Electronic Journal of Differential Equations, Vol. 2025 (2025), No. 93, pp. 1–13. ISSN: 1072-6691. URL: https://ejde.math.txstate.edu, https://ejde.math.unt.edu DOI: 10.58997/ejde.2025.93 MIXED LOCAL AND NONLOCAL CRITICAL SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS WITH LOGARITHMIC PERTURBATION SHENGBING DENG, GUORONG ZENG Abstract. In this article, we consider the mixed local and nonlocal critical Schrödinger-Kirchhoff- Poisson type system with logarithmic perturbation −M( ∫ Ω |∇u|2 dx)∆u+ a(−∆)su+ λϕu = η|u|q−2u ln |u|2 + |u|4u, in Ω, −∆ϕ = u2, in Ω, ϕ = u = 0, in R3 \ Ω. where Ω ⊂ R3 is a bounded domain with smooth boundary, 0 < s < 1, 4 < q < 6, λ, η > 0 are two parameters, M(t) = a+ bt and a, b are nonnegative constants. With the help of variational methods, the existence of a non-trivial ground state solution is obtained. 1. Introduction and statement of main result In this article, we consider the mixed local and nonlocal critical Schrödinger-Kirchhoff-Poisson type system with logarithmic perturbation −M (∫ Ω |∇u|2 dx ) ∆u+ a(−∆)su+ λϕu = η|u|q−2u ln |u|2 + |u|4u, in Ω, −∆ϕ = u2, in Ω, ϕ = u = 0, in R3 \ Ω. (1.1) where Ω ⊂ R3 is a bounded domain with smooth boundary ∂Ω, 0 < s < 1, 4 < q < 6, λ, η > 0 are two parameters, M(t) = a+ bt and a, b are nonnegative constants. When a = 1 and b = 0, problem (1.1) reduces to the boundary value problem −∆u+ (−∆)su+ λϕu = f(x, u), in Ω, −∆ϕ = u2, in Ω, ϕ = u = 0, in RN \ Ω. (1.2) We emphasize that operators of the form −∆ + (−∆)s are referred to as mixed operators, com- bining both local and nonlocal characteristics as well as different orders of differentiation, and this operators, derived from the superposition of the classical Laplacian −∆ and the fractional Laplacian (−∆)s for a fixed parameter s ∈ (0, 1) which, up to a normalization constant, is defined by (−∆)su(x) = lim ϵ→0+ ∫ RN\Bϵ(x) u(x) − u(y) |x− y|N+2s dy. 2020 Mathematics Subject Classification. 35M12, 35R11, 35A15, 35B33. Key words and phrases. Ground state solution; mixed local-nonlocal operators; logarithmic nonlinearity; Schrödinger-Kirchhoff-Poisson system. ©2025. This work is licensed under a CC BY 4.0 license. Submitted August 8, 2025. Published October 6, 2025. 1 2 S. DENG, G. ZENG EJDE-2025/93 As we know, the operators from the superposition of two stochastic processes with different scales, such as a classical random walk and a Lévy flight. Furthermore, the investigation of mixed operators is a very topical subject of investigation, arising naturally in several fields. For more information, one can see [13, 22, 23] and the references therein. The mixed operators have attracted the attention of many mathematicians. From the viewpoint of mathematics, there is a lack of scale invariances, which may produce unexpected complexity. More specifically, Lin et al. [19] concerned the mixed local and nonlocal Poisson system −∆pu+ (−∆)spu+ λV (x)|u|p−2u+ ϕu = α|u|p(x)−2u+ β|u|q(x)−2u, in Ω, −∆ϕ = up, in Ω, ϕ = u = 0, in RN \ Ω. here N ≥ p, Ω ⊂ RN is a bounded domain, V (x) is a potential function, p(x), q(x) are variable exponents. They investigated the multiplicity of solutions for λ > 0 and the concentration and multiplicity of solutions for λ → ∞. Biagi