Cosmological Number Counts under Disformal Transformations
  We investigate whether true physical observables associated with the
measurements of large scale structure in the universe are frame-independent. In
particular, we study if cosmological observables such as the galaxy number
counts and weak lensing observables are invariant under the disformal
transformations. In a previous work, it was shown that this frame-invariance
holds true for the case of conformal transformations. In this work, we find
that although the cosmological number counts remain invariant under the
disformal transformations, convergence and cosmic shear associated with the
weak lensing potential are generally not invariant. Since the lightcone
structure does not remain causal under disformal transformations, photon
geodesics do not remain null anymore, and as a result, weak lensing observables
are indeed affected. We also briefly comment on the disformal invariance of
other cosmological observables.
