QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector $D$ mesons and derive the corresponding Weinberg-type sum rules. This allows for the identification of such QCD condensates which drive the nondegeneracy of chiral partners in the lowest order of the strong coupling ${\alpha }_s$ and which, therefore, may serve as “order parameters” for chiral restoration (or elements thereof).

• Received 1 August 2011

DOI:https://doi.org/10.1103/PhysRevC.84.045202