et al. [7] showed the mixed Sobolev inequality and investigated the optimal constant. In [4, 6, 8, 25], the authors proved strong maximum principle, regularity theory, eigenvalues theory and existence results. In (1.2), if s = 1, then system (1.2) is reduced to the classical Laplace Schrödinger-Poisson system, which has been widely studied. It is widely known that the existence of solutions for system (1.2) can be studied using variational methods, provided that appropriate assumptions are made. For instance, one can see [1, 3, 2, 17, 21, 24] and the references therein. Then, considering solely the first equation in (1.1) with the potential set to zero, we obtain the problem −(a+ b ∫ Ω u2 dx)∆u+ a(−∆)su = f(x, u), in Ω, u = 0, in RN \ Ω. (1.3) which was proposed by Kirchhoff (see [11]) as a generalization of well-know D’Alembert wave equation ∂2u ∂t2 − (P0 h + E 2L ∫ L 0 |∂u ∂x |dx )∂2u ∂x2 = 0. For mixed operators involving the Kirchhoff function, only Wang et al. [31] considered equation (1.3) with f(x, u) = ( ∫ Ω |u(y)|p |x−y|µ dy ) |u|p−2u+ λ|u|q−2u, 1 < q < 2 < 2p, 0 < µ < N , employing the non-smooth variational principle to prove the existence of solutions. For s = 1, i.e. the system reduces to the Laplace operator with Kirchhoff function, which has been extensively investigated by many researchers using variational methods, see [14, 20, 28, 18]. Moreover, some studies of Schrödinger-Kirchhoff-Poisson type system with the Laplace operator can be referred to [26, 30] and the references therein. In recent years, equations with logarithmic nonlinearity have attracted increasing interest, mainly due to their wide application in modeling various phenomena in the physical sciences. The main challenge presented by logarithmic nonlinearity arises from its characteristic of sign change, which means it does not conform to the standard of monotonicity, nor does it follow the Ambrosetti-Rabinowitz conditions. Therefore, studying problems involving logarithmic nonlinear- ity presents a challenge. In the past few years, a significant amount of research work has focused on this area. For example, Deng et al. [12] considered the equation −∆u = λu+ µu lnu2 + |u|2 ∗−2u, in Ω, u = 0, in ∂Ω, where 2∗ := 2N N−2 is the critical Sobolev exponent. By using Mountain Pass Lemma they showed that the problem admits at least one nontrivial weak solution under some appropriate assumptions EJDE-2025/93 SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS 3 on λ and µ. Li et al. [18] studied the critical Kirchhoff problems with logarithmic nonlinearity, −(a+ b ∫ Ω |∇u|2 dx)∆u = λ|u|q−2u ln |u|2 + |u|4u in Ω, u = 0, in ∂Ω, (1.4) where Ω ⊂ R3 is a bounded domain with smooth boundary ∂Ω, 4 < q < 6, λ > 0 is a parameter, a ≥ 0, b > 0 and they investigated the existence of a solution. Additionally, many fascinating studies have been performed on problems involving logarithmic nonlinearity. Among the wide range of such studies, we refer readers interested to [27, 32, 33] and the related references for further exploration. Motivated by the results mentioned above, the aim of this paper is to consider the existence of nontrivial ground state solution for problem (1.1). Under some natural assumptions, by