Search for Rare and Forbidden Processes at BES

1. -- Only some selected topics Search for Rare and Forbidden Processes at BES Xiaobin Ji Institute of High Energy Physics, CAS Beyond the Standard Model Aug. 7 – 11, Beijing

2. Focus on the Following Topics • Invisible decays of mesons • Weak decays of  • Lepton Flavor/baryon number violated decays

3. Invisible Quarkonium Decays

4. Invisible Quarkonium Decays With in SM, the invisible quarkonium decays are predicted by: hep-ph/9806487, L.N Chang, O.Lebedlev and J. N. Ng With 2-3% uncertainty! One get: Theoretical clean process can be used to test model and probe new physics! Br(Y(1S) ) = 110-5 Br(J/  ) = 2.69 10-8 New physics may enhance the production rate of the invisible Charmonium decays.

5. MeV Dark Matter Candidates 511KeV emission line from SPI group at INTEGRAL satellite in France P. Jean et al Astron. Asronphys 407(2003) L55 The intrinsic line width is 2.950.5 KeV The Gamma-ray is centered just at positron mass, They are from the annihilation of positronium in the Galactic center. The low energy e+e- pair could be from the annihilation of lighter Dark Matter candidates C. Boehm et.al Phys. ReV. Lett. 92(2004)101301

6. Dark Matter (Exist?) A halo exist, and imply dark matter existence

7. (1-100)MeV Dark Matter: Has it been detected If the Dark Matter (DM) annihilation happened in Galactic center 00 e+e- The energy loss of e+e- will be inside (confined) in Galactic Bulge SPI can see the 511KeV line Phys. Report 405, 279(2005)

8. New Physics in Heavy QQ Decays H(QQ)   : looking for invisible decay in Y(nS) and (ns) n = 1, 2,3 ; hep-ph/0506151 Br(Y(1S)  ) = 0.41% Br(J/   ) = 0.023% Br(  ) =0.033% SM: Br(Y(1S) ) = 110-5 Br(J/  ) = 2.69 10-8 Search () invisible decay using 58 M J/ data of BES II

9. Missing direction Tag direction J//, where / invisible • Reconstructing K+K , looking at missing mass or missing momentum of  decays • Fast  (1.2 GeV) will help us define the decay direction of invisible decay of / No any hit information are required outside of the core of  decays.

10. Signal MC 58 M J/  missing momentum distribution Results ofJ//, where / invisible Extended ML fit is used hep-ex/0607006

11. Weak Decay of search for

12. Weak decays of J/y at BES II • Kinematically J/y can not decay into charmed meson D pairs, however it can decay into signal D meson. The study provides tests of SM theory and serve as a probe to New Physics • Feynman diagrams for the weak decays processes • The Feynman diagram for the Flavor Changing Neutral Current process , it is a typical contribution to cu FCNC transitions in the Minimal Supersymmetric SM.

13. Decay modes used in the analysis

14. Results 58 million J/y data at BES-II Accepted by PLB: hep-ex/0604005  K*

15. Results

16. Lepton flavor violating processes in J/ decays

17. Introduction of LFV • In the SM, the lepton flavor symmetries are conserved • In many extension of the SM, such as SUSY, GUT, left-right symmetric models, lepton flavor symmetries speculated to be violated • SuperK, SNO, and KamLAND experimental results indicates strongly m0, and mix with each others.

18. m momentum distribution BES II Results BESII upper limit BR(J/  e) < 1.110-6 BR(J/  et) < 8.310-6 BR(J/  mt) < 2.010-6 with 58M J/  sample BESII PLB561, 49 (2003) PLB598, 172(2004)

19. Prospects of BES III

20. BESIII Detector • Two rings, 93 bunches: • Luminosity • 1033 cm-2 s-1@1.89GeV • 6 1032 cm-2 s-1@1.55GeV • 6 1032 cm-2 s-1@ 2.1GeV Magnet: 1 T Super conducting MDC: small cell & He gas xy=130 m sp/p = 0.5% @1GeV dE/dx=6% TOF: T = 100 ps Barrel 110 ps Endcap Muon ID: 9 layer RPC Data Acquisition: Event rate = 3 kHz Thruput ~ 50 MB/s EMCAL: CsI crystal E/E = 2.5% @1 GeV z = 0.6 cm/E Trigger: Tracks & Showers Pipelined; Latency = 6.4 ms The detector is hermetic for neutral and charged particle with excellent resolution ,PID, and large coverage.

21. Charm Productions at BEPCII Average Lum:L = 0.5×Peak Lum.; One year data taking time: T = 107s Nevent/year = exp L T Huge J/ and (2S) sample at BESIII; Largest D/DS sample near the threshold.

22. Sensitivities of Charmonium Invisible Decays at BES-III 3X109 y(2S) events per year at BES-III Invisible The sensitivity at BESIII will be 10-6-10-7 for J/y, C and C Invisible ,

23. Study of invisible decays of , , ’,  and  in J/ two body decays 10X109 J/y events per year at BES-III Invisible The sensitivity at BESIII will be 10-6-10-7 for , ’ Invisible ,

24. Access to Weak J/ Decay at BESIII (1) • J/   DS (DS*) M (M = p, r, ,,’,K, K*,) hep-ph/9801202, K. Sharma < G (  DS*+p- ) R = ------------  3.5 G(  DS+p-) G (  DS*+r- ) R = ------------  1.4 G(  DS+r-) Sensitive to new physics if larger BRs measured.

25. Access to Weak J/ Decay at BESIII (2) • The rate of weak decay of J/ is at • 10-8 level, and the inclusive search • at BESIII may be available: • J/  D*+S X • D*+S  DS+g (soft g ) • D+S p+ • K*0K+ • KSK+ The sensitivity at BESIII: 10-7 – 10-8

26. LFV at BES III • J/y e, et, t, the sensitivity can be 10-8 – 10-9 at BES-III with 1010 J/y events per year • J/ye- proton +c.c, J/ym- proton +c.c can also be searched for.

27. Summary Using 58 M BES II data • The invisible decays of / are searched in the process J// • Measured weak decays of J/ in and • LFV processes J/y e, et, t • We can look for many rare and forbidden decays of Charm and charmonium, and challenge the SM at BES III

28. Thank You!