a 0 (980) and f 0 (980) mixing and analysis of J/ Ψ -> Φ ηη

1. a0(980) and f0(980) mixingand analysis of J/ Ψ->Φηη Wang Yadi 2009.09.07

2. outline • a0(980) and f0(980) mixing J/Ψ->Φa0(980)-> Φηπ0 • analysis of J/ Ψ->Φηη • systemic error of η and π0 selections • summary and future work

3. a0(980)-f0(980) mixing • Motivation • A possible way to distinguish the nature of a0/f0 : a0(980)-f0(980) mixing • ~200M J/psi @ BES3 (based on BOSS 6.5.0) • Event selection • Background analysis

4. ||2 : 0.01~0.2 Estimations from relevant measured parameters Model predictions KK q2q2 qq For a very recent prediction from chiral unitary approach, cf. Hanhart, Kubis & Pelaez, Phys.Rev. D76 074028 No firm direct observation of a0-f0 mixing available !

5. J.J.Wu, Q.Zhao & B.S.Zou, PR D75(2007)114012 : 2×108 J/ events with BES3 detector search for a narrow peak ( 987.4 – 995.4 ) MeV in isospin forbidden process BR(J/ f0(980)  a0(980) 0 ) ~ (0.2-20)*10-6 0-(1--)->0-(1--)+0+(0++)-> 0-(1--)+ 1-(0++)

6. Event selection • two charged tracks: • |Rxy |<5cm, |z|<20cm • Number of isolated photons: 4<= N<=20 • Ebarral>30MeV , Eendcap>50MeV; • 0<Time<14 • θγcharged>20o • K+,K- are identified (dE/dx+TOF) prob_K>prob_pi & prob_K>0.001 looping with all isolated photons: • To reconstruct  candidates: 21C() <=9; |cosθ|<0.95； M() ~ (0.457, 0.607)GeV • To reconstruct 0 candidates: • 21C() <=9; |cosθ|<0.95; M() ~ (0.075, 0.175)GeV decay angle

7. Event selection • if there are more than one distinct  or 0 candidates, the combination gives min 26C(K+K-0) is retained • 26C(K+K-0) <50; • 26C(K+K-0) <= 26C(K+K-); • 26C(K+K-0) <= 26C(K+K-0 0); • mass window of  |m(K+K-)-m|<=0.012 GeV/c2; • mass window of a0(980) (when fitting) 0.92 GeV/c2 <=M(0)<=1.05 GeV/c2;

8. Red --- signal J/Ψ->Φa0(980)->Φηπ0 blue --- J/ ψ-> Ф f_2(1270)-> Ф η η blue --- Inclusive MC blue --- J/ ψ-> Ф π0η

9. M(K+K-) distribution Red --- signal J/Ψ->Φa0(980)->Φηπ0 blue --- Inclusive MC blue --- J/ ψ-> Ф π0η blue --- J/ ψ->K*K η

10. distribution of M(K+K-) Double Gaussian fit σ1~2.1MeV σ2~6.4MeV σ ~ 3.7MeV M ~ 1.0197GeV

11. distribution of M(π0η) Output : M~0.9846GeV σ~8.6MeV Input : M~0.9847GeV σ~8.0MeV Eff ~ 12.2% Mass resolution of a0: 5.4 MeV

12. cut flow for J/ψ->Фa0(980)(8MeV)

13. background analysis • exclusive channels • inclusive channels

14. exclusive background analysis

15. exclusive background analysis

16. 90M J/Ψ inclusive backgrounds analysis

17. 4 main backgrounds J/ψ->γ*(KKbar) ->Фa0(980) J/ψ->ηh_1(1400), h_1(1400)->K*K J/ ψ-> Ф π0π0 J/ ψ->K*K η

