Dual meson condensates in the Polyakov-loop enhanced linear sigma model

The extent to which the dual meson condensates obtained in the Polyakov-loop enhanced linear sigma model can indicate deconfining transition is investigated by imposing the twisted boundary conditions. The influence of the improved unquenching effect, the dependence on the glue potential parametrization, and the role of the fermion vacuum contribution are focused on at the mean field level. At zero density, the rapid rise of the dual sigma condensate with T is confirmed, which is more sensitive to the chiral transition than the increase of the Polyakov loop. For finite isospin chemical potential μI>mπ/2, the dual sigma condensate shows abnormal thermal behavior which decreases with T below the melting temperature TI3c of pion superfluidity. In contrast, the dual pion condensate always increases with T, with the maximum slope located at TI3c rather than TPc, as determined by the Polyakov loop. The dual vector meson condensate for μI>mπ/2 is also more sensitive to the chiral restoration when considering the fermion vacuum contribution. The study suggests that the dual condensates calculated in this model are not appropriate indicators of deconfinement due to some limitations and uncertainty.