1 / 69

 ' Radiative Decay at BESII

 ' Radiative Decay at BESII. Lianliang Ma Mall@ihep.ac.cn. March 24, 2006 University of Toronto. B. Sc. 1995.9 --- 1999.7 Shandong University , Jinan, Shandong, China First prize scholarship every year Ph. D . 1999.9 --- 2002.4 Shandong University , Jinan, Shandong, China

eaton-watts
Download Presentation

 ' Radiative Decay at BESII

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ' Radiative Decay atBESII Lianliang Ma Mall@ihep.ac.cn March 24, 2006 University of Toronto

  2. B. Sc. 1995.9 --- 1999.7 Shandong University, Jinan, Shandong, China First prize scholarship every year Ph. D. 1999.9 --- 2002.4 Shandong University, Jinan, Shandong, China Work on detector simulation with Geant4: (a) Study the performance of TGC at the endcap of ATLAS; (b) Translate the package for ARGO experiment. HEP & NP, 2003, 27(9): 813-818(in Chinese) Journal of Shandong University, 2003, 38(5):80-85 (in Chinese) Talk given in the Workshop of ARGO Experiment, Beijing, Dec. 2002 Lianliang Ma

  3. Measurement of (2S) decays into and  • (To be submitted to PRD soon) • 2002.4 --- 2004.7 Institute of High Energy Physics, Beijing, China • Thesis on 'Vector + Pseudoscalar, published on • Phys. Rew. D 70, 112007 (2004); Phys. Rew. D 70, 112003 (2004); • Phys. Lett. B 614 (2005) 37-43; HEP & NP, 2004, 28(10):1021-1025(in Chinese) • Postdoctoral researcher • 2004.7 --- present Institute of High EnergyPhysics, Beijing, China • Work on the ' radiative decays: • Talk given at the 40th Rencontres de Moriond on QCD and High Energy • Hadronic Interactions, La Thuile, Italy, Mar. 2005 (hep-ex/0505044) • Coordinator of the working-group on ' radiative decays Lianliang Ma

  4. Outline • Introduction • Measurement of ’+– • Measurement of ’ • Summary

  5. The Beijing Electron Positron Collider Ecm~2-5 GeV L ~51030 /cm2s at J/ ~11031/cm2s at ' A unique e+e- machine in the -charm energy region since 1989! (CESRc is operating!) Beijing, China

  6. BESII Detector VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 220 m BSC: E/E= 22 % z = 5.5 cm dE/dx=8.5 % = 7.9 mr B field: 0.4 T p/p=1.7%(1+p2) z = 3.1 cm

  7. Charmonium Spectrum ' physics at BESII DD 14MBESII ' 3M 6.42 pb–1 @3.65GeV About 1/3 of the Luminosity of '

  8. ' decay (VP, VT, PP, NN, ……) ' physics Test theoretical predictions, such as “12% rule” predicted by pQCD M. Appelquist and H. D. Politzer,PRL34, 43 (1975) Clue to study ‘ and J/ decay

  9. ' physics • Hadron spectrum, (f0(600)) in '+–J/ • J/ decays via '+–J/ when systematic error is dominant (21.880.052.01) 10–3 from 58M J/ data (20.910.211.16) 10–3 from 14M ' data (21.0 1.2) 10–3 (combined) BES, PRD 70, 012005 (2004) Br(J/3 ) • cJ decays via '  cJ • hc(1P1) via ' 0hc

  10. ' physics • Few studies have been done for the ‘ radiative decays. • Search for or study glueball candidates; • Search for new decays of ’ and cJ; • Prepare for the projects at BESIII. C C ’ radiative decay ’   cJtransition

  11. Measurement on '+– Study the (1405/1475), named (1440) before • (1475) could be 1st radial excitation of ', with the (1295) being • 1st radial excitation of . (1405) has a large gluonic content (2) L3: Gluonium production is presumably suppressed in  collision. 148112 MeV L3 collab., Phys. Lett. B 501 (2001) 1-11 (3) CLEO : with 5 times larger sample CLEO collab., Phys.Rew. D 71, 072001 (2005)

