Like-Charge Attraction At Short Distances In A Charge-Asymmetric Two-Dimensional Two-Component Plasma: Exact Results

We determine exactly the short-distance effective potential between two 'guest' charges immersed in a two-dimensional two-component charge-asymmetric plasma composed of positively (q (1) = +1) and negatively (q (2) = -1/2) charged point particles. The result is valid over the whole regime of stability, where the Coulombic coupling (dimensionless inverse temperature) beta < 4. At high Coulombic coupling beta > 2, this model features like-charge attraction. Also, there cannot be repulsion between opposite-charges at short-distances, at variance with large-distance interactions.