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Paper IPM / Physic / 12587  


Abstract:  
Polarizable randomly charged dielectric objects have been recently shown to exhibit longrange lateral and normal interaction forces even when they are effectively netneutral. These forces stem from an interplay between the quenched statistics of random charges and the induced dielectric image charges. This type of interaction has recently been evoked to interpret measurements of Casimir forces in vacuo, where a precise analysis of such disorderinduced effects appears to be necessary. Here we consider the torque acting on a randomly charged dielectric surface (or a sphere) mounted on a central axle next to another randomly charged surface and show that although the resultant mean torque is zero, its sampletosample fluctuation exhibits a longrange behavior with the separation distance between the juxtaposed surfaces and that, in particular, its rootmeansquare value scales with the total area of the surfaces. Therefore, the disorderinduced torque between two randomly charged surfaces is expected to be much more pronounced than the disorderinduced lateral force and may provide an effective way to determine possible disorder effects in experiments, in a manner that is independent of the usual normal force measurement.
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