Bayesian Analysis of time dependence of DAMA annual modulation amplitude
  We implement a test of the variability of the per-cycle annual modulation
amplitude in the different phases of the DAMA/LIBRA experiment using Bayesian
model comparison. Using frequentist methods, a previous study (Kelso et al
2018) had demonstrated that the DAMA amplitudes spanning over the DAMA/NaI and
the first phase of the DAMA/LIBRA phases, show a mild preference for
time-dependence in multiple energy bins. With that motivation, we first show
using Bayesian techniques that the aforementioned data analyzed in Kelso et al,
show a moderate preference for exponentially varying amplitudes in the 2-5 and
2-6 keV energy intervals. We then carry out a similar analysis on the latest
modulation amplitudes released by the DAMA collaboration from the first two
phases of the upgraded DAMA/LIBRA experiment. We also analyze the single-hit
residual rates released by the DAMA collaboration to further look for any
possible time-dependency. However, we do not find any evidence for variability
of either of the two datasets by using Bayesian model selection. All our
analysis codes and datasets have been made publicly available.
