Color and baryon number fluctuation of preconfinement system in production process and Tcc structure

We suggest to study the production mechanism and some details of the production properties to probe the structure of the DDπ resonance Tcc recently observed by the LHCb Collaboration. If the resonance is produced as a four-quark state, one can find the corresponding signals via measurements on the production properties which are the same as those of Ξcc, i.e., the similarity of Tcc and Ξcc in the kinematics spectra, in the baryon number enhancement, and in the string effect, etc. The color connection of the preconfinement cluster in which the cc diquark pair hadronize to the Tcc or Ξcc plays the key role for their similarity. Moreover, the production cross section of Tcc in various rapidity regions and the production ratio between Tcc to a different isospin state Tcc′ (if it exists) are also important and clear tests. On the other hand, if Tcc is produced as a hadron molecule, the measurement on the momentum correlation of DD* can be a key judgement, since it determines the production ratio. From the present available information, the calculated cross section with nonrelativistic hadron molecule model is about an order of magnitude lower than the experimental measurement.