  In a comment on our article Time delays in molecular photoionization [1],
Baykusheva & W\"orner reproduce canonical scattering theory, and assert that
our results are inconsistent with this well-established theory [2]. We
absolutely refute this assertion and the spirit of the comment, although we do
agree with Baykusheva & W\"orner that the textbook theory is correct. In a
short response, Response to Comment on "Time delays in molecular
photoionization" [3], we have already provided a clear rebuttal of the comment,
but gave no technical details. In this fuller response we extend those brief
comments in the spirit of completeness and clarity, and provide three clear
rebuttals to Baykusheva & W\"orner based on (1) logical fallacy (category
error), (2) theoretical details of the original article, (3) textural content
of the original article. In particular, rebuttal (1) clearly and trivially
points to the fact that there is no issue here whatsoever, with recourse to
theoretical details barely required to demonstrate this, as outlined in the
short version of our response. Our numerical results are correct and reproduce
known physical phenomena, as discussed in the original article hence, as
careful readers will recognise, the formalism used is canonical scattering
theory, and cannot be anything other. In fact, there is no new fundamental
physics here to dispute whatsoever, and nor was this the raison d'etre of the
original article. Additionally, rebuttal (2) provides the opportunity to
discuss, at length, some of these textbook aspects of photoionization theory,
and we hope this discussion might be of service to new researchers entering
this challenging field.