  12. '+– (4) Studied in J/ with +–, , 0 and +–+–. With the J/ results, we can deduce we can observe the signal of ’  (1475/1405)+– and KK.  Search new decay modes of ‘ and cJ Test the “12% rule” in the ‘ radiative decays

  13. '+– • Two good charged tracks with net charge zero • Each charged track identified to be  candidate • Three good photon candidates • 24C(+–3)<15

  14. '+– Sig. MC DATA To reject the background from '+J/ J/ not from  decay Mass recoiling from  Sig. MC DATA To suppress the back- ground from 'X1+J/, J/  + + X2 m()

  15. '+– DATA Lund-MC Continuum   m() m() m() Lund-MC('X ): describe data in quality, but maybe not in quantity. J.C. Chen et al., Phys. Rev. D 55, 5657–5666 (1997) Br. are different: J/ 3, 2.10% from BESII; 1.87% in Lund-MC Study the background with: (1) PDG ; (2) 14M Lund-MC sample for 'X inclusive

  16. N(104) Br(10-5) Channel with  No survive 1, 2, 3, 4, Measured m() '+– These channels can only describes about 40% of the total Bg. in DATA

  17. (1) Signal Channel Method with Lund-MC 14M Lund-MC sample Modified,then put back (3) The other Bg. Channel(s) with small contribution (2) Known Bg. Channels With large contribution +–0, X+J/, J/ 3, K+K–0 simulated separately Lund-MC without channels in Part (1) and (2) +–

  18. '+– Change the Br. of: 1, +–; 2, XJ/ ,J/ 3; 3, +–0; 4, J/ ,J/ K+K–0 Lund-MC Br. Changed + continuum Signal taken out m() m()

  19. '+– NDt.=553.260.2 NBg. =134.952.226.8 Sig.: two-Gaussian(MC) Bg.shape: Legender 6.6 Method to Background: Nsig.= NDt. ― NBg. (Nsig.)=(NDt.) (NBg) taken as sys. of Nsig.

  20. candidates: • sidebands: 'x, x+– 6.6 ‘(958) NDt.=24.25.4; NBg. =0.91.4 1.4 (1405) NDt.=13.87.0; NBg. =4.04.5 Background events estimated from  sidebands

  21. 'x, x+– Get Nupper at 90% C.L. with Beyesian approach (1475) Nevt.=20 Li/Lo Li/Lo (1405) Nevt.=24 Nevt.

  22. 'x, x+– Suggest two-body decay of c1 NDt.=255.928.0 NBg. =34.1 15.4 8.8

  23. 'c1, c1 a0(980)+ +c.c. NDt.=79.014.2; NBg. =21.2 11.1 a0(980) candidate: 4.5 a0(980) sideband: m in (1.3---1.9) GeV

  24. 'c1, c1f2(1270) NDt.=65.212.9; NBg. =12.2 7.0  and f2(1270) candidates: 4.8 Sideband from  and f2(1270)

  25. 'c1, c1 a0(980), f2(1270) • cross-contamination is considered. • Interference is not considered (low statistic) Contamination from c1 a0 to c1f2 can be considered with f2(1270) sideband Contamination from c1f2 to c1 a0 can be considered with a0(980) sideband

  26. QED Background • Contamination to  signal • has been considered (2) No contamination to ' and c1 Lianliang Ma

  27. (1+cos2) (1-cos2 /3) ‘’, (1405) 'c1 cos Detection Efficiency Simbes: based on Geant3 Angular distribution is considered Eff. is weighted average for: ‘+– , c1+–

  28. Conventional ones Systematic error Int.: Uncertainty in Br. of resonances: , ‘ c1, ’ +– : Statistic of MC sample and of sub-processes for weighted Eff. Fit: Uncertainty in selection of Bg. shape and mass region to fit

  29. Results of ’+– 1, Improve the result of ’’,’+–: 2, The other results are all the first-time measurements 3, Upper limits are set for ’(1405/1475)+–

