  The three-dimensional galaxy power spectrum is a powerful probe of primordial
non-Gaussianity and additional general relativistic effects, which become
important on large scales. At the same time, wide-angle (WA) effects due to
differing lines-of-sight (LOS) on the curved sky also become important with
large angular separation. In this work, we accurately model WA and Doppler
effects using the spherical Fourier-Bessel (SFB) formalism, before transforming
the result into the commonly used power spectrum multipoles (PSM). This mapping
from the SFB power spectrum to PSM represents a new way to non-perturbatively
model WA and GR effects present in the PSM, which we validate with log-normal
mocks. Moreover, for the first time, we can compute the analytical PSM Gaussian
covariance on large scales, exactly including WA-induced mode-couplings,
without resorting to any plane-parallel approximations.
