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Houbing Jiang , Qiyun Li , Ke Li , Zhiqing Liu , β¦...Fix 4040and 4160 mass and width (PDG values);...
Transcript of Houbing Jiang , Qiyun Li , Ke Li , Zhiqing Liu , β¦...Fix 4040and 4160 mass and width (PDG values);...
Search for π+πβ β πΈπππ,ππ,ππ using data above π+πβ CM energy ~4 GeV
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Houbing Jiang , Qiyun Li , Ke Li , Zhiqing Liu , ChangZheng Yuan1 , Xingtao Huang
Shandong universityIHEP1
2019.3.13
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βMotivation
β’ We hope use π+πβ β πΎπππ to give more information about Y states ;
β’ E1 radiative transitions from the higher-mass charmonium states are especially interesting. For example : we can proof if Ο(4160) is 2D state
β’ Some work before this study;(CPC 39,041001) (PhysRevD.92.012011);
Phys. Rev. D 72, 054026
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Section I π+πβ β πΈπππ,ππ
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βDATA Set
β’ Boss version boss703
β’ DATA
21 energy points XYZ data
β’ Signal MC
π+πβ β π(4260) β πΎππ1,2 P2GC1/P2GC2
ππ1 β πΎJ/π AV2GV
ππ2 β πΎJ/π T2GV
C.M π(MeV) LοΌpb-1οΌ
4009 4007.6 482.0
4180 4173.0 3189.0
4190 4189.3 521.9
4200 4199.6 523.7
4210 4209.7 511.2
4220 4218.8 508.2
4230 4226.3 1047.3
4237 4235.8 508.9
4246 4243.9 532.7
4260 4258.0 825.7
4270 4266.9 529.3
4360 4358.3 539.8
4420 4415.6 1028.9
4600 4599.5 566.9
C.M π(MeV) LοΌpb-1οΌ
4090 4085.5 52.8
4280 4277.8 174.5
4310 4307.9 45.1
4390 4387.4 55.6
4470 4467.1 111.1
4530 4427.1 112.1
4575 4574.5 48.9
Named DataSet I : DataSet II:
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β Event Selection
β’ Initial selection:
β’ Charged track:N=2
β’ photon :good photons>=2;
β’ e , ΞΌ selection :
β’ The two photon candidates with the largest energies are retained;
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β’ Further selection:
β’ Clearly ππ½/π evnets, let M(πΎπΎ) < 0.52 || M(πΎπΎ) > 0.58 GeV;
β’ After above selection,the inclusiveMC study show the dominant backgrounds come from Bhabha events.
β Event Selection for π+πβ channel
M(πΈπΈ)@4180 DATA M(πΈπ³π±/π) >3.3GeV Signal MC M(πΈπ³π±/π) >3.3GeV
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βSuppress Bhabha events in π+πβ channel
β’ Let Cosπ+πΎπ»>-0.9&& CosπβπΎπ» >-0.9&&Cosπ+πΎπΏ <0.9&& CosπβπΎπΏ <0.9 ;β’ |Cos πΎπ» |<0.8 to remove Bhabha events;
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β’ Further selection:
β’ Clearly ππ½/π evnets, let M(πΎπΎ) < 0.52 || M(πΎπΎ) > 0.58 GeV;β’ Clearly π0 background, let | M(πΎπΎ) βM(π0 )|>0.015GeV;
β’ After above selection, the inclusiveMC study show the dominant backgrounds come fromπ+πβ β (ππΈ)π+πβ;
β Event Selection for π+πβ channel
Signal MCM(πΈπΈ)@4180 DATA M(πΈπ³π±/π) >3.3GeV
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β’ Let |Cos πΎπ» |<0.8 to suppress dimu events;
βSuppress dimu events in π+πβ channel
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βChisq4c cut
Chisq4c<40
β’ In πππ, πππ region:
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βM(πΈπ³π±/π) distribution@4180
β’ Clearly, there are ππ1,2 events.
β’ After above cut:
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ππ1 MC
Scatter Plot of MC
βPhotons distribution @4009
β’ Obviously, some ππ2 decay to πΎHJ/π at 4009 energy point. To ππ1 MC, also there is an overlap between the two photons distributions .so we decide to use two photons to search signal.
