Before revision:  Specifically, we show how the physics of DNA supercoiling leads, in bacteria, to the quantitative modeling of binding properties of ParB proteins around their centromere-like site, parS. We predict ParB clusters to be leaky, which actually hinders the precise measurementof \sigma. We propose avenues to circumvent this problem and present analyses demonstrating consistency between chromosomal and plasmid data {\it  {\it   .
After revision:  Specifically, we show how the physics of DNA supercoiling leads, in bacteria, to the quantitative modeling of binding properties of ParB proteins around their centromere-like site, {\it {\it .