Tensor susceptibilities of the vacuum from constituent quarks
  We show that the constituent quark model leads to simple expressions for the isoscalar and isovector tensor susceptibilities of the vacuum. The found values are negative and of magnitude compatible with QCD-sum-rule parameterizations of spectral densities in appropriate L=1-meson channels. 
Wojciech Broniowski, Maxim Polyakov, Hyun-Chul Kim, and Klaus Goeke