IOWA STATE UNIV,DEPT PHYS & ASTRON,AMES,IA 50011
; ACAD SINICA,INST HIGH ENERGY PHYS,BEIJING,PEOPLES R CHINA
We examine the experimental observability of the decay mode t --> cg at the Fermilab Tevatron via the flavor-changing neutral current vertex t(c) over barg$. We find that with the existing data, one should be able to probe the t(c) over barg$ coupling to a value smaller than indirect limits previously obtained from b --> s gamma and the measured branching fraction for t --> bW, reaching BF(t --> cg) similar to 15%-28%. A data sample of 1 fb(-1) (10 fb(-1)) at root s = 2 TeV may probe the t --> cg branching fraction to a level of 2% (0.5%).