Sharp regularity properties for the non-cutoff spatially homogeneous Boltzmann equation

TL;DR

This paper demonstrates that solutions to the non-cutoff spatially homogeneous Boltzmann equation with Maxwellian molecules exhibit Gelfand-Shilov regularity, with smoothing effects matching a fractional harmonic oscillator and optimal decay rates.

Contribution

It establishes sharp Gelfand-Shilov regularity and decay properties for the non-cutoff Boltzmann equation, introducing a spectral decomposition method for solution construction.

Findings

Solutions have Gelfand-Shilov regularity with sharp fractional power.

Solutions exhibit optimal exponential decay.

Spectral decomposition is effective for nonlinear Boltzmann equations.

Abstract

In this work, we study the Cauchy problem for the spatially homogeneous non-cutoff Boltzamnn equation with Maxwellian molecules. We prove that this Cauchy problem enjoys Gelfand-Shilov regularizing effect, that means the smoothing properties is same as the Cauchy problem defined by the evolution equation associated to a fractional harmonic oscillator. The power of this fractional is exactly the singular index of non-cutoff collisional kernel of Boltzmann operator. So that we get the regularity of solution in the Gevery class with the sharp power and the optimal exponential decay of solutions. We also give a method to construct the solution of the nonlinear Boltzmann equation by solving an infinite ``triangular'' systems of ordinary differential equations.The key tools is the spectral decomposition of linear and non-linear Boltzmann operators.