1 / 65

General Review of BES Physics, Achievement and Future Representing BES collaboration Weiguo Li

General Review of BES Physics, Achievement and Future Representing BES collaboration Weiguo Li IHEP, CAS liwg@ihep.ac.cn MENU 2004 Beijing, Aug. 30, 2004. Introduction BES Physics Results BEPCII/BESIII Project Summary.

george-foster
Download Presentation

General Review of BES Physics, Achievement and Future Representing BES collaboration Weiguo Li

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. General Review of BES Physics, Achievement and Future Representing BES collaboration Weiguo Li IHEP, CAS liwg@ihep.ac.cn MENU 2004 Beijing, Aug. 30, 2004

  2. Introduction • BES Physics Results • BEPCII/BESIII Project • Summary

  3. BEPC consists of Linac、Storage Ring、Detector(BES）and Synchrotron Facility(BSRF). Ground breaking in 1984，completed in 1988 within budget and according to the schedule. Soon after reached the designed performances.

  4. BESII Detector (1995-1997 upgraded) VC: xy = 100 m TOF: T = 180 ps counter: r= 3 cm MDC: xy = 250 m BSC: E/E= 22 % z = 5.5 cm dE/dx= 8.4 %  = 7.9 mr B field: 0.4 T p/p=1.8(1+p2) z = 2.3 cm Dead time/event: 〈10 ms

  5. The BES Collaboration Korea (4) Korea University Seoul National University Chonbuk National University Gyeongsang Nat. Univ. USA (4) University of Hawaii University of Texas at Dallas Colorado State University Stanford Linear Accelerator Center UK (1) Queen Mary University China (18) IHEP of CAS Univ. of Sci. and Tech. of China Shandong Univ., Zhejiang Univ. Huazhong Normal Univ. Shanghai Jiaotong Univ. Peking Univ., CCAST Wuhan Univ., Nankai Univ. Henan Normal Univ. Hunan Univ., Liaoning Univ. Tsinghua Univ., Sichuan Univ. Guangxi Univ., Guangxi Normal Univ. Jiangsu Normal Univ. Japan (5) Nikow University Tokyo Institute of Technology Miyazaki University KEK U. Tokyo

  6. Data collected with BESIand BESII

  7. world largest J/ and ’ data samples(106) J/   99.11-01.3 01.11-02.3

  8. BESII Detector Simulation Understanding the detector simulation and Data/MC consistency are very important to the physics results, BES simulation, SOBER(BESI), detector gaussian response, no hadron interaction (from MarkIII) SIMBES(BESII), Geant3 based, better detector responses For example, the wire resolution is affected by the dE/dx of the MDC hits.

  9. Example: Wire Resolution of MDC • dE/dx dependence • Double Gaussian Seems most difficult part! Wire res. vs dE/dx (data) Deviation Q OF HITS

  10. Important Variables To Be Checked • Shower Counter Reconstruction efficiency Resolutions (E, z, phi) Energy distributions for e, mu and hadrons Events used for Data/MC comparison J/ e+e-, +-, pp, , , pp+- (2S) J/ +- , etc. • Main Drift Chamber Reconstruction efficiency Momentum resolution Error matrix and chi2 dE/dx (PID efficiency) • TOF TOF quality (efficiency) Resolution & PID efficiency for , K, p

  11. Tracking eff. of  from J/  events Data/MC agrees well (for ) Histogram: MC With error bar: Data GeV/c

  12. Tracking eff. of p, p from pp+- events P MC DATA MC Data P MC DATA

  13. Error Matrix in +- channel SOBER SIMBES

  14. TOF eff. of pion TOF efficiency (pion) vs Momentum Eff. GeV/c

  15. Energy in sc of p and p Data: red, MC: black SOBER SIMBES

  16. Impacts on Physics Results (I) BR(J/  +-0 ) from SIMBES is about 30% higher than that from SOBER. It is also about 30% higher than PDG. Br(J/+-0) = (21.840.052.01)10-3 Babar’s new result confirms our result.

  17. Impacts on Physics Results (II) Angular Acceptance Impacts on PWA Results

  18. Hight lights of BES Physics Results • Precise measurement of the mass of tau lepton • Precise measurement of R value in the energy range of 2-5 GeV • (2S) decays Study many decay modes and the 12% rule • J/ decays Light hadron spectroscopy, search for multi-quark candidates • (3770) decays and D physics

  19. In 1992, BES made a scan over tau mass production threshold and measured the tau mass, BES +0.18+0.25 M  = 1776.96 -0.21-0.17 PDG +0.29 M  = 1776.99 -0.26 Corrected a mass shift of 7 MeV from previous measurements, proved that tau is one of the leptons.

  20. R Measurement • With an average error of 6.6%, compare with 15-20% • errors from previous measurements • fine measurement of the structure at 3.7-4.5GeV

  21. (95% C.L.) Prediction of Higgs mass from standard model

  22. Recent Physics Results J/ Decays Threshold enhancements in pp and pK  in  +- ;  in K*(892)0K+- / K+K- +- Study of scalars in J/ decays Many BF measurements See SHEN, Xiaoyan’s talk for details

  23. (2S) decays 12% Rule; (2S) ;  in (2S)  J/ +-; Many decay BF measurements of (2S) and CJ (3770) decays D BF measurements, (semi-leptonic, purely leptonic, hadronic decays) DD cross-section; (3770) resonance parameters from scanning

  24. Anomalous enhancement of pp near threshold Phys. Rev. Lett., 91 (2003) 022001 Fitted peak J/ygpp BES II +3 +5 -10 -25 Mass: M=1859 MeV/c2 Width: G < 30 MeV/c2 (90% CL) Fitted curve c2/dof=56/56 0 0.1 0.2 0.3 M(pp)-2mp (GeV) Eff. curve BG curve

  25. Observation of an enhancement near p mass threshold in J/pKprocess Accepted by P. R. L., hep-ex/0405050  Data/MC The clear Λ signal in data shows high purity of signal.