ππ2 MC
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βPhotons distribution @4180
ππ1 MC
Scatter Plot of MC
β’ Obviously, the distribution of two photons is essentially without overlap,andalmost all ππ1,2 decay to low energy photon . So we use low energy photon to search signal
ππ2 MC
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βSignal extraction(DataSet I)
β’ For dataset I, We use fit method;
Fit Method
β’ As analyzed above , we use both of the two photons to search signal at 4009 (2D- Fit), and use the low energy photon to search signal at others energy points.
β’ Fit π+πβ and π+πβ two channel Simultaneously.
β’ Fit Shape:β’ @4009Signal use signal MC M(πΎπΏπ½/π) and M(πΎπ»π½/π) 2-D shape ;Background use dimu or bhabha MC M(πΎπΏπ½/π) and M(πΎπ»π½/π) 2-D shape;
β’ others Signal use signal MC M(πΎπΏπ½/π) fit to dataBackground 2-order Chebychev
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βFit result @4009 (2-D simultaneously fit)
M(πΎπ»π½/π)
M(πΎπΏπ½/π)
π+πβ π+πβ combine
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βFit result @4180 (simultaneously fit)
π+πβ π+πβ combine
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β’ Using six xyz data to fill in large gaps between somehigh-statistic energy points , For dataset II,we use count method:
β’ Define signal region: ππ1(3.49,3.53) ππ2(3.54,3.58) ,note the number of events as n;
β’ Define sideband region (3.42,3.46) (3.6,3.64),note the number of events as b;
β’ Statistical error:Suppose n and b follow Poisson distribution;
βSignal extraction(DataSet II)
C.M N_c1 N_c2 b
4090 2 0 7
4280 10 5 20
4310 2 4 3
4390 3 3 4
4470 8 0 6
4530 2 2 3
4575 1 0 1
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βCross Section and lineshape of π+πβ β πΈπππ,ππ
β’ Firstly, we use π 4160 lineshape to get radiation correction factor;
β’ Using follow fumula measure cross section:
β’ Fit to π+πβ β πΈπππ,ππ cross section:
β’ Fit Method(likelihood Method): Define likelihood fuction:
@4180 We suppose the number of events follow Gaussion distribution; @ others We suppose the number of events follow possion distribution;
β =ΰ·
i=1
πΊ(π, πππ₯π)ΰ·
π
π(πfit , πππ₯π)
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βThe line shape of π+πβ β πΈπππ,ππ(Model I)
β’ Fit fuction(two coherent Breit-Wigner functions), because of the very similar line-shape ,we give a simultaneouslyοΌdecay from same resonenceοΌ fit:
πππππ π = BW1+ π΅π2πππ2
β’ Three times iteration of the radiative correction procedure to get converge values(For the first time , we use π(4160) line-shape to get radiative correction factor)
β’ π+πβ β πΈπππ (1+πΏ) β πππ only π+πβ
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π+πβ β πΈπππ
π+πβ β πΈπππ
βThe line shape of π+πβ β πΈπππ,ππ(Model I-2-BW)
β’ Parametersβ’ Fit result
Parameters I
M(R1) 3866.4Β± 326.6