using the concentration-compactness principle and the mountain pass theorem, we obtain the existence result of nontrivial ground state solution. To the best of our knowledge, there is little literature which essentially attacks the Brezis-Nirenberg problem for mixed local and nonlocal operators critical Schrödinger-Kirchhoff-Poisson type system with logarithmic nonlinearity. Now, we are ready to state the main result of this paper. Theorem 1.1. Assume that a > 0. If q ∈ (4, 6), then problem (1.1) has at least one nontrivial ground state solution provided that either (1) s ≤ 1 2 and λ, η > 0, or (2) s > 1 2 , λ ∈ (0, λ∗) and η > η∗. Corollary 1.2. Assume that a = 0. If q ∈ (4, 6), then problem (1.1) reduces to the Laplace degenerate Schrödinger-Kirchhoff-Poisson type system, which admits at least one nontrivial ground state solution for all λ, η > 0. Corollary 1.3. Assume that b = 0. If q ∈ (4, 6), then problem (1.1) reduces to the critical Schrödinger-Poisson type system, which admits at least one nontrivial ground state solution pro- vided that either (1) s ≤ 1/2 and λ, η > 0, or (2) s > 1/2, λ ∈ (0, λ̂∗) and η > η̂∗. To prove Theorem 1.1, which is the critical case, we face a complication due to the non- compactness of the embedding of X0(Ω) ↪→ L6(Ω), the standard variational techniques do not ap- ply in a straightforward way. The lack of compactness of this problem is expressed by the fact that the functional does not satisfy the Palais-Smale condition in all the energy range (−∞,+∞). To surmount this challenge, we attempt to recover compactness through the concentration-compactness principle. Moreover, there is a Kirchhoff term in (1.1), which will affect the functional satisfies the Palais-Smale condition in some range. The rest of this article is organized as follows. In Section 2, we introduce the functional setting of (1.1) and some necessary definitions and preliminary lemmas are given. In Section 3, we prove Theorem 1.1. 2. Preliminaries and variational setting We denote by | · |p the usual Lp-norm. Let s ∈ (0, 1), the fractional Sobolev space is Hs(Ω) = { u ∈ L2(Ω) : ∫ R3 ∫ R3 |u(x) − u(y)|2 |x− y|3+2s dx dy < +∞ } , which is endowed with the semi-norm [u]s := (∫ R3 ∫ R3 |u(x) − u(y)|2 |x− y|2s+3 dx dy )1/2 which is called the Gagliardo seminorm of u. The Sobolev space H1(Ω) is defined as the Banach space of weakly differentiable functions u : Ω → R equipped with the following norm ∥u∥2H1(Ω) = |u|22 + |∇u|22. 4 S. DENG, G. ZENG EJDE-2025/93 The space H1(R3) is defined similarly. We define the homogeneous Sobolev space H1 0 (Ω) as the completion of the space C∞ 0 (Ω) under the norm ∥u∥ = |∇u|2. However, to address the boundary condition specified in equation (1.1), it becomes necessary to extend our consideration to functions that are defined over the entire space R3. For this, H1 0 (Ω) is not enough and we consider the functional space X0(Ω) = { u ∈ H1(R3) : u|Ω ∈ H1 0 (Ω) and u = 0 a.e. in R3 \ Ω } endowed with the norm ∥u∥X0 = ( |∇u|22 + [u]2s )1/2 . It is well known that X0(Ω) is a real separable and uniformly convex space. Also, we have the following relation between the gradient seminorm and the Gagliardo norm. Lemma 2.1 ([9, Lemma 2.1]). Let Ω ⊂ R3 be bounded domain, there exists a constant C = C(s) ≥ 1, such that [u]s ≤ C∥u∥H1(Ω), ∀u ∈ H1(Ω). Lemma 2.2 ([10, Proposition 2.2]). Under the same hypothesis of Lemma 2.1, there exists a constant C = C(s,Ω) ≥ 1, such that∫ R3 ∫ R3 |u(x) − u(y)|2 |x− y|3+2s dx dy ≤ C ∫ Ω |∇u|2 dx, ∀u ∈ H1 0 (Ω) From Lemmas 2.1 and 2.2, it is easy to know that norms ∥u∥ and ∥u∥X0 are equivalent, when u ∈ X0(Ω). Since Ω is a bounded domain, we have H1 0 (Ω) ↪→ Lp(Ω) continuously for p ∈ [1, 6] and compactly for p ∈ [1, 6). Naturally, we define Sn as the best Sobolev constant for the embedding H1 0 (Ω) ↪→ L6(Ω), then Sn = inf u∈H1 0 (R3)\{0} ∫ R3 |∇u|2 dx ( ∫ R3 |u|6 dx)1/3 . Because the norms ∥u∥ and ∥u∥X0 are equivalent, we can obtain X0(Ω) ↪→ Lp(Ω) continuously for p ∈ [1, 6] and compactly for p ∈ [1, 6). Moreover, we have the following result. Lemma 2.3 ([7, Theorem 1.1]). Let Sn,s as the best Sobolev constant for the embedding X0(Ω) ↪→ L6(Ω). Then Sn,s(Ω) = inf u∈X0(Ω)\{0} ∥u∥2X0 |u|26 = Sn. Definition 2.4. We say that u ∈ X1 0 (Ω) is a weak solution of problem (1.1), if a ∫ Ω ∇u · ∇v + b∥u∥2 ∫ Ω ∇u · ∇v + a ∫ R3 ∫ R3 (u(x) − u(y))(v(x) − v(y)) |x− y|3+2s dx dy + λ ∫ Ω ϕuv dx = η ∫ Ω |u|q−2uv ln |u|2 dx+ ∫ Ω |u|4uv dx (2.1) for all v ∈ X1 0 (Ω). The following result is well known. Lemma 2.5 (see [1, 21]). For each u ∈ X0(Ω), there exists a unique element ϕu ∈ X0(Ω) such that −∆ϕu = u2, moreover, ϕu has the following properties: (a) there exists c > 0 such that ∥ϕu∥ ≤ c∥u∥2 and∫ Ω |∇ϕu|2 dx = ∫ Ω ϕuu 2 dx ≤ c∥u∥4; (2.2) (b) ϕu ≥ 0 and ϕtu = t2ϕu, ∀t > 0; EJDE-2025/93 SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS 5 (c) if un ⇀ u in X0(Ω), then ϕun ⇀ ϕu in X0(Ω) and lim n→+∞ ∫ Ω ϕun u2n dx = ∫ Ω ϕuu 2 dx. (2.3) By the above lemma, (u, ϕ) ∈ X0(Ω) ×H1 0 (Ω) is a solution of (1.1) if and only if ϕ = ϕu and u ∈ X0(Ω) is a solution of the problem −M (∫ Ω |∇u|2 dx ) ∆u+ a(−∆)su+ λϕuu = η|u|q−2u ln |u|2 + |u|4u, in Ω, u = 0, in R3 \ Ω. We define the energy functional associated with problem (1.1) by I(u) = a 2 ∥u∥2X0 + b 4 ∥u∥4 + λ 4 ∫ Ω ϕu2 dx+ 2η q2 |u|qq − η q ∫ Ω |u|q ln |u|2 dx− 1 6 |u|66. (2.4) Since 4 < q < 6, it is easy to prove that the functional I(u) is well defined and is a C1 functional in X0(Ω). Naturally, u is a weak solution to problem (1.1) if and only if u is a critical point of I. 3. Proof of main result Firstly, we prove that I(u) possesses a kind of mountain-pass geometrical structure. Theorem 3.1 (see [29]). Let X be a real Banach space and J ∈ C1(X;R) with J(0) = 0. Suppose that (i) there exist ρ, α > 0 such that J(u) ≥ α for all u ∈ X, with∥u∥X = ρ; (ii) there exists e ∈ X satisfying ∥e∥X > ρ such that J(e) < 0. Define Γ = {γ ∈ C1 ( [0, 1];X ) : γ(0) = 1, γ(1) = e}. Then c = inf γ∈Γ max 0≤t≤1 J(γ(t)) ≥ α and there exists a (PS)c sequence (un)n ⊆ X. To use Theorem 3.1, we show that the functional E satisfies the mountain pass geometry (i) and (ii). Lemma 3.2. The functional I has a mountain pass geometry shown as: (i) there exist α, ρ > 0 such that I(u) ≥ α for ∥u∥X0 = ρ; (ii) there exists ω ∈W 1,p 0 (Ω) such that I(ω) < 0. Proof. Using the well-know vector inequality |tq ln t| ≤ 1 eq , ∀t ∈ (0, 1), tq ln t ≤ 1 eδ tq+δ, ∀t ≥ 1, (3.1) where δ > 0 is chosen to