Fluctuations of the front in a one-dimensional model for the spread of an infection
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Jean Bérard [1] ; Alejandro Ramírez [2]
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[1] University of Strasbourg
University of Strasbourg
Arrondissement de Strasbourg-Ville, Francia
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[2] Pontificia Universidad Católica de Chile
Pontificia Universidad Católica de Chile
Santiago, Chile
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- Localización: Annals of probability: An official journal of the Institute of Mathematical Statistics, ISSN 0091-1798, Vol. 44, Nº. 4, 2016, págs. 2770-2816
- Idioma: inglés
- DOI: 10.1214/15-AOP1034
- Enlaces
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Resumen
We study the following microscopic model of infection or epidemic reaction: red and blue particles perform independent nearest-neighbor continuous-time symmetric random walks on the integer lattice ZZ with jump rates DRDR for red particles and DBDB for blue particles, the interaction rule being that blue particles turn red upon contact with a red particle. The initial condition consists of i.i.d. Poisson particle numbers at each site, with particles at the left of the origin being red, while particles at the right of the origin are blue. We are interested in the dynamics of the front, defined as the rightmost position of a red particle. For the case DR=DBDR=DB, Kesten and Sidoravicius established that the front moves ballistically, and more precisely that it satisfies a law of large numbers. Their proof is based on a multi-scale renormalization technique, combined with approximate sub-additivity arguments. In this paper, we build a renewal structure for the front propagation process, and as a corollary we obtain a central limit theorem for the front when DR=DBDR=DB. Moreover, this result can be extended to the case where DR>DBDR>DB, up to modifying the dynamics so that blue particles turn red upon contact with a site that has previously been occupied by a red particle. Our approach extends the renewal structure approach developed by Comets, Quastel and Ramírez for the so-called frog model, which corresponds to the DB=0DB=0 case.