Ξπ‘ππ‘(π 1) 523.1 Β± 87.9
Ξππβ¬(π 1β πΈπππ)
2.8 Β± 0.7
Ξππβ¬(π 1β πΈπππ)
4.2 Β± 0.7
M(R2) 4225.6 Β± 2.7
Ξπ‘ππ‘(π 2) 28.5 Β± 5.4
Ξππβ¬(π 2β πΈπππ)
0.094 Β± 0.006
Ξππβ¬(π 2β πΈπππ)
0.015 Β± 0.006
π1(πΈπππ) 79.2Β±0.3
π2(πΈπππ) 343.1Β±0.2
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βThe line shape of π+πβ β πΈπππ,ππ(Model I-2-BW)
β’ Cross section π+πβ β πΈπππ(Data Set I)
π L(pb-1) π_ππ π_ππ 1+πΉ ππ ππππ(ππ)ππ ππππ(ππ) Sig
4.0076 482.0 0.196 0.325 0.943 π. πβπ.π+π.π π. πβπ.π
+π.π 4.1π
4.1783 3194.5 0.184 0.308 0.972 π. πβπ.π+π.π π. πβπ.π
+π.π 7.6π
4.1888 522.5 0.188 0.319 0.941 π. πβπ.π+π.π π. πβπ.π
+π.π 3.9π
4.1989 524.6 0.196 0.329 0.898 π. πβπ.π+π.π π. πβπ.π
+π.π 3.1π
4.2092 518.1 0.201 0.338 0.839 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.2187 514.3 0.213 0.356 0.789 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
4226.3 1047.3 0.212 0.360 0.819 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
4.2357 530.6 0.204 0.347 0.970 βπ. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.2438 537.4 0.188 0.316 1.127 π. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.258 825.7 0.164 0.275 1.291 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.2668 529.3 0.152 0.258 1.336 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.3583 539.8 0.133 0.231 1.379 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
4.4156 1028.9 0.129 0.223 1.400 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
4.5995 566.9 0.114 0.204 1.520 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
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βThe line shape of π+πβ β πΈπππ,ππ(Model I-2-BW)
β’ Cross section π+πβ β πΈπππ(Data Set II)
π L(pb-1) π 1+πΉ ππ ππππ
4.0855 52.8 0.238 0.990 βπ. πβπ.π+π.π
4.2778 174.5 0.180 1.356 πβπ.π+π.π
4.3079 45.1 0.174 1.369 π. πβπ.π+π.π
4.3874 55.6 0.170 1.384 π. πβπ.π+π.π
4.4671 111.1 0.163 1.428 π. πβπ.π+π.π
4.4271 112.1 0.155 1.470 π. πβπ.π+π.π
4.5745 48.9 0.154 1.503 π. πβπ.π+π.π
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βThe line shape of π+πβ β πΈπππ,ππ(Model I-2-BW)
β’ Cross section π+πβ β πΈπππ(Data Set I)
π L(pb-1) π_ππ π_ππ 1+πΉ ππ ππππ(ππ)ππ ππππ(ππ) Sig
4.0076 482.0 0.182 0.297 0.959 ππ. πβπ.π+π.π π. πβπ.π
+π.π 3.2π
4.1783 3194.5 0.139 0.225 1.292 π. πβπ.π+π.π π. πβπ.π
+π.π 5.4π
4.1888 522.5 0.130 0.218 1.357 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.1989 524.6 0.128 0.216 1.337 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.2092 518.1 0.148 0.249 1.069 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.2187 514.3 0.182 0.313 0.811 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
4226.3 1047.3 0.202 0.338 0.749 βπ. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.2357 530.6 0.202 0.337 0.809 π. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.2438 537.4 0.195 0.331 0.877 π. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.258 825.7 0.186 0.316 0.964 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.2668 529.3 0.177 0.299 1.001 π. πβπ.π+π.π βπ.πβπ.π
