Dark Energy Survey Year 1 Results: Methodology and Projections for Joint
  Analysis of Galaxy Clustering, Galaxy Lensing, and CMB Lensing Two-point
  Functions
  Optical imaging surveys measure both the galaxy density and the gravitational
lensing-induced shear fields across the sky. Recently, the Dark Energy Survey
(DES) collaboration used a joint fit to two-point correlations between these
observables to place tight constraints on cosmology (DES Collaboration et al.
2017). In this work, we develop the methodology to extend the DES year one
joint probes analysis to include cross-correlations of the optical survey
observables with gravitational lensing of the cosmic microwave background (CMB)
as measured by the South Pole Telescope (SPT) and Planck. Using simulated
analyses, we show how the resulting set of five two-point functions increases
the robustness of the cosmological constraints to systematic errors in galaxy
lensing shear calibration. Additionally, we show that contamination of the
SPT+Planck CMB lensing map by the thermal Sunyaev-Zel'dovich effect is a
potentially large source of systematic error for two-point function analyses,
but show that it can be reduced to acceptable levels in our analysis by masking
clusters of galaxies and imposing angular scale cuts on the two-point
functions. The methodology developed here will be applied to the analysis of
data from the DES, the SPT, and Planck in a companion work.