satisfy q + δ < 6, we obtain |u|q ln |u|2 ≤ 2 eq + 2 eδ |u| q+δ. By applying (3.1) with q + δ < 6 and using the Sobolev embedding inequality, one has I(u) = a 2 ∥u∥2X0 + b 4 ∥u∥4 + λ 4 ∫ Ω ϕuu 2 dx+ 2η q2 |u|qq − η q ∫ Ω |u|q ln |u|2 dx− 1 6 |u|66 ≥ a 2 ∥u∥2X0 − η q ∫ Ω |u|q ln |u|2 dx− 1 6 |u|66 ≥ a 2 ∥u∥2X0 − C∥u∥q+δ X0 − 1 6 S−3 n ∥u∥6X0 = ∥u∥2X0 ( a 2 − C∥u∥q+δ−2 X0 − 1 6 S−3 n ∥u∥4X0 ). Then there exist positive constants α, ρ such that I(u) ≤ α, for all ∥u∥X0 = ρ. From this, (i) is proved. 6 S. DENG, G. ZENG EJDE-2025/93 To prove (ii), we fix v ∈W 1,p 0 (Ω) \ {0} and t > 0. According to (2.2), we have I(tv) = at2 2 ∥v∥2X0 + bt4 4 ∥v∥4 + λt4 4 ∫ Ω ϕvv 2 dx+ 2ηtq q2 |v|qq − ηtq q ∫ Ω |v|q ln |tv|2 dx− t6 6 |v|66 ≤ at2 2 ∥v∥2X0 + bt4 4 ∥v∥4 + λt4 4 c∥u∥4 + 2ηtq q2 |u|qq − t6 6 |v|66, From q < 6, we deduce that there exists t1 > 0 large enough such that ∥t1v∥X0 > ρ and I(t1v) < 0. Taking ω = t1v, (ii) also holds. □ As the functional I(u) does not meet the (PS)c condition for every value of c, we will restrict c to a range where the (PS)c condition holds true. The primary method employed for this is the concentration-compactness principle of Lions (see [15, 16]). Lemma 3.3. Let {un} ⊂ X0(Ω) be a Palais-Smale sequence for I(u) at the level c with c < c(A), where c(A) := a 2A+ b 4A 2 − 1 6 A3 S3 n with A = bS3 n+ √ b2S6 n+4aS3 n 2 , that is I(un) → c and I ′(un) → 0 as n → ∞. Then there exist a subsequence of {un} and a u ∈ X0(Ω) such that un → u in X0(Ω) as n→ ∞. Proof. First, we claim that {un} is bounded. From I(un) → c and I ′(un) → 0 as n → ∞, we obtain, for n large enough, that c+ 1 + o(1)∥un∥ ≥ I(un) − 1 q ⟨I ′(un), un⟩ = ( 1 2 − 1 q )a∥un∥2X0 + ( 1 4 − 1 q )(b∥un∥4 + λ ∫ Ω ϕun u2n dx) + 2η q2 |un|qq + ( 1 q − 1 6 )|un|66 ≥ ( 1 2 − 1 q )a∥u∥2 + ( 1 4 − 1 q )b∥un∥4, according to the assumption that a+ b > 0 and 4 < q < 6, which implies that {un} is bounded in X0(Ω). If ∥un∥ → 0 as n→ ∞, the proof is complete. Thus, we assume that ∥un∥ ̸→ 0 as n→ ∞, up to a subsequence, we may assume that un ⇀ u weakly in X0(Ω), un → u strongly in Lp(Ω)(1 ≤ p < 6), un → u a.e. in Ω, |∇un|2 ⇀ µ and |un|6 ⇀ ν, where µ and ν are a nonnegative bounded measures on Ω. Then, by concentration compactness principle, there exists some at most countable index set J such that ν = |u|6 + ∑ j∈J νjδxj , νj > 0, (3.2) µ ≥ |∇u|2 + ∑ j∈J µjδxj , µj > 0, (3.3) Snν 1/3 j ≤ µj , (3.4) where δxj is the Dirac measure mass at xj ∈ Ω. Take ψ(x) ∈ C∞ 0 (Ω) such that 0 ≤ ψ ≤ 1, ψ(x) = { 1, if x ∈ B(xj , ρ) 0, if x ∈ Ω \B(xj , 2ρ) and |∇ψ|∞ ≤ 2. EJDE-2025/93 SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS 7 For ρ > 0, we define ψj ρ = ψ( x−xj ρ ), where j ∈ J . Since I ′(un) → 0 and (ψj ρun)n is bounded, ⟨I ′(un), ψj ρun⟩ → 0 as n→ ∞, that is, (a+ b∥u∥2) ∫ Ω |∇un|2ψj ρ dx+ a ∫ R3 ∫ R3 |un(x) − un(y)|2ψj ρ |x− y|3+2s dx dy + λ ∫ Ω ϕun u2nψ j ρ dx = −(a+ b∥u∥2) ∫ Ω un∇un∇ψj ρ dx−G2(un, ψ j ρun) + η ∫ Ω |un|qψj ρ ln |un|2 dx+ ∫ Ω |un|6ψj ρ dx+ on(1), (3.5) where G2(un, ψ j ρun) = a ∫ R3 ∫ R3 (un(x) − un(y))un(x)(ψj ρ(x) − ψj ρ(y)) |x− y|3+2s dx dy. It is easy to prove that lim ρ→0 lim n→∞ ∫ R3 ∫ R3 |un(x) − un(y)|2ψj ρ |x− y|3+2s dx dy > 0. (3.6) By (2.3), we have lim ρ→0 lim n→∞ ∫ Ω ϕunu 2 nψ j ρ dx = lim ρ→0 ∫ B(xj ,2ρ) ϕuu 2ψj ρ dx = 0. (3.7) Note that the Hölder inequality implies |G2(un, ψ j ρun)| ≤ ∫ R3 ∫ R3 |un(x) − un(y)||un(x)||ψj ρ(x) − ψj ρ(y)| |x− y|3+2s dx dy ≤ (∫ R3 ∫ R3 |un(x) − un(y)|2 |x− y|3+2s dx dy )1/2(∫ R3 ∫ R3 |un(x)|2|ψj ρ(x) − ψj ρ(y)|2 |x− y|3+2s dx dy )1/2 ≤ C (∫ R3 ∫ R3 |un(x)|2|ψj ρ(x) − ψj ρ(y)|2 |x− y|3+2s )1/2 . With the same argument as in the proof of [34, Lemma 3.4], we have lim ρ→0 lim n→∞ ∫ R3 ∫ R3 |un(x)|2|ψj ρ(x) − ψj ρ(y)|2 |x− y|3+2s = 0. (3.8) It follows that limρ→0 limn→∞ |G2(un, ψ j ρun)| = 0. Using the Hölder inequality again, we have lim n→∞ ∫ Ω un∇un∇ψj ρ dx ≤ lim n→∞ C (∫ Ω |un∇ψj ρ|2 dx )1/2 ≤ C (∫ B(xj ,2ρ) |u|2|∇ψj ρ|2 dx )1/2 . (3.9) so we can get limρ→0 limn→∞ ∫ Ω un∇un∇ψj ρ dx = 0. On the other hand, since un → u a.e. in Ω as n→ ∞, we obtain ψj ρ|un|q ln |un|2 → ψj ρ|u|q ln |u|2, a.e. in Ω as n→ ∞, (3.10) With the help of (3.1), (3.10) and Lebesgue’s dominated convergence theorem, we obtain lim n→∞ ∫ Ω ψj ρ|un|q ln |un|2 dx = ∫ Ω ψj ρ|u|q ln |u|2 dx, which then guarantees that lim ρ→0 lim n→∞ ∫ Ω ψj ρ|un|q ln |un|2 dx = lim ρ→0 ∫ B(xj ,2ρ) ψj ρ|u|q ln |u|2 dx = 0. (3.11) 8 S. DENG, G. ZENG EJDE-2025/93 Since ψj ρ has compact support, letting n → ∞, ρ → 0 in (3.5), we deduce from (3.3), (3.6)-(3.9) and (3.11) that (a+ bµj)µj ≤ νj . (3.12) Next, we prove that µj = νj = 0. Otherwise, combining (3.12) with (3.4), we have µ2 j − bS3 nµj − aS3 n ≥ 0 and Sn(ν 1/3 j )2 − bS3 nν 1/3 j − aS2 n ≥ 0, which yields µj ≥ A, νj ≥ A3 S3 n , (3.13) where A := bS3 n+ √ b2S6 n+4aS3 n 2 satisfying A2 − bS3 nA − aS3 n = 0. Then, from I(un) → c and I ′(un) → 0 as n → ∞, letting n → ∞, ρ → 0 on both sides of the above inequality and in view of (3.13), we have c = I(un) − 1 q ⟨I ′(un), un⟩ + o(1) = ( 1 2 − 1 q )a∥un∥2X0 + ( 1 4 − 1 q )(b∥un∥4 + λ ∫ Ω ϕun u2n dx) + 2η q2 |un|qq + ( 1 q − 1 6 )|un|66 + o(1) ≥ ( 1 2 − 1 q )a∥un∥2 + ( 1 4 − 1 q )b∥un∥4 + ( 1 q − 1 6 )|un|66 + o(1) ≥ ( 1 2 − 1 q )aµj + ( 1 4 − 1 q )bµ2 j + ( 1 q − 1 6 )νj ≥ ( 1 2 − 1 q )aA+ ( 1 4 − 1 q )bA2 + ( 1 q − 1 6 ) A3 S3 n = a 2 A+ b 4 A2 − 1 6 A3 S3 n , where we use that fact in the above equality that A2 − bS3 nA − aS3 n = 0. This contradicts the assumption that c < c(A). Thus, µj = νj = 0 and we obtain lim n→∞ ∫ Ω |un|6 dx = ∫ Ω |u|6 dx. (3.14) Now, we are ready to show that {un} converges strongly to u in X0(Ω) as n → ∞. Let us write vn = un − u, hence, by the Brezis-Lieb Lemma, we have ∥un∥2 = ∥vn∥2 + ∥u∥2 + o(1), ∥un∥4 = ∥vn∥4 + ∥u∥4 + 2∥vn∥2∥u∥2 + o(1), [un]2s = [vn]2s + [u]2s + o(1), (3.15) by (2.3) and (3.11), we obtain ∫ Ω ϕunu 2 n dx = ∫ Ω ϕuu 2 dx+ o(1),∫ Ω |un|q ln |un|2 dx = ∫ Ω |u|q ln |u|2 dx+ o(1). (3.16) If vn = un − u and [vn]s ≤ ∥vn∥ → 0, the proof is complete. Otherwise there exists a subse- quence (still denoted by vn) such that limn→∞[vn]s = l, limn→∞ ∥vn∥ = k, where l, k are positive constants. Thus, from (3.15), (3.16) and I ′(un) → 0, it follows that o(1) = ⟨I ′(un), u⟩ = a∥u∥2X0 + b∥un∥2∥u∥2 + λ ∫ Ω ϕuu 2 dx− η ∫ Ω |u|q ln |u|2 dx− ∫ Ω |u|6 dx+ o(1) = a∥u∥2X0 + bk2∥u∥2 + b∥u∥4 + λ ∫ Ω ϕuu 2 dx− η ∫ Ω |u|q ln |u|2 dx− ∫ Ω |u|6 dx+ o(1). (3.17) EJDE-2025/93 SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS 9 By (3.14), (3.15), (3.17) and recalling