18. distribution of M(π0η) in data red --- M(K+K-) ~ (1.008 ~ 1.032)GeV blue---M(K+K-) ~ (1.560 ~ 1.032) GeV next step is fitting : bkg ~ c1*RooChebychev + c2*sideband + c3*bkg1 + c4*bkg2 bkg1 ~ J/Ψ->Φ a0(980) ->Φηπ0 bkg2 ~ J/Ψ->Φ f0(980) ->Φπ0π0 signal ~ shape of J/psi -> Φ a0 (8MeV)

19. analysis of J/Ψ-> Φηη • event selection is the same as J/Ψ-> Φηπ0 , • except : • 26C(K+K- ) <50; • 26C(K+K-) <= 26C(K+K-0) • 26C(K+K-) <= 26C(K+K-0 0)

20. distribution of Χ6C2(k+k-ηη) Red --- signal J/Ψ->ηΦ*(1680)->Φηη Pink --- signal J/Ψ->ηY(2175)->Φηη blue --- J/ ψ-> Ф f_2(1270)-> Фπ0π0 blue --- inclusive MC blue --- J/Ψ->Φηη

21. distribution of M(K+K-) Red --- signal J/Ψ->ηΦ*(1680)->Φηη Pink --- signal J/Ψ->ηY(2175)->Φηη blue --- J/ ψ-> Ф f_2(1270)-> Фπ0π0 blue --- inclusive MC blue --- J/Ψ->Φηη

22. cut flow for J/ψ-> ηФ (1680)

23. cut flow for J/ψ-> η Y(2175)

24. background analysis • exclusive channels • inclusive channels

25. exclusive background analysis

26. exclusive background analysis

27. 90M J/Ψ inclusive MC background analysis

28. 3 main backgrounds J/Ψ->Φf0(1500)->Φηη J/Ψ->Φf2’(1525)->Φηη J/Ψ->Φηη

29. distribution of M(ηΦ) compare signal and data J/ψ->ηФ (1680) data

30. distribution of M(ηΦ) compare signal and data J/ψ->η Y(2175) data

31. π0,η selection’s systematic error • π0 selections: decay angle : cosθ<0.95; 0.075GeV < Mγγ < 0.175GeV; • ηselections: decay angle : cosθ<0.95; 0.457GeV < Mγγ < 0.647GeV;

32. π0 systematic error J/ψ->ρ-π+ Initial cuts: good charged tracks: N=2 , using PID; good neutral: N>=2; 4C chisq<999 Final cuts: Nγ<4; Mπ+γγ >1.2GeV & Mπ+π->1.2GeV; 3.00GeV < Eπ+π-γγ < 3.14GeV; Ptr12 >0.001, Ptr22 >0.001; Ptr2 = 4pmiss2×sin2(σ/2)

33. the systematic error is about 1% Without Pi0 selections With Pi0 selections Eff_MC= 98.48% With Pi0 selections Without Pi0 selections Eff_data = 99.17%

34. η systematic error J/ψ->p pbar η Initial cuts: good charged tracks: N=2 , using PID; good neutral: N>=2; 4C chisq<999 Final cuts: Nγ= 2; 3.00GeV < Eπ+π-γγ < 3.14GeV; Ptr12 >0.001, Ptr22 >0.01; Ptr2 = 4pmiss2×sin2(σ/2)

35. the systematic error is about 1% Without η selections With η selections Eff_MC = 95.53% With η selections Without η selections Eff_data = 96.55%

36. Summary • a preliminary analysis of a0(980)-f0(980) mixing • structures observed in Mφη • determination of the preliminary systemic error of π0 ,η

37. Future work • full analysis of φπ0η (a0-f0 mixing), φηη • determination of systemic error of π0 ,η selection in different momentum region and with different Eγ1,Eγ2 Thanks!

38. backup

39. inclusive VS data M(phi , eta )

40. phi f0(1500) VS data M(eta phi)

41. phi f2(1525) VS data M(eta phi)

42. phi eta eta VS data M(eta phi)

43. maybe i should not use the sideband bkg to fit M(eta,pi0) and M(eta,phi) should i try to use some bkgs + signal +RooChebychev J/ψ->Фa0(980)(8MeV) J/Ψ->Φηη