The Zeldovich approximation and wide-angle redshift-space distortions
  The contribution of line-of-sight peculiar velocities to the observed
redshift of objects breaks the translational symmetry of the underlying theory,
modifying the predicted 2-point functions. These `wide angle effects' have
mostly been studied using linear perturbation theory in the context of the
multipoles of the correlation function and power spectrum. In this work we
present the first calculation of wide angle terms in the Zeldovich
approximation, which is known to be more accurate than linear theory on scales
probed by the next generation of galaxy surveys. We present the exact result
for dark matter and perturbatively biased tracers as well as the small angle
expansion of the configuration- and Fourier-space two-point functions and the
connection to the multi-frequency angular power spectrum. We compare different
definitions of the line-of-sight direction and discuss how to translate between
them. We show that wide angle terms can reach tens of percent of the total
signal in a measurement at low redshift in some approximations, and that a
generic feature of wide angle effects is to slightly shift the Baryon Acoustic
Oscillation scale.
