Normalized solution for Kirchhoff equation with upper critical exponent and mixed Choquard type nonlinearities

Abstract: In this paper, we consider the existence of normalized solution to the following Kirchhoff equation with mixed Choquard type nonlinearities: \begin{equation*} \begin{cases} -\left(a + b \int_{\mathbb{R}^3} |\nabla u|^2 \, dx\right) \Delta u - \lambda u = \mu |u|^{q-2} u + (I_\alpha * |u|^{\alpha + 3}) |u|^{\alpha +1} u, \quad x \in \mathbb{R}^3, \ \int_{\mathbb{R}^3} u^2 \, dx = \rho^2, \end{cases} \end{equation*} where $a,b,\rho >0$, $\alpha \in \left(0, 3\right)$, $\frac{14}{3} < q < 6$ and $\lambda \in \mathbb{R}$ will arise as a Lagrange multiplier. The quantity $\alpha + 3$ here represents the upper critical exponent relevant to the Hardy-Littlewood-Sobolev inequality, and this exponent can be regarded as equivalent to the Sobolev critical exponent $2^*$. We generalize the results by Wang et al.(Discrete and Continuous Dynamical Systems, 2025), which focused on nonlinear Kirchhoff equations with combined nonlinearities when $2< q< \frac{10}{3}$. The primary challenge lies in the necessity for subtle energy estimates under the (L^2)-constraint to achieve compactness recovery. Meanwhile, we need to deal with the difficulties created by the two nonlocal terms appearing in the equation.