  30. ●Call on a working-group (8 members) to study ‘ decays into  + n-prong final states a) +–, K+K– and pp-bar b) +(+–+–, +–K+K– , K+K–K+K– , +–pp) c) +(+–+–+–, +–+–K+K–) Lianliang Ma

  31. Measurement of '  pp Two good charged tracks and Qi=0 2 Good photon number ≥ 1 With the photon with the largest energy, a 4C-fit is performed, and the Prob(2comb , ndof )>0.01 2comb= 24C +(i2dE/dx + i2TOF)

  32. 'pp m(pp) c 1, Clear cJ is observed Events/20 MeV 2, Only study the signal with mpp<3.0 GeV • Mainly on signals • other than cJ • Background at 3.1 GeV from ‘x+J/ cJ Events/10 MeV

  33. Background of 'pp 1,Background without pp, neglected. dE /dx ’ 2,Background from QED TOF Lianliang Ma

  34. Background of 'pp Neglected 3,Background like pp + +– 4,Background like pp + n a) ' x1+J/, J/ x2+pp b) ' Measured pp + 20, 30, 20(neglected) Lianliang Ma

  35. 'pp m(pp) 1, QED 2, ' pp + n DATA Ntot =381 NBg.=218.8 NQED =16*3.0 Nsignal=114.2 Events/20 MeV Background

  36. 'pp 2(4C)distribution pp0 pp DT. 1, Sig. 2, Bg. 3, QED pp0 pp00 Lianliang Ma

  37. 'pp Components in the fitting 1, Sig.; 2, Bg. ; 3, QED. Failed to add other component with Legender of order 1 or 2 Background has been considered well Proved by the Lund-MC result

  38. 'pp '  X, Xpp m(pp) m(pp) dB/dm=(Nobs–Nbg)/(•N'•m) Eff. dB/dm (10–5 /100 MeV)

  39. 'pp dB/dm (10–5 /100 MeV) Analysis result Sys. error For mpp<3.0 GeV:Br.('pp)=(2.23±0.45±0.51)×10-5

  40. 'pp Nevt=21.7±8.5 Events/20 MeV m(pp) m(pp) – 2mp Nevt=21.8±7.8; Eff. =28.5% Br(‘c, cpp)=(0.55 ±0.20 ±0.07)×10-5 PDG: (0.36±0.14) ×10-5 c Events/10 MeV Phys. Rev. Lett. 91, 022001 (2003)

  41. Summary • Measurement on ’+– • First measurement of the Br. of ’+– • Improvement in the Br. of ''(958), (2.00± 0.59±0.29) ×10-5 reported by BESI Lianliang Ma

  42. Summary • First search for (1405/1475) with '+– J/(1405/1475)KK = (2.8 ± 0.6)×10-3 J/(1405/1475)+– = (3.0 ± 0.5)×10-4 '(1405) KK <0.8 ×10-5 '(1475) KK <1.5 ×10-5 Seem different from J/ decay '(1405) +– <1.6 ×10-5 '(1475) +– <0.83 ×10-5 Lianliang Ma

  43. Summary For the test of “12% rule”, ''(958) is suppressed, ’+– is consistent with. • First observation for c1+–, f2(1270), a0(980)+ + c.c. Lianliang Ma

  44. Summary • Measurement on ’ • First measure the branching ratio of ’ for mpp<3.0 GeV. • Report the differential branching ratios of ’ for mpp<3.0 GeV for the first time. Lianliang Ma

  45. Summary • There seems the near-threshold enhancement in mass spectrum • New method (fitting the 2(4C)) is developed to estimated background quantitatively • First working-group is organized, and is highly praised by the professors Lianliang Ma

  46. Summary These analyses will be good topics for BESIII (3.2  109/year for ') • Study (1405/1475) with '+– • Study c1+– about interference between c1 a0(980) and c1f2(1270) • Study the near-threshold enhancement 'pp Lianliang Ma

  47. That’s all! Thank you! 谢谢! Lianliang Ma

  48. Finished

  49. The “12% rule” M. Appelquist and H. D. Politzer, PRL34, 43 (1975) This is the famous (or notorious) “12% rule”. Lianliang Ma

  50. ‘+ Lianliang Ma

More Related