Multiplicity of the doubly charmed state Tcc+ in heavy-ion collisions

We study the evolution of the doubly charmed state T-cc(+) in a hot hadron gas produced in the late stage of heavy-ion collisions. We use effective Lagrangians to calculate the thermally averaged cross sections of T-cc(+) production in reactions such as D-(*D-)(()*()) -> T-cc(+)pi, T-cc(+)rho and its absorption in the corresponding inverse processes. We then solve the rate equation to follow the time evolution of the T-cc(+) multiplicity and determine how it is affected by the considered reactions during the expansion of the hadronic matter. We compare the evolution of the T-cc(+) abundance treated as a hadronic S-wave molecule and as a tetraquark state. Our results show that the tetraquark yield increases by a factor of about 2 at freeze-out, but it is still almost 2 orders of magnitude smaller than the final yield of molecules formed from hadron coalescence. We also analyze the dependence of the yields with the system size, represented by N = [dA(ch)/d(eta)(eta <0.5)](1/3). We make predictions that can be confronted with data, when they are available.

Automated summary

We studied the evolution and influence of the doubly charmed state T-cc(+) in a hot hadron gas produced in late-stage heavy-ion collisions, comparing its yield as a hadronic S-wave molecule and as a tetraquark state. Our results show an increase in the tetraquark yield, but it is still much smaller than the yield of molecules formed from hadron coalescence.