44,649 research outputs found

    Equilibrium fluctuation theorems compatible with anomalous response

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    Previously, we have derived a generalization of the canonical fluctuation relation between heat capacity and energy fluctuations C=β2<δU2>C=\beta^{2}<\delta U^{2}>, which is able to describe the existence of macrostates with negative heat capacities C<0C<0. In this work, we extend our previous results for an equilibrium situation with several control parameters to account for the existence of states with anomalous values in other response functions. Our analysis leads to the derivation of three different equilibrium fluctuation theorems: the \textit{fundamental and the complementary fluctuation theorems}, which represent the generalization of two fluctuation identities already obtained in previous works, and the \textit{associated fluctuation theorem}, a result that has no counterpart in the framework of Boltzmann-Gibbs distributions. These results are applied to study the anomalous susceptibility of a ferromagnetic system, in particular, the case of 2D Ising model.Comment: Extended version of the paper published in JSTA

    Investigations of electron emission characteristics of low work function surfaces Quarterly report no. 5, 1 Oct. - 31 Dec. 1965

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    Electron emission characteristics of low work function surfaces from magnetic deflection probe measurements of cesium adsorption on tungste

    Investigations of electron emission characteristics of low work function surfaces Quarterly report, 28 Sep. - 27 Dec. 1966

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    Coadsorption of cesium and fluorine on tungsten, and analysis of mechanisms leading to decay of field emission current from low work function zirconium/oxygen coated tungsten emitte

    Bell's theorem as a signature of nonlocality: a classical counterexample

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    For a system composed of two particles Bell's theorem asserts that averages of physical quantities determined from local variables must conform to a family of inequalities. In this work we show that a classical model containing a local probabilistic interaction in the measurement process can lead to a violation of the Bell inequalities. We first introduce two-particle phase-space distributions in classical mechanics constructed to be the analogs of quantum mechanical angular momentum eigenstates. These distributions are then employed in four schemes characterized by different types of detectors measuring the angular momenta. When the model includes an interaction between the detector and the measured particle leading to ensemble dependencies, the relevant Bell inequalities are violated if total angular momentum is required to be conserved. The violation is explained by identifying assumptions made in the derivation of Bell's theorem that are not fulfilled by the model. These assumptions will be argued to be too restrictive to see in the violation of the Bell inequalities a faithful signature of nonlocality.Comment: Extended manuscript. Significant change

    Geometrical aspects and connections of the energy-temperature fluctuation relation

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    Recently, we have derived a generalization of the known canonical fluctuation relation kBC=β2k_{B}C=\beta^{2} between heat capacity CC and energy fluctuations, which can account for the existence of macrostates with negative heat capacities C<0C<0. In this work, we presented a panoramic overview of direct implications and connections of this fluctuation theorem with other developments of statistical mechanics, such as the extension of canonical Monte Carlo methods, the geometric formulations of fluctuation theory and the relevance of a geometric extension of the Gibbs canonical ensemble that has been recently proposed in the literature.Comment: Version accepted for publication in J. Phys. A: Math and The
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