Different coalescence sources of light nucleus production in Au-Au collisions at GeV

We study the production of light nuclei in the coalescence mechanism of Au-Au collisions at midrapidity at GeV. We derive analytic formulas of the momentum distributions of two bodies, three bodies, and four nucleons coalescing into light nuclei and naturally explain the transverse momentum spectra of the deuteron ( d ), triton ( t ), helium-3 ( 3 He), and helium-4 ( 4 He). We reproduce data on the yield rapidity densities, yield ratios, and averaged transverse momenta of d , t , 3 He, and 4 He and provide the proportions of contributions from different coalescence sources for t , 3 He, and 4 He in their production. We find that besides nucleon coalescence, nucleon+nucleus coalescence and nucleus+nucleus coalescence may play requisite roles in light nucleus production in Au-Au collisions at GeV.