  Structure and production of doubly charmed tetraquarks T_cc (cc ubar dbar)
are studied from the viewpoint of color configurations. Based on the diquark
correlation, the tetraquark T_cc with I(JP)=0(1+) is considered to be stable
against strong decay. We discuss that the mixing probability of color
antitriplet and sextet cc components in T_cc is suppressed by 1/m_c^2, so the
two configurations are separately realized in the heavy quark limit. Utilizing
the nonrelativistic QCD framework, we evaluate the production cross sections of
T_cc in electron-positron collisions. The momentum dependence of the cross
section of color antitriplet is found to be different from that of sextet,
which can be used to discriminate the color structure of the T_cc states in
experimental measurements.
