Physical condition for the slowing down of cosmic acceleration
  The possible slowing down of cosmic acceleration was widely studied. However,
the imposition of dark energy parametrization brought some tensions. In our
recent paper, we test this possibility using a model-independent method,
Gaussian processes. However, the reason of generating these tensions is still
closed. In the present paper, we analyse the derivative of deceleration
parameter to solve the problems. The reconstruction of the derivative again
suggests that no slowing down of acceleration is presented within 95\% C.L.
from current observational data. We then deduce its constraint on dark energy.
The corresponding constraint clearly reveals the reason of tension between
different models in previous work. We also study the essential reason of why
current data cannot convincingly measure the slowing down of acceleration. The
constraints indicate that most of current data are not in the allowed region.
