物理可行性研究 27P

1、Dec. 16 2006,1,Invisible Decays of Quarkonia at BESIIIBES 物理可行性研究,Xiao-Bin JI and Hai-Bo Li Institute of High Energy Physics QCD and Hadron Physics 2006 December 16 Peking University,BES Collaboration, Phys.Rev.Lett.97:202002,2006,Dec. 16 2006,2,Budget of Universe,WIMPs (Weakly-Interacting-Massive-P

2、articles) are good dark matter candidates,Dec. 16 2006,3,Evidence of Dark Matter (1),Such a velocity implies that 94% of the mass is located beyond the optical image. A halo exist!,Suns position,Dec. 16 2006,4,Evidence of Dark Matter (2),Post-WMAP: (CMBR anisotropy + large scale structure ) DM 25% o

3、f universe. Analyses of Big Bang nucleosynthesis (BBN) DM largely non baryonic. B. Fields and S. Sarkar, in Review of Particle Physics Neutrinos can contribute only a small fraction: h2 0.0076 95%CL existence of an exotic, neutral, stable particle , with relic density : where the Hubble constant h =

4、 0.7. Dark matter particle should clump due to the gravitational attraction. At our galactic center, their density might be so high that their annihilation into light known particles could lead visible signals. Final state with hard photon: ray travel in straight line and are easy detected,N. Boroda

5、tchenkova et al. hep-ph/0510147, Phys.Rev.Lett. 96 (2006) 141802,Dec. 16 2006,5,Evidence of Dark Matter (2),2006年8月22号SLAC和NASA同时在头版报道 Chandra x射线望远镜与 the Hubble Space Telescope, the Magellan Telescopes, 和 the Very Large Telescope 合作看到暗物质的直接证据。,我们期望在加速器实验上能测量到暗物质的产生迹象。 如: LHC和低能区B工厂, 北京正负电子对撞机等。,Gra

6、vitational mass distribution from gravitational lensing.,Astro-ph/0608407,Dec. 16 2006,6,Dec. 16 2006,7,DAMA NaI 3s region,CDMS 04,CDMS 05,90% CL upper limits,Status of DM Direct Searches,Predictions: Ellis No any detector hits outside of 300 decay core; cos(missing) 0.7 ; 1.005 m(K+K-) 1.035 GeV;,M

7、issing direction,Tag direction,Reconstructed mass,Missing momentum,Dec. 16 2006,21,Looking for / Invisible Decays in J/,Reconstructed mass,Missing momentum,An unbinned extended Maximum Likelihood Fit:,NJ/ ( invisible) = -2.8 1.4 NJ/ ( invisible) = -2.2 3.4,58 M J/,Dec. 16 2006,22,Looking for / Invis

8、ible Decays in J/,Br( cc ) 6.410-4 90% Br( cc ) 1.410-3 90%,B.McElrath PRD 72, 103508 (2005) Br( cc ) 7.410-5 Br(prime cc ) 8.110-7,Dec. 16 2006,23,Study of invisible decays of , , , and in J/ two body decays,The sensitivity at BESIII will be 10-5 -10-6 for , Invisible,10109 (2S) data at BESIIII,Dec

9、. 16 2006,24,Other direct search of U boson,e+ e- e+e- g final states,e+e- g+nothing,Prof. S.H.Zhu is also working on this problem at BEPC energy region,Dec. 16 2006,25,Summary from Bob McElrath Talk at BNM 2006, KEK,Dec. 16 2006,26,Looking for the invisible,Our Universe is full of “Invisibles” Particles get energy from the Dark Field Most mass in the universe is Dark Matter Most Energy in the universe i