CCAST, World Lab, Beijing 100080, Peoples R China
; Nankai Univ, Dept Phys, Tianjin 300071, Peoples R China
; Tianjin Univ, Dept Appl Phys, Tianjin 300072, Peoples R China
; Univ Adelaide, Dept Phys & Math Phys, Adelaide, SA 5005, Australia
; Univ Adelaide, Special Res Ctr Subatom Struct Matter, Adelaide, SA 5005, Australia
; Inst High Energy Phys, Beijing 100039, Peoples R China
The two heavy quarks in a baryon which contains two heavy quarks and a light one can constitute a scalar or axial vector diquark. We study the electromagnetic radiation of such baryons: (i) Xi ((bc)1)--> Xi ((bc)0) + gamma, (ii) Xi ((bc)1)*--> Xi ((bc)0) + gamma (iii) Xi ((bc)0)**(1/2,l)--> Xi ((bc)0) + gamma, (iv) Xi ((bc)0)**(3/2,l=1)--> Xi ((bc)0) + gamma, and (v) Xi (bc)0**(3/2,l= 2)--> Xi ((bc)0) + gamma, where Xi ((bc)0(1)),Xi ((bc)1)* are S-wave bound states of a heavy scalar or axial vector diquark and a light quark, and Xi ((bc)0)**(l greater than or equal to1) are P- Or D-wave bound states of a heavy scalar diquark and a light quark. The analysis indicates that these professes can be attributed to two categories and the physical mechanisms which are responsible for them are completely distinct. Measurements can provide good judgment for the diquark structure and a better understanding of the physical picture.