World J/y and y(2S) Samples - (106)Largest from BESJ/y(2S)20022001146012501040830620410200MKIMKIIMKIICBALBESIBESIIMarklllDM2BESIBESII
World J/ and (2S) Samples (106 ) J/ (2S) 0 10 20 30 40 50 60 MarkIII DM2 BESI BESII 0 2 4 6 8 10 12 14 MKI MKII MKIII CBAL BESI BESII
Motivation> The enhancement near the ppbar mass threshold observed byBESII in J / y -→ pp could be interpreted as a ppbar boundstate (multi-quark meson)> The new observation of BESII as well as new resonancesobserved by other experiments makes the searches for multiguarkstates become a very hot topic of high energy physics field.> It is of special importance to search for possible baryon-antibaryon resonances or bound states.pp,pn,pA,pzAA,AZ
Motivation ➢ The enhancement near the ppbar mass threshold observed by BESII in could be interpreted as a ppbar bound state (multi-quark meson). ➢ The new observation of BESII as well as new resonances observed by other experiments makes the searches for multiquark states become a very hot topic of high energy physics field. ➢ It is of special importance to search for possible baryonantibaryon resonances or bound states. , pp, pn, p , p J / →pp
StrongenhancementthenearMthresholdofPA+c.c.R00600(b)(a)50400100MCData20050(Phase Space)0022M2.5M2Gevie?GevicpA+c.CPA00100A(a)(b)75755050DataData2525002.522.52GeV/c?GeV/c?MMPApA
M p+c.c. M p+c.c. Data MC (Phase Space) Data Data M p M p Strong enhancement near the threshold of M p+c.c
BW fit resultsS-wave福MINUITLikelihoodFittoPlot100&0w-m.-mFile:Homa/shanly/dit4/ntu/datamar12.hbk15-MAR-200416:48Plot Area Total/Fit53200./63200FitSttus3FuncAreaTotal/FitE.D.M.2.964E-12531.79/531.79M= (2075 +/- 12) MeVLikelihood=29.931.1for 30-4d.o.f.C.L.-22.5%noconvolutedwithGaussianofwidth4.50oE-03,intervalst00,sigma**T = (90 +/-35)MeVParabolicMinottion,1:Signal in Bw0.000EVNTS237.8557.230.000±MASS2.0751±1.1871E-020.0000.000WIDTH3.5037E-02BR =(1.18+/-0.28)*10**(-4)9.01547E020.0000.0002:phasespaceasBackgroundAO0.00000.0000.0000.000X0.000+9.2770.000NORM48.203X0.0000.0000.000IA1-6.2452+A237.3150.0000.0000.00040About 7 statistical significance3020100.000.050.100.15
S-wave BW fit results • M = (2075 +/- 12) MeV Γ = (90 +/- 35) MeV BR = (1.18+/- 0.28)*10**(-4) • About 7σ statistical significance
Features of signal and event selection
Features of signal and event selection