+π.π -
4.3583 539.8 0.149 0.251 1.167 π. πβπ.π+π.π π. πβπ.π
+π.π -
4.4156 1028.9 0.138 0.236 1.231 π. πβπ.π+π.π π. πβπ.π
+π.π 3.1π
4.5995 566.9 0.117 0.208 1.380 βπ. πβπ.π+π.π π. πβπ.π
+π.π -
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βThe line shape of π+πβ β πΈπππ,ππ(Model I-2-BW)
β’ Cross section π+πβ β πΈπππ(Data Set II)
π L(pb-1) π 1+πΉ ππ ππππ
4.0855 52.8 0.205 1.037 βππ. πβπ.π+π.π
4.2778 174.5 0.213 1.038 βπ. πβπ.π+π.π
4.3079 45.1 0.196 1.099 π. πβπ.π+ππ.π
4.3874 55.6 0.178 1.189 π. πβπ.π+π.π
4.4671 111.1 0.166 1.273 βπ. πβπ.π+π.π
4.4271 112.1 0.157 1.321 π. πβπ.π+π.π
4.5745 48.9 0.152 1.361 βπ. πβπ.π+π.π
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β’ Fit fuction: Suppose the line shape determined by π 4040 and π 4160 in 4~4.18GeV,we use(simultaneously fit ):
πππππ π = π΅π π 4040 + π΅π π 4160 πππ1 + π΅π(π 1)πππ22;
β’ Fix π 4040 andπ 4160 mass and width (PDG values);
β’ Three times iteration of the radiative correction procedure to get converge values (For the first time , we use π(4160) line-shape to get radiative correction factor)
β’ π+πβ β πΈπππ (1+πΏ) β πππ only mumu
βThe line shape of π+πβ β πΈπππ,ππ(Model II-3BW)
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βThe line shape of π+πβ β πΈπππ,ππ
π+πβ β πΈπππ
π+πβ β πΈπππ
β’ Fitting result : β’ Parameters:
Parameters I
M(π 4040 ) 4039(πππ₯ππ)
Ξπ‘ππ‘(π 4040 ) 80(fixed)
Ξππβ¬(π 4040 β πΈπππ) 0.8Β±0.3
Ξππβ¬(π 4040 β πΈπππ) 1.6 Β±0.4
M(π 4160 ) 4191(fixed)
Ξπ‘ππ‘(π 4160 ) 70(fixed)
Ξππβ¬(π 4160 β πΈπππ) 1.0 Β± 0.3
Ξππβ¬(π 4160 β πΈπππ) 1.8 Β± 0.6
M(R2) 4244.8 Β± 6.3
Ξπ‘ππ‘(π 2) 83.2 Β± 14.8
Ξππβ¬(π 2 β πΈπππ) 0.8 Β± 0.2
Ξππβ¬(π 2 β πΈπππ) 1.5 Β± 0.8
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βThe line shape of π+πβ β πΈπππ,ππ(Model II-3-BW)
β’ Cross section π+πβ β πΈπππ(Data Set I)
π L(pb-1) π_ππ π_ππ 1+πΉ ππ ππππ(ππ) ππ ππππ(ππ)
4.0076 482.0 0.233 0.378 0.763 π. πβπ.π+π.π π. πβπ.π
+π.π
4.1783 3194.5 0.220 0.375 0.778 π. πβπ.π+π.π π. πβπ.π
+π.π
4.1888 522.5 0.222 0.374 0.783 π. πβπ.π+π.π π. πβπ.π
+π.π
4.1989 524.6 0.220 0.375 0.802 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2092 518.1 0.216 0.363 0.825 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2187 514.3 0.215 0.362 0.844 βπ. πβπ.π+π.π π. πβπ.π
+π.π
4226.3 1047.3 0.214 0.363 0.853 βπ. πβπ.π+π.π π. πβπ.π
+π.π
4.2357 530.6 0.213 0.363 0.863 βπ. πβπ.π+π.π βπ.πβπ.π
+π.π
4.2438 537.4 0.214 0.349 0.875 π. πβπ.π+π.π βπ.πβπ.π
+π.π
4.258 825.7 0.207 0.347 0.917 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2668 529.3 0.198 0.334 0.957 π. πβπ.π+π.π π. πβπ.π
+π.π
4.3583 539.8 0.122 0.210 1.577 βπ. πβπ.π+π.π π. πβπ.π
+π.π
4.4156 1028.9 0.095 0.164 1.985 βπ. πβπ.π+π.π π. πβπ.π
