  In the Eliashberg integral equations for d-wave superconductivity, two
different functions $(\alpha^2 F)_n(\omega, \theta)$ and $(\alpha^2
F)_{p,d}(\omega)$ determine, respectively, the "normal" and the "pairing"
self-energies. We present a quantitative analysis of the high-resolution laser
based ARPES data on the compound Bi-2212 to deduce the function$(\alpha^2
F)_n(\omega, \theta)$. Besides its detailed $\omega$ dependence, we find the
remarkable result that this function is nearly independent of $\theta$ between
the ($\pi,\pi$)-direction and 25 degrees from it. Assuming that the same
fluctuations determine both the normal and the pairing self-energy, we ask what
theories give the function $(\alpha^2 F)_{p,d}(\omega)$ required for the d-wave
pairing instability at high temperatures as well as the deduced $(\alpha^2
F)_n(\theta, \omega)$. We show that the deduced $(\alpha^2 F)_n(\theta,
\omega)$ can only be obtained from Antiferromagnetic (AFM) fluctuations if
their correlation length is smaller than a lattice constant. Using $(\alpha^2
F)_{p,d}(\omega)$ consistent with such a correlation length and the symmetry of
matrix-elements scattering fermions off AFM fluctuations, we calculate $T_c$ an
show that AFM fluctuations are excluded as the pairing mechanism for d-wave
superconductivity in cuprates. We also consider the quantum-critical
fluctuations derived microscopically as the fluctuations of the observed
loop-current order discovered in the under-doped cuprates. We show that their
frequency dependence and the momentum dependence of their matrix-elements to
scatter fermions are consistent with the $\theta$ and $\omega$ dependence of
the deduced $(\alpha^2 F)_n(\omega, \theta)$. The pairing kernel $(\alpha^2
F)_{p,d}(\omega)$ calculated using the experimental values in the Eliashberg
equation gives $d-wave$ instability at $T_c$ comparable to the experiments.
