  We investigate the heat polarization, a heat analog of the charge
polarization, by using the gauge-covariant Keldysh formalism. In contrast to
the charge-heat analogy naively expected, we find that the heat polarization
does not appear spontaneously, since it consists not only of the heat-transfer
contribution but of the heat-generation contribution, leading to the Mott rule.
Nonetheless, it can be induced by a torsional magnetic field in $(3+1)$-D
topological insulators and superconductors, which is described by the temporal
part of the Nieh-Yan action.