+π.π
4.5995 566.9 0.054 0.097 3.244 βπ. πβπ.π+π.π π. πβπ.π
+π.π
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βThe line shape of π+πβ β πΈπππ,ππ(Model II-3-BW)
β’ Cross section π+πβ β πΈπππ(Data Set II)
π L(pb-1) π 1+πΉ ππ ππππ
4.0855 52.8 0.264 0.901 βπ. πβπ.π+π.π
4.2778 174.5 0.237 1.049 πβπ.π+π.π
4.3079 45.1 0.205 1.289 π. πβπ.π+π.π
4.3874 55.6 0.135 2.004 π. πβπ.π+π.π
4.4671 111.1 0.099 2.712 π. πβπ.π+π.π
4.4271 112.1 0.089 3.240 π. πβπ.π:+π.π
4.5745 48.9 0.075 3.657 π. πβπ.π+π.π
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βThe line shape of π+πβ β πΈπππ,ππ(Model II-3-BW)
β’ Cross section π+πβ β πΈπππ(Data Set I)
π L(pb-1) π_ππ π_ππ 1+πΉ ππ ππππ(ππ) ππ ππππ(ππ)
4.0076 482.0 0.222 0.357 0.760 ππ. πβπ.π+π.π π. πβπ.π
+π.π
4.1783 3194.5 0.208 0.339 0.779 π. πβπ.π+π.π π. πβπ.π
+π.π
4.1888 522.5 0.206 0.350 0.780 π. πβπ.π+π.π π. πβ.π.π
+π.π
4.1989 524.6 0.209 0.349 0.797 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2092 518.1 0.204 0.338 0.818 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2187 514.3 0.201 0.337 0.838 βπ. πβπ.π+π.π π. πβπ.π
+π.π
4226.3 1047.3 0.205 0.343 0.851 βπ. πβπ.π+π.π βπ.πβπ.π
+π.π
4.2357 530.6 0.203 0.335 0.864 π. πβπ.π+π.π βπ.πβπ.π
+π.π
4.2438 537.4 0.197 0.332 0.880 π. πβπ.π+π.π βπ.πβπ.π
+π.π
4.258 825.7 0.189 0.323 0.932 π. πβπ.π+π.π π. πβπ.π
+π.π
4.2668 529.3 0.186 0.315 0.979 π. πβπ.π+π.π βπ.πβπ.π
+π.π
4.3583 539.8 0.104 0.179 1.739 π. πβπ.π+π.π π. πβπ.π
+π.π
4.4156 1028.9 0.075 0.135 2.263 π. πβπ.π+π.π π. πβπ.π
+π.π
4.5995 566.9 0.043 0.075 3.882 βπ. πβπ.π+π.π π. πβπ.π
+π.π
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βThe line shape of π+πβ β πΈπππ,ππ(Model II-3-BW)
β’ Cross section π+πβ β πΈπππ(Data Set II)
π L(pb-1) π 1+πΉ ππ ππππ
4.0855 52.8 0.205 1.037 βππ. πβπ.π+π.π
4.2778 174.5 0.213 1.038 βπ. πβπ.π+π.π
4.3079 45.1 0.196 1.099 π. πβπ.π+ππ.π
4.3874 55.6 0.178 1.189 π. πβπ.π+π.π
4.4671 111.1 0.166 1.273 βπ. πβπ.π+π.π
4.4271 112.1 0.157 1.321 π. πβπ.π+π.π
4.5745 48.9 0.152 1.361 βπ. πβπ.π+π.π
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βCompare these two fit methods
β’ β log πΏ οΌ
2-BW β log πΏ =165.5 3βBW β log πΏ =173.8
Canβt distinguish these two methods;
β’ For Resonance: Consistent with each other , Also consistent with π+ πβ β π + π βπ±/π channel;
ParametersοΌMeVοΌ π+πβ β πΈπππ,π
M(R2) 4225.6Β±2.6
Ξ(R2) 28.5Β±5.4
2-BW 3-BW
Parameters(MeV) π+πβ β πΈπππ,π
M(R1) 4247.2Β±6.2
Ξ(R1) 82.5Β±14.1
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β~2683.2
β~1533.6
β~2221.5
βConfirm the dip around 4.23GeV
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βSystematic uncertaintyοΌCross SectionοΌ
β’ The luminosity : measured using Bhabha events, with uncertainty 1.0%;
β’ Tracking efficiency : 1% is assigned to each track, 2% in total ;
β’ branching ratios : 0.6% for each channel π½/π β π+πβ , π½/π β π+πβ;