that {un} is bounded in H1 0 (Ω), we obtain o(1) = ⟨I ′(un), un⟩ = a∥un∥2X0 + b∥un∥4 + λ ∫ Ω ϕuu 2 dx− η ∫ Ω |u|q ln |u|2 dx− ∫ Ω |u|6 dx = a∥u∥2X0 + a∥vn∥2X0 + b∥u∥4 + b∥vn∥4 + 2b∥vn∥2∥u∥2 + λ ∫ Ω ϕuu 2 dx− η ∫ Ω |u|q ln |u|2 dx− ∫ Ω |u|6 dx+ o(1) = ⟨I ′(un), u⟩ + a∥vn∥2X0 + b∥vn∥4 + b∥vn∥2∥u∥2 + o(1) = ak2 + al2 + bk4 + bk2∥u∥2 + o(1), which implies that k = l = 0, so un converges strongly to u in X0(Ω). The proof is complete. □ According to above Lemmas, we know that there exists a sequence {un}n ∈ X0(Ω) such that I(un) → c and I ′(un) → 0, where c = inf γ∈Γ max 0≤t≤1 I(γ(t)) with Γ = {γ ∈ C1 ( [0, 1];X ) : γ(0) = 1, γ(1) = e}. To better align with our aim, as illustrated in reference [29], we can employ the following equivalent definition of c, which is provided by c = inf u∈N I(u) = inf u∈X0(Ω)\{0} max t≥0 I(tu), where the Nehari manifold N associated to I is defined by N = {u ∈ X0(Ω) \ {0} : ⟨I ′(u), u⟩ = 0}. Fixed u ∈ X0(Ω) and define the function of the form Ju : t → I(tu) for t > 0, such map is famous in bifurcation theory. And the maps are closely related to the Nehari manifold defined by N = {u ∈ X0(Ω) : J ′ u(1) = 0}. We split N into three parts: N+ = {u ∈ N : J ′′ u (1) > 0}, N− = {u ∈ N : J ′′ u (1) < 0}, N 0 = {u ∈ N : J ′′ u (1) = 0}. which corresponds to local minima, local maxima and points of inflexion of the fibering maps. It is well known that each nontrival solution to problem (1.1) belongs to N . Furthermore, we have the following lemma. Lemma 3.4. N = N− Proof. For each fixed u ∈ N , we have J ′ u(1) = a∥u∥2X0 + b∥u∥4 + λ ∫ Ω ϕuu 2 dx− η ∫ Ω |u|q ln |u|2 dx− |u|66, and J ′′ u (1) = a∥u∥2X0 + 3b∥u∥4 + 3λ ∫ Ω ϕuu 2 dx− 2η|u|qq − (q − 1)η ∫ Ω |u|q ln |u|2 dx− 5|u|66 = − [ (q − 2)a∥u∥2X0 + (q − 4)b∥u∥4 + (q − 4)λ ∫ Ω ϕuu 2 dx+ 2η|u|qq + (6 − q)|u|66 < 0, which holds because λ, η > 0 and 4 < q < 6. Hence, u ∈ N− and the proof is complete. □ Remark 3.5. Since any critical point of I belongs to N−, if u is a critical point of I, it must be a ground state solution to problem (1.1). 10 S. DENG, G. ZENG EJDE-2025/93 Lemma 3.6. Assume that a > 0. If 4 < q < 6, then there exists a u∗ ∈ X0(Ω) such that sup t≥0 I(tu∗) < c(A), (3.18) where c(A) is the positive constant given in Lemma 3.3 Proof. Let U(x) = 31/4 (1+|x|2)1/2 . Then we know from [5] that U is a minimizer of Sn. Assume that Bδ ⊂ Ω ⊂ B2δ and let ω ∈ C∞ 0 (Ω) be such that 0 ≤ ω ≤ 1, ω(x) = 1 in Bδ and ω(x) = 0 in R3 \Ω. For ϵ > 0 we define Uϵ(x) := ϵ−1/2U( x ϵ ) and uϵ := ω(x)Uϵ(x). Then from [18], we know that as ϵ→ 0, ∥uϵ∥2 = S3/2 n +O(ϵ), (3.19) |uϵ|66 = S3/2 n +O(ϵ3), (3.20) |uϵ|qq =  O(ϵq/2), 1 ≤ q < 3, O(ϵq/2| ln ϵ|), q = 3, O(ϵ3− q 2 ), 3 < q < 6, (3.21) [uϵ] = O(ϵ2−2s), (3.22) and ∫ Ω |uϵ|q ln |uϵ|2 dx = Cϵ3− q 2 ln C ϵ +O(ϵ3− q 2 ) +O(ϵq/2 ln ϵ). (3.23) Now we consider the following two cases: Case 1. s ≤ 1 2 Given the definitions of the functions I(u) and Ju(t), it is evident that limt→0 Juϵ (t) = 0 and limt→∞ Juϵ (t) = −∞. This behavior is consistent across all ϵ values in the interval (0, ϵ0), where ϵ0 is a positive number that is sufficiently small but fixed. Thus, there exist 0 < t1 < t2 < +∞, independent of ϵ, such that I(tuϵ) < c(A), ∀t ∈ (0, t1] ∪ [t2,+∞). For t ∈ [t1, t2], we have