RecentResults of y(2S)BESDecays at F王至勇IHEP,Beijingfor the BES Collaboration第七届全国高能物理年会广西，桂林<页脚><日期/时间>
<日期/时间> <页脚> 1 Recent Results of (2S) Decays at BESII 王至勇 IHEP, Beijing for the BES Collaboration 第七届全国高能物理年会 广西，桂林
OutlineVy(2S)-→t+: 12% ruley(2S)→>3-bodyy(2S)→pn元,pn元(2S)→元元元K+K-(2S) → TT,KKVy'-BB(2S) →pp→ M12020mm2
Outline (2S)→ + − • 12% rule (2S)→ 3 -body (2S) →pn − ,pn − (2S)→ + − 0 K + K− – →BB –––– − 𝜓 (2𝑆 ) → γηππ ,𝛾𝐾 𝐾LJ 𝜋 𝜓 (2𝑆 ) → 𝑝 𝑝LJ → 𝛬 𝛬LJ → 𝛴 0 𝛴LJ 0 → 𝛯 + 𝛯 − − 2
(2S) → t+tFirst observation by DASP:PLB73,109(1978),no BRFirst measurementbyBESI:PRD65,052004(2002)B=(0.271±0.043±0.055)%BruyBreeBrTV(3/2-02/2）=u（3/2-02/2）=-(3/2-2/2)/1- (4m/ /M;(2s)with vi = VBrBree_Brμμ=0.3885BreeBrupBrTT/0.3885(7.0 ± 1.1 ± 1.4) × 10-37.5± 3.1 × 10-3(7.3 ± 0.8) × 10-33
𝜓(2𝑆) → 𝜏 +𝜏 − 3
0RESINT4元福M201QED+M2T2.s2(s-M2)2+M2T2-M2SF(,s)F(B)Ff(β)dVse-(Vs-Vs)/242d g(s'(1 - aJoV2元A[1-11(s'(1-a))]24m2where2=3Tu(1+)-1(1)-1/2,F,(a,s): initial state radiation correction;Ref.F.(β): coulomb correction;1.E.A.Kuraev and V.S.Fadin,Yad.Fiz.41,733(1985)2.F.A.Berends,etal.,Phys.Lett.63B,432(1976)Fr(β): final state radiation correction;3.J.M.Wu, High EnergyPhys.,Nucl.Phys.17,379 (1993II(s): vacuum polarization effect correction4
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Events selection and resultb(2S) →+-, +→μ+D-Ve, -→e-VDeParticle indentification:e:CLe >0.01, E/P>0.65, P<1.2GeV.μ:muid≥2,0.5GeV<P<1.2GeVTo require nophoton is observedData140120_MC+cont.+Bg.Results:120100.Cont.+Bg.10001015events atresonance.Bg8060146x3atcontinuum.604040B=(0.310±0.021±0.038)%2020Lepton universality checked00.50.40.60.81.201Pe(GeV)tGeyBESTZImprovement:Continuum contribution measured in data.Efficiency and background estimation.Interference subtraction more reasonable5
Data MC+cont.+Bg. Cont.+Bg. Bg. Events selection and result 5