Annual modulations from secular variations: not relaxing DAMA?
  In a recent paper [arXiv:2002.00459], Buttazzo et al. show how the annually
modulated rate of the DAMA experiments can be possibly interpreted as an
artefact due to the interplay between a time-dependent background and the
method to account for it. In this work, we compare this hypothesis against the
sinusoidal dark matter signal as proposed by the DAMA collaboration. We produce
in a Bayesian approach a quantitative comparison of how much the experimental
observations are in support of each hypothesis. Our conclusions are that the
odds against the hypothesis of a time varying background being responsible for
the annual modulation are decreased by a Bayes factor larger than 10^8 after
considering the public available data of the DAMA/NaI and DAMA/LIBRA
experiments. In this work we also elaborate on general aspects of the analysis
procedure. Indeed, in order to optimise the background subtraction procedure,
the DAMA collaboration only considers data-taking cycles with a duration of
roughly one year. We argue that any data-taking cycle is informative, and we
propose a procedure to include this effect, as well as the possibility to
include a slowly varying component for the background.
