Abstract:
We study the two-parametric $(k,a)$-generalized Fourier transform $\mathcal{F}_{k,a}$, $k,a>0$, on the line. For $a\neq 2$ it has deformation properties and, in particular, for a function $f$ from the Schwartz space $\mathcal{S}(\mathbb{R})$, $\mathcal{F}_{k,a}(f)$ may be not infinitely differentiable or rapidly decreasing at infinity. It is proved that the invariant set for the generalized Fourier transform $\mathcal{F}_{k,a}$ and differential-difference operator $|x|^{2-a}\Delta_kf(x)$, where $\Delta_k$ is the Dunkl Laplacian, is the class $$ \mathcal{S}_{a}(\mathbb{R})=\{f(x)=F_1(|x|^{a/2})+xF_2(|x|^{a/2})\colon F_1,F_2\in\mathcal{S}(\mathbb{R}),\,\, F_1,F_2 - \text{are even}\}.$$ For $a=1/r$, $r\in\mathbb{N}$, we consider two generalized translation operators $\tau^{y}$ and $T^y=(\tau^{y}+\tau^ {-y})/2$. Simple integral representations are proposed for them, which make it possible to prove their $L^{p}$-boundedness as $1\le p\le\infty$ for $\lambda=r(2k-1)>-1/2$. For $\lambda\ge 0$ the generalized translation operator $T^y$ is positive and its norm is equal to one. Two convolutions are defined and Young's theorem is proved for them. For generalized means defined using convolutions, a sufficient $L^{p}$-convergence condition is established. The generalized analogues of the Gauss–Weierstrass, Poisson, and Bochner–Riesz means are studied.
This work was carried out within the framework of the state assignment of the Ministry of Education of the Russian Federation, agreement no. 073-03-2023-303/2 dated 02.14.23, the topic of scientific research is “Number-theoretic methods in approximate analysis and their applications in mechanics and physics”.