1. Stability of the Caffarelli–Kohn–Nirenberg inequality: the existence of minimizers.
- Author
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Wei, Juncheng and Wu, Yuanze
- Abstract
In this paper, we consider the following variational problem: inf u ∈ D a 1 , 2 (R N) \ Z ‖ u ‖ D a 1 , 2 (R N) 2 - C a , b , N - 1 ‖ u ‖ L p + 1 (| x | - b (p + 1) , R N) 2 inf v ∈ Z ‖ u - v ‖ D a 1 , 2 (R N) 2 : = c BE ,
where N ≥ 2 , b FS (a) < b < a + 1 , a < 0 , a ≤ b < a + 1 , 0 ≤ a < a c : = N - 2 2 and a + b > 0
with b FS (a) being the Felli–Schneider curve, p = N + 2 (1 + a - b) N - 2 (1 + a - b) , Z = { c τ a c - a W (τ x) ∣ c ∈ R \ { 0 } , τ > 0 }
and up to dilations and scalar multiplications, W(x), which is positive and radially symmetric, is the unique extremal function of the following classical Caffarelli–Kohn–Nirenberg (CKN for short) inequality (∫ R N | x | - b (p + 1) | u | p + 1 d x) 2 p + 1 ≤ C a , b , N ∫ R N | x | - 2 a | ∇ u | 2 d x
with C a , b , N being the optimal constant. It is known in Wei and Wu (Math Ann 384:1509–1546, 2022) that c BE > 0 . In this paper, we prove that the above variational problem has a minimizer for N ≥ 2 under the following two assumptions: (i) a c ∗ ≤ a < a c and a ≤ b < a + 1 , (ii) a < a c ∗ and b FS ∗ (a) ≤ b < a + 1 , where a c ∗ = (1 - N - 1 2 N ) a c and b FS ∗ (a) = (a c - a) N a c - a + (a c - a) 2 + N - 1 + a - a c.
Our results extend that of König (J Eur Math Soc. [Math. AP]) for the Sobolev inequality to the CKN inequality. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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