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Publication 09-CNA-06

Global-in-Time Weak Measure Solutions, Finite-Time Aggregation and Confinement for Nonlocal Interaction Equations

J. A. Carrillo
ICREA and Departament de Matemàtiques
Universitat Autònoma de Barcelona
E-08193 Bellaterra, Spain
carrillo@mat.uab.es

M. DiFrancesco
Sezione di Matematica per L'Ingegneria
Dipartimento di Matematica Pura ed Applicata
Universit`a di L'Aquila
Piazzale E. Pontieri 2
Monteluco di Roio, 67040
L'Aquila, Italy
E-mail: difrance@univaq.it.

A. Figalli
Centre de Math'ematiques Laurent Schwartz
Ecole Polytechnique
UMR 7640, 91128 Palaiseau, France
figalli@math.polytechnique.f

T. Laurent
Department of Mathematics
University of California, Los Angeles
Los Angeles, CA 90095, USA
laurent@math.ucla.edu

D. Slepčev
Department of Mathematical Sciences
Carnegie Mellon University
Pittsburgh, PA 15213, USA
slepcev@math.cmu.edu

Abstract: In this paper, we provide a well-posedness theory for weak measure solutions of the Cauchy problem for a family of nonlocal interaction equations. These equations are continuum models for interacting particle systems with attractive/repulsive pairwise interaction potentials. The main phenomenon of interest is that, even with smooth initial data, the solutions can concentrate mass in finite time. We develop an existence theory that enables one to go beyond the blow-up time in classical norms and allows for solutions to form atomic parts of the measure in finite time. The weak measure solutions are shown to be unique and exist globally in time. Moreover, in the case of sufficiently attractive potentials, we show the finite time total collapse of the solution onto a single point, for compactly supported initial measures. Finally, we give conditions on compensation between the attraction at large distances and local repulsion of the potentials to have global-in-time confined systems for compactly supported initial data. Our approach is based on the theory of gradient flows in the space of probability measures endowed with the Wasserstein metric. In addition to classical tools, we exploit the stability of the flow with respect to the transportation distance to greatly simplify many problems by reducing them to questions about particle approximations.

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