β’ branching ratios : 3.5% for ππ1 β πΎJ/π, 3.6% for ππ2 β πΎJ/π;
β’ Photon efficiency: each 1%, total 2%;
β’ Fit to M(πΎπΏπ½/π) :β’ Change background shape 2nd β> 3nd ;
β’ Fit Range-----> οΌ3.4,3.65οΌ->οΌ3.45,3.7οΌπππ ~π. π% πππ ~π. π%
β’ Kinematic fit: The difference efficiency between before and after pull correction;
πππ~π. π%, πππ~π. π%
Use 4180
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β’ Radiative correction: Take the difference ν β (1 + πΏ) between two fit models as systematic uncertainty;ππ1~2.7% ππ2~1% @4180
β’ Total systematic uncertainty : π+πβ β πΎππ1 ~ 7.5% ;π+πβ β πΎππ2 ~ 8.9%;
βSystematic uncertainty (Cross Section)
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βSystematic uncertaintyοΌResonance Y(4220)οΌ
β’ The CMS energies of all dataset: 1MeV for mass mesurement;
β’ The difference of Two models(width and mass );
Parameters(MeV) π+πβ β πΈπππ,π
M(Y(4220)) 4225.6 Β± 2.7 Β±20.2
Ξπ‘ππ‘(π(4220)) 28.5 Β± 5.4 Β±54.7
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βUpper Limit for (significance <3π)
β’ To evaluate the upper limits of cross section at 90% C.L. :Define likelihood fuction:
β’ π0 is the fixed number of signal events;
β’ πΊ π0, π0π is Gauss function, π is systematic uncertainty ;
β’ The upper limit on the cross section is calculated with following formula:
β(π0) = ΰΆ±πΊ π0, π0π β β(π) ππ
ππππππ’π
=ππ’π
β β β¬ β π β (1 + πΏ) β (1 + πΏππ)
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βUpper Limit @4230
β’ After consider to system uncertainty, we give the number of signal upper limit at 90% confidence level:
β’ Total systematic uncertainty : π+πβ β πΎππ1 ~ 8.5% ;π+πβ β πΎππ2 ~ 15.8%;
π+πβ β πΎππ1 π+πβ β πΎππ2
ππππππ’π
< 0.8pb ππππππ’π
< 1.4pb
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βUpper Limit (For <3π)
β’ After consider to system uncertainty, we give the number of signal upper limit at 90% confidence level:
π+πβ β πΎππ1 π+πβ β πΎππ2
C.M Sys error(%) Upper Limit(pb)
4210 8.6 2.8
4220 10.8 1.8
4230 8.5 0.8
4237 10.3 1.3
4246 18.2 0.9
4260 13.5 2.2
4270 10.7 2.4
4360 8.1 1.6
4420 8.1 2.0
4600 7.3 2.24
C.M Sys error(%) Upper Limit(pb)
4190 12.1 4.1
4200 9.7 5.7
4210 9.6 5.1
4220 13.5 6.3
4230 15.8 1.4
4237 11.9 1.4
4246 8.8 4.0
4260 8.9 3.1
4270 9.4 2.1
4360 10.8 4.7
4600 9.0 1.9
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Section II π+πβ β πΈπππ
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βDATA Set
β’ Boss version boss703
β’ DATA
XYZ data
C.M π(MeV) LοΌpb-1οΌ
4009 4007.6 482.0
4180 4173.0 3189.0
4190 4189.3 521.9
4200 4199.6 523.7
4210 4209.7 511.2
4220 4218.8 508.2
4230 4226.3 1047.3
4237 4235.8 508.9
4246 4243.9 532.7
4260 4258.0 825.7
4270 4266.9 529.3
4360 4358.3 539.8
4420 4415.6 1028.9
4600 4599.5 566.9
DataSet :
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βMC Samples for πππ β π²+π²β π +π β/ π +π β π +π β
