5.2 5.6 15.3 16.2 17.1 180
10
20
30
40
50
60
m2(πD∗)(G
eV2/c4
)
m2(πD∗)(G
eV2/c4
)
eventsdatainc. MC Bg
events
m2(πD) (GeV2/c4)
events
m2(DD∗) (GeV2/c4)
Channel: D∗+ → D0π+946 events
29 / 44PhysSoft Sept16
N
Fit Results√s = 4.36 GeV
Resonances at√s = 4.36GeV
4.85.4
6
4.85.46
4.85.46
4.85.46
4.85.46
4.85.46
4.5 5.4 4.5 5.4 4.5 5.4 4.5 5.4
m2(πD∗)(G
eV2/c4
)
Production: aLSDecay: bLS
a01
b00
a21
b00D∗0(2400)
a10
b11D(2550)
a01
b01
a01
b21
a21
b01
a21
b21D1(2420)
a01
b20
a21
b20
a22
b20
a23
b20
a43
b20
D2(2460)
→ πDa22
b21
D2(2460)
→ πD∗
m2(πD) (GeV2/c4)
a01
b01
a01
b21
a21
b01
a21
b21Zc
Partial waves for possible resonances.Added a small phasespace term to show suppression (resonance out of phasespace, angularmomentum barrier).
30 / 44PhysSoft Sept16
N
Fit Results√s = 4.36 GeV
Fit with Zc, D1(2420)0 and phasespace term: Dalitz
4 4.5 5 5.5
4.5
5
5.5
6
4 4.5 5 5.5
Data
4 4.5 5 5.5
Fit
−4
−3
−2
−1
0
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 4 8 12 16 20 24
Fit Result at√s = 4.36 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
D1(2420)0 31.8± 4.6 2423.0± 2.7 41.3± 6.4
Z−c 29.2± 3.6 3894.9± 2.6 70.0± 14.1constant phasespace 34.5± 3.4 − −
Sum: 95.5± 6.5
Already an acceptable fit with Zc, D1(2420)0 and phasespace term.31 / 44
PhysSoft Sept16N
Fit Results√s = 4.36 GeV
Fit with Zc, D1(2420)0 and phasespace term: m2ij
102030405060708090
100
0102030405060708090100
−3−2−1
0123
02468
101214
4.2 4.5 4.8 5.1 5.4 4.8 5.2 5.6 6 15.2 16 16.8 17.6
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Main features of the distribution are well described.Systematic underestimation of data for small m2(πD).
32 / 44PhysSoft Sept16
N
Fit Results√s = 4.36 GeV
Fit with Zc, D1(2420)0 and phasespace term:Helicity Angles
10
20
30
40
50
60
−3−2−1
0123
1
02468
101214
-0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Main features of the distribution are described.Including D̄∗2(2460)
0 → D∗−π+ might yield a better description.33 / 44
PhysSoft Sept16N
√s = 4.42GeV
Fit Results√s = 4.42 GeV
Dalitz Distribution at√s = 4.42GeV
4.5
5
5.5
6
6.5
4.5
5
5.5
6
6.5
0 100 200 300
0
20
40
60
80
100
4 4.4 4.8 5.2 5.6 15 16 17 180
20
40
60
80
100
120
m2(πD∗)(G
eV2/c4
)
m2(πD∗)(G
eV2/c4
)
eventsdatainc. MC Bg
events
m2(πD) (GeV2/c4)
events
m2(DD∗) (GeV2/c4)
Channel: D∗+ → D0π+2533 events
34 / 44PhysSoft Sept16
N
Fit Results√s = 4.42 GeV
Resonances at√s = 4.42GeV
4.85.66.4
4.85.66.4
4.85.66.4
4.85.66.4
4.85.66.4
4.85.66.4
4 5 6 4 5 6 4 5 6 4 5 6
m2(πD∗)(G
eV2/c4
)
Production: aLSDecay: bLS
a01
b00
a21
b00D∗0(2400)
a10
b11D(2550)
a01
b01
a01
b21
a21
b01
a21
b21D1(2420)
a01
b20
a21
b20
a22
b20
a23
b20
a43
b20
D2(2460)
→ πDa22
b21
D2(2460)
→ πD∗
m2(πD) (GeV2/c4)
a01
b01
a01
b21
a21
b01
a21
b21Zc
Partial waves for possible resonances.Added a small phasespace term to show suppression (resonance out of phasespace, angularmomentum barrier).
35 / 44PhysSoft Sept16
N
Fit Results√s = 4.42 GeV
Fit with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ andphasespace term: Dalitz
4 4.5 5 5.5 6
4.5
5
5.5
6
6.5
4 4.5 5 5.5 6
Data
4 4.5 5 5.5 6
Fit
−6−5−4−3−2−10
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 5 10 15 20 25 30 35
Fit Result at√s = 4.6 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
D1(2420)0 42.9± 3.0 2447.8± 2.2 63.4± 1.2
D̄∗2(2460)0 → D∗−π+ 18.1± 2.4 2537.8± 6.0 54.5± 8.6
D∗2(2460)+ → D0π+ 5.0± 1.1 2401.7± 4.3 15.5± 3.5
constant phasespace 32.1± 2.0 − −
Sum: 98.1± 4.3
Structure in lower half of Dalitz plot is most probable caused by background.Significant discrepancy to known D∗∗ masses.
