  The conjecture made recently by the group at Sherbrooke, that their observed
anomalous thermal Hall effect in the pseudo-gap phase in the cuprates is due to
phonons, is supported on the basis of an earlier result that the observed
loop-current order in this phase must induce lattice distortions which are
linear in the order parameter and an applied magnetic field. The lowered
symmetry of the crystal depends on the direction of the field. A consequence is
that the elastic constants change proportional to the field and are shown to
induce axial thermal transport with the same symmetries as the Lorentz force
enforces for the normal electronic Hall effect. Direct measurements of elastic
constants in a magnetic field are suggested to verify the quantitative aspects
of the results.