β’ In PDG , πππ πππππππππ π ππππ ππ π²+π²β π +π β , through the following channel:π +π β π +π β
π+πβ π+πβ
πΎ+πΎβ π+πβ
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βMC Samples for πππ β π²+π²β π +π β/ π +π β π +π β
β’ Signal MC π+πβ β π(4260) β πΎππ0 P2GC0
β’ π+πβ π+πβ
1. ππ0 β π+πβ π+πβ ; PHSP
2. ππ0 β π0π+πβ ;
3. ππ0 β π0(980)π0(980);
β’ πΎ+πΎβ π+πβ
1.ππ0 β π²+π²βπ+πβ ; PHSP
2. ππ0 β πΎ0β(1430)0πΎ0
β(1430)0;
3. ππ0 β πΎ0β(1430)0πΎ2
β(1430)0+c.c. ;4. ππ0 β πΎ1(1270)
+ +c.c.;5. ππ0 β πΎ1(1400)
+ +c.c.;6. ππ0 β π0(980)π0(2200);7. ππ0 β π0(1370)π0(1710);8. ππ0 β ΰ΄₯πΎβ(892)0πβ πΎ++c.c.;9. ππ0 β ΰ΄₯πΎβ(892)0 πΎβ (892)0;
43
β’ Initial selection:β’ Charged tracks:
N=4β’ photon :
good photon>=1;β’ PID:
K: Prob(K)>Prob(π),Prob(K)>0.001π: Prob(π)>Prob(πΎ),Prob(π)>0.001
β’ Retain the photon with the large energyβ’ 4C Kinematic fit:
Ο2 < 30 ππ0 β πΎ+πΎβ π+πβ
Ο2 < 30 ππ0 β π+πβ π+πβ
β Event Selection
ππ0 β πΎ+πΎβ π+πβ ππ0 β π+πβ π+πβ
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βBackground study in π²+π²β π +π β mode
β’ background events mainly come from:
1. π+πβ β (π)πΎπΌππ πΎ+πΎβ π+πβ;
2. π+πβ β πΎπΌππ πΎβΰ΄₯πΎβ;
3. π+πβ β (π)πΎπΌππ πΎβ πβπΎβ+c.c.;
4. include π β πΎ+πΎβ background;5. include πβ² β πΎπ0(π0 β π+πβ)background;6. include π0 β π+πβ background;
β’ For π β πΎ+πΎβ background in M(πΎ+πΎβ π+πβ)β [3.2,3.6]οΌ
β’ M(πΎ+πΎβ)>1.05 GeV
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βBackground study in π²+π²β π +π β mode
β’ πβ² background in M(πΎ+πΎβ π+πβ)β [3.2,3.6] :
β’ background events mainly come from:
1. π+πβ β (π)πΎπΌππ πΎ+πΎβ π+πβ;
2. π+πβ β πΎπΌππ πΎβΰ΄₯πΎβ;
3. π+πβ β (π)πΎπΌππ πΎβ πβπΎβ+c.c.;
4. include π β πΎ+πΎβ background;5. include πβ² β πΎπ0(π0 β π+πβ)background;6. include π0 β π+πβ background;
π΄ πΈπ +π β > π. ππ
46
βBackground study in π +π β π +π β mode
β’ All combinations of πΎπ+πβ pairs in M(π+πβ π+πβ)β [3.2,3.6]
β’ M(πΎπ+πβ_hh)
β’ background events mainly come from: 1. π+πβ β (π)πΎπΌππ π
+πβπ+πβ;2. π+πβ β (π)πΎπΌππ π
+πβπ+πβ;3. include π0 β π+πβ background;4. include πβ² β πΎπ+πβ background;
β’ M(πΎπ+πβ_lh) β’ M(πΎπ+πβ_ll)
|M(πΎπ+πβ)-M(πβ²)|>0.01GeV
47
βFit to M(π +π β π +π β) and M(π+πβ π +π β)
β’ Fit Method: Fit two channel simultaneously;β’ MC shape + 2nd polynomial;
ππ0 β π+πβ π+πβππ0 β πΎ+πΎβ π+πβ
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βFit to M(π +π β π +π β) and M(π+πβ π +π β)
β’ Fit Method: Fit two channel simultaneously;β’ MC shape + 2nd polynomial;
ππ0 β π+πβ π+πβππ0 β πΎ+πΎβ π+πβ
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βSystematic uncertainty
β’ The luminosity : measured using Bhabha events, with uncertainty 1.0%;
β’ Tracking efficiency : 1% is assigned to each track, 4% in total ;
β’ branching ratios : 8% for ππ0 β π+πβ π+πβ, 8% for ππ0 β π+πβ π+πβ;
β’ PID: ,1.0% per kaon or pion ~ 4%;