36 / 44PhysSoft Sept16
N
Fit Results√s = 4.42 GeV
Fit with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ andphasespace term: m2ij
20406080
100120140160180200220
020406080100120140160180200220
−3−2−1
0123
02468
101214
4 4.4 4.8 5.2 5.6 4.8 5.2 5.6 6 6.4 15.2 16 16.8 17.6 18.4
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Main features of the distribution are described by the fit.Significant discrepancy to known D∗∗ masses.Most probable caused by incomplete ampltiude model (possible contribution fromD∗0(2400)
+, D(2550)0).37 / 44
PhysSoft Sept16N
Fit Results√s = 4.42 GeV
Fit with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ andphasespace term: Helicity Angles
20
40
60
80
100
120
−3−2−1
0123
1
02468
101214
-1 -0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Main features of the distribution are described by the fit.Systematic discrepancies might indicate the used model is too simple.
38 / 44PhysSoft Sept16N
√s = 4.6GeV
Fit Results√s = 4.6 GeV
Dalitz Distribution at√s = 4.6GeV
4.5
5
5.5
6
6.5
7
7.5
4.5
5
5.5
6
6.5
7
7.5
0 10 20 30 40 50
010203040506070
4.2 4.8 5.4 6 6.6 15 16 17 18 19 200510152025303540
m2(πD∗)(G
eV2/c4
)
m2(πD∗)(G
eV2/c4
)
eventsdatainc. MC Bg
events
m2(πD) (GeV2/c4)
events
m2(DD∗) (GeV2/c4)
Channel: D∗+ → D0π+935 events
39 / 44PhysSoft Sept16
N
Fit Results√s = 4.6 GeV
Resonances at√s = 4.6GeV
5678
5678
5678
5678
5678
5678
4 5 6 7 4 5 6 7 4 5 6 7 4 5 6 7
m2(πD∗)(G
eV2/c4
)
Production: aLSDecay: bLS
a01
b00
a21
b00D∗0(2400)
a10
b11D(2550)
a01
b01
a01
b21
a21
b01
a21
b21D1(2420)
a01
b20
a21
b20
a22
b20
a23
b20
a43
b20
D2(2460)
→ πDa22
b21
D2(2460)
→ πD∗
m2(πD) (GeV2/c4)
a01
b01
a01
b21
a21
b01
a21
b21Zc
Partial waves for possible resonances.Added a small phasespace term to show suppression (resonance out of phasespace, angularmomentum barrier).
40 / 44PhysSoft Sept16
N
Fit Results√s = 4.6 GeV
Fit with D∗1(2420)0, D∗2(2460)
0, D∗2(2460)+ and phases-
pace term: Dalitz
4 4.5 5 5.5 6 6.5
4.5
5
5.5
6
6.5
7
7.5
4 4.5 5 5.5 6 6.5
Data
4 4.5 5 5.5 6 6.5
Fit
−5−4−3−2−10
1
2
3
(N−N
fit)/√N
Residuals
m2(πD∗)(G
eV2/c4
)
m2(πD) (GeV2/c4)
0 2 4 6 8 10 12 14 16 18
Fit Result at√s = 4.6 GeV
Resonance fit fraction (%) massMeV/c2 widthMeV
D1(2420)0 8.7± 1.8 2425.9± 2.3 20.1± 5.6
D̄∗2(2460)0 → D∗−π+ 6.9± 1.7 2473.6± 3.9 24.4± 7.7
D∗2(2460)+ → D0π+ 37.1± 3.0 2470.9± 1.7 39.3± 4.4
constant phasespace 46.4± 3.7 − −
Sum: 99.1± 5.0
Acceptable description of data with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ and phasespaceterm.
41 / 44PhysSoft Sept16
N
Fit Results√s = 4.6 GeV
Fit with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ and phases-pace term: m2ij
102030405060708090
100110120
0
10
20
30
40
50
60
70
−3−2−1
0123
02468
101214
4 4.5 5 5.5 6 6.5 5 5.5 6 6.5 7 15 16 17 18 19
events
DataFit
events
N−N
fit
√N
ε(%
)
m2πD (GeV2/c4) m2πD∗ (GeV
2/c4) m2DD∗ (GeV2/c4)
Biggest deviation between data and fit in m2(DD∗).Masses of D∗∗ are estimated in the fit with to high values (O(10 MeV)).
42 / 44PhysSoft Sept16
N
Fit Results√s = 4.6 GeV
Fit with D1(2420)0, D∗2(2460)0, D∗2(2460)
+ and phases-pace term: Helicity Angles
10
20
30
40
50
60
−3−2−1
0123
1
02468
101214
-1 -0.5 0 0.5 -0.5 0 0.5 1-0.5 0 0.5
events
DataFit
N−N
fit
√N
ε(%
)
cos(θπR(πD)) cos(θπR(πD∗)) cos(θ
DR(DD∗))
Improvent of logL for fit with Zc not very significant: 2.1σ (by likelihood ratio test).
43 / 44PhysSoft Sept16
N
Fit Results√s = 4.6 GeV
Summary
What has been doneFirst PWA fits performed at
√s = 4.23, 4.26, 4.36, 4.42, 4.6 GeV.
ResultsMain features of the data can be described with D1(2420)0, D∗2(2460)
0 andD∗2(2460)
+.
Strong Zc signal at√s = 4.36 GeV.
Simple Breit-Wigner-Amplitude hypothesis of Zc with JP = 1+ fails to describe dataat√s = 4.23, 4.26 GeV.
What’s in progressOptimize cuts for each
√s.
Not only use D∗+ → D0π+ but also D∗+ → D+π0, D∗0 → D0π0 and D∗0 → D0γ.Compare different quantum numbers for Zc.
Allow in the fit a coupling of Zc to J/ψπ (Flatte, K-Matrix).
Check by MC if shift of D∗∗ resonances in mass is systematic.
Find a way to extract background shape from data.44 / 44
PhysSoft Sept16N
Basic Event ReconstructionOverview of analysed Data SamplesBackgroundFit Results s=4.23GeVFit Results s=4.26GeVFit Results s=4.36GeVFit Results s=4.42GeVFit Results s=4.6GeV