We study the coupled Choquard type system with lower critical exponents \t\t\t{−Δu+λ1(x)u=μ1(Iα∗|u|N+αN)|u|αN−1u+β(Iα∗|v|N+αN)|u|αN−1u,x∈RN,−Δv+λ2(x)v=μ2(Iα∗|v|N+αN)|v|αN−1v+β(Iα∗|u|N+αN)|v|αN−1v,x∈RN,u,v∈H1(RN),\\documentclass[12pt]{minimal}\t\t\t\t\\usepackage{amsmath}\t\t\t\t\\usepackage{wasysym}\t\t\t\t\\usepackage{amsfonts}\t\t\t\t\\usepackage{amssymb}\t\t\t\t\\usepackage{amsbsy}\t\t\t\t\\usepackage{mathrsfs}\t\t\t\t\\usepackage{upgreek}\t\t\t\t\\setlength{\\oddsidemargin}{-69pt}\t\t\t\t\\begin{document}$$ \\textstyle\\begin{cases} -\\Delta u+\\lambda _{1}(x)u=\\mu _{1}(I_{\\alpha }* \\vert u \\vert ^{ \\frac{N+\\alpha }{N}}) \\vert u \\vert ^{\\frac{\\alpha }{N}-1}u+\\beta (I_{\\alpha }* \\vert v \\vert ^{ \\frac{N+\\alpha }{N}}) \\vert u \\vert ^{\\frac{\\alpha }{N}-1}u,\\quad x\\in {\\mathbb{R}}^{N}, \\\\ -\\Delta v+\\lambda _{2}(x)v=\\mu _{2}(I_{\\alpha }* \\vert v \\vert ^{ \\frac{N+\\alpha }{N}}) \\vert v \\vert ^{\\frac{\\alpha }{N}-1}v+\\beta (I_{\\alpha }* \\vert u \\vert ^{ \\frac{N+\\alpha }{N}}) \\vert v \\vert ^{\\frac{\\alpha }{N}-1}v,\\quad x\\in {\\mathbb{R}}^{N}, \\\\ u, v\\in H^{1}({\\mathbb{R}}^{N}), \\end{cases} $$\\end{document} where Nge 3, mu _{1}, mu _{2}, beta >0, and lambda _{1}(x), lambda _{2}(x) are nonnegative functions. The existence of at least one positive ground state of this system is proved under certain assumptions on lambda _{1}, lambda _{2}.
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