Exact TT[over ¯] Deformation of Two-Dimensional Maxwell Theory

We study the partition function of TT[over ¯]-deformed two-dimensional Maxwell theory by solving the relevant flow equation at the level of individual flux sectors. Summing exactly the "instanton" series, we obtain a well-defined expression for the partition function at arbitrary μ. For μ>0, the spectrum of the theory experiences a truncation and the theory undergoes infinite-order quantum phase transitions associated with the vanishing of Polyakov-loop correlators. For μ<0, the appearance of nonperturbative contributions in μ drastically modifies the structure of the partition function.

Particles with nonlinear electric response: Suppressing van der Waals forces by an external field

We study the classical thermal component of Casimir, or van der Waals, forces between point particles with highly anharmonic dipole Hamiltonians when they are subjected to an external electric field. Using a model for which the individual dipole moments saturate in a strong field (a model that mimics the charges in a neutral, perfectly conducting sphere), we find that the resulting Casimir force depends strongly on the strength of the field, as demonstrated by analytical results. For a certain angle between the external field and center-to-center axis, the fluctuation force can be tuned and suppressed to arbitrarily small values. We compare the forces between these particles with those between particles with harmonic Hamiltonians and also provide a simple formula for asymptotically large external fields, which we expect to be generally valid for the case of saturating dipole moments.