  26. S-wave BW fit results M = (2075 12  5) MeV Γ = (90  35  9) MeV BR = (5.9  1.4  2.0) 10-5 2/d.o.f = 31.1/26 About 7σ effect Phase space Phase Space Data Data

  27. Near K threshold enhancement in J/pK Nx Nx Events/10MeV (Arbitrary normalization) PS, eff. corrected Nx

  28. Its mass and width: (large uncertainty near threshold, high statistics is crucial!) Mass 1500~1650MeV Width70~110MeV JP favors 1/2- • large BR(J/pNx)Br(NxK) (2*10-4). What is it?? Possibly N*(1535) with large coupling to K Kmolecular state ??

  29.  in J/K+K-+- ρ(770) K*(892) K0*(1430), K2*(1430) K1(1270), K1(1400)

  30. K*(892)0 in J/K+K-+- K*0(1430) κ BES Preliminary

  31.  in J/ K*(892)0K+- κ κ BES Preliminary

  32. Accepted by PLB (hep-ex/0406038)

  33. b1(1235) Spin 0 Spin 2 σ f2(1270) No f0(1710)

  34. f2(1270) σ b1(1235) BG

  35. (2S) decays and 12% Rule VP Modes • BRs for (2S)(,,)(,,’),K*K measured • PWA for (2S)+  - 0 • Background from continuum considered using Ecm=3.65 GeV data sample

  36. VP Mode (Con’t)  hep-ex/0408047 submitted to PRL Dalitz plot for J/ and  (2S)3 are very different J/ Ψ 3 Ψ(2S) 3 PRD70 (2004) 012005 BESII Preliminary

  37. VP Mode (Con’t) M in (2S) 3 (770), (2150) -- dominant BESII Preliminary ( PWA ) 1.1 

  38. 1. VP Mode (Con’t) BESII Preliminary ( PWA ) 1.1  (Con’t) Results on BRs ____________________________________________________________________________________________________________________________________________ BR BESII (10 – 5 ) PDG04 (10 – 5 ) Ψ(2S) + -0 18.1  1.8  1.9 8  5 Ψ(2S) 5.1  0.7  0.8 < 8.3 Ψ(2S)  (2150) + -0 19.4  2.5 ____________________________________________________________________________________________________________________________________________ # 1st measurement or precision much improved # Interference taken into account

  39. Test of pQCD 12% Rule BESII preliminary

  40. D BF Measurements Semi-leptonic decays BF(D0 K-e+e) = (3.820.400.27)%, PDG (3.58 0.18)% BF(D0 -e+e) = (0.330.130.03)%, PDG (0.36 0.06)% Phys. Lett. B597(2004)39-46 preliminary BF(D+K0e+e) = (8.471.920.66)%, PDG (6.7 0.9)% = 1.15 0.290.09 PDG 1.4 0.2 Purely Leptonic decays, Three D+ + candidates,

  41. D hadronic decay branching fractionby double tagging method 04

  42. (3770) production BES-II Preliminary ! To get right resonance parameters, the two resonance productions and decays should be considered simultaneously. In this way the “correct” QED background( ) can be determined correctly ! Fitting results M(3770) =3772.51.3 MeV PDG: 3769.92.5 MeV tot= 25.5 4.0 MeV PDG: 23.6 2.7 MeV ee= 22536 eV PDG: 260 40 eV M((3770)- (2S)) =86.8 1.3M eV PDG: 83.9 2.4 MeV

  43. D Cross-section preliminary From D0K-+, K-+ + - D+K- + + obs(DD)=6.140.120.50 nb tree(DD)=7.880.150.74 nb Evidence for (3770)J/ +- preliminary BF( (3770)J/ +- )=(0.3420.142 0.083)% ( (3770)J/ +- )=(8032 21)KeV

  44. BEPCII/BESIII Project Two rings

  45. BEPCIIDesign Goals

  46. Expected Number of Events in One Year’s Running With such a data sample, a precise measurements are expected

  47. BEPCII/BESIII Physic Goals • Precise measurements of J/、(2S)、(3770）Decays • Precise measurement of CKM parameters • Light quark hadron spectroscopy • Excited baryon spectroscopy • Other D and Ds physics: • precise measurement of D and Ds decays • measurement of fD, fDs • D0 –D0 mixing • Check VDM, NRQCD, PQCD, study  puzzle

  48. BEPCII/BESIII Physics Goals（2） • Mechanism of hadron production，low energy QCD： precise R measurement •  physics：charged current，m and m • Search for new particles: 1P1 、c ?、glueballs、quark-gluon hybrid、exotic states… • Search for new phenomena: • rare decays; • lepton number violation; • CP violation in J/ and (2s) decays;

  49. BESIII Detector 工

  50. BESIII Main Parameters

More Related