β’ Kinematic fit: The difference efficiency between before and after pull correction;
ππ0 β π+πβ π+πβ ~6%, ππ0 β π+πβ π+πβ ~2%;Use 4180
β’ Radiative correction:use π+πβ β πΎππ1 line shape, take the difference ν β (1 + πΏ)between 2-bw and 3-bw model as systematic uncertainty; ~2.7% ~1%
β’ @4180 Total systematic uncertainty : ππ0 β π+πβ π+πβ ~11.8% ;ππ0 β π+πβ π+πβ~10.9%;
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βUpper Limit
β’ To evaluate the upper limits of cross section at 90% C.L. :Define likelihood fuction:
β’ π0 is the fixed number of signal events;
β’ πΊ π0, π0π is Gauss function, π is systematic uncertainty ;
β’ The upper limit on the cross section is calculated with following formula:
β(π0) = ΰΆ±πΊ π0, π0π β β(π) ππ
ππππππ’π
=ππ’π
β β β¬ β π β (1 + πΏ) β (1 + πΏππ)
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Upper limit @4180
β’ Suppose π+πβ β πΎππ0 follow π+πβ β πΎππ1β² line shape (P19), we generate signal MC samples ;
β’ Similarly, After consider to systematic uncertainty,we give the number of signal upper limit at 90% confidence level:
β’ ππππππ’π <2.4pb;
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βSummary
β’ Using data above π+πβ CM energy ~4 GeV, we observed π+πβ β πΎππ1,π2at 4180, evidence for π+πβ β πΎππ1 at 4009@4190@4200,evidence for π+πβ β πΎππ2 at 4009@4420;
β’ Branch ratio(4180) about β¬(π+πβ β πΎππ1/ π+πβ β πΎππ2)β 0.767β0.242+0.258, there is a big
difference from theoretical prediction about π(4160) E1 radiative transitions ;
β’ Both π+πβ β πΎππ1 and π+πβ β πΎππ2 show there are a dip around 4230, which might be due to the interference of the Y(4220) resonance;
β’ Using ππ0 β πΎ+πΎβ π+πβ/ π+πβ π+πβ ,we don`t observe π+πβ β πΎππ0 signal, upper limit of born cross sections are given;
Thanks!
53
Back Up
54
βMC for πππ β π²+π²β π +π β/ π +π β π +π β
β’ Decay cardοΌ
π +π β π +π β π²+π²β π +π β
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Scan data
56
Fit result @4180&4190&4200
π+πβ π+πβ combine
57
Fit result @4210&4220&4230
π+πβ π+πβ
combine
58
Fit result @4237&4246&4260
π+πβ π+πβ combine
59
Fit result @4270&4280&4360
π+πβ π+πβ combine
60
Fit result @4420&4600
π+πβ π+πβ
combine
61
β β log πΏ = 85.116Ndf=6Sig>10
Significance test
β’ π+πβ β πΈπππ
β’ π+πβ β πΈπππ
β β log πΏ = 46.906Ndf=5Sig>10
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βCompare these two fit methods
β’ β log πΏ οΌ2-BW β log πΏ =165.5 3βBW β log πΏ =173.8
Canβt distinguish these two methods;
β’ For Resonance: Consistent with each other , Also consistent with π+ πβ β π + π βπ±/π channel;
ParametersοΌMeVοΌ π+πβ β πΈπππ,π
M(R2) 4225.6Β±2.6
Ξ(R2) 28.5Β±5.4
2-BW 3-BW
Parameters(MeV) π+πβ β πΈπππ,π
M(R1) 4247.2Β±6.2
Ξ(R1) 82.5Β±14.1
π+ πβ β π + π βπ±/π
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βMC for πππ β π²+π²β π +π β/ π +π β π +π β
β’ Decay cardοΌ
π +π β π +π β π²+π²β π +π β