I(tuϵ) = a 2 t2∥uϵ∥2X0 + b 4 t4∥uϵ∥4 + λ 4 t4 ∫ Ω ϕuϵ u2ϵ dx+ 2ηtq q2 |uϵ|qq − ηtq q ∫ Ω |uϵ|q ln |tuϵ|2 dx− t6 6 |uϵ|66 ≤ a 2 t2∥uϵ∥2X0 + b 4 t4∥uϵ∥4 + λ 4 t4|ϕϵ|6|uϵ|212 5 + 2η q2 tq|uϵ|qq − η q tq ∫ Ω |uϵ|q ln |tuϵ|2 dx− 1 6 t6|uϵ|66 ≤ max t∈[t1,t2] g(t) + λ 4 t4|ϕϵ|6|uϵ|212 5 + 2η q2 tq|uϵ|qq − η q tq ∫ Ω |uϵ|q ln |tuϵ|2 dx ≤ max t>0 g(t) + C1|ϕϵ|6|uϵ|212 5 + C2|uϵ|qq − C3 ∫ Ω |uϵ|q ln |uϵ|2 dx, (3.24) where g(t) := a 2 t2∥uϵ∥2X0 + b 4 t4∥uϵ∥4 − 1 6 t6|uϵ|66. Since limt→0 g(t) = 0 and limt→+∞ g(t) = −∞, so there exists a unique tϵ > 0 such that maxt>0 g(t) = g(tϵ) and g′(tϵ) = tϵ(a∥uϵ∥2X0 + bt2ϵ∥uϵ∥4 − t4ϵ |uϵ|66) = 0, where t2ϵ = b∥uϵ∥4 + √ b2∥uϵ∥8 + 4a∥uϵ∥2X0 |uϵ|66 2|uϵ|66 . EJDE-2025/93 SCHRÖDINGER-KIRCHHOFF-POISSON TYPE SYSTEMS 11 Using the estimates in (3.19)-(3.22), combining 1 < 2 − 2s, we have ∥uϵ∥X0 = ∥uϵ∥ as ϵ → 0. Hence, one sees that as ϵ→ 0, t2ϵ∥uϵ∥2X0 = b∥uϵ∥6 + √ b2∥uϵ∥12 + 4a∥uϵ∥6X0 |uϵ|66 2|uϵ|66 = bS3 n + √ b2S6 n + 4aS3 n 2 +O(ϵ) = A+O(ϵ), (3.25) and t6ϵ |uϵ|66 = (b∥uϵ∥4 + √ b2∥uϵ∥8 + 4a∥uϵ∥2X0 |uϵ|66 2|uϵ|46 )3 = (bS2 n + √ b2S4 n + 4aSn 2 +O(ϵ) )3 = A3 S3 n +O(ϵ). (3.26) It follows from (3.25), (3.26) and the definition of g(t) that max t>0 g(t) = g(tϵ) = c(A) +O(ϵ), as ϵ→ 0. (3.27) From (3.21), (3.23), (3.24) and (3.27), we have that I(tuϵ) ≤ c(A) +O(ϵ) +O(ϵ) +O(ϵ3− q 2 ) − Cϵ3− q 2 ln C ϵ +O(ϵq/2 ln ϵ), as ϵ→ 0, (3.28) for t ∈ [t1, t2]. Since 4 < q < 6, we see that 3 − q 2 < 1 < q 2 , together with lim ϵ→0 ϵ3− q 2 ϵ3− q 2 ln C ϵ = 0 shows that O(ϵ) +O(ϵ) +O(ϵ3− q 2 ) − Cϵ3− q 2 ln C ϵ +O(ϵq/2 ln ϵ) < 0 (3.29) for suitably small ϵ. Fix such an ϵ > 0. It then follows from (3.28) and (3.29) that I(tuϵ) < c(A), ∀t ∈ [t1, t2]. Case 2. s > 1/2 Since limt→0 Juϵ (t) = 0 and limt→∞ Juϵ (t) = −∞, so there exists tη verifying I(tηuϵ) = maxt≥0 I(tuϵ). Hence at2η∥uϵ∥2X0 + bt4η∥uϵ∥4 + λt4η ∫ Ω ϕuϵu 2 ϵ dx− η ∫ Ω tqη|uϵ|q ln |tηuϵ|2 dx− t6η|uϵ|66 = 0, so we have at2η∥uϵ∥2X0 + bt4η∥uϵ∥4 + λt4η ∫ Ω ϕuϵ u2ϵ dx+ ∣∣∣η ∫ Ω tqη|uϵ|q ln |tηuϵ|2 dx ∣∣∣ ≥ t6η|uϵ|66, which implies that tη is bounded. We claim that tη → 0, as η → ∞. (3.30) Arguing by contradiction, we can assume that there exists t0 > 0 and a sequence ηn with ηn → ∞ such that tηn → 0 as n→ ∞. Consequently, there is M > 0 such that at2ηn ∥uϵ∥2X0 + bt4ηn ∥uϵ∥4 + λt4ηn ∫ Ω ϕuϵu 2 ϵ dx ≤M as n→ ∞, for λ <∞ and so ηn ∫ Ω tqηn |uϵ|q ln |tηnuϵ|2 dx− t6ηn |uϵ|66 = ∞ as n→ ∞, 12 S. DENG, G. ZENG EJDE-2025/93 which is absurd. Indeed, by combining (3.24) with (3.30), we have 0 ≤ max t≥0 I(tuϵ) = I(tηuϵ) → 0 as η → ∞, and this readily implies the existence of η∗ > 0 such that max t≥0 I(tuϵ) < c(A), for all η > η∗ provided that ϵ > 0 is small enough but fixed. Taking u∗ = uϵ, we see that (3.18) is valid. The proof is complete. □ Proof of Theorem 1.1. 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Shengbing Deng (corresponding author) School of Mathematics and Statistics, Southwest University, Chongqing 400715, China Email address: shbdeng@swu.edu.cn Guorong Zeng School of Mathematics and Statistics, Southwest University, Chongqing 400715, China Email address: grzengmath@163.com 1. Introduction and statement of main result 2. Preliminaries and variational setting 3. Proof of main result Acknowledgements References