title: Definition of temperature in dense granular media.
abstract: In this paper we report the measurement of a pseudotemperature for compacting granular media on the basis of the fluctuation-dissipation relations in the aging dynamics of a model system. From the violation of the fluctuation-dissipation theorem emerges an effective temperature (a dynamical temperature T(dyn)) whose value depends on the particle density. We compare the results for T(dyn) at several densities with the values of Edwards' compactivity at the corresponding densities [S. F. Edwards, in Granular Matter: An Interdisciplinary Approach, edited by A. Mehta (Springer-Verlag, New York, 1994) and references therein]. It turns out that the dynamical temperature and Edwards' compactivity coincide on a large range of densities, opening in this way the door to experimental checks as well as theoretical constructions.
authors.affiliation: Università degli Studi di Roma La Sapienza, Dipartimento di Fisica, Piazzale Aldo Moro 5, 00185 Rome, Italy.
authors.forename: Vittoria
authors.initials: V
authors.lastname: Colizza
authors.forename: Alain
authors.initials: A
authors.lastname: Barrat
authors.forename: Vittorio
authors.initials: V
authors.lastname: Loreto
mesh_terms: D000465:Algorithms; D055592:Biophysical Phenomena; D001703:Biophysics; D004058:Diffusion; D015233:Models, Statistical; D008962:Models, Theoretical; D013696:Temperature