\(L^ p\) regularity of velocity averages. (English) Zbl 0763.35014

DiPerna, R. J.; Lions, P. L.; Meyer, Y.

Ann. Inst. Henri Poincaré, Anal. Non Linéaire 8, No. 3-4, 271-287 (1991).

The paper is concerned with the regularity of velocity averages for solutions of transport equations: \[ v.\nabla_ xf=g\quad\text{for } x\in\mathbb{R}^ N,\quad v\in\mathbb{R}^ N,\quad\text{or} \tag{1} \]
\[ \partial f/\partial t+v.\nabla_ xf=g\quad\text{for } x\in\mathbb{R}^ N,\quad v\in\mathbb{R}^ N,\quad t\in\mathbb{R}. \tag{2} \] In the time-independent case (equation (1)), the authors prove that, if \(f\in L^ p(\mathbb{R}^ N\times\mathbb{R}^ N)\) and \(g\in L^ p(\mathbb{R}^ N\times\mathbb{R}^ N)\), \(1<p\leq 2\), then for every \(\psi\in D(\mathbb{R}^ N)\), the velocity average \(\bar f(x)=\int_{\mathbb{R}^ N}f(x,v)\psi(v)dv\) belongs to the Besov space \(B_ 2^{s,p}(\mathbb{R}^ N)\) where \(s=1/p'\).
In the time dependent case (equation (2)), they prove similar results when \(g\) admits the following decomposition: \(g=(I-\Delta_ x)^{\tau/2}(I-\Delta_ v)^{m/2}G\), \(\;\tau\in[0,1)\), \(\;m\geq 0\), \(\;G\in L^ p(\mathbb{R}^ N\times\mathbb{R}^ N\times\mathbb{R})\).
Some applications to Vlasov-Maxwell systems and to other models are also given. These results extend many previous results [see for example F. Golse, P. L. Lions, B. Perthame, R. Sentis, J. Funct. Anal. 76, No. 1, 110-125 (1988; Zbl 0652.47031)].

Reviewer: J.-P.Raymond (Toulouse)

MSC:

35B65	Smoothness and regularity of solutions to PDEs
35F05	Linear first-order PDEs
35Q40	PDEs in connection with quantum mechanics
42B25	Maximal functions, Littlewood-Paley theory
42B30	\(H^p\)-spaces
46E35	Sobolev spaces and other spaces of “smooth” functions, embedding theorems, trace theorems
42B15	Multipliers for harmonic analysis in several variables
82B40	Kinetic theory of gases in equilibrium statistical mechanics
42B20	Singular and oscillatory integrals (Calderón-Zygmund, etc.)

Keywords:

Littlewood-Paley type decompositions; interpolating arguments; spectral decomposition; Sobolev; Besov spaces; \(L(\sup p)\)-multipliers; transport equations; time-independent case; time dependent case; Vlasov-Maxwell systems

Citations:

Zbl 0652.47031

References:

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