Excursion set peaks: a self-consistent model of dark halo abundances and
  clustering
  We describe how to extend the excursion set peaks framework so that its
predictions of dark halo abundances and clustering can be compared directly
with simulations. These extensions include: a halo mass definition which uses
the TopHat filter in real space; the mean dependence of the critical density
for collapse delta_c on halo mass m; and the scatter around this mean value.
All three of these are motivated by the physics of triaxial rather than
spherical collapse. A comparison of the resulting mass function with N-body
results shows that, if one uses delta_c(m) and its scatter as determined from
simulations, then all three are necessary ingredients for obtaining ~10%
accuracy. E.g., assuming a constant value of delta_c with no scatter, as
motivated by the physics of spherical collapse, leads to many more massive
halos than seen in simulations. The same model is also in excellent agreement
with N-body results for the linear halo bias, especially at the high mass end
where the traditional peak-background split argument applied to the mass
function fit is known to underpredict the measured bias by ~10%. In the
excursion set language, our model is about walks centered on special positions
(peaks) in the initial conditions -- we discuss what it implies for the usual
calculation in which all walks contribute to the statistics.
